The Effects of Callus Elicitation on Lepidine, Phenolic Content, and Antioxidant Activity of Lepidium sativum L.: Chitosan and Gibberellic Acid

Lepidium sativum L. is an annual herb with various medicinal and industrial applications. In addition, the elicitation process is considered as a highly effective technique for increasing the production of pharmaceutically active compounds through in vitro cultures. In this regard, the present study investigated the effects of two elicitors, namely, chitosan (CHT) (100, 250, and 500 mg L−1) and gibberellic acid (GA3, 1–2 mg L−1), on growth-related traits, total phenolics content (TPC), lepidine, some antioxidant enzymes such as catalase (CAT), guaiacol peroxidase (GPX), and phenylalanine ammonia lyase (PAL), and the reactive scavenging ability (RSA) by DPPH method in the callus cultures of L. sativum. The most enhanced accumulations of total phenolics, PAL activity, RSA, and relative callus fresh weight were observed in calli treated with 250 mg L−1 of CHT. The results showed the highest CAT and GPX activities under 100 mg L−1 of CHT elicitation. Furthermore, high-performance liquid chromatography analyses revealed a 19.87-fold enhancement for the lepidine accumulation (207.67 µg g−1 DW) in 250 mg L−1 of CHT. Based on the results, GA3-treated calli demonstrated lower accumulations of TPC and lepidine, which significantly differed from those of CHT-treated cultures. The results further represented a positive and significant correlation between lepidine and RSA (0.59**), suggesting that lepidine was an important substance with antioxidant activity in calli of L. sativum. Therefore, these novel findings are valuable for scaling up callus cultures regarding the commercial production of lepidine, as a pharmaceutically unique compound in L. sativum.