Document Type : Research Article
Authors
1 Faculty of Agriculture, Ferdowsi University of Mashhad, Mashad, Iran
2 Horticulture department, Agriculture Faculty, Ferdowsi university of Mashhad
3 Medical School, Mashhad University of Medical Sciences
4 School of Medicine, Mashhad University of Medical Sciences, Mashhad
Abstract
Introduction:
Ganoderma lucidum is a high medicinal value mushroom have been widely used in the Far East countries especially in traditional Chinese medicine as promoting human health and treatment of many diseases. Nowadays, many published studies have established it contains a high source of nutraceutical and pharmaceutical substances with potent and unique properties as immune suppressors, hypercholesterolemic agents, or coadjutant treatments in diseases such as cancer, hypertension, insomnia, anorexia, dizziness, and chronic hepatitis, among others. This species is rich in several bioactive compounds (over 400 compounds) mainly, including polysaccharides, triterpenoids, steroids, fatty acids, amino acids, nucleotides, proteins, and alkaloids. Herein, the fruiting bodies of G. lucidum were studied in terms of nutritional value and chemical composition analysis. and further assessment of antioxidant activity of extracts from the fruiting body.
Materials and methods: In order to detection of nutrient elements, the samples were homogenized by microwave digestion (Milestone Ethos, Germany) with 1000 W maximum power and further characterized using Inductively coupled plasma optical emission spectroscopy (ICP-OES). Biochemical molecule contents were characterized using Acquity Ultra-Performance Liquid Chromatograph (UPLC, Waters) coupled to a photodiode array detector (PDA, Waters) and an electrospray ionization quadrupole time-of-flight tandem mass spectrometer (ESI–QTOF/MS; Waters). In order to assess antioxidant activity, two kinds of extract including methanol 80 % (ME) and hot water (HWE) as solvent were prepared by ultrasonic method. Six different in vitro assays are used for the determination of antioxidant capacity including ABTS, DPPH, superoxide (SO), nitric oxide (NO) free radicals scavenging, iron-reducing power (FRAP), and iron chelating activity (ICA). The data were analyzed by one-way analysis of variance (ANOVA) and the means were separated by the Newman-Keuls Multiple Comparison test (GraphPad Prism 8, San Diego, CA, USA)). All data were expressed as mean ± standard deviation. P ≤ 0.05 values or less were considered to indicate a statistically significant difference. Furthermore, Half-maximum inhibitory concentration (IC50) values for each assay were calculated from linear or logarithmic regression using Excel software.
Results and Discussion: G.lucidum was characterized in terms of nutritional value and chemical composition. Generally, to study the nutraceutical value of G.lucidum, 14 elements were analyzed by ICP-OES. Amongst the macronutrient group, phosphorus and potassium (2910.8 and 1510.8 mg/kg dry matter) and in the micronutrient iron and zinc (8.5 and 7.74 mg/kg dry matter) have the highest amounts, respectively. In terms of biochemical compounds, totally 37 compounds were identified in which Ganoderic acid was observed as most abundant (15890.1 ± 232.1 μg per g dry matter) followed by Sinapic acid and Succinic acid (2011.4 ± 28.11 and 1505.33 ± 31.5 μg per g dry matter) were the predominant compounds. The results of antioxidant assays clearly revealed that, the methanolic extract proved to have higher antioxidant potential than one corresponding hot water extract for all assays. In ABTS radical scavenging activity assay, ME with the best antioxidant activity (IC50,48.46±2.42 µg/ml) had a higher activity which was significantly different (P ≤ 0.05) from HWE (163.51±4.51 µg/ml). For DPPH assay, radical scavenging capacity was dose-dependent and IC50 values of ME (111.93±1.39 µg/ml) and HWE (213.48±5.42µg/ml) was a significant difference (P ≤ 0.05). In FRAP assay, The highest level of iron-reduction was observed in the highest level of ME(IC50, 308.13±4.13 µg/ml). This extract had higher iron-chelating activity (IC50, 671.75±5.66 µg/ml) as well. These values in both assays were significantly more potent than HWE (P ≤0.01). In SO assay, ME extract (IC50, 488.8±7.38 µg/ml) and HWE (IC50, 645.92±5.48 µg/ml) showed no difference significantly. In addition, in the NO assay, both extracts released slight weak activity for neutralization of nitric oxide radicals, however, the highest activity level was related to ME (IC50, 1189.5±8.5 µg/ml) in comparison to HWE (IC50, 1343.2±10.6 µg/ml) that was significant (P ≤0.01). The results clearly indicate that different solvents used in this study significantly affected antioxidant capacities and total biochemical contents.
Conclusions: G. lucidum, as a high medicinal value mushroom, proved is a very important source of nutrients and antioxidant compounds such as terpenoids, especially triterpenoids, and polysaccharides. The free radical scavenging properties, reducing power and iron-chelating inhibition of G. lucidum seemed to be correlated with phenolic compounds and triterpenoids mostly. Therefore, based on the nutritional and biochemical profile of G. lucidum, and also its antioxidant power, this mushroom possesses a high nutrient potential that reflects positively on its health benefits.
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