Pleurotus ostreatus extract Enhances the Phagocytic Actions of Neutrophils against Streptococcus pneumoniae

Abstract

Introduction:Edible mushrooms have played prominent roles in improving the health of people for centuries. Pleurotus ostreatus is an edible mushroom with history of medicinal uses. This study was designed to examine, in vitroand in vivo, the possibility of methanolic and hot aqueous extracts of the mushroom modulating Streptococcus pneumoniae infection. Methods: Bioactive constituents of the methanolic and hot aqueous extracts were determined quantitatively and qualitatively using standard methods. Isolation, identification and confirmation of Streptococcus pneumoniae in infected blood were done using standard protocols. The effect of the extract on cellular immune responses was assessed by phagocytosis evaluation and quantitative Nitroblue Tetrazolium Test. In vivoimmunological response against Streptococcal infection was evaluated using the neutrophil adhesion test and Hemagglutinating antibody (HA) titre post infection in mice. Results: Methanol and aqueous extracts revealed the presence of flavonoids (6.41%; 3.01%), alkaloids (10.01%; 11.01%), saponins (2.02%; 2.02%), phenols (1.55%; 0.01%), tannins (0.02%; 0.03%), carbohydrate (14.05%; 11.09%), and proteins (45.09%; 41.00%). Percentage stimulation of the polymorphonuclear neutrophils (PMNs) was 48% and 53% for the highest concentration (500 mg/mL) of the extracts used, while the quantitative Nitroblue Tetrazolium test score ranged from 58.00 ± 9.64 and 57.33 ± 2.91 for 400 mg/ml to 27.33 ± 4.84 and 25.67 ± 1.40 for 50 mg/ml. Oral administration of the extract in mice significantly increased neutrophil adhesion to nylon fiber when compared to control group and significant increased circulating antibody titer and phagocytic index in a concentration dependent manner. Conclusions: Pleurotus ostreatus has high carbohydrate and protein content and may help the immune system in defense against infections caused by Streptococcus pneumoniae.