Isolation and identification of polyphenols from Marsilea quadrifolia with antioxidant properties in vitro and in vivo.

Marsilea quadrifolia is an edible aquatic medicinal plant used as a traditional health food in Asia. Four new polyphenols including kaempferol 3-O-(2″-O-E-caffeoyl)-ß-d-glucopyranoside (1), kaempferol 3-O-(3″-O-E-caffeoyl)-α-l-arabinopyranoside (3), 4-methy-3'-hydroxypsilotinin (4) and (±)-(E)-4b-methoxy-3b,5b-dihydroxyscirpusin A (18) together with 14 known ones (2, 5-17) were isolated from the ethanol extract of M. quadrifolia. Structures of the new compounds were elucidated by extensive spectroscopic analyses. In DPPH and oxygen radical absorbance capacity antioxidant assays, some compounds showed stronger antioxidant activities and quercetin (9) was the most potent antioxidant in both assays. In a restraint-induced oxidative stress model in mice, quercetin significantly attenuated the increase in plasma ALT and AST levels as well as liver MDA content of restrained mice. Liver SOD activity was also significantly increased by quercetin, indicating a significant in vivo antioxidant activity. As a rich source of polyphenols with strong antioxidant activities, M. quadrifolia may be developed to a product for relieving oxidative stress.

Cyclodepsipeptides from the ascocarps and insect-body portions of fungus Cordyceps cicadae.

A new cyclodepsipeptide cordycecin A (1), together with four known ones beauvericin E (2), beauvericin J (3), beauvericin (4), and beauvericin A (5) was isolated from the ascocarps and insect-body portions of fungus Cordyceps cicadae. Their structures were identified by NMR and MS analyses. The absolute configuration of 1 was confirmed by crystal X-ray diffraction. Compounds 2-5 exhibited a significant inhibitory effect on HepG2 and HepG2/ADM cells with IC50 values ranging from 2.40±0.37 to 14.48±1.68 µM. Interestingly, compounds 3-5 showed cytotoxic activity against multiple drug resistant HepG2 cell line (HepG2/ADM) with IC50 value 25-fold more sensitive to doxorubicin.

New monoterpenoid alkaloids from the aerial parts of Uncaria hirsuta.

To investigate the chemical constituents of medicinal plant Uncaria hirsuta, three new monoterpenoid alkaloids, named hirsutanines A-C (1-3), were isolated. Their structures with absolute configurations were elucidated by means of NMR, X-ray diffraction and CD analysis. Compound 3 was the first dimeric monoterpenoid alkaloid obtained from genus Uncaria.