Development of an efficient method for production of α-mangostin reference standard from Garcinia mangostana L. rinds using liquid flow processing

Abstract

Over centuries, world populations exclusively have used medicinal plants as therapeutic agents. Currently, some studies have proven that α-mangostin, a natural xanthone isolated from part of Garcinia mangostana L. tree especially from stem bark or fruit rinds has many potential activities including antioxidant, anti-bacterial, antivirus, antiinflammatory, and anticancer that has resulted in many mangosteen products appearing on the market. To standardise and quality control mangosteen and herbal products in general, an acceptable reference standard which is isolated from the plant itself is required. Separation and purification techniques using liquid flow processing known as countercurrent chromatography (CCC) are widely applied for this purpose. However, generally only a single injection of the sample into a CCC apparatus is used due to sample complexity. Multiple injections to increase the overall yield and scale of the purification are seldom used. But this has the advantage of reducing the cost of the purification process. The purpose of this has been to develop an efficient method for production of α-mangostin reference standard from fruit rind of Garcinia mangostana L. using liquid flow processing. The experiment were conducted initially by sample loading studies at analytical scale using a Mini HPCCC (17.4 mL coil, 0.8 mm bore) with a hexane/ethyl acetate/methanol/water (5:5:10:4 v/v) solvent system. Extract was prepared by overnight maceration of mangosteen rinds powder in 80% aqueous ethanol at 30⁰C. The extract in lower phase was injected up to 10 times without any replacement or topping up the stationary phase. The studies establsiehd 22.8 mg extract in 0.86 mL lower phase as the optimum amount of sample with multiple injections; and produced α-mangostin with 98.82% purity and 93.68% yield. Scaled up 8 times with 10 injections on Spectrum-CCC and 50 times with 7 injections on Midi-CCC gave α-mangostin with 99.24% purity and 96.35% yield; and 98.24% purity and 94.42% yield respectively. The concentration was then optimised nearly 3 times on Spectrum giving α-mangostin with 98.11% purity and 93.81% yield. These α-mangostin products with purity >98% can be accepted as reference standard for quality control of mangosteen based products, allowing the precise calibration of analytical instruments with this target compound. The purified α-mangostin was identified using commercial reference standard on HPLC and NMR.