Simultaneous microwave assisted extraction and HPTLC quantification of mangiferin, amarogentin, and swertiamarin in Swertia species from Western Himalayas

Abstract

Swertia is one of the most widely traded genus of 150 species, many of which are used in Ayurvedic, Chinese, Tibetan and traditional medicine. Swertia herb is mostly traded and exported in dried or in extract forms. In this present study, a microwave-assisted extraction (MAE) method coupled with simultaneous quantification of swertiamarin, amarogentin, and mangiferin from different species of Swertia using high performance thin layer chromatography (HPTLC) was developed. A three-level factor Box-Behken statistical design was used for optimization, where microwave power, irradiation time, and solvent-to-solid ratio were used as independent variables whereas swertiamarin, amarogentin and mangiferin were used as the dependent variables. Densitometric-HPTLC method was developed for the simultaneous estimation of swertiamarin, amarogentin, and mangiferin using mobile phase of ethyl acetate: acetic acid glacial: formic acid: water (10:1.2:1.2:2.7 v/v/v/v) and stationary phase as silica gel F254 HPTLC plate. In this study, five different Swertia species viz. S. angustifolia, S. cordata, S. chirata, S. paniculata, and S. nervosa collected from Western Himalayan, India were used to screen the elite Swertia species. Optimal extraction conditions to achieve the maximum yield of swertiamarin, amarogentin, and mangiferin were found to be 5.86%, 0.710%, and 4.93% respectively which were very close to the predicted values of 5.916%, 0.711%, and 5.084% respectively by keeping microwave power (530 W), time (4 min), and solvent-to-solid (30 mL). Densitogram patterns obtained from all the test samples and standard compounds revealed that the peaks corresponding to Rf 0.57, 0.64, and 0.74 were meant for swertiamarin, mangiferin, and amarogentin respectively. HPTLC studied showed that S. paniculata and S. angustifolia contained high content of bioactive compounds and could be used as a substitute for S. chirata, whereas S. cordata and S. nervosa could not be recommended as substitutes for S. chirata. Thus, the newly developed optimized MAE and HPTLC-densitometry method for simultaneous quantification of three bioactive marker compounds in five species of Swertia can be effectively implemented for quality control of herbal formulations.