New Bioactive Molecules with Potential Antioxidant Activity from Various Extracts of Wild Edible Gelam Mushroom (&amp;lt;i&amp;gt;Boletus&amp;lt;/i&amp;gt; spp.)

M H M Y Yuswan,Jameel R Al-Obaidi,A Rahayu,D Fauzi,S Sahidan,F Shazrul

doi:10.4236/abb.2015.64031

Abstract

Boletus spp. is a wild edible Gelam mushroom, which is only available at coastal area of Bachok, Kelantan. Locals have used this mushroom as a food source and as a traditional medicine. In this study, antioxidants were extracted using Mili-Q water and methanol. Extraction of 1.0 g of Boletus spp. mushroom pileus and stipe by water produced 0.22 ± 0.09 g and 0.3 ± 0.07 g of total aqueous soluble extracts, respectively. Methanol extraction of 1.0 g Boletus spp. mushroom pileus and stipe produced 0.31 ± 0.08 mg and 0.37 ± 0.05 mg of total methanol soluble extracts, respectively. DPPH assay has been used to determine the value of antioxidant efficiency of each extracts. DPPH assay revealed that the EC50 value of pileus aqueous soluble extract and both pileus and stipe methanol soluble extracts were 1.2 mg/ml. The EC50 value of stipe aqueous soluble extracts was 1.4 mg/ml. The EC50 value of ascorbic acid, an antioxidant control was 0.5 mg/ml. Liquid chromatography- DPPH (LC-DPPH) assay combined with Quadrupole Time-of-flight Mass Spectrometry (QTOF-MS) analysis of 3:2 ratio methanol and water extract has detected 43 antioxidant compounds that were involved in the reduction of DPPH. To identify these compounds, SIMCA 3.0 software that consists of PCA, OPLS-DA and s-plot analyses had been used. PCA analysis had shown the antioxidant activity from sample on DPPH as 73.6%. This antioxidant activity confirmed by OPLS-DA analysis had shown the variability between sample and control as 99.6% with 99.3% prediction. S-plot selection had shown ten antioxidant compounds significantly involved in the DPPH assay. Four of these compounds were identified by the METLIN and NIST databases. The antioxidant metabolites were 2,4,6-trimethylacetophenone imine, glutamyl tryptophan, azatadine and lithocholic acid glycine conjugate. In conclusion, this study revealed that Boletus spp. mushroom is rich with natural antioxidants, which are potentially useful for multiple nutritional and health applications.

Highlights

Number of chronic human diseases such as cardiovascular and cancer are increasing globally
In order to determine active compounds in Boletus spp., extraction yield from methanol and water solvent are calculated from five replicates
Yield of extract percentage from fresh Boletus spp. is significantly high in methanol extract either for pileus or stipe compares to all type of water extract. This result is in line with those data obtained in previous studies done on different wild tropical edible mushroom like Pleurotus porrigens, Hygrocybe conica, Xerula furfuracea, Schizophyllum commune and Polyporus tenuiculus [17], Lentinus edodes and Volvariella volvacea [23] suggesting that most of the active compounds in Boletus spp. are organic compounds which soluble readily in methanol but not in aqueous medium

Summary

Introduction

Number of chronic human diseases such as cardiovascular and cancer are increasing globally. Several publications designate that one of the most important factor of causing human diseases is posed by uncontrolled production of free radicals, very active by-products having one or more unpaired electrons [1]-[5]. As a result, these free radicals will accumulate in the body and leading to those diseases when the free radicals abundance in the human body becomes unbalance [6]. Isolation of natural antioxidants from plants or fungi for food applications is necessary

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