Antioxidant and antimicrobial activities of callus culture and leaf extracts of wild Crotalaria retusa (rattlepod)
The present study describes the in vitro antimicrobial and antioxidant activity of methanol extracts of callus culture and leaves of wild plants of Crotalaria retusa Linn. Callus cultures from leaves were initiated on MS media supplemented with various combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6 Benzyloaminopurine (BAP). Optimum callus regeneration was obtained on MS medium supplemented with 0.5 mg/L BAP and 1.0 mg/L 2,4-D with 50% cultures response at 20 days. The wild plant extracts (WPE) showed the highest antibacterial activity with zone of inhibition (ZI) of 13.83±0.33 mm on Pseudomonas aeruginosa (Gram negative), as the most affected organism. The callus culture extract (CCE) gave the lowest MIC value of 0.78 mg/ mL for most of the bacteria and fungi and the lowest MBC values of 0.78 mg/ mL and 1.56 mg/ mL against bacteria and fungi, respectively. The WPE showed a higher antioxidant activity (91%) than the CCE (58%). Comparable total phenol content was observed in the WPE and CCE, whereas the WPE showed a higher flavonoids content (6.56±1.52 mg equivalent of quercetin/g of extract) than the CCE (3.22±1.01 mg equivalent of quercetin/g of extract). The in vitro propagation protocol employed in this study supported the rapid development of calluses from Crotalaria retusa seed explants which may offer an alternative to the exploitation of this valuable medicinal plant for its antimicrobial and antioxidant properties via optimization of the tissue culture technique.
Keywords: Crotalaria retusa; In vitro propagation; Callus culture; Antimicrobial activity; Antioxidant activity