The antioxidant, radical-scavenging, anti-inflammatory, cytotoxic and antibacterial activities of methanolic extracts of seven Hedyotisspecies were investigated. The antioxidant activity was evaluated by the ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods while the radical scavenging activity was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The anti-inflammatory activity related to NO inhibition of the plant extracts was measured by the Griess assay while cytotoxicity were measured by the MTT assay against CEM-SS cell line. The antibacterial bioassay (against 4 bacteria, i.e. Bacillus subtilis B28 (mutant), Bacillus subtilis B29 (wild-type), Pseudomonas aeruginosa UI 60690 and methicillin resistant Staphylococcus aureus, (MRSA) was also carried out using the disc-diffusion method. All tested extracts exhibited very strong antioxidant properties when compared to Vitamin E (alpha-tocopherol) with percent inhibition of 89-98% in the FTC and 60-95% in the TBA assays. In the DPPH method, H. herbacea exhibited the strongest radical scavenging activity with an IC50 value of 32 microg/ml. The results from the Griess assay showed that the tested extracts are weak inhibitors of NO synthase. However, all tested extracts exhibited moderate cytotoxic properties against CEM-SS cell line giving CD50 values in the range of 21-41 microg/ml. In the antibacterial bioassay, the stems and the roots of H. capitellata showed moderate activity against the 4 tested bacteria while the leaves showed moderate activity towards B. subtilis B28, MRSA and P. aeruginosa only. The roots of H. dichotoma showed strong antibacterial activity against all 4 bacteria. All other extracts did not exhibit any antibacterial activity.

Clinacanthus nutans has had a long history of use in folk medicine in Malaysia and Southeast Asia; mostly in the relief of inflammatory conditions. In this study, we investigated the effects of different extracts of C. nutans upon lipopolysaccharide (LPS) induced inflammation in order to identify its mechanism of action. Extracts of leaves and stem bark of C. nutans were prepared using polar and non-polar solvents to produce four extracts, namely polar leaf extract (LP), non-polar leaf extract (LN), polar stem extract (SP), and non-polar stem extracts (SN). The extracts were standardized by determining its total phenolic and total flavonoid contents. Its anti-inflammatory effects were assessed on LPS induced nitrite release in RAW264.7 macrophages and Toll-like receptor (TLR-4) activation in TLR-4 transfected human embryonic kidney cells (HEK-BlueTM-hTLR4 cells). The levels of inflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-6, IL-12p40, and IL-17) in treated RAW264.7 macrophages were quantified to verify its anti-inflammatory effects. Western blotting was used to investigate the effect of the most potent extract (LP) on TLR-4 related inflammatory proteins (p65, p38, ERK, JNK, IRF3) in RAW264.7 macrophages. All four extracts produced a significant, concentration-dependent reduction in LPS-stimulated nitric oxide, LPS-induced TLR-4 activation in HEK-BlueTM-hTLR4 cells and LPS-stimulated cytokines production in RAW264.7 macrophages. The most potent extract, LP, also inhibited all LPS-induced TLR-4 inflammatory proteins. These results provide a basis for understanding the mechanisms underlying the previously demonstrated anti-inflammatory activity of C. nutans extracts.

Phytochemical studies on roots of Morinda elliptica have resulted in the isolation of a new anthraquinone, 2-formyl-1-hydroxyanthraquinone, and 10 known anthraquinones. The structures of the anthraquinones were established based on spectral studies.

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