Enhanced Rhinacanthin Production in Rhinacanthus nasutus Roots Using a Hydroponics and Elicitation System

Abstract

Background: A proficient hydroponic system for the cultivation of Rhinacanthus nasutushas been implemented with the aim of augmenting rhinacanthin production. Elicitation stands out as a viable technique for bolstering the yield of rhinacanthin.Materials and Methods: A hydroponics system of R. nasutuswas treated with six elicitors, namely chitosan, Trichoderma harzianumextract, sodium alginate, lawsone, methyl jasmonate, and salicylic acid at three concentrations. A suitable elicitation period for the selected elicitor was also determined.The contents of rhinacanthin-C, -D, and -N accumulated were determined using an HPLC method.Results: Amongst these, chitosan (0.15 mg/mL) and T. harzianumextract (1.0 mg/mL) significantly enhanced rhinacanthin production and gave the highest total rhinacanthin content, up to 6.0-6.1% w/w, which was 2.2-fold higher than the untreated roots (2.7% w/w). In addition, lawsone (3.0 μM) and salicylic acid (100 μM) significantly increased rhinacanthin production up to 4.6% and 3.4% w/w, respectively, while neither methyl jasmonate nor sodium alginate increased rhinacanthin production. The suitable elicitor-contact periods for chitosan, T. harzianumextract, and lawsone were 48, 24, and 72 h, respectively. Moreover, the leaves harvested from these optimized conditions also contained markedly high contents of rhinacanthins, up to 5.4%, 6.7%, and 5.1% w/w, respectively.Conclusion: The present study established the optimized elicitation methods for the R. nasutushydroponics system using chitosan, T. harzianumextract, and lawsone as elicitors to obtain the high-rhinacanthin-producing roots and leaves. These hydroponics and elicitation systems might be alternative sources of the high-quality R. nasutusroots and leaves.

Keywords: Chitosan; Elicitation; Hydroponics; Lawsone; Rhinacanthin; Salicylic acid; Trichoderma harzianum