Effect of jasmonic acid elicitation period on enhancement of bioactive compounds and antioxidant activity in callus cultures of Hibicus sabdariffa Linn

Abstract

This study investigated jasmonic acid (JA) elicitation of the callus of two roselle accessions: HS003 (orange-red calyx) and HS005 (dark-red calyx). The goal was to identify the optimal exposure period for production of total anthocyanin, phenolics, and flavonoids and for enhancing DPPH radical scavenging. Dark-red callus was cultured on Murashige and Skoog (MS) medium supplemented with 4.52 µM 2,4-dichlorophenoxyacetic acid (2,4-D), 4.44 µM 6-benzyladenine, combined with 0 and 50 µM JA for treatment of HS003, and with 0 and 100 µM JA for treatment of HS005. Elicitation periods of 7, 14, 21, and 28 days were compared. Significant increases in both accumulation of bioactive compounds and enhancement of antioxidant activity were observed. In the case of HS003, the optimal exposure periods were 21 days for enhancement of total anthocyanin accumulation (1.48 ± 0.07 mg cyd-3-glu L⁻¹, or 3.70 times that of the control) and 14 days for enhancement of total phenolic and flavonoid contents (114.72 ± 6.63 mg GAE g⁻¹ dry extract and 106.15 ± 9.06 mg CE g⁻¹ dry extract, or 6.89 and 18.59 times that of the control). In the case of HS005, elicitation with 100 µM JA for 28 days yielded the greatest increase in total anthocyanin (0.86 ± 0.06 mg cyd-3-glu L⁻¹, or 6.61 times that of the control), phenolics (48.01 ± 2.47 mg GAE g⁻¹ dry extract, or 3.37 times that of the control), and flavonoids (21.41 ± 1.89 mg CE g⁻¹ dry extract, or 3.30 times that of the control). At all periods, and for both accessions, JA elicitation increased DPPH radical scavenging, compared with the control. Our results demonstrated that the dark-red callus of roselle accumulated greater amounts of bioactive compounds and exhibited enhanced antioxidant activity, following elicitation with JA for 14–21 days in the case of HS003 and 28 days in the case of HS005.