Submitted to: Journal of Herbs, Spices and Medicinal Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2007
Publication Date: 12/1/2007
Citation: Brauer, D.K., Kimmons, T., Phillips, M. 2007. Comparison of two methods for the quantitation of beta-glucans from shiitake mushrooms. Journal of Herbs, Spices and Medicinal Plants. 13:15-26.
Interpretive Summary: Fungal polysaccharides and glucans, including lentinan from shiitakes, have been identified as promoting human health, and consequently, the sale of mushroom-based health products has increased significantly in recent years. Increased sales of these mushroom-based health products are dependent on quantitation of the health promoting constituents. In many instances quantitation methods for these constituents have not been extensively researched. Investigators from the Shirley Community Development Corporation and Booneville AR characterized two methods for the quantitation of beta-glucans from aqueous extracts of shiitake mushrooms. Results from this study demonstrated that a method that measures the production of glucose by enzymes that specifically hydrolyze plant beta-glucans did not detect mushroom beta–glucans like lentinan. These results are of interest to shiitake producers and consumers purchasing shiitake based health aides.
Technical Abstract: Fungal polysaccharides and glucans, including lentinan from shiitakes, have been identified as promoting human health, and consequently, the sale of mushroom-based health products has increased significantly in recent years. Reliable methods for the quantitation of lentinan must be available if shiitakes or shiitake-derived products are to be promoted as health-promoting food. The objective of this study was to characterize two methods for the quantitation of beta-glucans from aqueous extracts of shiitake mushrooms. The first method utilized ethanol precipitation and batch size exclusion chromatography to isolate a fraction enriched in lentinan, called high molecular weight polysaccharides, HMWP. Gel filtration chromatography characterization of HMWP fraction indicated that the size distribution of carbohydrates was similar to that of a lentinan standard. Analyses for total starch and glycogen, to a lesser extent, indicate these polysaccharides are less than 10% of the total carbohydrates in HMWP. These results suggest that the HMWP fraction had a high level of lentinan. The second method measured the production of glucose by enzymes that specifically hydrolyze plant beta-glucans. The amount of carbohydrate detected by the enzymatic beta-glucan assay was significantly less than the carbohydrate found in the HMWP fraction. The low content of beta-glucan was not due to a failure of the assay’s enzymes to function. In addition, no glucose was produced when a lentinan standard was subjected to the beta-glucan assay. These results indicate that the carbohydrate content of HMWP fraction was a better indicator of lentinan content of shiitakes compared to the mushroom’s beta–glucan content.