High frequency in vitro plantlet regeneration and antioxidant activity of Enicostema axillare(Lam.) Raynal ssp. littoralis (Blume) Raynal: An important medicinal plant

Abstract

Objective: To develop a method for high frequency plantlets regeneration protocol for Enicostema axillare (Lam.) Raynal ssp. littoralis (Blume) Raynal (E. axillare) without intermediate callus phase and to determine the content and correlation of phenolic compounds and their antioxidant activity of both the plants derived from nature and nodal culture by DPPH assay. Methods: The nodal explants were cultured on MS basal medium fortified with different concentration of various growth regulators such as BAP, KIN, TDZ and 2iP (0.5–2 mg/L) individually and in combinations with or without GA3 for shoot bud induction and multiplication. Total phenol and flavonoid content was determined in both plants from nature and nodal culture and antioxidant activity was determined by DPPH assay. Results: The highest number of multiple shoot (108.00±3.55 shoots/explants) was obtained on MS medium supplemented with BAP (2 mg/L) in combination with KIN (0.5 mg/L) and GA3 (2 mg/L). Rooting was optimized on half-strength MS medium supplemented with IAA (0.5 mg/L). The rooted plantlets were transferred to paper cups containing vermiculite and hardening was successfully attained with 75% survival. Among the four extract of methanol and water extract from both the plantlet from nature and nodal culture, the concentration of flavonoid was found to be higher in methanol extract of the plants from nature (146.57±1.68 mg rutin/g extract) and phenol content was higher in the water extract of plant from nature (52.53±1.67 mg GAE/g extract). The radical scavenging activity of four extracts. Methanol extract of plant grown in nature showed the highest radical scavenging activity (IC50 = 87.10 μg/mL) was investigated by DPPH test. Conclusion: The present study not only enables reinforcement of wild plant populations using ex situ growth of individuals, but it also helps for high scale production of plantlets. A high correlation between antioxidant capacities and their total phenolic contents indicated that flavonoid compounds were a major contributor of antioxidant activity of both plants grown from nature and nodal culture.

Keywords

• Enicostema axillare
• Nodal explants
• Shoot and root regeneration
• Total flavonoid and phenol content
• DPPH activity