Abstract
Purpose: Passiflora edulis Sims (P. edulis) is rich in secondary metabolite flavonoids such as flavonoid C-glucoside (C-glycosyl flavones). Therefore, it is plausible that flavonoids are the causative compound of its anxiolytic effect. However, despite the total flavonoid content of Passiflora alata Curtis (hereinafter P. alata) being half that of P. edulis, both species showed similar anxiolytic effects. In this regard, it is possible that the anxiolytic effect of P. alata is due to the involvement of other bioactive substances (secondary metabolites) in addition to flavonoids. In this study, the author conducted a literature survey on the phytochemical analysis and pharmacological and biological activity of steroids and triterpenoid O-glycosides (saponins) that were isolated and identified as bioactive substances in addition to flavonoids in the historical process of analyzing the phytochemical components of P. alata extracts. The author then considered the involvement of steroids and triterpenoid O-glycosides (saponins) in the psycho-neurological effects.
Methods: From the research reports used in reference of Noriega, et al. Passiflora alata Curtis: a Brazilian medicinal plant (2011), reports refered in the author's 29th report were extracted as materials for this report. From these materials, research was conducted on the phytochemical and pharmacological activities of the bioactive substances isolated and identified from P. alata, mainly C-glycosyl flavones, steroids, and triterpenoid O-glycosides (saponins). Furthermore, a Web search was used to extract report materials as recent research report materials on terpenoid saponins, a component of P. alata.
Results: Reginatto, et al. (2001) separated the n-butanol fraction (crude saponin fraction) of the ethanol extract of P. alata leaves into five compounds (glycosides) by chromatographing on a Silica gel column, and identified their chemical structures by a combination of MS and 1H-NMR. Birk, et al. (2005) reported that in the saponin patterns shown in the TLC fingerprints of 14 species of Passiflora sp., only the extracts of P. alata and the reference substances of 3-O-beta-D-glucopyranosyl-(1 to 2)-beta-D-glucopyranosyl-oleanolic acid and quadranguloside showed distinctive spots under visible light and UV366 light. In other words, among the extracts of 14 species of Passiflora sp., the extracts of P. alata showed saponins as the main metabolites, while the other 13 metabolites appeared to be flavonoids. Dutra, et al. (2023) identified saponin quadranguloside, 3-O-beta-Dglucopyranosyl-(1 to 2)-beta-D-glucopyranosyl-oleanolic acid, and vitexin-2-O-rhamnoside from 1H-NMR related signals (metabolic profiles). These components were identified as metabolites involved in the discrimination of P. alata from Passiflora sp. According to Xu, et al. (2023), four genes (HMGR, DXR, HDS, and SM) of the terpenoid biosynthetic pathway were all found in large quantities in P. alata.
Conclusion: C-glycosylflavones were thought to be the causative bioactive substances for the mental and neurological effects of Passiflora sp., such as anxiolytic, sedative, and antidepressant effects. In P. alata, the flavonoid composition is simpler and flavonoid content is lower than that of P. edulis, so the presence of other bioactive substances is considered to be the causative agent. Among the five steroid and triterpenoid O-glycosides (saponins) identified by Reginatto, et al. (2001) from the ethanol extract of P.alata leaves, the quantification results of quadranguloside by Reginatto, et al. (2004) and the identification of three metabolites from the ethanol extract of P. alata leaves by 1H-NMR metabolic profiling by Dutra, et al. (2023) suggest that quadranguloside is the most likely causative agent of the anxiolytic effect. However, detailed academic information on the central nervous system depressant effect (anxiolytic effect) of this compound was not obtained from a search of this literature.
