Thai medicinal plants and the search for new anti-inflammatory and anticancer agents

Nine plant species with anti-inflammatory effects were selected from Thai textbooks. It is expected that long history of their uses might offer opportunities for the discovery of novel anti-inflammatory and/or anticancer agents. In this study, anti-inflammatory NF-κB inhibitory activities were determined by luciferase assay and effects on LPS-induced pro-inflammatory cytokines PGE2, IL-6, IL-1β, and TNFα were assessed by ELISA [1]. Cytotoxicity activities were examined by the MTT test in HeLa cells, and the XTT test in leukaemia CCRF-CEM cells including their multidrug-resistant CEM-ADR5000 subline [2]. Among all the tested extracts, Gynura pseudochina (L.) DC. var. hispida Thv. (Asteraceae) (ME) and Oroxylum indicum (L.) Kurz. (Bignoniaceae) (EA) showed the greatest NF-κB inhibitory effects with the lowest IC50 values (41.96µg/ml and 47.45µg/ml, respectively). While G. pseudochina var. hispida (ME) inhibited the release of IL-1β (IC50 2.46µg/ml), O. indicum (EA) also inhibited the release of PGE2 (IC50 26.98µg/ml). Muehlenbeckia platylclada F., Muell., Meisn. (Polygonaceae) (EA and ME) did not inhibit NF-κB activation but inhibited the release of IL-6, IL-1β and TNF-α with the lowest IC50 values ranged from 0.28–8.67µg/ml. Pouzolzia indica (L.) Gaudich. (Urticaceae) (PE) show the strongest antileukemic effects on both CCRF-CEM cells and the multidrug resistant subline at 10µg/ml (90.25±0.29% and 89.52±0.12% cell dead, respectively). The active compounds isolated from G. pseudochina var. hispida (ME), the strongest NF-κB inhibitory extract, were identified as the known compounds quercetin-3-rutinoside (IC50 =24.78µg/ml) and quinic acid (IC50=49.18µg/ml).

Acknowledgement: The Royal Thai Government for funding.

References: [1] Bremner, P. et al. (2004) Planta Med. 70:1–5.

[2] Efferth, T. et al. (2002) Blood Cell. Mol. Dis. 28:160–168.