Anti inflammatory potential of Decalepis hamiltonii (Wight and Arn) as evidenced by down regulation of pro inflammatory cytokines-TNF-alpha and IL-2

Abstract

Ethnopharmacological relevance: Ancient tribes in the Western Ghats of India use the roots of Decalepis hamiltonii Wight and Arn (Asclepiadaceae) for several medicinal purposes particularly inflammation.

Aim: To investigate whether the pure compounds obtained from the Decalepis hamiltonii have anti inflammatory activity.

Materials and methods: The bioactive lead molecules from the roots of Decalepis hamiltonii were extracted into dichloromethane/methanol and purified by silica gel column chromatography. Structural elucidation of the purified compounds was performed with (1)H and (13)C NMR and mass spectrometry. The in vitro anti inflammatory activity of the pure compounds was studied in mitogen induced peripheral blood mononuclear cells (PBMCs) employing [(3)H] thymidine uptake assay and their effect on cytokine expression by reverse transcriptase polymerase chain reaction (RT-PCR). The inhibition of nuclear factor kappaB (NF-kappaB) activity in the presence of pure compounds was determined in J774 A.1 cells. The cytotoxicity of the compounds was tested using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay kit.

Results and discussion: Lupeol acetate (Compound 1) and (2S)-5,7,4'-trihydroxy flavanone 4'-O-beta-d-glucoside (Compound 2) isolated from Decalepis hamiltonii roots inhibited the proliferation of mitogen induced PBMCs with an IC(50) value of 8 and 0.5mug/ml respectively. MTT assay revealed the compounds to be non-cytotoxic. Though, both the compounds down regulated the synthesis of mRNA of the pro inflammatory cytokines, interleukin-2 (IL-2) and tumour necrosis factor-alpha (TNF-alpha), the anti inflammatory cytokine interleukin-10 (IL-10), was found to be up regulated. NF-kappaB activation in J774 A.1 cells were also inhibited by both the compounds.

Conclusion: Lupeol acetate and (2S)-5,7,4'-trihydroxy flavanone 4'-O-beta-d-glucoside isolated from Decalepis hamiltonii roots showed anti inflammatory activities by down regulating TNF-alpha and IL-2 specific mRNA, besides up regulating the synthesis of mRNA of IL-10.