Production and purification of glucosamine and angiotensin-I converting enzyme (ACE) inhibitory peptides from mushroom hydrolysates

Glucosamine and ACE inhibitory peptides were produced from five mushrooms by sulfuric acid hydrolysis. Straw mushroom, hydrolysed at 100 °C for 4.03 h by 5.67 mol L−1 sulfuric acid, had the highest glucosamine yield (56.81 mg/g), while oyster mushroom hydrolysate presented the maximum ACE inhibitory activity (IC50, 64.111 mg/mL). Glucosamine was enriched 2-fold in the ethanol-soluble fraction after ultrafiltration and ethanol precipitation. The potent ACE inhibitory peptides were purified 69-175 folds by a four-step purification procedure. All the purified peptides showed satisfactory residual activity against heat, pH, and in vitro gastrointestinal digestion. Eighteen novel peptides were identified, of which ASPYAFGL was found to exhibit high inhibition potency with IC50 values of 1.080 × 10−7 mol L−1. These results suggested that mushroom hydrolysates containing glucosamine and ACE inhibitory peptides could be exploited as multifunctional ingredients for drugs or functional foods against osteoarthritis and hypertension.