Antibacterial activity of aerial parts as well as in vitro raised calli of the medicinal plant Saraca asoca (Roxb.) de Wilde

Leaves, stem, and flowers of Saraca asoca, an endangered medicinal plant in India, and young explants cultivated on Murashige & Skoog's medium containing 6-benzylaminopurine were analyzed for antibacterial potential. Alcoholic and aqueous extracts from parent explants and their in vitro raised calli were tested by an agar well diffusion method. Minimal inhibitory concentrations (MICs) of the extracts were determined by broth microdilution method. Aqueous extracts showed antibacterial activity against limited bacterial species, whereas alcoholic extracts were active against a wider range of bacteria. Although the alcoholic extracts of all the explants and calli showed antibacterial activity, the extracts derived from flowers and their calli showed better results. Extracts derived from calli showed comparable results to the extracts from explants. Overall, the MICs of the extracts ranged from 0.039 to 1.25 mg/mL. MICs against gram-positive bacteria ranged from 0.078 to 1.25 mg/mL, whereas they ranged between 0.039 and 0.625 mg/mL against gram-negative bacteria. A MIC distribution plot showed that gram-negative bacteria were more susceptible to the extracts than gram-positive bacteria. It is concluded that extracts of S. asoca contain antibacterial agent, and as the calli gave good results, in vitro cultivation of the explants may be used to obtain antibacterial compounds. This is the first report on antibacterial activity of S. asoca, especially through in vitro raised calli.