Plant regeneration through direct somatic embryogenesis, antioxidant properties, and metabolite profiles of Swertia corymbosa (Griseb.) Wight ex CB Clarke

A protocol for induction of direct somatic embryogenesis and subsequent plant regeneration for the medicinally important and endangered plant of Swertia corymbosa has been developed for the first time. In the present study, in vitro derived leaf explants were cultured on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) individually and in combination with cytokinins for its effectiveness to induce the differentiation of somatic embryos. The antioxidant activities of methanolic extracts from non-embryonic callus (NEC), pre-embryoid masses (PEM), somatic embryos at globular stage (SEG), somatic embryos at heart-shaped stage (SEHS), and cotyledonary embryos (SEC) of S. corymbosa were evaluated using three in vitro assays: scavenging of free radicals (DPPH and ABTS) and ferric reducing antioxidant test. In all cases, the methanolic extract from SEG demonstrated better antioxidant activity than those taken from other tested samples. Higher amounts of swertianin (1), methylswertianin (2), and 1,2- dihydroxy-6-methoxyxanthone-8-O--D-xylopyranosyl (3) were found in SEG stage followed by SEHS and PEM when compared to NEC and SEC.