Chemical and biological studies on the methanol extract of Gynura pseudochina var. hispida
In continuation of our search for bioactive natural products from Thai medicinal plants as potential anti-inflammatory, anticancer and antioxidant agents , Gynura pseudochina (L.) var. hispida Thv. (GPH) (Asteraceae) was studied for potential NF-kB inhibitory compounds. Traditionally the fresh leaves and rhizomes have been used externally to treat inflammations of the skin as well as for viral infections and has been investigated as a potential AIDS remedy [2–4]. Extraction of the leaves was carried out by cold extraction using petroleum ether, ethyl acetate and methanol. Separation and isolation were achieved using Sephadex LH-20 column chromatography, TLC and HPLC. For the structure elucidation, 1D and 2D NMR and ESI-MS experiments were used. Quercetin-rutinoside, 3, 5- dicaffeoyl quinic acid, 4, 5 dicaffeoyl quinic acid and 3-, or 5- caffeoyl quinic acid were isolated and found to possess NF-kB inhibitory properties with the IC50 values ranging from 25 to 83µg/ml. All are reported from this species for the first time. Gynura spp. is a member of the Senecioneae, and G. segetum and G. divaricata were reported to contain hepatotoxic pyrrolizidine alkaloids (PAs) . Consequently, the presence of PAs in the methanol extract of GPH was assessed. TLC with spray reagents were used and the results were compared with the PAs fraction separated from Comfrey (Symphytum officinale L.). No hepatotoxic PAs were found to present in the methanol extract of GPH.
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