Traditionally used Thai medicinal plants: In vitro anti-inflammatory,anticancer and antioxidant activities

Aims of the study

In order to assess traditional Thai claims about the therapeutic potential of medicinal plants and to select plants for future phytochemical research, nine plant species with anti-inflammatory uses were selected from Thai textbooks and assessed for their in vitro anti-inflammatory, antiproliferative and antioxidant activities.

Methods

Nuclear factor-kappaB (NF-κB) inhibitory effects in stably transfected HeLa cells were determined by luciferase assay, and effects on LPS-induced pro-inflammatory mediators prostaglandin E2 (PGE2), interleukin (IL)-6, IL-1β, and tumour necrosis factor (TNF)α in primary monocytes were assessed by ELISA. Cytotoxic activities were examined against HeLa cells, human leukaemia CCRF-CEM cells and the multidrug-resistant CEM/ADR5000 subline using the MTT and XTT tests. However, a redox status has been linked with both inflammation and cancer, antioxidant effects were also assessed using the DPPH, lipid-peroxidation, and Folin-Ciocalteau methods.

Results

Among all the nine species, Gynura pseudochina var. hispida and Oroxylum indicum showed the most promising NF-κB inhibitory effects with the lowest IC₅₀ values (41.96 and 47.45 μg/ml, respectively). Muehlenbeckia platyclada did not inhibit the NF-κB activation but effectively inhibited the release of IL-6, IL-1β and TNF-α with IC₅₀ values ranging between 0.28 and 8.67 μg/ml. Pouzolzia indica was the most cytotoxic against CCRF-CEM cells and the multidrug-resistant CEM/ADR5000 cells (9.75% and 10.48% viability, at 10 μg/ml, respectively). Rhinacanthus nasutus was the most potent cytotoxicity against HeLa cells (IC₅₀ 3.63 μg/ml) and showed specific cytotoxicity against the multidrug-resistant CEM/ADR5000 cells (18.72% viability at 10 μg/ml, p < 0.0001 when compared to its cytotoxicity against CCRF-CEM cells). Moreover, Oroxylum indicum showed a high level of antioxidant activity by inhibiting lipid-peroxidation (IC₅₀ 0.08 μg/ml).

Conclusions

This study provides in vitro evidence for the use of the Thai plants, most importantly Gynura pseudochina var. hispida, Oroxylum indicum and Muehlenbeckia platyclada as Thai anti-inflammatory remedies and these plants are now a priority for further phytochemical research.