Flavonoids, Hydroxycinnamates, and Phenolamides of Phacelia tanacetifolia Benth. (Boraginaceae) Herb
摘要
Phacelia tanacetifolia Benth. (Boraginaceae) is an unpretentious melliferous plant species that is widely cultivated as a cover crop. Spectrophotometric analysis of eight Russian varieties of P. tanacetifolia revealed the presence of flavonoids (0.96 – 3.25 mg/g) and phenylpropanoids (1.53 – 15.69 mg/g) in the herb of this species. Liquid chromatography mass spectrometric studies identified 47 phenolic compounds, including caffeoylquinic and feruloylquinic acids; caffeic acid depsides; glycosides of isorhamnetin, quercetin, kaempferol, luteolin and apigenin; and hydroxycinnamoyl conjugates of spermidine and putrescine, most of which were new for the species. Chromatographic separation of the BuOH extract of P. tanacetifolia isolated a new compound (phaceliaside) that was N1,N5,N10-tri-O-(EEE)-p-coumaroyl spermidine 4′′-O-β-Dglucopyranoside, the structure of which was elucidated using UV and NMR spectroscopy and mass spectrometry. Quantitative analysis data indicated a high content of flavonoids (up to 3.61 mg/g), hydroxycinnamates (up to 5.71 mg/g), and phenolamides (up to 9.50 mg/g) in the herb of P. tanacetifolia. The effect of individual compounds on the activity of three tyrosinases was studied. It was shown that phenolamides, including N1, N10-di-O-(EE)-p-coumaroyl-N5-O-(E)-caffeoyl spermidine, N1,N10-di-O-(EE)-p-coumaroyl putrescine, and N1,N5,N10-tri-O-(EEE)-p-coumaroyl spermidine, effectively inhibited human tyrosinase. The studies showed that P. tanacetifolia is a source of various phenolic compounds with antityrosinase activity.