Abstract: This study revealed that antioxidant properties, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and reducing power were observed in different mushroom species namely Agaricus bisporus, Pleurotus sajor-caju, Pleurotus euos, Hybsizus ulmarius, Pleurotus florida, Volveriela volvaciea, Pleurotus platypus, Pleurotus djamor and Calocybe indica. Methonolic extract of P. euos was recorded maximum levels of DPPH free radical scavenging (6 mg mL-1), reducing power (6 mg mL-1) and enzymatic antioxidants viz., catalase, superoxide dismutase and peroxidise, 68.7±1.1, 0.39±0.01, 42.21±0.06, 37.12±0.04 and 7.21±0.05, respectively. The maximum amount of enzymatic antioxidants were recorded viz., CAT, SOD and POX; 42.21±0.06, 37.12±0.04 and 7.21±0.05 μmol, respectively.
INTRODUCTION
Free radicals are responsible for aging and causing various human diseases. A study shows that antioxidant substances which scavenge free radicals play an important role in the prevention of free radical-induced diseases. By donating hydrogen radicals, the primary radicals are reduced to non radical chemical compounds and are then converted to oxidize antioxidant radicals (Jadhav et al., 1995; El-Enshasy et al., 2010; Yamagushi et al., 1998). This action helps in protecting the body from degenerative diseases. Epidemiological studies have shown the beneficial effects of diets rich in vegetables, fruits and grain products in reducing the risk of cardiovascular disease and certain cancers (Beecher, 1999). The degenerative diseases associated with aging include cancer, cardiovascular disease, immune-system decline, brain dysfunction and cataracts (Ames et al., 1993). Weisburger (1999) and Ames et al. (1993) reported that, the consumption of plant foods, such as fruits, vegetables, red wines and juices provides protection against various diseases, including cancer, cardio and cerebrovascular diseases. Exogenous chemical and endogenous metabolic processes in the food system might produce highly reactive free radicals, especially oxygen derived radicals, which are capable of resulting in cell death and tissue damage. However, antioxidant supplements containing foods might be used to help human body cells to reduce oxidative scratch (Halliwell and Gutteridge, 1999). Mushrooms are considered to be a good source of antioxidants, such as variegatic acid and diboviquinone, which have been found in mushrooms (Kasuga et al., 1995). Cheung et al. (2003) reported that the methanol and water extract mushrooms were found to rich antioxidative activities. Mushroom species had been shown to possess antioxidant capacity in in vitro systems (Ribeiro et al., 2006). Seline and Johein (2007) reported that the l-carnitine concentration in mushroom ranged from 133 to 530 mg kg-1 DM (mean 320 mg kg-1 DM). The aim of this study was to determine the antioxidant property, scavenging activity and reducing power in the fruiting bodies of 9 edible mushroom species were collected from Namakkal district, Tamil Nadu and Southeast India.
MATERIALS AND METHODS
Mushroom collection: The species were collected from Namakkal district, Tamil Nadu and Southeast India, during April to June in 2009. The study was carried out of Centre of Advanced study in Marine Biology, Annamalai University, Parngipettai, Tamil Nadu, India.
Estimation of antioxidant activity: A fine dried mycelial mat (biomass filtrate paper) and harvested mushroom powder (20 meshes) samples (5 g) were continuously extracted with methanol in a Soxhlet apparatus for 24 h. The methanolic extract was evaporated to dryness at 40°C and redissolved in methanol at a concentration of 5 mg mL-1 and stored at 4°C prior to further use (Barros et al., 2007).
CAT: The mean CAT activity (μmol of H2O2 consumed/min/mg protein) was assayed following the method described by Sinha (1972).
SOD: The mean activity of SOD (units/min/mg protein) was determined by the method of Marklund and Marklund (1974), in which one unit was considered to be the amount of enzyme that inhibited pyrogallol autooxidation by 50%.
POX: Mean POX activity (μmol of pyrogallol oxidized/min/mg protein) of the mushroom extracts was measured according to the method described by Sadasivam and Manickam (2004).
DPPH radical scavenging activity: The scavenging activity of the free and bound extracts on 1, 1-diphenyl 2-picrylhydrazyl (DPPH) radical was measured according to the method of Cheung et al. (2003) with some modifications. Aliquots (various concentration of methanol extract) of 0.8 mL of 0.2 mM DPPH methanolic solution was mixed with 0.2 mL of the extracts. The mixture was vigorously shaken and left to stand for 10 min under subdued light. The absorbance was measured at 520 nm. The DPPH radical scavenging activity (%) was calculated by the following equation:
where, Asample is the absorbance in the presence of sample and Acontrol is the absorbance in the absence of sample, respectively. All extracts were analyzed in triplicate.
Reducing power: The reducing power was determined according to the method of Oyaizu (1986) with some modifications. Various concentrations of methanolic extracts from mushrooms (2.5 mL) were mixed with 2.5 mL of 200 mM sodium phosphate buffer (pH 6.6, Wako Pure Chemical Co., Osaka, Japan) and 2.5 mL of 1% potassium ferricyanide (Sigma) and the mixture was incubated at 50°C for 20 min. After 2.5 mL of 10% trichloroacetic acid (w/v, Wako) were added, the mixture was centrifuged at 650 rpm for 10 min. The upper layer (5 mL) was mixed with 5 mL of deionised water and 1 mL of 0.1% ferric chloride (Wako) and the absorbance was measured at 700 nm in a 2020 double beem spectrophotometer. A higher absorbance indicates a higher reducing power.
Statistical analysis: All experiments were done in three replicates and mean values are presented. Statistical analysis was performed on the data by Duncan’s multiple range test with means followed by a common letter are not significantly different at the 5% level by DMRT. Values are expressed as Mean±SD.
RESULTS AND DISCUSSION
Antioxidant, DPPH and reducing power results were clearly indicated that among sp., P. eous was significantly increased the enzymatic antioxidative substances, compared to other sp. The maximum amount of enzymatic antioxidants were recorded viz., CAT, SOD and POX; 42.21±0.06, 37.12±0.04 and 7.21±0.05 μmol, respectively (Table 1). Yang et al. (2002) was reported methanol extraction with; two mushrooms strains had the highest antioxidant activity. This report was similar values to compare our study. In the past few years, the suspected toxicity of some synthetic compounds used in food has raised interest in natural products (Stone et al., 2003). Some food industries and pharmaceuticals have increased their efforts in preparing bioactive compounds from natural sources by extraction and purification. Antioxidant compounds can scavenge free radicals and increase shelf life by retarding the process of lipid peroxidation, which is one of the major reasons for deterioration of food products during processing and storage (Halliwell and Gutteridge, 1999). So we need for identifying alternative natural and secure sources of food antioxidants has been created and the search for natural antioxidants, particularly of plant origin, has remarkably increased in recent years (Skerget et al., 2005).
Jose and Janardhanan (2000) have reported that the methanol extracts of Pleurotus sp., exhibited effective radical scavenging. The concentrations of cysteine, methionine and aspartic acid are reported to be higher in P. ostreatus than those in other edible mushrooms, such as Agaricus sp. and Lentinula sp. (Mattila et al., 2002). In addition, P. ostreatus has also been reported to possess excellent reducing power of ferric ions (Lin, 1999). In this study, methanolic extracts were prepared in different concentration; these are 2, 4 and 6 mg mL-1. DPPH scavenging activities and reducing power in various concentrations of methanol extracts were also higher in P. euos; this was followed by A. bisporus (Fig. 1, 2).
| Table 1: | Antioxidant activities of catalase, superoxide dismutase and glutathione peroxidase in dried mushroom |
| Values are expressed as Mean±SD of nine mushroom sp. in each group. Mean of three replications. Means followed by a common letter are not significantly different at the 5% level by DMRT. Units: CAT: 1 μmole of H2O2 utilized /min /mg protein, SOD: μmole of Inhibition of 50% nitrite formation/min/mg protein, POX: 1 μmole of pyrogallol oxidized/min/mg protein | |
| Fig. 1: | Scavenging effect of methanolic extracts from 9 edible mushrooms on 1, 1-diphenyl-2-picrylhydrazyl radical. Each value is expressed as Mean±SD. spp1: Agaricus bisporus, spp2: Pleurotus sajor-caju, spp3: Pleurotus euos, spp4: Hybsizus ulmarius, spp5: Pleurotus florida, spp6: Volveriela volvaciea, spp7: Pleurotus platypus, spp8: Pleurotus djamor and spp9: Calocybe indica |
| Fig. 2: | Reducing power of different concentrations of methanol extract of 9 edible mushrooms. Values are expressed as Mean±SD. spp1: Agaricus bisporus, spp2: Pleurotus sajor-caju, spp3: Pleurotus euos, spp4: Hybsizus ulmarius, spp5: Pleurotus florida, spp6: Volveriela volvaciea, spp7: Pleurotus platypus, spp8: Pleurotus djamor and spp9: Calocybe indica |
Different concentrations of DPPH scavenging activities of methanolic extracts from P. eous were 34.7 to 68.5%. The methanolic extract of mushroom species has presented in significant antioxidant activity. Antioxidant activity of the mushroom extracts include scavenging of free radicals also find good accountable. In addition, the mushroom is utilize, the source of natural antioxidants in food industry.
ACKNOWLEDGMENTS
We would like to thank Dean and the authorities of the Annamalai University, Parangipettai for the facilities provided. We also thank the anonymous reviewers and editor for helpful comments that improved the manuscript.