Toxicity and Nutritional Assessment of Extracts of Medicinal Tiger Sawgill Mushroom, Lentinus tigrinus (Agaricomycetes), a Newly Domesticated in Iran

Information on the biosafety of tiger sawgill mushroom, Lentinus tigrinus, is limited and controversial. In the present study, the toxicity of a native L. tigrinus strain was evaluated in both cell cultures and mice. In addition to proximate analysis, the amino acid composition and the substrate-dependent uptake of elements were also evaluated. The mushroom (dry weight) had 7.53 ± 0.11% ash, 4.23 ± 0.23% lipid, 13.4 ± 0.04% fiber, 74.84 ± 0.38% total carbohydrate, and 4.16 ± 0.08 (mg GAEs/g) total phenol. Lysine was found at the highest amount among the L-amino acids determined in the L. tigrinus soluble protein. Comparison of the elemental profile of L. tigrinus with that of the substrate demonstrated a great capacity for absorption of K, P, S, and Mg elements, while the Na uptake was low. Neither the substrate nor the mushroom contained toxic elements beyond the standards of the joint FAO/WHO. The viability of normal human and mouse-derived cells was not influenced by the extract up to 250 μg/mL, where 70% of cancerous PC3 and MCF-7 cells were killed. Selectivity index analysis suggested that the L. tigrinus extract was selective only against MCF-7 cells. The extract also did not affect mice treated orally or via i.p. injection, while i.v. injection caused some mortality in mice with an LD50 of 47.19 mg/mL. In conclusion, L. tigrinus may be considered a source of macronutrients and micronutrients with a selective anticancer activity, while it is much less likely to have detrimental effects on humans at low serving levels.