Medicinal and nutraceutical potential of giant mushroom (Macrocybe gigantea (Massee) Pegler & Lodge)

Abstract

The study entitled “Medicinal and nutraceutical potential of giant mushroom (Macrocybe gigantea (Massee) Pegler & Lodge)” was conducted at the Ethnomedicine and Ethnopharmacology Division and Microbiology Division of Jawaharlal Nehru Tropical Botanic Garden and Research Institute (JNTBGRI), Palode, Thiruvananthapuram, during the year 2013 to 2014. The objectives of the study was to assess the medicinal and nutraceutical potential of Macrocybe gigantea with special emphasis on immunomodulation, hepatoprotection and diversity evaluation. Macrocybe gigantea cultures were procured from DMR, Solan. The culture and cultivation conditions were standardised in different substrates, media, pH and temperature. The temperature preference for substrates and the effect of sterilization methods were also studied. The immunomodulatory potential of M. gigantea was determined by delayed type hypersensitivity (DTH) test, active paw anaphylaxis test, inhibition of cyclophosphamide induced myelosuppression, carbon clearance assay and mast cell study. The hepatoprotective potential of M. gigantea was determined using acetaminophen induced hepatotoxicity study and carbon tetrachloride induced liver damage. In the nutritive analysis, the total carbohydrates, protein and glycogen contents were estimated. The diversity analysis was done using ITS sequence data. Cultural studies conducted showed that SDA was as effective as PDA in favouring the growth of Macrocybe gigantea. The maximum mycelia growth of M.gigantea was observed at temperature 35○ C (8.20 cm) and pH 7 (8.60 cm). Highest yield of mushroom was obtained in paddy straw beds with biological efficiency of 72.40 per cent and the best time period for cultivation was found to be March – April. No contaminations were observed in both methods of substrate sterilization i.e. chemical and boiling methods. The hepatoprotection and immunomodulation studies revealed that Macrocybe gigantea possess significant hepatoprotective activity at 300mg kg-1 and immunomodulatory activity at 100mg kg-1. Analysis of the nutrient composition of Macrocybe gigantea indicated that the protein, carbohydrate and glycogen content were found to be 24.10 per cent, 10.20 per cent and 5.6 per cent respectively. Sequence analysis revealed that ITS region of M. gigantea (Solan strain) showed 92 per cent similarity with Tricholoma giganteum and Venjaramood isolate showed 93 per cent similarity with the Calocybe indica sequences of NCBI database. The phylogenetic tree constructed using MEGA 4 revealed that the wild species obtained from Venjaramood was morphologically similar to M. gigantea but on sequence analysis it was found to be Calocybe indica. Based on the findings of the present investigation, it is confirmed that Macrocybe gigantea can be cultivated in Kerala during March – April for increasing its biological efficiency. For the first time, the hepatoprotective potential and immunomodulatory potential of M. gigantea has been scientifically validated. Further studies are needed to explorate the correct mechanism of its action with a biomarker-based approach for upgrading M. gigantea from functional food to holistic medicine to utilize its therapeutic potential.