Adventitious root cultures from leaf explants of Helicteres angustifolia L. as a novel source for production of natural bioactive compounds

In this study, adventitious roots of Helicteres angustifolia L. (H. angustifolia) were generated on Murashige and Skoog salt mixture (MS) medium with auxin and ascorbic acid as additives. The root initiation ratio reached 100% on MS medium supplemented with 3.0 mg/L NAA and 0.4 mg/L ascorbic acid at 28 °C. The root number reached 15 ± 2 per leaf explant with a length of 1.70 ± 0.52 cm. Moreover, the cultured roots exhibited similar functional groups with wild plant roots and produced abundant classes of phenolic secondary metabolites. The contents of total phenolics and flavonoids of the cultured roots reached 9.68 mg GAE/g and 25.66 mg RE/g, respectively. Compared to the wild plant roots, the cultured roots produced more gallic acid (1.97 ± 0.09 mg/g), catechol (0.17 ± 0.00 mg/g), caffeic acid (0.34 ± 0.01 mg/g), and quercetin (0.84 ± 0.02 mg/g). Additionally, the adventitious root extract showed dose-dependent antioxidant capability (IC50 of DPPH = 4.10 ± 0.27 mg/mL, IC50 of hydroxyl = 1.59 ± 0.07 mg/mL) and inhibition activities on rat intestinal maltase and sucrase (IC50 of maltase = 5.66 ± 0.20 mg/mL, IC50 of sucrase > 8.0 mg/mL). The adventitious root cultures are promising alternatives to produce bioactive phenolic compounds and functional foods of H. angustifolia.