Sacchachitin, a novel chitin-polysaccharide conjugate macromolecule present in Ganoderma lucidum: Purification, composition, and properties

Context: The extraction method and the crude wound healing effects of sacchachitin from Ganoderma tsugae Murr. (Ganodermataceae) has been cited. However, its purity is still largely limited. Objective: An improvement of the fractionation protocol to purify the sacchachitin from Ganoderma lucidum L. (Ganodermataceae) (SGL) is needed. Methods: Fruiting bodies were extracted with double distilled water and subsequently the residue treated with 95% ethanol and then 40% ethanol. After being filtered, the pH of the supernatant was adjusted to 4.0 with 1 N HCl and lyophilized. The supernatant was added (3:1 v/v) ethanol, the precipitate was collected, 2% NaOH was added and refluxed. The supernatant was collected with pH adjusted to 4.0, then treated with 10% potassium hydroxide (KOH) with repeating acid precipitation and (3:1) ethanol precipitation twice more to obtain the sacchachitin. Results: SGL had a hexosamine content 16.3% (w/w), firmly linked to a talomannan. Its Fourier Transform Infrared Spectroscopy (FTIR) spectrum revealed specific absorption (in cm^-1) νO-H 3455.5 b,s, amide νC=O 1678.5, and amide I° δN-H 1550.4. The percentage deacetylation degree was 37.6 and 39.4% for SGL and MSC, respectively. As contrast, MSC contained only 6.6% of hexosamine with a low protein/carbohydrate ratio 0.35 comparing to 0.82 for SGL. SGL was only moderately strong antioxidant regarding the anti-DPPH, antihydroxyl free radical, and antisuperoxide anion capabilities, exhibiting an IC33 values of 10 mg/mL (the highest scavenging capability never exceeding 33%), 0.9 mg/mL, and 4.8 mg/mL, respectively. Conclusion: We have successfully isolated the pure sacchachitin from the fruiting bodies of G. lucidum that exhibits potent antioxidative activity and may be useful in fabrication of the artificial skin composite substitute.