Towards medicinal tea from untapped Namibian Ganoderma: Phenolics and in vitro antioxidant activity of wild and cultivated mushrooms
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Date
2022
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South African Journal of Science
Abstract
Ganoderma is a genus of mushrooms that is prized in developed nations, especially those in Asia, due to its health-promoting properties, which are attributed to bioactive compounds such as phenolics. However, in developing countries, particularly in Africa, Ganoderma mushrooms are untapped and are barely identified. In this study, we identified Ganoderma species collected from different host trees in the wild in Namibia, cultivated them on one substrate and determined their water absorption and solubility indices. Total phenolics (TP), total flavonoids (TF), condensed tannins (CT) and in vitro antioxidant activity (AA) were determined in hot water infusions made from wild and cultivated Ganoderma mushrooms. Folin–Ciocalteu, aluminium chloride, vanillin-HCl, and DPPH assay methods were used to determine TP, TF, CT and AA, respectively. 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, but lower levels of TF than those prepared from wild Ganoderma species, suggesting that they have potential as nutraceuticals.
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Keywords
lingzhi, medicinal tea, Ganoderma enigmaticum, G. wiireonse, G. lucidum