Antimicrobial and Antioxidant Potential of Wild Edible Mushrooms

Wild edible mushrooms have a high nutritional property that has been consumed by people from different parts of the world, producing a wide variety of bioactive compounds such as polysaccharides, peptides, glycoproteins, triterpenoids, lipids, and their derivatives. In the world, multidrug-resistant pathogens have been increasing drastically, and it is very urgent to search for alternative solutions to fight against multidrug-resistant pathogens. Moreover, unhealthy foods, ultraviolet radiation, as well as other environmental effects, are responsible for generating free radicals, oxidative stress, and numerous health diseases. Hence, the wild edible mushroom could be an alternative source of new antimicrobial potential and possesses antioxidant properties that can play significant roles in preventing various health diseases. In this book chapter, we focus on investigating the antimicrobial and antioxidant potential of wild edible mushrooms and their bioactive compound production.


Introduction
Fungi are eukaryotic and spore-bearing organisms with a life cycle divided into two phases: a growth phase and a reproductive phase. Macro fungi or mushrooms are species with a natural fruit body that can grow large enough to be visible or can grow underground. The spores, produced by the fruiting body, are the unit of sexual and asexual reproduction and are responsible for fungi's spread [1].
About 14,000 mushroom species have been reported, among them, 2000 mushrooms are reported as edible [2]. Additionally, less than 1% of the recognized fungus is poisonous, and a less percentage is fatal species [3]. Edible mushrooms have high medicinal properties due to their great rich content of polysaccharides, especially β-glucans. Many researchers reported that edible mushrooms have enormous features, including antioxidants, cholesterol-lowering properties, anti-hypertensive, anti-inflammatory, liver protection, as well as anti-diabetic, anti-viral, and anti-microbial potential (Figure 1) [4][5][6][7]. Antimicrobial and Antioxidant Potential of Wild Edible Mushrooms DOI: http://dx.doi.org /10.5772/intechopen.90945 involved in the development of different humans' diseases as diabetic disease, Alzheimer's disease, and cancer, among others. Hence, it is necessary to investigate the different extracts of mushroom displayed potent antioxidant activity. For example, Melanoleuca species could be considered for pharmacological studies because of its high antioxidant capacity [15]. Additionally, a few researchers suggested that higher content of antioxidants present in the mushroom could be used as a food supplement that can supply high nutrient ability in the body [16,17].
As we know, edible mushrooms have wide range of industrial and pharmaceutical applications. In this chapter, we will focus to describe the importance of wild edible mushrooms with their antimicrobial potential against pathogens as well as determine their antioxidant activities.

General information about mushroom
Mushrooms are eukaryotic heterotrophic organisms defined as macrofungi with a fruiting body formed by a cap and a stalk [18]. These macrofungi contain a wide variety of species belonging to the class Basidiomycota [19]. The mushrooms are filamentous fungi with both sexual and asexual reproduction cycle. The characteristic of basidiomycetes is a spore-producing structure or fruiting body called basidium. The morphological unit of the basidium is the hyphae, and a mass of hyphae is called mycelium. The spores produced inside the basidium are called basidiospore and are responsible for its reproduction and its dissemination. Sexual reproduction begins when the basidiospore germinates and grown as a haploid mycelium in optimal environmental conditions [1,20]. Mushrooms are well-known as edible and nonedible macro-fungi. The edible and non-edible mushroom can differentiate based on morphological characteristics like color, appearance, and shape of the cap [3].
In recent years, many studies have been reported that mushroom has extreme nutritional properties like vitamins, fats, proteins, etc. and could have high therapeutic properties that can be used as an antioxidant, anticancer, antidiabetic, cardiovascular protector, and hepatoprotective effects [19]. Moreover, the mushroom could be used as potential sources to obtain peptides, vitamins, proteins, lipids, amino acids, fiber, and antimicrobial compounds [14]. Last 20 years, most of the food industry could use the mushroom as a food product to prepare different kinds of jam, pickle, sweets, etc. [21].

Antimicrobial potential of edible mushroom
The use of antibiotics is the single most crucial factor leading to increased resistance of pathogenic microorganisms around the world [22]. Antibiotics are among the most commonly prescribed drugs used in human medicine. However, up to 50% of all the antibiotics prescribed for people are not needed or not optimally effective as prescribed [23]. Another major factor in the growth of antibiotic resistance is spread of the resistant strains of bacteria from person to person, or from the non-human sources in the environment, including food [24]. Natural resources have been taken advantage over the years, and among them, wild edible mushrooms vast diversity of active compounds with nutritional and antimicrobials properties [25][26][27]. Mushrooms have long been playing an essential role in several aspects, having medicinal value; mushrooms have been playing an indispensable role in several aspects of human activity, like feed and medicinal properties [28,29]. Current researches have been focused on searching for new antimicrobials therapeutically potential compounds of edible mushrooms [22] recognizing that some of these molecules have health beneficial effects, including antimicrobial properties. MIC-minimum bactericidal concentration; MBC-minimum inhibitory concentration; IZ-inhibition zone (disc diffusion). Table 1.

Mushroom extracts with antimicrobial activity against Gram-positive and Gram-negative bacteria.
Nowadays, researchers are interested in searching antimicrobial compounds isolated from edible mushrooms that can be useful to inhibit the multidrug-resistant (MDR) pathogens. Recently, Kosanić et al. [30] state that acetone extract of Craterellus cornucopioides has strong minimum inhibitory concentration (MIC) against Grampositive (Staphylococcus aureus, Bacillus cereus, and Bacillus subtilis) and Gram negative (Escherichia coli and Proteus mirabilis) bacteria with a range of 0.1-0.2 mg/ mL. Interestingly, the effect of feeding C57BL/6 mice Agaricus bisporous (white button mushroom) was used to feed in mice and to evaluate the bacterial microflora, urinary metabolome, and resistance to a gastrointestinal (GI) pathogen along with control untreated mushroom. As a result, mice treat with mushrooms increased the diversity of the microflora and decreased the GI tract Clostridia pathogen [31]. Chaiharn et al. [32] reported that different types of extracts such as ethyl-acetate, methanol, and ethanol and aqueous solvent of Flammulina velutipes, Ganoderma lucidum, Pleurotus ostreatus, and Pleurotus pulmonarius showed significant antibacterial activity against Gram-positive and Gram-negative bacterial pathogens ( Table 1).

Antioxidant potential of edible mushroom
Free radical is unstable and very reactive molecules defined as any molecule containing unpaired electrons. These molecules attack nearby chemical compounds to capture the needed electron for gaining stability [44,45]. Free radicals can be derivate from nitrogen compounds [Reactive Nitrogen Species (RNS)] or molecular oxygen (O 2 ) [Reactive Oxygen Species (ROS)]. ROS are the ruling class of radical species producing by endogenous and exogenous sources in living systems [25]. The endogenous source is present in aerobic cells that include metabolism of energy production, respiratory burst, respiratory chain inside the mitochondrial, and some intracellular enzymes reactions. Exogenous sources are tobacco smoke, stress, drugs, environmental pollution, xenobiotics, among others [44,46].
In physiological conditions, antioxidant compounds control ROS levels by an enzymatic system or a non-enzymatic system. The enzymatic system comprises superoxide dismutase (SOD), glutathione peroxidases, and catalase, whereas ascorbic acid (vitamin C), α tocopherol (vitamin E), glutathione, carotenoids, and flavonoids make part of the non-enzymatic system [45]. However, ROS can be maintained at low concentrations because they require different cell processes, including cell proliferation, apoptosis, and gene expression [46]. The oxidant stress is formed due to in balance of ROS production and antioxidant defenses. The cellular lipids, proteins, and DNA can damage due to increase of ROS that can form various stress like diabetes, cancer, neurological disorders, cardiovascular diseases, mutagenesis, and the aging process [25]. For that reason, the improvement of antioxidantcontaining foods may help to reduce the harmful effects caused by oxidative damage [45]. Nowadays, researchers are focused on mushroom antioxidant potential due to their high levels of antioxidants like phenolic compounds, polysaccharides, tocopherols, carotenoids, ergosterol, and ascorbic acid are present in the mushroom [47].
In Table 2, we have mentioned various mushroom extracts that have abundant antioxidant activity and produced several phenolic compounds. Total phenolic content varied from 5.1 ± 0.5 to 81.33 ± 1.1 mg GAE/g of extract found in Boletus edulis and Boletus griseipurpureus, respectively. These compounds can act as oxygen scavengers, peroxide decomposes, and free radical inhibitors as per the various researchers [44,46]. Additionally, few other compounds like pyrogallol, polysaccharides, flavanols, ascorbic acid, and carotenoid compounds are beneficial for antioxidant potential.  (NMR) analysis, chromatographic method or gas chromatography-mass spectrometry (GC-MS). Moreover, Table 2 described that the different kinds of mushrooms could be used to determine the antioxidant activity potential in several ways, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS), and ferric-reducing antioxidant power (FRAP). Further, Sriramulu and Sumathi [57] demonstrated that extract of edible Agaricus bisporus and wild Ganoderma lucidum mushroom was used to synthesize silver nanoparticles that showed photocatalytic activity and biological activities such as in vitro antioxidant activity, anti-inflammatory activity, and antimicrobial activity against bacterial pathogens such as E. coli and S. aureus. Garrab et al. [48] reported that ethyl acetate extract of Agaricus silvaticus Schaeff., Hydnum rufescens Pers., and Meripilus giganteus (Pers.) Karst. exhibited antioxidant and anticholinesterase activity. Interestingly, ethyl acetate extract of Hydnum rufescens Pers. indicated the highest antioxidant activity in DPPH and catalase potential. Recently, many researches are focusing on extracting the compound like chitosan and chitosan + procyanidin obtained from a mushroom that can be used to coat the blueberries, which revealed the higher antioxidant potential as compared to no coated berries [61]. Similarly, Velez et al. [62] reported that AA-loaded chitosan/tripolyphosphate nanoaggregates obtained from mushrooms, which can be useful to coat the fresh-cut mushrooms that displayed significant antioxidant activity. Moreover, some studies had reported that antioxidant activity, total phenolic compounds, and total flavonoid compounds increased in tarhana and bread after the addition of Morchella conica, Ramaria flava, and Agaricus bisporus powder [16,17]. In addition, some researchers are investigated to study the antiangiogenic potential to prevent neurological disorders and hepatoprotective properties. A p-terphenyl compound is derived from two edible mushrooms that showed the anticancer effect to averts vascular endothelial growth factor with the presence of antioxidant and anti-inflammatory activity [63]. Few researchers reported that benzoic acid derivative compounds such as be p-hydroxybenzoic, protocatechuic, gallic, gentisic, homogentisic, vanillic, 5-sulphosalicylic, syringic, veratric, and vanillin obtained from diverse types of much room such as Phellinus rimosus, Ganoderma lucidum, Ganoderma [25]. Recently, a few different polyphenols like curcumin, resveratrol, and quercetin showed pro-oxidant activity that can act as photosensitizers to produce 1O 2 as per Lagunes and Trigos [64]. Additionally, Li et al. [65] reported that the aqueous extract of Amanita caesarea was estimated in an L-glutamic acid to induce the HT22 cell apoptosis model. In contrast, D-galactose and AlCl 3 have improved Alzheimer's disease (AD) in the mice model to prevent neurogenerative diseases. One of the interesting studies Chen et al. [66] explored is that polysaccharides isolated from Grifola frondosa could be used to improve memory impairment in aged rats by increasing total antioxidant capacity, glutathione peroxidase activity, superoxide dismutase activity, and catalase activity. Dong et al. [67] indicated that enzymeassisted M. esculenta polysaccharide enhances hepatic antioxidant enzymes that can decrease the amount of lipid peroxidation in mice models.

Conclusion and concluding remarks
Mushroom is widely useful as food supplements and suitable for all the age groups due to their high content of protein, dietary fiber, vitamins, and mineral. Moreover, they contain various bioactive molecules such as polysaccharides, terpenoids, glycoproteins, antimicrobial compounds, antioxidants, etc. that can play a major role in the treatment of numerous diseases like improving immune strength, decreasing the cancer level in the body, reducing blood sugar level, inhibiting the multidrug resistant bacterial pathogen, and many more. In this review, we have focused on antioxidant and antimicrobial activity of edible and non-edible mushrooms all over the world and their uses. We have found that few of the mushroom are producing wide variety of bioactive phenolic compounds such as pyrogallol, polysaccharides, flavanols, ascorbic acid, and carotenoid compounds that can be used to control various diseases like antitumor, antimicrobial, antioxidant and anti-hypertensive, hypocholesterolemic, and hepatoprotective activity. Mushrooms  Lentinula edodes exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria as shown in the table. It can be concluded that mushroom has high therapeutic potential that could be used for the development of new formulations, which can be beneficial for new nutraceutical products. Hence, new methods should be used to isolate novel compounds from different mushrooms that can be used for the deterrence and decrease of several diseases.