Chitosan-mediated elicitation of secondary metabolism in Rhazya stricta and the in-silico exploration of phytochemicals as potential drug candidates against H1299-NSLC cell lines

Abstract

Rhazya stricta is a medicinally important plant known for its diverse pharmaceutical benefits, particularly in biosynthesizing anticancer and anti-inflammatory metabolites. For the eco-friendly and sustainable synthesis of phytochemicals and plant biomass, a biotechnological technique, ‘elicitation,’ is highly effective in various in vitro cultures. This study investigated the use of different concentrations of chitosan as a biotic elicitor in callus cultures of R. stricta, aiming to enhance biomass production, biological activities, and secondary metabolism. The findings demonstrated that maximum biomass production (FW: 40.91 ± 1.65 g/L; DW: 3.53 ± 0.11 g/L) was observed at 5 mg/L of chitosan as compared to the control. Secondary metabolites showed immense production [Phenolic content (14.50 ± 0.14 µg/mg; Flavonoid content (17.73 ± 0.80 µg/mg)] in callus cultures treated with 5 mg/L of chitosan as compared with control. Additionally, at a chitosan concentration of 1 mg/L, the elicited callus cultures had the maximum antioxidant capacity as measured by a phosphomolybdenum-based assay and DPPH free radical scavenging assay, with values of 131.82 1.53 µg/mg TAC and 94.6 % of DPPH inhibition. Callus extracts treated with 2 μg/mL of chitosan for 15 days significantly decreased the viability of H1299 cells to 60.52 %, showcasing the ability of chitosan to promote the cytotoxicity of plant extracts. In contrast to the control, cultures with chitosan concentrations of 5 mg/L revealed a considerable accumulation of pharmacologically active components, with 14 out of 19 alkaloids being the most accumulated compounds, as determined by LC-HRMS/MS analyses. Among the identified compounds, Eburnamine emerges as the most viable drug candidate that can be further screened against non-small cell lung cancer. This study highlights the potential of chitosan in augmenting the secondary metabolism of R. stricta callus cultures and provides insight into the cytotoxic potential of extracted phytochemicals, which could enhance the anticancer potential of pharmaceuticals.