Abstract:
Ganoderma is a fungus that grows in natural habitants from different parts of the world. It is a prized mushroom in developed nations especially in Asian countries due to its health promoting properties such as anticancer, antibacterial, anti-inflammatory, antioxidant, anti-diabetic. These health promoting effects are attributed to bioactive compounds such as the phenolics. However, in developing countries such as Namibia, Ganoderma is still an untapped and barely identified resource. The objectives of this study was to identify and cultivate wild Ganoderma species harvested from different host trees in Namibia and to determine their physicochemical properties (moisture, ash, water absorption and water solubility indices). The phenolics composition (total phenolics (TP), total flavonoids (TF), condensed tannins (CT)) and in vitro antioxidant activity (AA) of hot water infusions of the wild and cultivated mushrooms were also determined. Folin-Ciocalteu, Aluminium Chloride, Vanillin-HCl, DPPH assay methods were used to determine TP, TF, CT and AA, respectively. Ganoderma species were identified using DNA based on the sequences in the GenBank with 98-100% similarity. Two new Ganoderma species: Ganoderma enigmaticum and Ganoderma wiireonse were identified for the first time in Namibia. Wild species had 6.12- 11.70% moisture, 1.91- 5.32% ash, 11.55- 24.40 (g of absorbed water/g of dry sample) water absorption index, 3.60- 24.10% water solubility index, 18.37- 44.78 (mg GAE/g of sample) TP, 0.09- 1.67 (mg QE/g of sample) TF, 2.97- 6.37 (mg CAE/g of sample) CT and 40.8- 49.3% AA. Cultivated species had 9.64- 13.45% moisture, 2.34- 6.20% ash, 13.55- 28.30 water absorption index, 6.40- 25.35% water solubility index, 36.70- 52.73 (mg GAE/g of sample) TP, 0.41- 0.86 (mg QE/g of sample) TF, 11.38- 15.29 (mg CAE/g of sample) CT and 53.6- 63.7% AA. Infusions prepared from cultivated Ganoderma species had higher levels of TP, CT and AA than those prepared from wild Ganoderma species suggesting that they can be potential nutraceuticals and source of healthful antioxidants. Further studies should be done on in vitro and in vivo medicinal effects of Ganoderma species in Namibia.
