Flavonol Glycosides from the Leaves of Embelia Keniensis

Five new flavonol glycosides characterized as syringetin 3‐O‐α‐rhamnoside‐7‐O‐β‐glucoside, syringetin 3‐O‐α‐rhamnoside‐7,4′‐di‐O‐β‐glucoside, quercetin‐7‐O‐β‐galactosyl (1→3)‐β‐galactoside, myricetin 3‐O‐α‐rhamnosyl (1→4)‐β‐galactoside and myricetin 3‐O‐β‐glucosyl (1→2)‐β‐glucoside‐7‐O‐β‐glucosyl‐(1→4)‐α‐rhamnoside have been isolated from a methanolic extract of Embelia keniensis leaves. Known flavonols isolated from the same extract included myricetin, quercetin, kaempferol, myricetin 3‐O‐α‐rhamnoside, myricetin 3‐O‐β‐glucoside, quercetin 3‐O‐α‐rhamnoside, quercetin 3‐O‐β‐glucoside, quercetin 3‐O‐β‐xyloside, isorhamnetin 3‐O‐α‐rhamnoside and myricetin 3‐O‐rutinoside. Their structures were established from extensive spectroscopic and chemical studies and by comparison with authentic samples.     

New pentacyclic triterpene saponins with strong anti-leishmanial activity from the leaves of Maesa balansae

Six new triterpene saponins bearing an oxygen bridge between C-13 and C-28 and with pronounced anti-leishmanial activity were isolated from the methanolic extract of leaves of the Vietnamese medicinal plant Maesa balansae. The structure was established on the basis of detailed NMR (COSY, NOESY, HMQC, HMBC, TOCSY and DEPT) and FAB-MS studies along with chemical degradation. All saponins identified contained the same pentaglycosidic side chain, but a different esterification pattern on the triterpenoid part. Biological evaluation of the individual compounds against visceral leishmaniasis (Leishmania infantum amastigotes) revealed a much better activity in vitro compared to the reference compound Pentostam^®, which is currently used as first-line treatment for leishmaniasis.     

New triterpenoid sapoin from Ardisia gigantifolia Stapf

<正>One new triterpenoid sapoin with two known triterpenoid sapoins:3β-O-{α-L-rhamnopyranosyl-(1→3)-[β-D-xylopyranose-(1→2)]-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl}-3β-hydroxy-13β,28-epoxy-oleanan-16-oxo-30-al(1),3β-O-{α-L-rhamnopyranosyl-(1→3)-[(β-D-xylopyranosyl-(1→2)]-β-D-galactopyranosyl-(1→4)-[(β-D-glucopyranosyl-(1→2)]-α-L-ara-binopyranoside}-16α-hydroxy-13,28-epoxy-oleanane(2) and cyclamiretin A 3β-O-α-L-rhamnopyranosyl-(l→3)-[P-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside(3) were isolated fromArdisia gigantifolia Stapf.Their structures were elucidated by means of ~1H and ~(13)C NMR spectroscopic studies,including2D-NMR technique.     

A new 5-alkylresorcinol glucoside derivative from Cybianthus magnus

One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds, isolated from four plants belonging to Myrsinaceae family (2, 3 isolated from C. magnus; 4–7, 10 and 11 isolated from Myrsine latifolia; 4, 8 and 9 isolated from Myrsine sessiflora; 6, 7, 10, 12 and 13 isolated from Myrsine congesta). Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. So far, only nine 5-alkylresorcinol glucosides were isolated from leaves of Grevillea robusta. Since resorcinols are known to exhibit strong cytotoxic activity, compounds 1 and 2 were tested against cell lines 3T3, H460, DU145 and MCF-7 for cytotoxicity in vitro and compounds 3–13 were tested for their antileishmanial activity. Compound 2 displayed a strong cytotoxic activity with IC₅₀ values ranging between 22 and 100 μM for all tested cell lines. Compounds 3–13 were not active against Leishmania amazonensis amastigotes.