Comparative secondary metabolite expression in callus cultures and mother plant in Barleria prionitis L.

Abstract The present study is the first report on the quantitative determination of secondary metabolites in callus cultures of B. prionitis L, an important medicinal plant. We examined the stem-derived and leaf-derived callus for their antioxidant potential and accumulation of phenolics, flavonoids, and active principles viz. shanzhiside methyl ester (SME) and squalene and compared these parameters vis a vis mother plant counterpart. Four solvents viz. methanol, ethanol, acetone, and distilled water (aqueous) extracts were prepared for analysis. Callus cultures not only preserved the metabolite profile of the mother plant but also displayed their elevated levels. Leaf-derived callus surpassed stem-derived callus in most of the parameters studied. The highest phenolic content (21.46 mg GAE g− 1 FW) and flavonoid content (24.58 mg of RE g− 1 FW) was observed in methanol extract of leaf-derived callus, representing a 3-fold and 2-fold increase over mother plant leaf, respectively. Antioxidant capacity based on FRAP and DPPH assay was highest in methanol extract of leaf-derived callus (7-fold and 3-fold increase over mother plant, respectively) while ABTS assay showed the highest activity (122-fold increase) in acetone extract of leaf-derived callus. HPTLC analysis revealed an enhanced concentration of squalene (10-fold) and SME (2.3-fold) in acetone and methanol extract of leaf-derived callus, respectively, compared to mother explants. Results of RP-HPLC for phenolics showed the highest gallic acid content (99-fold increase) in ethanol extract of stem-derived callus whereas catechol was maximum (37- fold increase) in aqueous extract of leaf-derived callus. These findings suggest that callus cultures of B. prionitis can be a potential source of active metabolites. Further, cell suspension cultures can be established from the callus which could be an avenue for the large-scale production of bioactive compounds.