The Effects of Abiotic Stressors and Signal Molecules on Phenolic Composition and Antioxidant Activities of in Vitro Regenerated Hypericum Perforatum (St. John's Wort)

Abstract

Hypericum perforatum L. is a pharmaceutically and industrially significant natural source due to its rich phenolic content and antioxidant potential. This study aimed to establish an optimized development protocol through plant tissue culture methods and evaluate the effects of abiotic stressors and signal molecules on phenolic composition and antioxidant responses. Methanol based extracts prepared from lyophilized powders of plant samples obtained from nature and aseptic seedlings, and calluses obtained from abiotic stress factors and signal molecules were analysed for phenolic composition using HPLC-MS/MS and antioxidant responses through complementary methods (FCR, FRAP and ORAC). Experimental analysis revealed the use of B5 and SH media for in vitro plant regeneration as the most proper chemical environments for the development and standardization of Hypericum perforatum. Chromatographic findings showed that quercetin, pseudohypericin and partially chlorogenic acid compounds as key phenolic compounds of calluses and plant samples of Hypericum perforatum. The analyses deduced that UV and sucrose increased the level of chlorogenic acid, while ascorbic acid increased the level of quercetin and drought applications increased the concentration of pseudohypericin compared to the control. Rutin compound was only produced in pot samples, which indicates a significant response to the drought stress. Additionally, it was found that B5, SH, and MS media containing of 2 mg/L NAA+1 mg BA with elicitors of 50 mu mol of ascorbic acid and 6% sucrose and a UV stress of 5 (or 10) min-24 h harvesting might be a proper protocol for the optimization and standardization of Hypericum perforatum L. Findings obtained within this study revealed novel contributions for optimization, standardization and production of antioxidative phenolic compounds of Hypericum perforatum plant samples for pharmaceutical and industrial utilization. (C) 2020 SAAB. Published by Elsevier B.V. All rights reserved.