Evaluation of plumbagin synthesis: mimicking in vivo plant systems through the application of elicitors inducing stress on in vitro regenerated Plumbago zeylanica L.

Abstract

Plumbago zeylanica L., a wild shrub, is a vital natural source of plumbagin, a potent 1,4-naphthoquinone renowned for its anti-cancer properties, notably effective against breast, prostate, and ovarian cancers. Traditional plumbagin extraction, involving root uprooting and plant destruction, raises ecological concerns. The primary objective of this study is to enhance plumbagin production by incorporating the elicitation process into in vitro cultivation with regenerated plants that retain all of their intact organs. Seven different elicitors categorized into three distinct groups were employed to stimulate plumbagin content. Among the various elicitors used, this study marks the first application of biogenic silver nanoparticles (AgNPs) from Curcuma amada in stimulating plumbagin production in this plant. The maximum plumbagin content, recorded at 8.98 ± 0.24 mg/g dry weight basis, was found in the roots when elicited with AgNPs at a concentration of 15 mg/l. In addition to that, biotic elicitors (yeast extract, chitosan and casein hydrolysate) and heavy metals (lead, cobalt and nickel) also successfully elicit plumbagin in the root and aerial parts of the plants, quantified through High Performance Liquid Chromatography (HPLC). In our study, we found that certain elicitors induced root browning and tissue necrosis, as confirmed by propidium iodide (PI) staining. The most significant browning effects were observed with chitosan from biotic sources and lead from heavy metals, while no such effects were associated with AgNPs at any concentration. Utilizing intact, entire plants as the subjects for elicitation in our study is a valuable aspect. This approach closely replicates the natural process occurring in intact plants, enhancing the relevance of our findings to practical situations.