Outlook and Future Prospects

Abstract

The major step before consumption of the collected macrofungal species is correct identification. Misidentification of macrofungi often leads to the consumption of toxigenic species causing adverse health effects and sometimes may prove lethal. Without correct scientific nomenclature of the collection material, further studies have no validity. For example, in earlier pharmacological investigations, most of the species reported as Lingzhi or Reishi (G. lucidum) were mistakenly identified. G. lucidum represents a taxon-linneon or species-complex, and the future subdivision of this needs caution (Wasser et al. 2006). Therefore, due to misidentification, the publications, patents, and products are also at risk. Classical methods include the study of morphology (color, size, shape, etc.) and microscopic examination (hyphae, spores, sporing structures, sterile elements, etc.) of the specimen. Field guides, monographs, and identification keys bearing photographs and detailed descriptions of species are also beneficial in identification. Preserving wild specimen in different herbaria is greatly encouraged to physically compare and identify the specimens collected later. In addition to classical taxonomic methods, advances in electron microscopy and molecular techniques bring significant improvements and rapidity in the identification, nomenclature, and classification of the specimens (Abdel-Azeem et al. 2018; Wu et al. 2018). The gathered information from different sources is compiled into various databases and is made available online on various websites such as Mycobank, Species Fungorum, MyCoPortal, etc. A vast diversity of macrofungi exists on earth with continuous additions of species from different parts of the world. Still there are some regions left unexplored or are underexplored. More field work is needed to explore and document macrofungal diversity, particularly in the tropics utilizing morphological and molecular identification techniques (Lopez-Quintero et al. 2012; Ambrosio et al. 2015; Iqbal et al. 2016). Macrofungi have long history of use in human life as is evident from ethnomycology. In addition to cultural significance, the information pertaining to the edibility, medicinal value, or toxicity of macrofungi can be gathered by conducting ethnomycological surveys to different parts of the world (Yamin-Pasternak, 2011; Ingvar 2018). The ethnomycological data about the uses of macrofungi in human health need scientific valorization which is possible through the analysis of mycochemical composition and evaluation of biological activities. This has become possible with use of biotechnology involving genomics, proteomics, and other modern-day techniques such as WDXRF, chromatography, and mass spectrometry, e.g., GC/MS, LC/MS, etc. (Lozano et al. 2012; Lau et al. 2014; Parmar and Kumar 2015; Ham et al. 2020; Shao et al. 2020). Besides aiding in identification, biotechnology makes it possible to generate complete mycochemical profiles, to elucidate the structures of bioactive compounds, and to evaluate the pharmacological activities of macrofungal species (Liu et al. 2017; Dong et al. 2018). However, numerous species of macrofungi still need scientific evaluation with respect to their mycochemical composition and pharmacological potential. Further advances in medical mycology are the need of the hour to make the clinical use of macrofungi in the treatment of various ailments. Empirical evidences may prove helpful to decide the edibility of a species. The scientific literature also proves as the best source of advice. The ingestion of fresh mushrooms rich in health boosting nutrients and other bioactive metabolites is beneficial, e.g., it enhances the serum levels of anti-β-glucan antibodies. As per the opinion of the Ohno Group from Japan, mushrooms when taken fresh would provide defense from pathogenic fungi in a better way (Ishibashi et al. 2005). Currently, much attention is paid to develop mushroom biomass or extracts as DSs or functional foods or prebiotics (indigestible β-glucans). However, a number of significant queries arise with establishing DSs and medicinal mushroom products concerning their safety, standardization, regulation, efficacy, and mechanism of action. However, this is a pity that even today standardization of DSs and medicinal mushroom products is in its early stages including the insufficient knowledge of the bioactive constituents and consequences of consumption of DSs. The standards and protocols employed to produce and test the medicinal mushroom products are not well recognized. The lack of proper standards and protocols results into adulterated and less durable mushroom products making them markedly different in composition and affectivity. It is unclear whether the health effect is produced by a single component or is the outcome of synergistic action of several ingredients. Moreover, insufficient data is available to decide which components possess better potential – those recovered from sporocarps or from submerged mycelia powder versus extracts. Other questions which frequently arise include whether the simple dried sporocarps or mycelia powders are more effective compared to aqueous, alcoholic, or hydroalcoholic extracts. Moreover, between crude extracts and isolated fractions, which one is more effective and safe? What is the role of low molecular weight compounds present in medicinal macrofungi? What is more effective, the combination of bioactive component-enriched biomass or extracts of 2–10 different species in a single pill or one species in one pill? Is it possible to access the potential of different mushroom products when mixing in several species in single product (“shotgun” approach)? Since the mushroom products can be cytokine stimulants, at what age these can be safe to administer in young children as their immune system is immature? The other controversial thing is what dosages are safe and affective especially during pregnancy and nursing? In several clinical trials, six capsules (three capsules twice a day or two capsules thrice a day) of 500–1000 mg each (biomass or extracts) have been accepted as the affective dosage of medicinal mushroom formulations. As per the traditional Chinese medicine, the standard dose of tablets, capsules, liquid extracts, etc. made from dried sporocarps or biomass must be 100–150 g a day of fresh mushroom material (Wasser 2014). The high molecular weight compounds, especially polysaccharides of medicinal macrofungi are used for drug development. However, these cannot be synthesized, and their production is confined to isolation from sporocarps/cultured mycelium or cultured broth which is an expensive approach (Papaspyridi et al. 2018). Therefore, an attempt should be made for drug development from low molecular weight compounds (Zaidman et al. 2005). Furthermore, the adulteration of mushroom products causes adverse health impacts such as nephropathy, acute hepatitis, coma, and fever. For example, the production of pure β-glucans is difficult, and 90–95% of β-glucan in the market are considered adulterated (Deng et al. 2009; Wasser 2011). Therefore, we must pay attention to adopt regulations, standards, and practices most valuable in the quest for human health promotion. Research should lay emphasis on improvements in cultivation technology, and attempts should be made for successful cultivation of useful macrofungi which are not under cultivation yet. The protection of intellectual properties (IPs) of genetic resources of medicinal macrofungi needs more attention. These are used and exploited by the pharmaceutical, cosmetic, agricultural, food, enzyme, and chemical industries. We should educate the public and make them aware of the use value of macrofungi in boosting human health. The most important above all is the conservation of the inexpensive natural treasure of macrofungi for sustainable use.