Anti-mycobacterial, -oxidative, -proliferative and -inflammatory activities of dichloromethane leaf extracts of Gymnosporia senegalensis (Lam.) Loes

A crude dichloromethane leaf extract of Gymnosporia senegalensis and its six fractions were tested for anti-mycobacterial activity using a fluorescent microplate assay against the H37Rv strain of Mycobacterium tuberculosis as well as antioxidant activity using the cell free based assays, DPPH and ferric ion reducing power as well as a colorimetric assay for measuring nitric oxide production in RAW 264.7 cells. The in vitro anti-inflammatory potential of fractions was screened by measuring tumor necrosis-alpha production in RAW 264.7 cells. The test agents exhibited anti-mycobacterial activity in the following sequence; SP2-1F5 > crude extract > SP2-1F2 > SP2-1F6 > SP2-1F1 > SP2-1F3 > SP2-1F4 with minimum inhibitory values ranging from 21.4 to 54.2 μg/mL. Fractions SP2-1F1, SP2-1F3 and SP2-1F5 exhibited significant antioxidant activities at concentrations between 125 μg/mL and 500 μg/mL employing the cell free-based and colorimetric assays. The crude extract of the plant leaf also exhibited ferric ion reducing power at 250 and 500 μg/mL. Fractions SP2-1F1, SP2-1F3 and SP2-1F5 showed noticeable tumor necrosis factor-alpha production in RAW cell at 125 to 500 μg/mL. The laboratory activities conducted in the present study presumably indicate that the leaf extract of Gymnosporia senegalensis contain chemical entities that exhibit in vitro inhibition of mycobacterium growth, production of nitric oxide and tumor necrosis factor-alpha in a mouse macrophage cell line as well as increased radical scavenging potential. Further laboratory studies are to be conducted in pursuance of the active chemical ingredients of leafs of this plant species.