Tetrahydroanthraquinone derivatives from the mangrove-derived endophytic fungus Stemphylium globuliferum

Diversity of fungal endophytes from mangrove plants of Santa Catarina Island, Brazil

The mangrove ecosystem plays a crucial role in preserving the biodiversity of plants, animals, and microorganisms that are essential for materials cycles. However, the exploration of endophytic fungi isolated from mangroves, particulary in Santa Catarina (SC, Brazil), remains limited. Therefore, the purpose of this study was to assess the biodiversity of endophytic fungi found in Avicennia schaueriana, Laguncularia racemosa, Rhizophora mangle, and Spartina alterniflora from two mangroves on the Island of Santa Catarina: one impacted by anthropic action (Itacorubi mangrove) and the other environmentally preserved (Ratones mangrove). Samplings were carried out between January 2020 and May 2021. Fungi were isolated from leaves, stems, and roots, identified, and clustered into groups through morphological characteristics. Further, a representative strain of each group was identified through ITS1 sequencing. A total of 373 isolates were obtained from plant tissues, of which 96 and 277 isolates were obtained from Itacorubi and Ratones mangroves, respectively. Molecular identification showed that the endophytic fungal community comprised at least 19 genera. The data on fungal community diversity revealed comparable diversity indices for genera in both mangroves. However, we observed differences in the total frequency of fungal genera between impacted (27.38%) and non-impacted (72.62%) mangroves. These findings suggest that anthropic activities in and around the Santa Catarina mangroves have had negative impact on the frequency of endophytic fungi. This emphasizes the reinforcing the significance of preserving these environments to ensure the maintenance of fungal community diversity.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

Bioactivities and Structure-Activity Relationships of Natural Tetrahydroanthraquinone Compounds: A Review

Tetrahydroanthraquinones are a kind of important microbial secondary metabolites with promising biological activities. Most of them were found in microorganisms, a few were derived from Chinese herbal medicine. In this review, aiming to provide basis for the further research and development of tetrahydroanthraquinone compounds, we summarized the physiological activities of natural tetrahydroanthraquinone compounds, including anti-cancer, anti-microbial, and antidiabetic activities. The source, structure, and action mechanisms of active tetrahydroanthraquinones are described in detail. Furthermore, this review firstly analyzed the structure–activity relationship of tetrahydroanthraquinones. Our study will serve as a valuable guideline for further research on the structural optimization, mechanism study, and development of tetrahydroanthraquinone as novel drugs. Aiming to provide references for further studies and development of tetrahydroanthraquinone compounds.

Antifungal polyketide derivatives from the endophytic fungus Aplosporella javeedii

Six new polyketides aplojaveediins A-F (1-6) were isolated from the endophytic fungus Aplosporella javeedii associated with the host plant Orychophragmus violaceus (Brassicaceae). The structures of the new metabolites were elucidated by analysis of their NMR and MS data. Compound 1 exhibited antifungal activity against the hyphae form of Candida albicans strain ATCC 24433 in the agar plate diffusion assay and the microbroth dilution assay. The kinetic of killing of C. albicans cells for compound 1 was considerably faster than that of the positive control hygromycin B. Compounds 1 and 6 also exhibited moderate antibacterial activities against sensitive (ATCC 29213) and drug-resistant (ATCC 700699) strains of Staphylococcus aureus.

Beyond Enzyme Production: Solid State Fermentation (SSF) as an Alternative Approach to Produce Antioxidant Polysaccharides

Solid state fermentation (SSF) is a sustainable process that uses low amounts of water and transforms plant-based agro-industrial residues into valuable products such as enzymes, biofuels, nanoparticles and other bioactive compounds. Many fungal species can be used in SSF because of their low requirements of water, O2 and light. During SSF, plant-based wastes rich in soluble and insoluble fiber are utilized by lignocellulolytic fungi that have enzymes such as lignases, celullases or hemicelullases that break fiber hard structure. During the hydrolysis of lignin, some phenolic compounds are released but fungi also synthetize bioactive compounds such as mycophenolic acid, dicerandrol C, phenylacetates, anthraquinones, benzofurans and alkenyl phenols that have health beneficial effects such as antitumoral, antimicrobial, antioxidant and antiviral activities. Another important group of compounds synthetized by fungi during SSF are polysaccharides that also have important health promoting properties. Polysaccharides have antioxidant, antiproliferative and immunomodulatory activities as well as prebiotic effects. Fungal SSF has also proved to be a process which can release high contents of phenolics and it also increases the bioactivity of these compounds.

Fused multicyclic polyketides with a two-spiro-carbon skeleton from mangrove-derived endophytic fungus Epicoccum nigrum SCNU-F0002

A pair of uncommon fused multicyclic polyketides, (±)-isoepicolactone and one new isobenzofuranone monomer, together with four other known biosynthetically related compounds were isolated from the fermentation of fungus Epicoccum nigrum SCNU-F0002.

Applications of OR/ECD/VCD to the structure elucidation of natural products

OR, ECD and VCD are powerful methods to determine the absolute configuration of natural products either applied independently or in combination.

Marine natural products

Covering: 2016. Previous review: Nat. Prod. Rep., 2017, 34, 235-294This review covers the literature published in 2016 for marine natural products (MNPs), with 757 citations (643 for the period January to December 2016) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1277 in 432 papers for 2016), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included.

Marine Fungi: A Source of Potential Anticancer Compounds

Metabolites from marine fungi have hogged the limelight in drug discovery because of their promise as therapeutic agents. A number of metabolites related to marine fungi have been discovered from various sources which are known to possess a range of activities as antibacterial, antiviral and anticancer agents. Although, over a thousand marine fungi based metabolites have already been reported, none of them have reached the market yet which could partly be related to non-comprehensive screening approaches and lack of sustained lead optimization. The origin of these marine fungal metabolites is varied as their habitats have been reported from various sources such as sponge, algae, mangrove derived fungi, and fungi from bottom sediments. The importance of these natural compounds is based on their cytotoxicity and related activities that emanate from the diversity in their chemical structures and functional groups present on them. This review covers the majority of anticancer compounds isolated from marine fungi during 2012-2016 against specific cancer cell lines.

Structure revision of aspergicin by the crystal structure of aspergicine, a co-occurring isomer produced by co-culture of two mangrove epiphytic fungi

The structure of aspergicin (1), an antibacterial alkaloid produced by co-culture of two marine-derived mangrove epiphytic fungi, were revised by the co-occurring isomer named as aspergicine (2), whose structure was determined on the basis of spectroscopic analysis and X-ray crystallography.