Synergistic effects of salicylic acid and light stress on bioactive metabolites in basil callus cultures

Abstract

Thai basil is a well-known medicinal plant that is rich in bioactive antioxidant compounds having a variety of health benefits, including cancer, diabetes, and cardiovascular disease prevention. Plant cell and tissue culture technologies can be systematically developed as a valuable, low-cost biomass supply for the production of high-value phytochemicals. The aim of this study is to create an effective protocol for producing “Thai basil” leaf derived callus cultures with a high yield of biomass and antioxidants as an alternative to growing plants using salicylic acid and various light regimes as elicitors. Salicylic acid (SA) and light significantly affects many metabolic processes coupled with biosynthesis of secondary metabolites in plants. Callus was exploited with various SA concentrations under 3 different light regimes. Indeed, the results of our research disclose that continuous light with moderate SA concentration (10 μM) significantly increased total phenolic content (18.7 ± 1.13 mg/g DW), flavonoid content (7.2 ± 0.21 mg/g DW), eugenol (0.56 ± 0.015 mg/g DW), rosmarinic acid (54.35 ± 1.85 mg/g DW), chicoric acid (64.46 ± 6.71 mg/g DW) cyanidin (0.42 ± 0.021 mg/g DW) and peonidin (0.32 ± 0.002 mg/g DW) production followed by photoperiod and dark. SA treatment (25 μM) under photoperiod showed maximum biomass accumulation (FW: 226.6 ± 3.91 g/L and DW: 16.44 ± 0.59 g/L) and caffeic acid production (0.54 ± 0.025 mg/g DW). Moreover in vitro antioxidant potential (DPPH and ABTS) and cellular antioxidant capacity was found higher in continuous light treated callus along with 10 μM SA treatment. Callus extracts also showed biocompatibility with human erythrocytes that indicates their nontoxic nature and moderate potential against alpha-amylase inhibition which will help in regulating glucose level. Compared to commercial leaves, callus extracts showed higher production of chicoric acid and rosmarinic acid associated with higher antioxidant capacity. In addition, this biological system also has a large capacity for continuous biomass production, thus demonstrating its high potential for possible nutraceutical applications.