Chitin extraction and characterization from cell wall of two mushroom species (Boletus bovinus and Laccaria laccata)

Abstract

Medicinal mushrooms have attracted more and more attention as potential natural agents for the prevention and treatment of many diseases, such as cancer, cardiovascular diseases and diabetes mellitus. But there are limited number of studies on the properties of chitin which is important component of the cell wall of mushrooms. In this study, chitin was obtained from the cell wall of two different mushroom species using chemical process, which included following steps: 1 - glucan extraction, 2 - demineralization in solution of hydrochloric acid to remove inorganic compounds, 3 – deproteinization in solution of sodium hydroxide, 4 – depigmentation and bleaching. Obtained chitins were physicochemically characterized. The dry weight chitin contents of the mushroom species were determined as 8.5% for Laccaria laccata and 6.2% for Boletus bovinus. The chitins were characterized by FT-IR, elemental analyses, nuclear magnetic resonance spectroscopy, thermogravimetric analyses and X-ray diffraction (XRD) profiles. The characteristic bands of the chitin molecule: O-H stretching (3438 cm-1), N-H stretching (3262 cm−1), amide I (1653 and 1620 cm−1), amide II (1550 cm−1), and amide III (1306 cm -1) are prominent bands observed in the FT-IR spectra of B. bovinus and L. laccata chitins and are similar to the commercial chitin. The crystalline index values of B. bovinus and L. laccata chitins were calculated as 85% and 78%, respectively according to the XRD analysis results (74% for commercial chitin). The thermal stabilities of chitins from these mushroom species were lower than those of crustacean and insects. All analyzes demonstrated typical patterns of α-chitin. The results of this study revealed that L. laccata and B. bovinus had higher chitin content than some other insects and mushroom species reported in the literature and these species may be used as a potential chitin source.