Antioxidants and ACE inhibitors (inhibitors of angiotensin I-converting enzyme) are used to control blood pressure. Synthetic ACE inhibitors have many side effects, so natural sources are needed. (Control of hypertension reduces cardiovascular disease.)
Mushrooms are considered good functional foods. Mushroom preparations usually consist of boiling the mushrooms before eating them for easier digestion. The present study evaluates the antioxidant and ACE inhibitory activity of hot water extracts of 14 culinary medicinal mushrooms. The mushrooms were cut into smaller pieces and boiled at 100 degrees centigrade for 30 minutes.
Phenol chemicals, also, play an important role in antioxidant activity. When measured in a number of mushrooms. Ganoderma lucidum was found to have the highest phenolic levels. This was followed by Agrocybe sp. and Pleurotus eryngii (oyster mushroom). Flammulina velutipes had the weakest activity. Gallic acid, tannic acid, protocatechuic acid, and gentisic acids were the phenolics found at the highest levels in water extracts of mushrooms.
The various antioxidant tests show somewhat differing results. Therefore, an antioxidant index (AI) has been developed. The antioxidant values of the mushrooms were expressed as an “antibiotic index” compared to the antioxidant value of quercetin being 100. By this index G. lucidum (ganoderma mushroom) and Schizophyllum commune (not commonly eaten in the U.S.) show the highest values. Moderate antioxidant values were seen by Hericium erinaceus (Lion’s Mane mushroom), Volvariella volvaceae (straw mushroom), Auricularia auricular judae (jelly ear fungus), and T. heimii (Termitomyces heimii). F. velutipes ranked lowest. The highest ranking oyster mushrooms are Pleurotus flabellatus, P. florida, P. eryngii, P. cystidiosus, and P. sajor-caju. Poor activity is seen in Termitomyces microcarpus.
ACE inhibitory activity (expressed as percentage of inhibition) is best in G. lucidum and oyster mushrooms, Pleurotus spp., followed by Tricholoma giganteum, Grifola frondosa (maitake), and Pholiota adiposa varieties. Hot water extracts of mushrooms have higher ACE inhibitory activity than methanol or ethanol extracts. The ACE inhibitors in mushrooms are mostly small proteins.
CONCLUSION: Culinary mushrooms have antioxidant and blood pressure lowering activity. Among the highest rated are G. lucidum, Schizophyllum, Hericium erinaceus (Lion’s mane mushroom), and G. frondosa (maitake mushroom).
NOTE: Schizophyllum commune can be a human pathogen, and some Agrocybe sp. mushrooms can be poisonous.