What Are the Active Ingredients in Passionflower Extract Powder?

Passionflower (Passiflora) is a genus of herbaceous or woody perennial vines belonging to the Passifloraceae family, native to South America and primarily distributed in tropical and subtropical regions [1]. Its fruits are nutrient-rich and are often consumed fresh or processed into juice. There are six popular edible passionflower varieties worldwide.

In some tropical major production areas, such as Europe and the Americas, purple-skinned passion fruit, winged-stem passion fruit, yellow-fruited passion fruit, large-fruited passion fruit, and blue passion fruit (P. caerulea L.) are traditional medicinal plants used for diuretic, cough-suppressing, anti-inflammatory, analgesic, blood pressure-lowering, sedative, anticonvulsant, and anti-addictive purposes [2-4]. Currently, various extracts of passion fruit are approved for medicinal use in the pharmacopoeias of countries such as the United States, Brazil, and the United Kingdom [5].

China introduced purple-skinned passion fruit in 1901 [6], and there are now multiple cultivated varieties in regions such as Guangxi Province, Yunnan Province, Fujian Province, and Chongqing Municipality. Local residents have discovered that passion fruit has detoxifying, skin-nourishing, anti-inflammatory, and anti-aging effects [7].

Phenolic compounds are an important class of plant secondary metabolites, with approximately 8,000 species identified in nature [9]. Modern research has shown that passion fruit extract powder contains phenolic compounds, alkaloids, triterpenoids, and other chemical components, with phenolic compounds being its characteristic secondary metabolites [10]. These compounds exhibit beneficial physiological effects such as antioxidant, anti-inflammatory, antibacterial, and blood sugar-lowering properties [9,11].

Previous studies on Passiflora species have primarily focused on purple-skinned passion fruit and its component analysis, with no comprehensive review or summary of phenolic compound research in edible Passiflora plants to date. Therefore, this study systematically reviews the content, types, chemical structural characteristics, and activities of phenolic compounds in edible passion fruit, aiming to identify natural sources of phenolic compounds for further development and promote scientific research and rational development of the edible passion fruit industry in China.

1 Phenolic content in edible passion fruit

Passion fruit plants have been reported as excellent natural sources of phenolic compounds, with total phenolic content typically exceeding 1,000 μg GAE/g. However, the total phenolic content in edible passion fruit varies significantly due to factors such as variety, maturity stage, and extraction site. Carmona-Hernandez et al. [12] used kaempferol as the standard reference and determined the total phenolic content in purple-skinned passion fruit pulp to be 1.62 ± 0.09 mg GAE/g (dry weight), while the total polyphenol content in sweet passion fruit pulp was 1.55 ± 0.00 mg GAE/g (dry weight), and in yellow passion fruit pulp, it was 1.18 ± 0.01 mg GAE/g (dry weight). Other researchers used the Flavin method to determine the total phenolic content of yellow passion fruit, finding that the total phenolic content in the fruit pulp increased continuously during maturation, from 281.8 ± 7.2 mg GAE/L (fresh weight) to 361.9 ± 3.3 mg GAE/L [13].

There are limited data on the content of specific phenolic compounds in Passiflora species. The main compounds reported include isoorientin (14), which was found in the peel of purple-skinned passion fruit at a concentration of 0.653 ± 0.037 mg/g (dry weight, unless otherwise specified) [14], and 0.580 ± 0.004 mg/g in yellow passion fruit. Orientin (15) was found in purple passion fruit peel and yellow passion fruit leaves at concentrations of 0.370 ± 0.011 and 0.260 ± 0.004 mg/g, respectively [15]. Isovitexin (36) was found in the fruit pulp of yellow-fruited passion fruit at a concentration of 0.424 mg/g [16]. Quercetin (4) was found in the fruit pulp of yellow-fruited passion fruit at a concentration of 2.21 ± 0.32 mg/100 g. Kampferol (5) was found in yellow passion fruit pulp at a concentration of 1.78 ± 0.06 mg/100 g [17]. The above research data demonstrate that edible passion fruit contains abundant phenolic compounds, but their concentrations vary, and their chemical structures also differ. The following sections will provide a detailed discussion of these findings.

2 Types and chemical structures of phenolic compounds in edible passion fruit

A total of 104 compounds have been reported in edible passion fruit (Tables 2 and 3). Based on the natural compound parent nucleus structure, they can be classified into flavonoids and phenolic acids. Among them, flavonoids are further subdivided into flavonoids, flavonols, dihydroflavonoids, flavanols, and anthocyanins. In nature, flavonoids are predominantly found in the form of glycosides [18], where flavonoids are linked to sugar substituents via C-O or C-C bonds, forming flavonoid glycosides or carbon glycosides. Among these, oxosides are the most common type of glycosides in plant secondary metabolites [19], but flavonoid carbon glycosides have also been found in significant amounts in edible passion fruit.

2.1 Flavonoids and Their Glycosides

The chemical structural characteristics of flavonoids are based on a 2-phenylchromenone core with no oxygen substituents at the 3-position. The main flavonoid aglycones in edible passion fruit plants include luteolin (luteolin, 1), apigenin (apigenin, 2), and chrysin (chrysin, 3) (see Figure 1), and 54 flavonoid glycosides containing these aglycones have been identified.

2.1.1 Luteolin

Flavonoid glycosides with luteolin (1) as the aglycone have been reported in purple-skinned passion fruit, yellow-fruited passion fruit, banana passion fruit, winged-stem passion fruit, large-fruited passion fruit, and P. edulis f. edulis. including 16 flavonoid carbon glycosides (10–25) (Table 2), 5 flavonoid oxygen glycosides (26–30), and 5 mixed glycosides containing both C–C and C–O bonds (31–35) [20–22]. The characteristic features of the glycosidic bonds in these glycoside compounds are as follows: the C-C bonds of the carbon glycosides are primarily attached to the 6th and 8th positions of the luteolin A ring, the C-O bonds of the oxygen glycosides are primarily attached to the 7th position of the A ring, while the mixed glycosides are connected to the sugar substituents via C-C and C-O bonds at different carbon positions.

Isocentroside (14) and centroside (15) are flavonoid glycosides with luteolin as the aglycone in passionflower, both with the molecular formula C₂₁H₂₀O₁₁ (Figure 2a), and are characteristic compounds of the Passiflora genus [23]. and have been reported in various edible Passiflora species. In 2009, Zou et al. [24] reported the isolation of isocentroside and centroside from the peel and leaves of purple-skinned passion fruit from multiple origins, but the content of isocentroside was higher than that of centroside in samples from the same origin.

Gomes et al. [15] studied 17 passion fruit leaf samples, extracted flavonoids, and found that the leaves of yellow passion fruit and P. edulis f. edulis contained higher levels of isoquercitrin and quercitrin, while the leaves of winged passion fruit contained lower levels of these two compounds. while only passiflorin was detected in the leaves of large-fruited passionflower. In the same year, Wosch et al. [25] identified the components in 12 species of passionflower leaves, the results showed that isorhamnetin was only isolated from the leaves of winged stem passion fruit and yellow-fruited passion fruit, while P. edulis f. edulis leaves contained both isorhamnetin and ramnol. The authors suggested that differences in growth environments might have caused variations in the chemical composition of passion fruit leaves.

Additionally, luteolin-8-C-β-boivinopyranoside (luteolin-8-C-β-boivinopyranoside, 16) (Figure 2a) and luteolin-8-C-β-digitoxopyranosyl-4'-O-β-D-glucopyranoside glucoside (luteolin-8-C-β-digitoxopyranosyl-4'-O-β-D-glucopyranoside, 32) (see Figure 2c) were only identified in the stem and leaf extracts of purple-skinned passion fruit [26].

2.1.2 Apigenin

Apigenin (2) is the second most widely distributed flavonoid aglycone in Passiflora species. Eleven flavonoid glycosides (36–46) with apigenin as the aglycone, six flavonoid oxosides (47–52), and five flavonoid mixed glycosides (53–57) have been identified in edible Passiflora species [21,27–30].

The most common apigenin glycoside compounds in passionflower are isomuggenin (36) and muggenin (37), both with the molecular formula C₂₁H₂₀O₁₀. with the chemical structural difference being that the glucose glycoside of isomuggenin is located at position 6 of the A ring, while that of muggenin is at position 8 of the A ring (Figure 2a). In 1968, Glotzbach et al. [31] first demonstrated the presence of isomuggenin and muggenin in the stems and leaves of large-fruited passionflower. Subsequently, Oga et al. [32-35] successively isolated isomugikans and mugikans from the leaves of winged stem passionflower, purple-skinned passionfruit, banana passionflower, and yellow-fruited passionflower. Additionally, they identified mugikans-2'-O-xyloside (vitexin-2'-O-xyloside, 49) and mugikans from the leaves of large-fruited passionflower, winged stem passionflower, P. edulis f. edulis leaves.

Other commonly found apigenin glycosides in edible passionflower plants include isoharpic acid (45) and harpic acid (46), which are diosaccharide glycosides that are structural isomers, with the molecular formula C₂₆H₂₈O₁₄, with the structural formula shown in Figure 2a. Mareck et al. [36] isolated isohaftafuranoside and haftafuranoside from the fruit pulp of yellow passionflower; Simirgiotis et al. [37] subsequently isolated and identified isohaftafuranoside and haftafuranoside from banana passionflower fruit pulp; Farag et al. [21] used nuclear magnetic resonance and mass spectrometry techniques to establish fingerprint metabolomic profiles of leaf samples from 17 Passiflora species from different regions, identifying multiple compounds including luteolin, apigenin, and xanthoflavone; Furthermore, Hivrale et al. [38] found that isoflavone and xanthoflavone are important flavonoid glycoside active compounds in the whole fruit of passion fruit.

Additionally, apigenin-8-C-β-boivinopyranoside (39) and apigenin-8-C-β-digitoxopyranoside (40) (see Figure 2a) have been reported only in the stem and leaf extracts of purple-skinned passion fruit [26]. 40) (see Figure 2a) have only been reported in the stem and leaf extracts of purple-skinned passion fruit [26]. Apigenin-4 '-O-β-glucopyranosyl,8-C-β-(6″ acetyl)-glucopyranoside (apigenin-4 '-O-β-glucopyranosyl,8-C-β-(6″ acetyl)-glucopyranoside,55) and apigenin-4'-O-β-glucopyranosyl-8-C-β-neohesperidoside (apigenin-4-O-β-glucopyranosyl-8-C-β-neohesperidoside, 56) have only been reported in banana passionflower leaves (see Figure 2c) [39].

2.1.3 Populin

Chrysin (3) is an important flavonoid aglycone in Passiflora species. To date, three flavonoid glycosides (58–60), one oxo-flavonoid (61), and two mixed glycosides (62–63) have been identified from edible Passiflora species [21, 26, 33, 40]. These glycoside compounds are primarily found in purple-skinned passion fruit, such as chrysin-6-C-hexoside (58), chrysin-6,8-C-di-hexoside (59), chrysin-C-hexosyl-6″-O-deoxyhexoside (chrysin-C-hexosyl-6″-O-deoxyhexoside, 62), etc. [33].

2.2 Flavonols and their glycosides

Flavonols are flavonoids with a 2-phenylchromenone core and an oxygen substituent at the 3-position. The main flavonol glycoside aglycones identified in Passiflora species include two: quercetin (quercetin, 4) and kaempferol (kaempferol, 5) (Figure 1). Additionally, 11 flavonoid glycosides (64–74) are commonly found in edible Passiflora species.

2.2.1 Quercetin

The earliest record of quercetin (4) in edible passion fruits was reported by Lutomski et al. in 1975 during an activity test of purple-skinned passion fruit and yellow-fruited passion fruit pulp [41]. Recently, Rotta et al. [42] reported the content of phenolic compounds in purple-skinned passion fruit, winged-stem passion fruit, and sweet-fruited passion fruit pulp, The results showed that all three Passiflora species contained quercetin, but purple-skinned passion fruit had the highest content of quercetin and its glycoside rutin (quercetin-3-O-rutinoside, 65) (Figure 2b), while sweet-fruited passion fruit had the lowest content of both rutin and quercetin, both below the limit of quantification. Previous studies have identified the glycosides of quercetin in edible passion fruits, primarily forming glycosidic bonds at the 3rd and 7th positions of quercetin. For example, Medina [28] identified rutin (65), quercetin-7-O-glucoside (quercetin-7-O-glucoside, 67), quercetin-3,7-di-O-hexoside (68), and carmon-Hernandez et al. [12] identified quercetin-3-glucoside (71), among others.

2.2.2 Kaempferol

Kaempferol (5), molecular formula C₁₅H₁₀O₆, chemical name 3,5,7,4'-tetrahydroxyflavone. In 1982, small amounts of kaempferol were detected in the stem and leaf extracts of Australian dragon fruit (P. foetida Linn.) [43]; kaempferol was found in high concentrations in the fruit pulp extracts of yellow passion fruit and orange passion fruit, but not in the fruit pulp extracts of purple passion fruit [44]. Subsequently, some kaempferol glycosides, such as kaempferol-3-O-glucoside (kaempferol-3-O-glucoside, 73) from purple-skinned passion fruit peel and 3,7,4'-tri-O-methyl kaempferol (3,7,4'-tri-O-methyl kaempferol, 74) from Colombian dragon's blood fruit leaves, were also isolated [28,45].

2.3 Dihydroflavones and their glycosides

Dihydroflavones are a class of flavonoids formed by the hydrogenation of the carbon-carbon double bond at positions 2 and 3 of the flavonoid ring, also known as flavanones [46]. The main dihydroflavonoid aglycones in Passiflora species are naringenin (naringenin, 6) and hesperetin (hesperetin, 7) (Figure 1). Additionally, three dihydroflavonoid glycoside derivatives (75–77) have been identified in commonly consumed Passiflora species.

2.3.1 Naringenin

Naringin (6), molecular formula C₁₅H₁₂O₅, chemical name 4',5,7-trihydroxy dihydroflavone. Naringin (naringin, 75) is a dihydroflavone glycoside compound with naringin as the aglycone (Figure 2b), both of which are active components of many traditional Chinese medicines [47]. Deng et al. [48] investigated the changes in phenolic compounds in purple passion fruit juice during fermentation, during which they isolated and identified naringin and naringin glycoside, and noted that both were present before and after fermentation without undergoing conversion.

2.3.2 Hesperetin

Hesperetin (7), with the molecular formula C₁₆H₁₄O₆, and the chemical name 5,7,3'-trihydroxy-4'-methoxyflavanone, is a widely distributed dihydroflavonoid compound found in fruits and flowers. In nature, it is commonly found in the form of hesperidin (76) and neohesperidin (77) [49]. Hesperidin is formed by the 7-position of hesperetin being connected to rutin via a C-O bond, while neohesperidin is formed by the 7-position of hesperetin being connected to neohesperidin via a C-O bond (Figure 2b). Spínola et al. [27] identified hesperidin and neohesperidin in the pulp of purple passion fruit.

2.4 Anthocyanins and Their Glycosides

Anthocyanins are characterized by a 2-phenylbenzopyran ring connected to multiple substituents on the ring, and are widely distributed natural pigments in plants such as grapes and sweet potatoes, belonging to the flavonoid class of compounds [50]. Over 20 anthocyanins have been identified, including cyanidin, peonidin, malvidin, and pelargonidin. In nature, these anthocyanins often form anthocyanidins by binding to sugars via C-O bonds. Fourteen anthocyanidins (8, 78–90) were identified in edible passion fruit.

Hu et al. [51] identified and extracted anthocyanins from the peel of purple passion fruit. Kidoy et al. [52] identified large amounts of cyanidin-3-O-glucoside (cyanidin-3-O-glucoside, 78) in the peel of purple passion fruit, small amounts of cyanidin-3-(6''-malonyl) glucoside (82), and pelargonidin-3-O-glucoside (89) from the peel of purple-skinned passion fruit.

Peng [53] isolated three anthocyanins from the peel of purple passion fruit and speculated that they might be cyanidin-3-O-glucoside (78), malvidin-3-O-glucoside (87), and petunidin-3-O-glucoside (88). Zhu [54] identified five anthocyanins in the peel of purple passion fruit using HPLC-MS, including cyanidin-3-O-glucoside (78), cyanidin-3-O-rutinoside (79), cyanidin-3-(6 ' '-succinyl) glucoside (82), and peonidin-3-O-glucoside (85), Geraniol-3-O-glucoside (89). He et al. [55] reported 12 anthocyanins in the peel of Fujian 'Zixiang No. 1' purple-skinned passion fruit (P. edulis Sims cv. Zixiang 1), with representative anthocyanin structures shown in Figure 2b.

2.5 Flavanols and Their Derivatives

Flavanols are widely distributed in traditional Chinese medicine and fruits. Based on their chemical structural characteristics, they are generally classified into three categories: flavan-3-ols, flavan-3,4-diols, and condensed proanthocyanidins [56]. All compounds identified in edible passion fruit belong to the flavan-3-ol class and their derivatives. García-Ruiz [57] was the first to identify catechin glucoside (94) from banana passion fruit pulp; Carmona-Hernandez [12] identified (+)-catechin (94) from sweet passion fruit, purple-skinned passion fruit, and yellow-fruited passion fruit pulp. epigallocatechin (92), and epigallocatechin gallate (93) from sweet passion fruit, purple-skinned passion fruit, and yellow-fruited passion fruit juice.

2.6 Phenolic acids

Other phenolic acid compounds were also isolated from edible passion fruit juice, seeds, peel, and stems/leaves (Figure 3, Table 3), such as o-hydroxycoumaric acid (95), syringic acid (96), caffeic acid (97), and sinapic acid (98) and 99–104.

3. Biological activity

The physiological effects of medicinal plants are typically associated with the biological activity of their secondary metabolites. Literature evidence indicates that the phenolic compounds in passion fruit possess antioxidant, antibacterial, and anti-inflammatory activities. Additionally, some studies have reported hypoglycemic, neuroprotective, and anxiolytic effects of passion fruit.

3.1 Antioxidant activity

Excessive production or slow clearance of free radicals can cause varying degrees of damage to tissues and organs and may lead to conditions such as cancer and cardiovascular diseases. Passiflora plants are rich in phenolic compounds and serve as natural sources of antioxidants. Purple passion fruit pulp demonstrated a high scavenging capacity for 2,2-dinitro-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt free radicals (121.20 ± 4.88 mg VCE/100 g juice) and oxygen free radicals (608.65 ± 44.9 3 μmol TE/100 g juice) are comparable to those of lemon and strawberry fruit pulp [27]. Saravanan et al. [58] found that passion fruit's antioxidant capacity is significantly positively correlated with its total phenolic and total flavonoid content. Experimental results showed that among all tested samples, sweet passion fruit pulp had the highest total phenolic and total flavonoid content, and exhibited the strongest scavenging capacity against 1,1-diphenyl-2-trinitrobenzene hydrazide free radicals, 2,2'-biphenyl-4,4'-diol-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, and nitric oxide free radicals.

López-Vargas et al. [16] found through a series of studies on yellow passion fruit that its antioxidant activity stems from the combined effects of flavonoids, catechins, and other phenolic compounds, and that the antioxidant capacity of yellow passion fruit is related to the extraction solvent and extraction site. For example, the antioxidant capacity of the DMSO extract of its fruit pulp and seeds is significantly higher than that of its aqueous extract, and also higher than that of the DMSO extract of the fruit peel. García-Ruiz et al. [57] demonstrated that the flavonoids and carotenoids in banana passion fruit pulp possess free radical scavenging capacity and can scavenge 1,1-diphenyl-2-trinitrobenzyl radical, with higher active component content the stronger the radical scavenging capacity. Tao et al. [61] reported that the scavenging capacity of flavonoid extracts from purple-skinned passion fruit against hydroxyl radicals and superoxide anion radicals increased with the increase in sample solvent volume. He et al. [55] compared the antioxidant activity of crude anthocyanin extracts from purple-skinned passion fruit peel, purified anthocyanin samples, and vitamin C (Vc). The results showed that the antioxidant activity of the purified anthocyanin samples was higher than that of Vc and significantly higher than that of the crude extract.

3.2 Anti-inflammatory activity

Inflammation is a complex natural biochemical response of an organism to harmful stimuli, such as tissue damage or microbial invasion, primarily occurring through the activation of immune cells and molecular signaling pathways, with the aim of maintaining bodily balance. Benincá et al. [62] investigated the therapeutic effects of water extracts from purple passion fruit leaves on a mouse air sacculitis model, finding that luteolin (1) and its glycosides could inhibit the synthesis of thromboxane and leukotrienes, while apigenin (36) and other apigenin glycosides inhibited the expression of inducible nitric oxide synthase mRNA in LPS-activated macrophages by suppressing the activation of nuclear factor NF-κB and interfering with the phosphorylation of IκB, thereby achieving an anti-inflammatory effect.

The peel of passion fruit is a primary source of phenolic compounds, containing apigenin (2), quercetin (3), and kaempferol (4), isomuggenin (36), muggenin (37), and xanthoquinone (46), all of which exhibit anti-inflammatory activity [27,63-66]. Experiments have shown that in mice with colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS), long-term administration of passion fruit peel powder can regulate the intestinal microbiota of mice, increase the number of beneficial bacteria in the microbiota, effectively improve intestinal health, and have therapeutic effects on colitis [67]. Wang et al. [68] established a mouse inflammation model by stimulating peritoneal macrophages with lipopolysaccharide (LPS) and found that Xaftaoside (46) and other compounds reduced the release of inflammatory mediator nitric oxide (NO) and the secretion of inflammatory factor tumor necrosis factor-α (TNF-α), making them key anti-inflammatory active components.

3.3 Antimicrobial Activity

In 1973, Birner et al. [69] demonstrated that banana passion fruit peel extract possesses antifungal and antibacterial activity; in 1997, Qureshi et al. [70] reported that purple-skinned passion fruit exhibits inhibitory effects against fungi such as Microsporum gypseum, Trichophyton terrestri, and Chry- sosporium tropicum. Dzotam et al. [71] used the micro-broth dilution method to find that flavonoid extracts from purple-skinned passion fruit peel exhibit antibacterial activity against Escherichia coli and Pseudomonas aeruginosa, among other bacterial strains, with the best inhibitory activity against the E. coli AG100 strain, with a minimum inhibitory concentration (MIC) of 128 μg/mL. Additionally, Liu et al. [72] found that luteolin (1), quercetin (4), and their derivatives exhibit synergistic interactions, conferring broad-spectrum antibacterial activity against Gram-negative bacteria, Gram-positive bacteria, and fungi.

Su et al. [73] investigated the in vitro antibacterial activity of luteolin (1), apigenin (2), and quercetin (4) against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolates, and found that compared to apigenin, luteolin and quercetin exhibited significant antibacterial activity against both MRSA and MSSA, with MIC values ranging from 128 μg/mL to 100 μg/mL. MSSA) isolates. The results showed that compared to apigenin, luteolin and quercetin exhibited significant antibacterial activity against both MRSA and MSSA, with MIC values ranging from 31.2 to 125 μg/mL. while luteolin and quercetin exhibited synergistic antibacterial activity against Staphylococcus aureus when used in combination. Amin et al. [74] not only found that luteolin (1) combined with quercetin (4) enhanced antibacterial activity but also discovered that luteolin combined with antibiotics or quercetin combined with antibiotics exhibited complementary effects in inhibiting MRSA, and their combined use can inhibit the biosynthesis of damaged cell walls in bacteria, thereby achieving antibacterial effects. Since passion fruit contains the above-mentioned phenolic compounds, it can be developed as a natural antibacterial agent.

3.4 Hypoglycemic Activity

Diabetes is a metabolic disorder characterized by elevated blood glucose levels and impaired glucose metabolism, posing a significant threat to human health. α-Amylase and α-glucosidase are key enzymes closely associated with type 2 diabetes. He [55] reported that extracts of purple passion fruit peel anthocyanins can bind to these two key enzymes, inhibit their enzymatic activity, thereby preventing blood glucose levels from rising and achieving therapeutic effects for type 2 diabetes. Salles et al. [75] administered an extract of purple passion fruit leaves to rats with diabetes induced by streptozotocin and found that the blood glucose, creatinine, total cholesterol, hemoglobin A1c, and advanced glycation end products (AGEs) in the blood were significantly reduced, and the renal function of the diseased rats improved, indicating that purple passion fruit leaves have a preventive effect against chronic complications of diabetes. Further analysis demonstrated that these effects are associated with the flavonoid glycosides present in the extract, particularly isorhamnetin (14) and other active components.

Additionally, literature reports that luteolin (1) can regulate reactive oxygen species (ROS) levels by upregulating superoxide dismutase (SOD) levels, and through modulating p53 and mammalian target of rapamycin (mTOR)-dependent apoptosis to treat diabetes [76]. Apigenin (2) and its carbon glycoside isovitexin (36) and vitexin (37) can all induce apoptosis in diabetic cells by inhibiting the mTOR pathway [77]. mTOR) to treat diabetes [76]. Apigenin (2) and its carbon glycoside isovitexin (36) and vitexin (37) can all inhibit aldose reductase (AR), AGEs, and protein tyrosine phosphatase 1B (PTP1B) to treat diabetes. Choi [77] also revealed differences in the inhibitory effects of flavonoid glycosides on AR, AGEs, and PTP1B, and suggested that these differences are related to the glycosylation sites of the compounds.

3.5 Neuroprotective effects

Xu et al. [26] found that luteolin (1) in the stems and leaves of purple-skinned passion fruit increased the proportion of PC12 neurons induced by nerve growth factor at a concentration of 50 μmol/L. Tal et al. [78] prepared crude extracts of the whole fruit of purple-skinned passion fruit and a passion fruit hybrid strain 428 in 2016, added them separately to HT4 neuronal culture medium, and found that glutamate-induced cell death, mitochondrial depolarization, and glutathione depletion were all inhibited, indicating that both varieties of passion fruit exhibit significant neuroprotective activity.

Liu et al. [79] administered quercetin (4) to rats with diabetes and cerebral ischemia-reperfusion injury for three days, and observed reduced blood glucose levels, cerebral infarct area, and neurological dysfunction in the rats, but no oxidative stress-induced neuronal damage, and neuronal density was even increased. Wang et al. [80] found that apigenin (15) can exert neuroprotective effects on rats with cerebral ischemia-reperfusion injury by inhibiting autophagy. Wang [81] pointed out that vitexin (37) can increase the phosphorylation of extracellular regulated protein kinase (ERK) 1/2, reducing c-Jun N-terminal kinase (JNK) phosphorylation, decreasing P38 expression, downregulating pro-apoptotic protein Bax levels, and upregulating anti-apoptotic protein Bcl-2 levels to inhibit neuronal apoptosis in a mouse model of cerebral ischemia-reperfusion injury, thereby achieving neuroprotection.

3.6 Anxiolytic and Sedative Activity

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that exerts its inhibitory effects by binding to GABAA receptors and generating inhibitory potentials. Increasing GABA levels in the brain produces anxiolytic, sedative, and hypnotic effects. In fact, various Passiflora species have been used in Western countries for sedation, treat anxiety. Miguel et al. [20] found that flavonoid components in purple passion fruit leaves exhibit anxiolytic effects in mice, with luteolin-7-O-2-rhamnoside (27) demonstrating anxiolytic activity without affecting mouse locomotion. Barbosa et al. [82] reported that intraperitoneal injection of Passiflora incarnata leaf water extracts at doses of 100, 150 mg/kg or Passiflora grandiflora leaf water extracts at doses of 50, 100, 150 mg/kg in rats produced anxiolytic effects similar to those of diazepam. This is because some flavonoids in the water extracts act as agonists of GABAA receptors, enabling them to exert anxiolytic effects.

Ayres et al. [33] administered water extracts of different Passiflora leaves, primarily containing flavonoid glycosides, orally to mice. They found that 300 mg/kg of purple-skinned passion fruit water extract and 100, 300 mg/kg of yellow-fruited Passiflora water extract significantly reduced anxiety levels in mice, and oral administration of 1,000 mg/kg of purple-skinned passion fruit water extract further shortened the mice's movement distance, indicating that high doses of flavonoid glycosides possess sedative activity. Gazola et al. [83] found that diseased rats administered water extracts of large-fruited passion fruit leaves exhibited anti-anxiety activity in behavioral tests, while oral administration of its fruit peel water extracts it prolonged the ether-induced hypnotic duration, demonstrating sedative activity. Further experiments confirmed that the sedative activity of Passiflora grandiflora water extract is positively correlated with flavonoid content, and is primarily mediated by morin-2'-O-xyloside (49) acting on the GABA system, exerting related effects.

4 Conclusion

Edible passion fruit is a natural treasure trove of phenolic compounds, offering benefits such as disease prevention and enhanced physical fitness upon consumption. Existing studies have shown that, in addition to direct fresh consumption, these phenolic compounds hold significant potential for development into pharmaceuticals and functional foods tailored to the personalized needs of different populations.

Researchers both domestically and internationally have focused on the phenolic compounds in edible passion fruit, measuring total phenolic content, total flavonoid content, and bioactivity. However, existing studies are insufficient and require further investigation into the following issues: 1) The active compounds identified in edible passion fruit are primarily flavonoid glycosides and hydroxy glycosides, but current methods for determining total flavonoids or total phenolic content use rutin or kaempferol as reference standards, which do not fully represent or reflect the phenolic compound content in edible passionflower.

Therefore, it is necessary to establish methods for determining total phenolic content using main flavonoid glycosides such as luteolin and chrysoberyl as reference standards, Additionally, methods for determining the content of these flavonoid glycosides or hydroxy glycosides in passion fruit should be established to provide scientific data support for the cultivation of high-quality edible passion fruit and the development of related products; 2) Existing studies on the bioactive compounds in edible passion fruit have primarily focused on crude extracts, making it difficult to identify the specific bioactive components and their regulatory pathways. Therefore, it is essential to prioritize the separation and purification of compounds, and conduct in-depth investigations into the active mechanisms of these compounds and determine their structure-activity relationships to provide a basis for the scientific utilization of edible passion fruit; 3) Edible passion fruit is rich in phenolic compounds throughout its entire fruit, but existing research has primarily focused on the fruit pulp, with low utilization of the stems, leaves, and fruit peel. Future research should prioritize the study of phenolic compounds in these parts to achieve efficient utilization of natural resources.

Reference

[1]Carvalho DSF,et al.Chemical composition and antioxidant capacity of Brazilian Passiflora seed oils［J］.J Food Sci, 2015,80 : C2647-2654 .

[2]Ichimura T,et al.Antihypertensive effect of an extract  of Passiflora edulis rind in spontaneously hypertensive rats［J］. Biosci Biotech Bioch,2006,70:718-721 .

[3]Zhou YJ,et al.Update review of Passiflora［J］.China J Chin Mater Med,2008,33 : 1789-1793.

[4]Zhao RR , et al.Progress on the research of anxiolytic ingredi- ents and the mechanisms of Passiflora Linn.［J］.Food Drug,2011,13 : 354-357 .

[5]Dhawan K,et al.Anti-anxiety studies on extracts of Passiflora incarnata Linneaus［J］.J Ethnopharmacol,2001,78 : 165- 170.

[6]He ZC.The emerging tropical advanced beverage fruit to be developed urgently-egg fruit［J］.Fujian Sci Technol Trop Crops,1986,12(2) : 11-13.

[7]Wang BM.Nutritional characteristics and cultivation manage- ment measures of passion fruit［J］.China Fruit Veg,2020,40(7) : 111-113.

[8]Xing XN,et al.Current status,existing problems and devel- opment suggestions of Guangxi passion fruit industry［J］.J South Agr,2020,51 : 1240-1246.

[9]Singh B,et al.Phenolic composition and antioxidant potential of grain legume seeds : a review［J］.Food Res Int,2017, 101 : 1-16.

[10]Corrêa RCG,et al.The past decade findings related with nu- tritional composition,bioactive molecules and biotechnologi- cal applications of Passiflora spp.(passion fruit) ［J］.Trends Food Sci Tech,2016,58 :79-95 .

[11]Yang LM,et al. Research progress on chemical structures and pharmacological activities of natural phloro-glucinols［J］.Nat Prod Res Dev,2019,31 : 1656-

1667.

[12]Carmona-Hernandez JC,et al.Polyphenol extracts from three colombian Passifloras ( passion fruits) prevent inflammation- induced barrier dysfunction of Caco-2 cells［J］.Molecules, 2019,24(24) :4614 .

[13]Macoris MS,et al.The influence of ripening stage and culti- vation system on the total antioxidant activity and total phe- nolic compounds of yellow passion fruit pulp［J］.J Sci Food Agr,2012,92 : 1886-1891.

[14]Zerailk ML,et al.Evaluation of the antioxidant activity of passion fruit(Passiflora edulis and Passiflora alata) extracts on stimulated neutrophils and myeloperoxidase activity assays ［J］.Food Chem,2011,128 :259-265 .

[15]Gomes SVF,et al.Accelerated solvent extraction of phenolic compounds exploiting a Box-Behnken design and quantifica- tion of five flavonoids by HPLC-DAD in Passiflora species ［J］.Microchemi J,2017,132:28-35 .

[16]López-Vargas JH,et al.Chemical,physico-chemical,techno- logical,antibacterial and antioxidant properties of dietary fi- ber powder obtained from yellow passionfruit(Passiflora edu- lis var.flavicarpa) co-products［J］.Food Res Int,2013,51 : 756-763.

[17]Konta EM,et al.Evaluation of the antihypertensive properties of yellow passion fruit pulp ( Passiflora edulis Sims f.fla- vicarpa Deg.) in spontaneously hypertensive rats［J］.Phyto- ther Res,2014,28( 1) : 28-32 .

[18]Shao Y,et al. Research progress on C-glycosyl flavones for protection of myocardial  ischemia ［J］.Chin  Tradit Herb Drugs,2015,46 : 128-139.

[19]Jiang N,et al.Flavones : from biosynthesis to health benefits ［J］.Plants,2016,5 (2) : 27 .

[20]Miguel C,et al.Neuropharmacological evaluation of the puta- tive anxiolytic effects of Passiflora edulis Sims,its sub-frac- tions and flavonoid constituents［J］.Phytother Res,2006, 20 : 1067-1073.

[21]Farag MA,et al.Comparative metabolite profiling and finger- printing of genus Passiflora leaves using a multiplex approach of UPLC-MS and NMR analyzed by chemometric tools［J］.  Anal Bioanal Chem,2016,408 : 3125-3143 .

[22]Zhou YJ,et al.Studies on the chemical constituents of Passi- flora edulis f.flavicarpa［J］.J Chin Med Mater, 2009,32 : 1686-1688.

[23]Chagas M,et al.Bioinspired oxidation in the CYP of isomers orientin and isoorientin using Salen complexes［J］. Rapid Commun Mass Sp,2020,34 : 1-11.

[24]Zou JB,et al.HPLC determination of isorientin and orientin in Passiflora incamata extract simultaneously［J］.Pharm J Chin PLA,2009,25 :443-445 .

[25]Wosch L,et al.Comparative study of Passiflora taxa leaves : II.A chromatographic profile ［J］. Rev Bras Farmacogn, 2017,27( 1) :40-49 .

[26]Xu FQ,et al.C-dideoxyhexosyl flavones from the stems and leaves of Passiflora edulis Sims［J］.Food Chem,2013,136 ( 1) : 94-99 .

[27]Spínola V,et al.Identification and quantification of phenolic compounds of selected fruits from Madeira Island by HPLC- DAD-ESI-MS(n) and screening for their antioxidant activity ［J］.Food Chem,2015,173 : 14-30.

[28]Medina S,et al.Quantification of phytoprostanes bioactive ox- ylipins and phenolic compounds of Passiflora edulis  Sims shell using UHPLC-QqQ-MS / MS and LC-IT-DAD-MS / MS ［J］.Food Chem,2017,229 : 1-8.

[29]Hadas E,et al.The use of extracts from Passiflora Spp.in helping the  treatment of acanthamoebiasis ［J］.Acta Pol Pharm,2017,74:921-928 .

[30]Li Y,et al.In vivo antioxidant capacity and flavonoid compo- sition of the seeds of Passiflora edulis Sims［J］.Food Sci,2020,41 ( 1) : 203-208 .

[31]Glotzbach B,et al.Flavenoids from Passiflora incarnata L. , Passiflora quandrangularis L.and Passiflora pulchella H.B. V.A chromatographic study［J］.Planta Med,1968,16 ( 1) : 1-7.

[32]Oga S,et al.Pharmacological trials of crude extract of Passi- flora alata［J］.Planta Med,1984,50: 303-306 .

[33]Ayres ASFSJ,et al.Comparative central effects of the aque- ous leaf extract of two populations of Passiflora edulis［J］.  Rev Bras Farmacogn,2017,25 :499-505 .

[34]Pereira CA,et al.Distinction of the C-glycosylflavone isomer pairs orientin / isoorientin and vitexin / isovitexin using HPLC- MS exact mass measurement and in-source CID［J］.Phyto- chem Anal,2005,16:295-301 .

[35]Costa GM,et al.Chemical profiles of traditional preparations of four south American Passiflora species by chromatographic and capillary  electrophoretic  techniques ［J］.  Rev  Bras Farmacogn,2016,26:451-458 .

[36]Mareck U,et al.Identifizierung von passionsfruchtsaft in fruchtprodukten mittels HPLC［J］.Z Lebensm Unters For- sch,1990,191 : 194-198.

[37]Simirgiotis M,et al.The Passiflora tripartita ( banana pas- sion) fruit : a source of bioactive flavonoid C-glycosides isola- ted by HSCCC and characterized by HPLC-DAD-ESI / MS / MS［J］.Molecules,2013,18 : 1672-1692.

[38]Hivrale AU.Pharmacological studies of Passiflora sp.and their bioactive compounds［J］.Plant Sci,2010,4:417-426 .

[39]Castellanos L,et al.Metabolic fingerprinting of banana pas- sion fruits and its correlation with quorum quenching activity［J］.Phytochemistry,2020,172 : 112272.

[40]Hu Y,et al.A new C-glycosyl flavone and a new neolignan glycoside from Passiflora edulis Sims peel［J］.Nat Prod Res, 2018,32:2312-2318 .

[41]Lutomski J,et al.Pharmacochemical investigations on raw materials genus Passiflora［J］.Planta Med,1975,27 : 112- 121.

[42]Rotta EM,et al.Determination of phenolic compounds and antioxidant activity in passion fruit pulp(Passiflora spp.) u- sing a  modified QuEChERS method and UHPLC-MS / MS ［J］.LWT-Food Sci Technol,2018,100: 397-403 .

[43]Ulubelen A,et al.C-Glycosyl flavonoids from Passiflora foeti- da var.hispida and P.foetida var.hibiscifolia［J］.J  Nat Prod,1982,45 ( 1) : 103.

[44]Reis LCRD,et al.Antioxidant potential and physicochemical characterization of yellow,purple and orange passion fruit ［J］.J Food Sci Tech,2018,55 :2679-2691 .

[45]Echeverri F,et al.Ermanin : An insect deterrent flavonoid from Passiflora foetida resin［J］.Phytochemistry,1991,30 : 153-155.

[46]Liang H,et al. Reviews on flavanone compounds synthesis re- search［J］.J Pharm Pract,2015,33 : 97- 101.

[47]Li PB,et al.An overview of pharmacological actions of narin- gin and its aglycone naringenin on respiratory diseases［J］.J Pharm Res,2020,39 :249-255 .

[48]Deng NQ,et  al.Analysis of conversion of phenolic  com- pounds in passion fruit juice fermentation by HPLC［J］.J Guangdong Univ Petrochem Tech,2019,29( 1) :41-44 .

[49]Shi LL,et al.Advances in research of anti-tumour medicinal value of hesperetin［J］.Chin J Ethnomed Ethnopharm,2017,26(9) : 66-71 .

[50]Qiao YY,et al. Research progress of anthocyanin sources, structural characteristics  and physiological functions ［J］.  Chin Tradit Pat Med,2019,41 : 388-392 .

[51]Hu M,et al.A Study on extraction process and stability of anthocyanin in peel of Passiflora edulis skin［J］.Acta Agr Univ Jiangxi,2018,40: 825-834 .

[52]Kidoy L,et al.Anthocyanins in fruits of Passiflora edulis and P.suberosa［J］.J Food Compos Anal,1997,10( 1) :49-54 .

[53]Peng B.Study on extraction and separation of pigment from Passiflora edulis peel and its structure［D］.Fuzhou : Fujian Agriculture and Forestry University,2012 .

[54]Zhu H.Study on anthocyanin components of Passiflora edulis and polypeptide components of Harbin red intestine［D］. Suzhou: Soochow University,2015 .

[55]He D,et al.Identification and bioactivity evaluation of anthocyanins from Passiflora edulis Sims peel［J］.Food Sci,2020,41 ( 11) : 57-63 .

[56]Liu YL.Advances in chemical research offlavanols［J］.Acta Pharm Sin,1980,15 ( 1) : 50-64 .

[57]García-Ruiz A,et al.Banana passion fruit(Passiflora mollis- sima(Kunth) L.H.Bailey) : microencapsulation,phytochem- ical composition and antioxidant  capacity［J］.Molecules, 2017,22( 1) : 85.

[58]Saravanan S,et al.In vitro antioxidant,antimicrobial and anti- diabetic properties of polyphenols of Passiflora ligularis Juss.  fruit pulp［J］.Food Sci Hum Well,2014,3 (2) : 56-64 .

[59]Talcott ST,et al.Phytochemical composition and antioxidant stability of fortified yellow passion fruit ( Passiflora edulis) ［J］.J Agr Food Chem,2003,51 :935-941 .

[60]Liang HQ,et al.Advances in studies on endophytes and poly- phenols in Morinda citrifolia fruits［J］.Mod Food Sci Techn- ol,2019,35 ( 11) : 310-319 .

[61]Tao YY,et al.Extraction and antioxidant ability of flavonoids from passion fruit［J］.Food Res Dev, 2014,35 ( 17) : 25-29 .

[62]Benincá JP,et al.Evaluation of the anti-inflammatory efficacy of Passiflora edulis［J］.Food Chem,2007,104 : 1097-1105.

[63]Liu SW,et al.Advances in the pharmacological effects of quercetin［J］.Chin J Lung Dis, 2020,13 ( 1) : 104-106.

[64]Yu JH,et al. Research progress of functional ingredients and biological activity of Apium graveolens L.［J］.Jiangsu Agr Sci,2019,47(7) : 5-10 .

[65]Wang J,et al.Progress in structure modifications and biologi- cal activities of chrysin derivatives［J］.Chem Reag,2018,40:225-230 .

[66]Cheng JZ,et al.Study on analgesic and anti-inflammatory effects of vitexin［J］.Guide Chin Med, 2016,14(31) : 29-30 .

[67]Cinthla BBC,et al.Passiflora edulis peel intake and ulcera- tive colitis: approaches for prevention and treatment［J］.Exp Biol Med,2014,239 :542-551 .

[68]Wang JJ,et al.Analysis of schaftoside and it ’s anti-inflam- matory activity in the water extracts from 8 Lotus Plumule ［J］.J Chin Inst Food Sci Technol( 中国食品学报) ,2018, 18(3) : 291-298 .

[69]Birner J,et al.Passicol,an antibacterial and antifungal agent produced by Passiflora plant species: preparation and physi- cochemical characteristics［J］.Antimicrob Agents Ch,1973, 3 ( 1) : 105-109.

[70]Qureshi S,et al.In vitro evaluation of inhibitory nature of ex- tracts of 18-plant species of Chhindwara against 3-keratino- philic fungi［J］.Hindustan Antibiot Bull,1997,39( 1-4) : 56-60.

[71]Dzotam JK,et al.Antibacterial and antibiotic-modifying activ- ities of three food plants(Xanthosoma mafaffa Lam.,Morin- ga oleifera( L.) Schott and Passiflora edulis Sims) against multidrug-resistant( MDR) Gram-negative bacteria［J］.BMC Complem Altern M,2016,16:9.

[72]Liu H,et al.Flavonoids from Halostachys caspica and their antimicrobial and antioxidant activities［J］.Molecules,2010, 15 :7933-7945 .

[73]Su YL,et al.Studies of the in vitro antibacterial activities of several polyphenols against clinical isolates of methicillin-re- sistant Staphylococcus  aureus ［J］.Molecules,2014,19 : 12630-12639.

[74]Amin MU,et al.Effects of luteolin and quercetin in combina- tion with some conventional antibiotics against methicillin-re- sistant Staphylococcus aureus［J］.Int J Mol Sci,2016,17 ( 11) : 1947.

[75]Salles BCC,et al.Passiflora edulis leaf extract : evidence of antidiabetic and antiplatelet effects in rats［J］.Biol Pharm Bull,2020,43 : 169-174.

[76]Ambasta RK,et al.Can luteolin be a therapeutic molecule for both colon cancer and diabetes? ［J］.Brief Funct Genomics, 2018,18 :230-239 .

[77]Choi JS,et al.Effects of C-glycosylation on anti-diabetic,an- ti-Alzheimer ’s disease and anti-inflammatory potential of apigenin［J］.Food Chem Toxicol,2014,64:27-33 .

[78]Tal Y,et al.The neuroprotective properties of a novel variety of passion fruit［J］.J Funct Foods,2016,23 : 359-369 .

[79]Liu XF,et al.Neuroprotective effect of quercetin on diabetic rats with cerebral ischemia-reperfusion injury［J］.West Chin J Pharm Sci,2019,34:654-658 .

[80]Wang XR , et al.The neural protective effect of orientin in rats undergoing cerebral ischemialreperfusion ［J］.Chin J Clin Pharmacol,2018,34 : 565- 568.

[81]Wang YN.Neuroprotective effect and mechanisms of vitexin on focal cerebral ischemia / reperfusion injury in mice［D］. Hefei: Anhui Medical University,2015.

[82]Barbosa PR , et al.The aqueous extracts of Passiflora alata and Passiflora edulis reduce anxiety-related behaviors without affecting memory process in rats［J］.J Med Food,2008,11 : 282-288.

[83]Gazola AC,et al.The sedative activity of flavonoids from Pas- siflora quadrangularis is mediated through the  GABAergic pathway［J］.Biomed Pharmacother,2018,100: 388-393 .

[84]Shanmugam S,et al.UHPLC-QqQ-MS / MS identification, quantification of polyphenols from Passiflora subpeltata fruit pulp and determination of nutritional,antioxidant,α-amylase and α-glucosidase key  enzymes inhibition properties［J］.  Food Res Int,2018,108 :611-620 .