Antibacterial potential of the extracts derived from leaves and in vitro raised calli of medicinal plants Pterocarpus marsupium Roxb., Clitoria ternatea L., and Sanseveiria cylindrica Bojer ex Hook

다국어 초록 (Multilingual Abstract)

Pterocarpus marsupium, Clitoria ternatea, and Sanseveiria cylindrica are some of the important and endangered medicinal plant species of India. Despite of medicinal properties, antibacterial potential of the plants have not yet been explored. The present study was designed to optimize the in vitro technique for micropropagation and to screen the extracts from leaves and in vitro raised calli for antibacterial properties. Excised leaf-explants from the parent plants were surface sterilized and cultivated on Murashige & Skoog's (MS) medium containing $N^6$-benzyladenine (BA) in concentrations of 1, 2, 5, and $10{\mu}M$. Optimal growth of calli was noticed at a concentration of $5{\mu}M$, therefore the extracts from calli grown at this concentration were further studied for antibacterial activity. Both alcoholic and aqueous extracts from leaves of respective plants, and their in vitro raised calli were tested for antibacterial activity by agar well diffusion method against a range of Gram-positive and Gram-negative bacteria. Aqueous extracts showed antibacterial activity against limited number of bacterial species; notably the extracts of C. ternatea which showed antibacterial activity against Streptococcus pyogenes, Bacillus subtilis and Bacillus cereus. Alcoholic extracts of all three plants showed antibacterial activity against a wider range of bacteria. Among the Gram-positive bacteria, extracts from C. ternatea showed strong antibacterial activity against Bacillus spp., whereas the extracts of S. cylindrica showed good antibacterial potential for Staphylococcus aureus, S. epidermidis and S. pyogenes. The extracts from all three plants showed antibacterial activity against Gram-negative bacteria, including, Salmonella spp. and Shigella dysenteriae; organisms causing enteric fever and dysentery. In most of the cases, the extracts from respective calli showed comparable, and in some cases better, result in comparison to the extracts from parent leaves. To the best of our knowledge this is the first preliminary report on antibacterial potential, especially through calli extracts, of these plants; and in vitro cultivation of the explants may be used to obtain phytotherapeutic compounds.