Antioxidant flavonoids and phenolic acids from leaves of Leea guineense G. Don (Leeaceae)

Abstract

From leaves of Leea guineense (Leeaceae) three hydrophilic flavonoids were isolated and identified as quercetin-3'-sulphate-3-O-alpha-L-rhamnopyranoside, quercetin-3,3'-disulphate and a new flavonoid sulphate, quercetin-3,3',4'-trisulphate, together with kaempferol, quercetin, quercitrin, mearnsitrin, gallic acid and ethyl gallate. The structures were established by spectroscopic analysis (UV, MS, (1)H-NMR, (13)C-NMR and 2D-NMR). Their antioxidant effect on free radical scavenging was evaluated in the DPPH assay.

Evaluation of Larvicidal andin Vitro. Antiparasitic Activities of Plants in a Biodiversity Plot in the Altos de Campana National Park, Panama

“…Ethyl gallate and methyl gallate have been reported to possess other biological activities such as antioxidant effect on free-radical scavenging (Op de Beck et al, 2003) and relaxant effect in guinea-pig trachea in vitro by activation of large conductance Ca 2þ activated K þ channels (Paulino et al, 1999). The only report on the chemistry of the genus Talisia is about the isolation of isolectins from T. escualenta (Freire et al, 2001).…”

Prokaryotic and Eukaryotic Aryl Sulfotransferases: Sulfation of Quercetin and Its Derivatives

“…Besides this, some sulfated flavonols, including quercetin and rutin, possess anticoagulant or antiaggregant activity and also substantial antiviral activity . Quercetin sulfates were shown to display some lipid peroxidation inhibitory effect and antiradical activity (in the 2,2‐diphenyl‐1‐picrylhydrazyl assay) . Quercetin 3′‐ O ‐sulfate demonstrated not only inhibition of cyclooxygenase‐2 activity but also reduction of the expression of cyclooxygenase‐2 messenger RNA .…”

“…[23] Quercetin sulfates were shownt od isplay some lipid peroxidation inhibitory effect [24] anda ntiradical activity (in the 2,2-diphenyl-1-picrylhydrazyl assay). [25] Quercetin 3'-O-sulfate demonstrated not only inhibition of cyclooxygenase-2a ctivity but also reduction of the expression of cyclooxygenase-2 messenger RNA. [26,27] Other interesting biological activities (antimicrobial, anti-inflammatory,a nti-HIV,a ntitumor,e tc.)…”

Leeaoside, a new megastigmane diglycoside from the leaves of Leea thorelii Gagnep

“…The phytochemical study on the chemical constituents of this plant has not been reported. However, previous investigation of plants in the same genus reported the presence of flavonoids and phenolic acid [1][2][3]. The present paper deals with the isolation and structural determination of five compounds, including a new megastigmane diglycoside (1), as well as one known benzyl glycoside (2), two flavonol glycosides (3 and 4) and one megastigmane glucoside (5) from the leaves of this plant.…”