Flavonoids, Phenylpropanoids and Iridoids of Patrinia Sibirica (Caprifoliaceae) and Its Bioactivity

Patrinia sibirica (L.) Juss. is a perennial plant species of the Caprifoliaceae family, preparations of which are used in Tibetan medicine as a sleeping remedy, but still poorly studied of chemical composition and biological activity. Fourteen compounds were isolated from P. sibirica herb growing in the Republic of Buryatia, including firstly identified iridoids as patrinoside, patrinoside A, patriridosides H and I, rupesin B and aglycones of patrinoside and patrinoside A, and flavonoids, including quercetin 3-O-robinobioside-7-O-glucoside, clovin, flavovilloside, quercetin 3-O-galactoside-7-O-rhamnoside, quercetin 3-O-robinobioside, hyperoside, as well as quercetin, which was discovered earlier. Additionally, using chrom liquid chromatography–mass spectrometry profiling, the presence of 41 components of phenolic and terpene nature was revealed. The study of the dynamics of accumulation of individual compounds in the above-ground organs of P. sibirica showed that the highest content of iridoids, flavonoids and phenylpropanoids was found in the flowering phase. The study of the biological activity of P. sibirica metabolites indicates that some iridoid aglycones have a high affinity for 5-HT2C receptors, and flavonoids and phenylpropanoids have antioxidant activity. The results obtained allow us to characterize P. sibirica as a plant source for obtaining compounds with potential hypnotic and antioxidant activity.