Isolation and Purification of Ergosterol and Ergosterolperoxide from an Edible and Medicinal Higher Ascomycete Mushroom Xylaria striata by High-speed Countercurrent Chromatography

Abstract

Zhiqiang Zhang, Yi Huang, Qingxin Yang and Dan Zhang

Phytosterols, which serve as structural components of biological membranes of plants, are the most abundant dietary supplement. To date, numerous studies have demonstrated that phytosterols can block cholesterol absorption sites in the human intestine, thus helping to reduce cholesterol absorption in humans. However, phytosterols standards are either not commercially available or very expensive, mainly because their structural complexity and diversity complicate their fractionation and isolation from plant extracts by conventional separation techniques. High-speed countercurrent chromatography (HSCCC) is based on continuous liquid-liquid partitioning, which enables one to eliminate irreversible adsorption on solid supports. This technique has been extensively used for natural product isolation. It is well suited to the effective large-scale separation of phytosterols and their derivatives, achieving high purities and yields of up to several hundred milligrams per run within several hours. The present study successfully used an effective HSCCC method to isolate and purify Ergosterol and Ergosterol peroxide from an edible and medicinal higher ascomycete mushroom, Xylaria striata. This method's optimal conditions are as follows: using n-hexane-ethylacetate-ethanol-water (3:1:2:0.8, v/v) as the two-phase solvent system; the rotation speed was set to 850 rpm (forward); the flow rate of the lower phase was 3mL/min. Ergosterol with 96% purity and Ergosterol peroxide with 97% purity were obtained. The chemical structures of these compounds were identified by 1H-NMR and 13C-NMR. In addition, the antimicrobial activities of these compounds for nine kinds of plant pathogens fungi are evaluated. Ergosterol exhibited excellent fungistatic activities against Valsa mali�?�Sclerotinia sclerotiorum�?�Fusarium graminearum, and Helninthosporiun maydwas. Ergosterol peroxide also exhibited strong antifungal activity against Helninthosporiun maydwas.

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