Chiuming Chen

Withangulatin A, a new withanolide from Physalis angulata

A new withanolide as a topoisomerase II inhibitor, withangulatin A was isolated from the whole herb of Physalis angulata L. (Solanaceae). The structure of withangulatin A was established as (20S, 22R)-15α-acetoxy-5β,6β-epoxy-4β,14α-dihydroxy-1-oxowitha-2,16,24-trienolide on the basis of spectroscopic and chemical evidence

A mansonone from Helicteres angustifolia

Abstract Four sesquiterpenoid quinones were isolated from the root bark of Helicteres angustifolia and identified as mansonones E, F, H and M on the basis of chemical and spectroscopic evidence. Mansonone M is new. It is shown that helicquinone is identical with mansonone H.

Pterosin-derivate aus der familie pteridaceae

Abstract The investigation of four pteridaceous ferns afforded, in addition to known pterosins, six new pterosins and three new pterosides. The structures are elucidated mainly by spectroscopic methods.

New flavoid glycosides of Helicteres angustifolia

Two new flavonoid glycosides, takakin 8-O-β-D-glucuronide 6″methyl ester (2), takakin 8-O-β-D-glucuronide 2″-sodium sulfate (3) together with a known flavonoid glycoside, takakin 8-O-β-D-glucuronide were isolated from the root bark of Helicteres angustifolia (Sterculiaceae). The stru- ctures of these compounds were established on the basis of spectrosco- pic and chemical evidence

Cytotoxic Triterpenoids from the Root Bark of Helicteres angustifolia

Three new triterpenoids, 3β‐acetoxy‐27‐[(E)‐cinnamoyloxy]lup‐20(29)‐en‐28‐oic acid methyl ester (1), 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]lup‐20(29)‐en‐28‐oic acid (2), and 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]olean‐12‐en‐28‐oic acid methyl ester (3), together with nine known triterpenoids, 4–12, were isolated from the root bark of Helicteres angustifolia. The structures of these compounds were established on the basis of spectroscopic methods including 2D‐NMR experiments. All twelve compounds were tested for their cytotoxic activities against human colorectal cancer (COLO 205), human hepatoma (Hep G2), and human gastric cancer (AGS) cell lines in vitro. Among them, compounds 2, 3, 3β‐O‐[(E)‐coumaroyl]betulinic acid (6), and pyracrenic acid (7) showed significant cytotoxic activities against human cancer cells COLO 205 and AGS.

A New Sesquiterpene Lactone Glucoside of Ixeris chinensis

A new sesquiterpene lactone glucoside, 8-epicrepioside G(1) together with two known compounds, 8-epidesacylcynaropicrin glucoside (2) and ixerin D (3) were isolated from the whole plant of Ixeris chinensis. Their structures were determined on the basis of chemical and spectro- scopic evidence. Compounds (1),(2) and (3) taste of strong bitterness