Deep-Sea Fungi Could Be the New Arsenal for Bioactive Molecules

Abstract

Growing microbial resistance to existing drugs and the search for new natural products of pharmaceutical importance have forced researchers to investigate unexplored environments, such as extreme ecosystems. The deep-sea (>1000 m below water surface) has a variety of extreme environments, such as deep-sea sediments, hydrothermal vents, and deep-sea cold region, which are considered to be new arsenals of natural products. Organisms living in the extreme environments of the deep-sea encounter harsh conditions, such as high salinity, extreme pH, absence of sun light, low temperature and oxygen, high hydrostatic pressure, and low availability of growth nutrients. The production of secondary metabolites is one of the strategies these organisms use to survive in such harsh conditions. Fungi growing in such extreme environments produce unique secondary metabolites for defense and communication, some of which also have clinical significance. Despite being the producer of many important bioactive molecules, deep-sea fungi have not been explored thoroughly. Here, we made a brief review of the structure, biological activity, and distribution of secondary metabolites produced by deep-sea fungi in the last five years.

Antibiotics from Extremophilic Micromycetes

“…Many of the known compounds isolated according to the bioactivity screening have been obtained from different producers many times. For example, antibiotic anthraquinone emodin (35) was developed and characterized seven times during the period considered [61,[73][74][75][76][77][78][79]. The use of the modern omics approaches and prioritization and dereplication strategies [336] can significantly increase the efficiency of the study of natural compounds including those from extremophilic econiches, thus avoiding the resource overuse for the isolation of known compounds.…”

“…In some cases, new cytotoxic [76] and antitubercular [75] types of bioactivity were revealed for emodin (34). Known emodin-related anthraquinones, i.e., questin (34) [70], physcion (35) [80], and chrysophanic acid (chrysophanol) (36) [79,81,82] turned out to be significantly less common. Dimeric anthraquinones (42) and (43) that contain the unusual C-O-C ether bond have been isolated from the culture fluid of the Aspergillus versicolor marine strain [83].…”

“…Due to the unique features of polyextremophilic adaptation and a wide range of secondary metabolites, marine fungi are an interesting object in terms of expanding the pharmacophore space [7,17]. High interest in marine micromycetes is reflected in some reviews of the literature data on their biodiversity and the spectrum of metabolites [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Secondary metabolites of marine micromycetes are mentioned in reviews concerning the biotechnological potential of the entire biodiversity of marine microorganisms [18,24,26,27,33,34].…”

“…Deep-sea fungi are mainly present in seafloor sediments [15,16]. Antibiotic secondary metabolites of fungi from deep-sea habitats are mentioned in several recent reviews on the biotechnological potential and biodiversity of deepsea econiche [26], anoxic water fungi [31], and other deep-sea habitats [35].…”

New Monoterpenoids and Polyketides from the Deep-Sea Sediment-Derived Fungus Aspergillus sydowii MCCC 3A00324

“…Deep-sea-derived fungi inhabiting extreme sea environments have proven to be a new source for a wide array of structurally intriguing and biologically active secondary metabolites [ 1 , 2 , 3 ]. As of December 2019, about 700 new secondary metabolites were reported from deep-sea-derived fungi, such as terpenoids, polyketides, alkaloids, and steroids.…”