Medicinal Properties of Pleurotus spp include
Various crude extracts of Pleurotus species have been shown to possess relatively strong antitumour activities. Methanol extracts of P. florida and P. pulmonarius fruiting bodies significantly reduced solid tumours in mice. P. ostreatus mycelium extract, alone and combined with the chemotherapeutic agent cyclophosphamide, inhibited in vivo tumour growth in mice. The combined administration of the extract with cyclophosphamide decreased the degree of leukopenia compared to administration of cyclophosphamide alone. A water extract of P. ostreatus exhibited the most significant cytotoxicity by inducing apoptosis of human carcinoma cells, when compared to many other mushroom extracts. It has been suggested that the active compounds in the extract were water-soluble proteins or polypeptides . Antitumour effects have also been shown on different human tumour cell lines. P. tuber-regium polysaccharides exerted antitumour activity, through cytotoxicity and antiproliferative activity, against human leukaemia cells in vitro. The polysaccharides induced apoptosis and caused cell cycle arrest. A P. eous lectin exerted antiproliferative effects on human tumour cell lines while showing no cytotoxicity. Furthermore, two ribonucleases isolated from P. sajor-caju and P. ostreatus fruiting bodies exhibited antiproliferative effects on tumour and leukaemia cell lines. Another protein, eryngeolysin, isolated from P. eryngii fruiting bodies, exhibited cytotoxicity against leukaemia cells.
Immunomodulatory and antimitogenic activities:
Several compounds from Pleurotus species with immunostimulatory activities on humoral and cell-mediated immunity have been isolated. Water-soluble polysaccharides extracted from P. citrinopileatus fermentation broth administered to mice resulted in a significant increase in the number of macrophages, T, CD4+ and CD8+ cells. Glucans isolated from P. florida fruiting bodies activated the phagocytic response of mouse macrophages in vitro and significantly induced the proliferative response as well as phagocytic activity of fish leukocytes in vitro. Moreover, proteoglycans from P. ostreatus mycelia exerted immunomodulatory effects by elevating mouse natural killer cell cytotoxicity and by macrophage stimulation. DNA isolated from P. ostreatus fruiting bodies stimulated mouse natural killer cytotoxic activity in vitro. Methanol extracts of P. ostreatus and P. cystidiosus fruiting bodies possessed antioxidant, reducing power, radical scavenging and iron chelating activities that were higher than those of other commercial mushrooms. Methanol extracts of P. florida and P. pulmonarius fruiting bodies showed similar antioxidant activities, and an ethanol extract from P. citrinopileatus fruiting bodies had antioxidant activities comparable to those from P. eryngii, P. ferulae and P. ostreatus mushrooms.
Hypersensitive immune responses, such as inflammation in delayed allergy, were suppressed by an ethanol extract of P. eryngii. It exhibited antiallergic activity after oral or percutaneous administration to mice with oxazolone-induced type IV allergy. Cardiovascular disease protection and antihyperglycaemic activities: Oyster mushrooms possess bioactive compounds with hypocholesterolaemic activities, such as polysaccharides, mevinolin and other statins. It has recently been reported that P. citrinopileatus fruiting body extracts exerted antihyperlipidaemic effects. Serum triglyceride and total cholesterol levels were lowered in hyperlipidaemic rats supplemented with the extracts, while high-density lipoprotein levels were significantly increased. Similar effects were noted when powdered P. ostreatus fruiting bodies or a water-soluble polysaccharide extracted from P. citrinopileatus fermentation broth were fed to hypercholesterolaemic or diabetic rats, respectively. Pleurotus species also possess blood-pressure-lowering activity. Recently, P. cornucopiae has exhibited antihypertensive activity; this might be due in part to D-mannitol, which inhibits angiotensin I converting enzyme. A methanol extract of P. florida fruiting bodies significantly inhibited platelet aggregation. The antiplatelet-aggregating activity, along with the anti-inflammatory activities discussed above, suggest its potential therape.
P. ostreatus : Crude extracts from fermentation broth against Gram-positive, Gram-negative bacteria and Aspergillus niger. Hexane-dichloromethane extract containing p-anisaldehyde againsts Bacillus subtilis, Pseudomonas aeruginosa, Aspergillus niger and Fusarium oxysporum and various extracts; two main unidentified compounds against Bacillus spp., Escherichia coli, Vibrio cholerae and Salmonella typhi.
P. eryngii : Eryngin – an antifungal peptide againsts Fusarium oxysporum and Mycosphaerella arachidicola. Eryngeolysin – a haemolysin againsts Bacillus spp. P. sajor-caju: 12 kDa ribonuclease againsts Fusarium oxysporum, Mycosphaerella arachidicola, Pseudomonas aeruginosa and Staphylococcus aureus.
Antiviral activity : Mushrooms contain substances that exert direct or indirect antiviral effects as a result of immunostimulatory activity. Inhibitory activity against human immunodeficiency virus (HIV)-1 reverse transcriptase has recently been demonstrated for P. sajor-caju and P. pulmonarius hot water extracts. Anti-HIV activity was also demonstrated for a ubiquitin-like protein isolated from P. ostreatus fruiting bodies. Moreover, in contrast to water-insoluble b-glucans isolated from P. tuber-regium sclerotia, their corresponding water-soluble sulphated derivatives exert antiviral activities against herpes simplex virus type 1 and type 2. The effect is presumably elicited by the binding of sulphated b-glucans to viral particles, thus preventing them from infecting the host cells.