دانلود رایگان مقاله فعالیت آنتی اکسیدانی عصاره پنج قارچ خوراکی

Abstract

Extractions were performed of the total phenolic and flavonoid contents and antioxidant properties of five edible mushroom samples—Lentinus edodes, Volvariella volvacea, Pleurotus eous, Pleurotus sajor-caju and Auricularia auricular—using three different extractants. Among the three different extractants, 50% (volume per volume; v/v) ethanol was the most suitable for antioxidant extraction from the mushroom samples. The 50% (v/v) ethanolic extract of dried L. edodes contained higher total phenolic and flavonoid contents than in the other mushroom extract samples. The antioxidant activities of 50% (v/v) ethanolic extract of dried L. edodes showed the strongest 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay (64.34%) compared to butylated hydroxyanisole (BHA) and α-tocopherol at 500 μg/mL. The ethanolic extract showed a lower reducing power of 0.10 compared to BHA and α-tocopherol at 500 μg/mL. Moreover, the L. edodes ethanolic extract also had the highest chelating ability (66.28%) which was lower than for ethylenediaminetetraacetic acid at 500 μg/mL and showed the strongest superoxide radical-scavenging activity (64.17%) compared to BHA and α-tocopherol. Therefore, the 50% (v/v) ethanolic extract of L. edodes could be used as a potential natural antioxidative source or as an ingredient in the fish and fishery product industries.

Chelating effect on ferrous ions

Transition metals such as the ferrous ion (Fe2þ) are good promoters of free radical reactions because of their single electron transfer during their change in oxidation state, with Fe2þ being the most powerful pro-oxidant among various species of metal ions (Jadhav et al., 1996). In addition, transition metals assist the catalytic decomposition of hydroperoxide which appears to be the major source of free radicals. Chelating agents act as secondary antioxidants because they stabilize transition metals in living systems, and are important in retarding the radical degradation and inhibiting the generation of radicals (Gordon, 1990). In the current assay, the chelating activity of the mushroom extracts was determined using a ferrozine assay. Ferrozine can form complexes with Fe2þ and the mushroom extracts interfered with the formation of Fe2þ and the ferrozine complex, which demonstrated that the mushroom extracts have chelating activity and can capture Fe2þ before ferrozine with the result that the red color of the complex is decreased. The rate of red color reduction can be evaluated as the chelating activity of the coexisting chelating agents (Yamaguchi et al., 2000). The results of the chelating effects of five edible mushroom extracts and EDTA on ferrous ions were determined as a percentage that increased with increased concentrations as shown in Fig. 3. The results showed that 50 percent EE with L. edodes exhibited the highest chelating effect because this combination had high total phenolic and flavonoid contents which led to strong chelating effects that were 66.28 percent, which was lower than for EDTA (78.64%) at 500 mg/mL.