Novel natural compounds from endophytic fungi with anticancer activity

Electrochemical Dehydrogenative sp2-Coupling Reaction of Naphthols Accessing a Polycyclic Naphthalenone Motif

A novel polycyclic naphthalenone motif was obtained by electrochemical synthesis starting from naphthols. The process is solvent controlled, and the highly diastereoselective cyclization is due to a solvent cage. The direct, anodic dehydrogenative sp2-coupling was carried out by flow electrolysis. Ten derivatives containing this motif were synthesized in yields up to 88%, resulting in novel polycycles structurally similar to bioactive compounds like Daldionin, potentially exploring the bioactive profile.

Anti-cancer activity of secreted aspartyl proteinase protein from Candida tropicalis on human cervical cancer HeLa cells

Cervical cancer is the fourth leading cause of cancer-related death in women worldwide. Microbial products are valuable sources of anti-cancer drugs. The aim of this study was to isolate secreted aspartyl proteinase protein from Candida tropicalis, investigate its inhibitory effect on human cervical cancer HeLa cells, and analyze the expression profiling of selected nuclear stem cell-associated transcription factors. The presence of secreted aspartyl proteinase protein was confirmed by the expression of SAP2 and SAP4 genes in C. tropicalis during the yeast-hyphae transition phase. The enzyme was purified and characterized using the aqueous two-phase system purification method, as well as proteolytic activity and the Bradford and micro-Kjeldahl methods, respectively. The in vitro anti-cancer properties of secreted aspartyl proteinase protein were evaluated by MTT assay, microscopic image analysis, nitric oxide (NO) scavenging activity assay, intracellular reactive oxygen species (ROS) production assay, and RT-qPCR. The isolated C. tropicalis secreted aspartyl proteinase protein exhibited proteinase activity with values ranging from 93.72 to 130.70 μg/mL and 89.88-127.72 μg/mL according to the Bradford and micro-Kjeldahl methods, respectively. Secreted aspartyl proteinase showed effective cytotoxicity in HeLa cell line leading to significant morphological changes. Additionally, it exhibited increased free radical scavenging activity compared to the untreated control group, as evidenced by nitrite inhibition. ROS production increased in HeLa cells exposed to secreted aspartyl proteinase. The expression levels of the nuclear stem cell-associated transcription factors octamer-binding transcription factor 4 (OCT4), sex determining region Y-box 2 (SOX2), and Nanog homeobox (NANOG) were significantly downregulated in the HeLa cells treated with secreted aspartyl proteinase. Secreted aspartyl proteinase protein may be a promising anti-cancer agent, as it effectively affects gene expression and may ultimately reduce the development and progression of cervical cancer. Targeting the genes related to nuclear stem cell-associated transcription factors may provide a novel amenable to cancer treatment.

Endophytic fungi: A future prospect for breast cancer therapeutics and drug development

Globally, breast cancer is a primary contributor to cancer-related fatalities and illnesses among women. Consequently, there is a pressing need for safe and effective treatments for breast cancer. Bioactive compounds from endophytic fungi that live in symbiosis with medicinal plants have garnered significant interest in pharmaceutical research due to their extensive chemical composition and prospective medicinal attributes. This review underscores the potentiality of fungal endophytes as a promising resource for the development of innovative anticancer agents specifically tailored for breast cancer therapy. The diversity of endophytic fungi residing in medicinal plants, success stories of key endophytic bioactive metabolites tested against breast cancer and the current progress with regards to in vivo studies and clinical trials on endophytic fungal metabolites in breast cancer research forms the underlying theme of this article. A thorough compilation of putative anticancer compounds sourced from endophytic fungi that have demonstrated therapeutic potential against breast cancer, spanning the period from 1990 to 2022, has been presented. This review article also outlines the latest trends in endophyte-based drug discovery, including the use of artificial intelligence, machine learning, multi-omics approaches, and high-throughput strategies. The challenges and future prospects associated with fungal endophytes as substitutive sources for developing anticancer drugs targeting breast cancer are also being highlighted.

Pararorine A, isoindolinone alkaloid from the endophytic fungus Paramyrothecium roridum and its anti-tumor activity

Pararorine A, a new isoindolinone alkaloid was isolated from Paramyrothecium roridum, an endophytic fungus from the medicinal plant Gynochthodes officinalis (F.C. How) Razafim. & B. Bremer. The structure of this compound was elucidated by extensive spectroscopic (UV, IR, MS, and NMR) analyses. In addition, the antitumor activity of pararorine A was evaluated against SF-268, MCF-7, HepG2, and A549 tumor cell lines. The results revealed that pararorine A exhibited potent antitumor activities with the IC50 values ranging from 1.69 to 8.95 μM. Moreover, the tumor cell inhibitory activity of pararorine A was evidenced by promoting cytochrome C release and cell cycle arrest as well as the induction of apoptosis by the up-regulation of the protein expressions of JNK and Bax through PARP-cleavage and caspase 3-cleavage.

Irpexols A-C, xanthone derivatives from the endophyte fungus Irpex laceratus A878

Three new xanthone derivatives irpexols A-C (1-3) and five known xanthones including three dimeric ones were successfully isolated from Irpex laceratus A878, an endophytic fungus of the family Irpicaceae from the medicinal plant Pogostemon cablin (Blanco) Bentham (Lamiaceae). The structures of these compounds were elucidated by extensive spectroscopic analyses including ultraviolet-visible spectroscopy (UV), infrared spectroscopy (IR), mass spectrometry (MS), and nuclear magnetic resonance (NMR). All of the three new compounds (1-3) share a de-aromatic and highly‑oxygenated xanthone skeleton. In addition, the cytotoxic activity of compounds 1-8 were evaluated against SF-268, MCF-7, HepG2, and A549 tumor cell lines. The results revealed that compound 6 showed moderate cytotoxic activity with the IC50 values ranging from 24.83 to 45.46 μM, while the IC50 values of the positive control adriamycin was ranging from 1.11 to 1.44 μM.

Exploring the antioxidant potential of endophytic fungi: a review on methods for extraction and quantification of total antioxidant capacity (TAC)

Endophytic fungi have emerged as a significant source of natural products with remarkable bioactivities. Recent research has identified numerous antioxidant molecules among the secondary metabolites of endophytic fungi. These organisms, whether unicellular or micro-multicellular, offer the potential for genetic manipulation to enhance the production of these valuable antioxidant compounds, which hold promise for promoting health, vitality, and various biotechnological applications. In this study, we provide a critical review of methods for extracting, purifying, characterizing, and estimating the total antioxidant capacity (TAC) of endophytic fungi metabolites. While many endophytes produce metabolites similar to those found in plants with established symbiotic associations, we also highlight the existence of novel metabolites with potential scientific interest. Additionally, we discuss how advancements in nanotechnology have opened new avenues for exploring nanoformulations of endophytic metabolites in future studies, offering opportunities for diverse biological and industrial applications.

Chemical constituents of Penicillium ferraniaense GE-7 and their cytotoxicities

Phytochemical investigation on the plant endophytic fungus Penicillium ferraniaense GE-7 led to the isolation of 18 compounds including one new α-pyrone derivative, peniferranige A (1). The structure including the absolute configuration of compound 1 was elucidated by NMR, HRMS, and ECD data. Demethoxyfumitremorgin C (16) and meleagrin (17) possessed moderate activities against the human lung cancer cell line H1975 with IC50 values of 28.52 ± 1.07 and 13.94 ± 1.92 μM, respectively.

Phytochemical investigation of Nigrospora zimmermanii isolated from Poincianella pluviosa (Sibipiruna): metabolites characterisation and screening for anti-inflammatory activity

Endophytic fungi residing symbiotically in plant tissues are promising sources of bioactive natural products. This study explored the anti-inflammatory potential of an endophytic fungus isolated from the Brazilian medicinal plant Poincianella pluviosa (Sibipiruna). The extract from the endophyte FPD13 exhibited potential ex vivo anti-inflammatory effects by inhibiting prostaglandin E2 (PGE2) release by 75.22%. Phytochemical analysis using High-Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR), and Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) enabled the isolation and identification of three compounds, including the macrolide Nigrosporolide, the phenyl-propanol Tyrosol, and the terpene Decarestrictine A. Morphological characteristics and Internal Transcribed Spacers region (ITS) sequencing classified fungus FPD13 as Nigrospora zimmermanii. The results reveal the anti-inflammatory potential and chemical diversity of P. pluviosa endophytes, warranting further investigation into the bioactivity and structure elucidation of their bioactive metabolites.

Discovery of Natural Potent HMG-CoA Reductase Degraders for Lowering Cholesterol

Exploitation of key protected wild plant resources makes great sense, but their limited populations become the major barrier. A particular strategy for breaking this barrier was inspired by the exploration of a resource-saving fungal endophyte Penicillium sp. DG23, which inhabits the key protected wild plant Schisandra macrocarpa. Chemical studies on the cultures of this strain afforded eight novel indole diterpenoids, schipenindolenes A-H (1-8), belonging to six diverse skeleton types. Importantly, semisyntheses suggested some key nonenzymatic reactions constructing these molecules and provided targeted compounds, in particular schipenindolene A (Spid A, 1) with low natural abundance. Remarkably, Spid A was the most potent HMG-CoA reductase (HMGCR) degrader among the indole diterpenoid family. It degraded statin-induced accumulation of HMGCR protein, decreased cholesterol levels and acted synergistically with statin to further lower cholesterol. Mechanistically, transcriptomic and proteomic profiling suggested that Spid A potentially activated the endoplasmic reticulum-associated degradation (ERAD) pathway to enhance the degradation of HMGCR, while simultaneously inhibiting the statin-activated expression of many key enzymes in the cholesterol and fatty acid synthesis pathways, thereby strengthening the efficacy of statins and potentially reducing the side effects of statins. Collectively, this study suggests the potential of Spid A for treating cardiovascular disease.

Insight of endophytic fungi promoting the growth and development of woody plants

Microorganisms play an important role in plant growth and development. In particular, endophytic fungi is one of the important kinds of microorganisms and has a mutually beneficial symbiotic relationship with host plants. Endophytic fungi have many substantial benefits to host plants, especially for woody plants, such as accelerating plant growth, enhancing stress resistance, promoting nutrient absorption, resisting pathogens and etc. However, the effects of endophytic fungi on the growth and development of woody plants have not been systematically summarized. In this review, the functions of endophytic fungi for the growth and development of woody plants have been mainly reviewed, including regulating plant growth (e.g., flowering, root elongation, etc.) by producing nutrients and plant hormones, and improving plant disease, insect resistance and heavy metal resistance by producing secondary metabolites. In addition, the diversity of endophytic fungi could improve the ability of woody plants to adapt to adverse environment. The components produced by endophytic fungi have excellent potential for the growth and development of woody plants. This review has systematically discussed the potential regulation mechanism of endophytic fungi regulating the growth and development of woody plants, it would be of great significance for the development and utilization of endophytic fungi resource from woody plants for the protection of forest resources.

Proposing of fungal endophyte secondary metabolites as a potential inhibitors of 2019-novel coronavirus main protease using docking and molecular dynamics

In this study, the inhibitory potential of 99 fungal derived secondary metabolites was predicted against SARS-CoV-2 main protease by using of computational approaches. This protein plays an important role in replication and is one of the important targets to inhibit viral reproduction. Among the 99 reported compounds, the 9 of them with the highest binding energy to Mpro obtained from the molecular docking method were selected for the molecular dynamic simulations. The compounds were then investigated by using the SwissADME serve to evaluate the compounds in terms of pharmacokinetic and druglikness properties. The overall results of different analysis show that the compound RKS-1778 is potentially more effective than others and form strong complexes with viral protease. It also had better pharmacokinetic properties than other metabolites, so predicted to be a suitable candidate as anti SARS-CoV-2 bioactive.

In vitro and in vivo anti-colorectal cancer effect of the newly synthesized sericin/propolis/fluorouracil nanoplatform through modulation of PI3K/AKT/mTOR pathway

The present work aimed to assess the potential effect of sericin/propolis/fluorouracil nanoformula against colorectal cancer (CRC) (the fourth most common cause of cancer-related mortalities). A novel anti-cancerous formula of the synthesized sericin/propolis nanoparticles was developed and tested both in vitro (using Caco-2 cell line) and in vivo (in experimentally induced colorectal cancer animal models). The combination index of the prepared nanoformula proved that the combination between sericin/propolis nanoparticles and 5-fluorouracil demonstrated the highest synergistic effect (0.86), with dose reduction index (DRI) of the chemotherapeutic drug reaching 1.49. The mechanism of action of the prepared nanoformula revealed that it acts through the inhibition of the PI3K/AKT/mTOR signaling pathway and consequently inhibiting cancerous cells proliferation. Treatment and prophylactic studies of both sericin and propolis showed increased TBARS (Thiobarbituric Acid Reactive Substance) formation, downregulated BCL2 (B-cell lymphoma 2) and activated BAX, Caspase 9 and Caspase 3 expression. The prepared nanoformula decreased the ROS (Reactive Oxygen Species) production in vivo owing to PI3K/AKT/mTOR pathway inhibition and FOXO-1 (Forkhead Box O1) activation that resulted in autophagy/apoptosis processes stimulation. The potent anticancer effect of the prepared nanoformula was further emphasized through the in vivo histopathological studies of experimentally induced tumors. The newly formulated sericin/propolis/fluorouracil nanoparticles exhibited clear-cut cytotoxic effects toward tumor cells with provided evidence for the prophylactic effect.

Diaporaustalides A-L, Austalide Meroterpenoids from a Plant Endophytic Diaporthe sp

Twelve new austalide meroterpenoids (1-12) were isolated from the endophytic fungus Diaporthe sp. XC1211. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of compounds 1, 3, 4, and 6 were established by single-crystal X-ray diffraction, whereas those for the others were established by experimental electronic circular dichroism (ECD) data analysis. Compounds 1-12 represent a rare class of austalides with a 24α-CH3. Compounds 2 and 5 demonstrated potent proliferation inhibitory effects against LPS-induced B cells with IC50 values of 6.7 (SI = 3.6) and 3.8 (SI > 13) μM, respectively. Compounds 2 and 5 decreased the secretion of IL-6 in LPS-induced B cells in a dose-dependent manner.

Advances in Antitumor Effects Using Liposomal Citrinin in Induced Breast Cancer Model

The study aimed to evaluate the antitumor and toxicogenetic effects of liposomal nanoformulations containing citrinin in animal breast carcinoma induced by 7,12-dimethylbenzanthracene (DMBA). Mus musculus virgin females were divided into six groups treated with (1) olive oil (10 mL/kg); (2) 7,12-DMBA (6 mg/kg); (3) citrinin, CIT (2 mg/kg), (4) cyclophosphamide, CPA (25 mg/kg), (5) liposomal citrinin, LP-CIT (2 μg/kg), and (6) LP-CIT (6 µg/kg). Metabolic, behavioral, hematological, biochemical, histopathological, and toxicogenetic tests were performed. DMBA and cyclophosphamide induced behavioral changes, not observed for free and liposomal citrinin. No hematological or biochemical changes were observed for LP-CIT. However, free citrinin reduced monocytes and caused hepatotoxicity. During treatment, significant differences were observed regarding the weight of the right and left breasts treated with DMBA compared to negative controls. Treatment with CPA, CIT, and LP-CIT reduced the weight of both breasts, with better results for liposomal citrinin. Furthermore, CPA, CIT, and LP-CIT presented genotoxic effects for tumor, blood, bone marrow, and liver cells, although less DNA damage was observed for LP-CIT compared to CIT and CPA. Healthy cell damage induced by LP-CIT was repaired during treatment, unlike CPA, which caused clastogenic effects. Thus, LP-CIT showed advantages for its use as a model of nanosystems for antitumor studies.

Antitumor and antibacterial activity of metabolites of endophytic Colletotrichum siamense isolated from coffee (Coffea arabica L. cv IAPAR-59)

Endophytic fungi produce a range of known metabolites and several others, not yet explored, which present important biological activities from the pharmaceutical and industrial perspective. Several studies have reported the diversity of endophytes in Coffea arabica plants, although few have been described in organic cultures. In the current paper, we describe the chemical profile of specialized metabolites in the ethyl acetate phase in a strain of the endophytic fungus Colletotrichum siamense associated with coffee (Coffea arabica L.) (Rubiaceae) and its potential against tumor cells and bacteria of medical and food importance. Cytotoxicity assays in tumor cells MCF-7 and HepG2/C3A were performed by MTT and microdilution in broth to evaluate the antibacterial action of metabolic extract. The antiproliferative assay showed promising results after 24 h of treatment, with 50% injunction concentrations for the two cell types. UHPLC-MS/MS analyses with an electrospray ionization source were used to analyze the extracts and identify compounds of species Colletotrichum siamense, which is still little explored as a source of active metabolites. Many of these compounds observed in the endophytic need to be chemically synthesized in industry, at high costs, while production by the fungus becomes a chemically and economically more viable alternative. Pyrocatechol, gentisyl alcohol, and alpha-linolenic acid, associated with different mechanisms of action against tumor cells, were detected among the main compounds. The extract of the endophytic fungus Colletotrichum siamense presented several compounds with pharmacological potential and antibacterial activity, corroborating its potential in biotechnological applications.

Proteomics, Transcriptomics, and Phosphoproteomics Reveal the Mechanism of Talaroconvolutin-A Suppressing Bladder Cancer via Blocking Cell Cycle and Triggering Ferroptosis

Talaroconvolutin-A (TalaA) is a compound from the endophytic fungus T. convolutispora of the Chinese herbal medicine Panax notoginseng. Whether TalaA exerts anticancer activity in bladder cancer remains unknown. Using CCK8 assay, EdU staining, crystal violet staining, flow cytometry, living/dead cell staining, and Western blotting, we studied the anticancer activity of TalaA in vitro. Moreover, we performed xenograft tumor implantation. The antitumor effects were evaluated through H&E and immunohistochemistry staining. Proteomics was conducted to detect changes in the protein profile; transcriptomics was performed to detect changes in mRNA abundance; phosphoproteomics was used to detect changes in protein phosphorylation. TalaA inhibited tumor cell proliferation, DNA replication, and colony formation in a dose-dependent manner in bladder cancer cells. The IC50 values of TalaA on SW780 and UM-UC-3 cells were 5.7 and 8.2 μM, respectively. TalaA (6.0 mg/kg) significantly repressed the growth of xenografted tumors and did not affect the body weight nor cause obvious hepatorenal toxicity. TalaA arrested the cell cycle by downregulating cyclinA2, cyclinB1, and AURKB and upregulating p21/CIP. TalaA also elevated intracellular reactive oxygen species and upregulated transferrin and heme oxygenase 1 to induce ferroptosis. Moreover, TalaA was able to bind to MAPKs (MAPK1, MAPK8, and MAPK14) to inhibit the phosphorylation of ∗SP∗ motif of transcription regulators. This study revealed that TalaA inhibited bladder cancer by arresting cell cycle to suppress proliferation and triggering ferroptosis to cause cell death. Conclusively, TalaA would be a potential candidate for treating bladder cancer by targeting MAPKs, suppressing the cell cycle, and inducing ferroptosis.

New steroid produced by Periconia pseudobyssoides K5 isolated from Toona sureni (Meliaceae) and its heme polymerization inhibition activity

A new ergostane-type steroid named (22E)-3α,6α,9α-ergosta-7,22-diene-3,6,9-triol (1), along with six known steroids 5α,8α-epidioxy-24-ethyl-cholest-6-en-3β-ol (2), ergosterol-5,8-peroxide (3), cerevisterol (4), isocyathisterol (5), 6β-hydroxystigmast-4-en-3-one (6), 6β-hydroxy-4-campesten-3-one (7), were isolated from the fermented unpolished rice media by Periconia pseudobyssoides K5 (Periconiaceae), an endophytic fungus from medicinal plant Toona sureni (Meliaceae). The fermentation takes at 28 ± 2 °C for 30 days. The structure of new steroid (1) was elucidated by extensive spectroscopic measurements (IR, HR-ESI-TOFMS, and 1D and 2D NMR) analyses. The isolated compounds (1-7) were evaluated for heme polymerization inhibition assay (HPIA). The IC50 HPIA value of 1 is 8.24 ± 0.03 mg/ml.

Towards further understanding the applications of endophytes: enriched source of bioactive compounds and bio factories for nanoparticles

The most significant issues that humans face today include a growing population, an altering climate, an growing reliance on pesticides, the appearance of novel infectious agents, and an accumulation of industrial waste. The production of agricultural goods has also been subject to a great number of significant shifts, often known as agricultural revolutions, which have been influenced by the progression of civilization, technology, and general human advancement. Sustainable measures that can be applied in agriculture, the environment, medicine, and industry are needed to lessen the harmful effects of the aforementioned problems. Endophytes, which might be bacterial or fungal, could be a successful solution. They protect plants and promote growth by producing phytohormones and by providing biotic and abiotic stress tolerance. Endophytes produce the diverse type of bioactive compounds such as alkaloids, saponins, flavonoids, tannins, terpenoids, quinones, chinones, phenolic acids etc. and are known for various therapeutic advantages such as anticancer, antitumor, antidiabetic, antifungal, antiviral, antimicrobial, antimalarial, antioxidant activity. Proteases, pectinases, amylases, cellulases, xylanases, laccases, lipases, and other types of enzymes that are vital for many different industries can also be produced by endophytes. Due to the presence of all these bioactive compounds in endophytes, they have preferred sources for the green synthesis of nanoparticles. This review aims to comprehend the contributions and uses of endophytes in agriculture, medicinal, industrial sectors and bio-nanotechnology with their mechanism of action.

Diversity of Fungal Communities on Diseased and Healthy Cinnamomum burmannii Fruits and Antibacterial Activity of Secondary Metabolites

The composition and structure of fungal communities on healthy and diseased fruits of Cinnamomum burmannii (Nees and Nees) Blume were characterized, with evaluation of the antibacterial activity of secondary metabolites from culturable fungi following the first identification of secondary metabolites in the fungus Medicopsis romeroi (Esf-14; GenBank accession number OK242756). These results are significant for understanding the functional variation in bioactivity in fungal communities and developing a broader range of bioactive resources. High-throughput sequencing results indicated that the fungal community in diseased fruit differed from that in healthy fruit at the phylum, class, order, or genus level, with significant differences in the species and relative abundance of the dominant flora. A total of 49 (healthy fruit) and 122 (diseased fruit) artificially cultivable endophytic fungi were isolated, and 41 different strains (11 from healthy fruit and 30 from diseased fruit) were successfully identified by morphological and molecular biological analyses, which were classified into 8 groups and 23 genera by phylogenetic tree analysis, with Pleosporales, Glomerellales, and Hypocreales being the dominant groups at the order level and Colletotrichum being the dominant group at the genus level. The results of the antibacterial assay demonstrated that the secondary metabolites of all strains had different degrees of antibacterial activity, while the secondary metabolites of endophytic fungi from diseased fruit were generally stronger than those of fungi from healthy fruit, with the active secondary metabolites dominated by small and moderately polar compounds. Combined analysis of fungal communities, phylogenetic tree analysis, and bioactivity analysis of culturable strains revealed strong antibacterial activity of both upregulated and downregulated flora in diseased fruit. Five compounds, including two new (5,6-dimethoxy-[1',1:4,1″-terphenyl]-2-ol [compound 1] and 5-(methoxycarbonyl)-2-methylbenzo[d][1,3]dioxole-2-carboxylic acid [compound 2]) and three known compounds (3,7-dihydroxy-1,9-dimethyldibenzofuran [compound 3], methyl 3-hydroxybenzoate [compound 4], and uracil [compound 5]), were isolated and identified for the first time from the endophytic fungus Medicopsis romeroi. In general, the diversity of fungal communities on diseased fruit was lower than that on healthy fruits, while the antibacterial activity of artificially cultured endophytic fungi on diseased fruits was generally stronger than that on healthy fruits, suggesting excellent promise for the development of secondary metabolites from active strains on diseased fruit as antibacterial agents. IMPORTANCE Powdery fruit disease is a notorious disease of Cinnamomum burmannii that causes severe loss in fruit production. Studies on the function of endophytic fungal communities in healthy plant tissues are not new, while little is known about the functional changes of fungal communities in disease-causing plant tissues. Our results demonstrate that fungal communities in diseased fruits differ from those in healthy fruits at the level of phylum, class, order, or genus, with significant differences in the species and relative abundance of dominant groups. Endophytic fungi in diseased fruits appeared to produce secondary metabolites with stronger antibacterial properties, although the community diversity was not as varied as that in healthy fruits. In addition, secondary metabolites of the Medicopsis romeroi strain from diseased fruits were identified for the first time. These results have important implications for understanding the functional variation of bioactivity in fungal communities and for developing a broader resource of bioactivity.

Computational identification of drug-like marine natural products as potential RNA polymerase inhibitors against Nipah virus

Nipah virus (NiV) has been an alarming threat to human populations in southern Asia for more than a decade. It is one of the most deadly viruses in the Mononegavirales order. Despite its high mortality rate and virulence, no chemotherapeutic agent or vaccine is publicly available. Hence, this work was conducted to computationally screen marine natural products database for drug-like potential inhibitors for the viral RNA-dependent RNA polymerase (RdRp). The structural model was subjected to molecular dynamics (MD) simulation to obtain the native ensemble of the protein. The CMNPDB dataset of marine natural products was filtered to retain only compounds following Lipinski's five rules. The molecules were energy minimized and docked into different conformers of the RdRp using AutoDock Vina. The best 35 molecules were rescored by GNINA, a deep learning-based docking software. The resulting nine compounds were evaluated for their pharmacokinetic profiles and medicinal chemistry properties. The best five compounds were subjected to MD simulation for 100 ns, followed by binding free energy estimation via Molecular Mechanics/ Generalized Born Surface Area (MM/GBSA) calculations. The results showed remarkable behavior of five hits as inferred by stable binding pose and orientation to block the exit channel of RNA synthesis products in the RdRp cavity. These hits are promising starting materials for in vitro validation and structural modifications to enhance the pharmacokinetic and medicinal chemistry properties for developing antiviral lead compounds.

Phytochemistry and Biological Activities of Endophytic Fungi from the Meliaceae Family

Meliaceae plants are found worldwide in tropical or subtropical climates. They are important ethnobotanically as sources of traditional medicine, with 575 species and 51 genera. Previous research found that microorganisms are plant pioneers to produce secondary metabolites with diverse compound structures and bioactivities. Several plants of the Meliaceae family contain secondary metabolites isolated from endophytic fungi. Furthermore, related articles from 2002 to 2022 were collected from SciFinder, Google Scholar, and PubMed. About 276 compounds were isolated from endophytic fungi such as terpenoids, polyketides, lactones, pyrones, quinone, anthraquinones, xanthones, coumarines, isocoumarines, resorcylic acid lactones, cytochalasins, aromatics, ester, quinols, alkaloids, nitro compound, fatty acids, and sugars with bioactivities such as antioxidant, antibacterial, antifungal, anti-influenza, neuroprotective activities, anti-HIV, cytotoxic, allelopathic, anti-inflammatory, antifeedant effects, and BSLT toxicity. Meanwhile, secondary metabolites isolated from endophytic fungi were reported as one of the sources of active compounds for medicinal chemistry. This comprehensive review summarizes the ethnobotanical uses and secondary metabolites derived from Meliaceae endophytic fungi.

LC-MS/MS and GC-MS based phytochemical perspectives and antimicrobial effects of endophytic fungus Chaetomium ovatoascomatis isolated from Euphorbia milii

The antimicrobial activity of endophytic fungi isolated from Euphorbia milii was evaluated against Gram-positive, Gram-negative bacteria, unicellular yeast, and filamentous fungi. Chaetomium ovatoascomatis NRC was identified morphologically and genetically as the most active strain. The total ethyl acetate extract of C. ovatoascomatis NRC demonstrated significant antimicrobial activity against Gram-negative; Escherichia coli, Salmonella enteric, and fungi; Aspergillus niger with MIC of 62.5 ug/ml. Whereas n-hexane fraction demonstrated broader activity against Gram-positive; Bacillus subtilis, Lactobacillus cereus, Gram-negative; Escherichia coli and Salmonella enteric, fungi; Candida albicans and F. solani. LC–MS/MS analysis of ethyl acetate strain extract and GC–MS analysis of the n-hexane fraction were used to identify the metabolites of the strain extract. LC–MS/MS determined three major metabolites with potential antimicrobial activities including grevilline B, aflatoxin G2 and apigenin. GC–MS analysis of n-hexane fraction tentatively identified 30 compounds, where 9,12-octadecadienoic acid methyl ester was the major compound.

Pigment produced from Arcopilus aureus isolated from grapevines: Promising natural yellow colorants for the food industry

Interest in the use of natural non-toxic pigments by the food industry has grown. Some filamentous fungi are producers of natural pigments that are more stable at temperature and pH than other pigments also classified as natural, such as those produced by plants. Production potential of natural pigments by endophytic fungi from grapevines was evaluated. Arcopilus aureus was selected as a potential source for a yellow pigment, which was characterized and tested for stability to variations in temperature and pH. Components, cochlioquinol II and riboflavin, were detected, which has not previously been reported in A. aureus. The pigment was stable and showed increased absorption at lower / acidic pH. These results provide information on the potential of this fungus and a yellow pigment for the first time, which can be used for further development and industrial application.

Colonization characteristics of fungi in Polygonum hydropipe L. and Polygonum lapathifolium L. and its effect on the content of active ingredients

Polygonum hydropiper, is a plant of the Persicaria genus, which is commonly used to treat various diseases, including gastrointestinal disorders, neurological disorders, inflammation, and diarrhea. However, because of different local standards of P. hydropiper, people often confuse it with Polygonum lapathifolium L. and other closely related plants. This poses a serious threat to the safety and efficacy of the clinical use of P. hydropiper. This study aims to determine the six active ingredients of P. hydropiper and P. lapathifolium. Then the endophytic fungi and rhizosphere soil of the two species were sequenced by Illumina Miseq PE300. The results show significant differences between the community composition of the leaves, stems, and roots of the P. hydropiper and the P. lapathifolium in the same soil environment. Of the six secondary metabolites detected, five had significant differences between P. hydropiper and P. lapathifolium. Then, we evaluated the composition of the significantly different communities between P. hydropiper and P. lapathifolium. In the P. hydropiper, the relative abundance of differential communities in the leaves was highest, of which Cercospora dominated the differential communities in the leaves and stem; in the P. lapathifolium, the relative abundance of differential community in the stem was highest, and Cladosporium dominated the differential communities in the three compartments. By constructing the interaction network of P. hydropiper and P. lapathifolium and analyzing the network nodes, we found that the core community in P. hydropiper accounted for 87.59% of the total community, dominated by Cercospora; the core community of P. lapathifolium accounted for 19.81% of the total community, dominated by Sarocladium. Of these core communities, 23 were significantly associated with active ingredient content. Therefore, we believe that the community from Cercospora significantly interferes with recruiting fungal communities in P. hydropiper and affects the accumulation of secondary metabolites in the host plant. These results provide an essential foundation for the large-scale production of P. hydropiper. They indicate that by colonizing specific fungal communities, secondary metabolic characteristics of host plants can be helped to be shaped, which is an essential means for developing new medicinal plants.

Dereplication of Cytochalasans and Octaketides in Cytotoxic Extracts of Endophytic Fungi from Casearia arborea (Salicaceae)

Endophytes have been shown to be a source of novel drug prototypes. The Casearia genus is known for presenting cytotoxic clerodane diterpenes; however, there are few reports on secondary metabolites produced by its fungal microbiota. Thus, in the present study endophytic fungi obtained from the fresh leaves of C. arborea were grown in potato dextrose broth and rice to perform a secondary metabolite prospection study. The cytotoxic profile of the crude extracts at 10 µg/mL was determined by a colorimetric assay on tumor cell lines. The endophytes producing cytotoxic extracts were identified through phylogenetic analysis and belong to Diaporthe and Colletotrichum species. Metabolites present in these extracts were organized in molecular networking format based on HRMS-MS, and a dereplication process was performed to target compounds for chromatographic purification. Metabolic classes, such as lipids, peptides, alkaloids, and polyketides were annotated, and octaketide and cytochalasin derivatives were investigated. Cytochalasin H was purified from the cytotoxic Diaporthe sp. CarGL8 extract and its cytotoxic activity was determined on human cancer cell lines A549, MCF-7, and HepG2. The data collected in the present study showed that molecular networking is useful to understand the chemical profile of complex matrices to target compounds, minimizing the cost and time spent in purification processes.

Global regulatory factor VeA upregulates the production of antitumor substances in endophytic Fusarium solani

A number of studies have demonstrated that endophytic fungi have the potential to produce antitumor active substances with novel structures and significant activities. In our previous studies, we isolated a Fusarium strain from the stem of the medicinal plant Nothapodytes pittosporoides (Oliv.). In this study, we identified this strain as Fusarium solani and found that its crude extract has significant antitumor activity against human alveolar adenocarcinoma cells (A549). We overexpressed the global regulatory factor VeA in F. solani (VeA^OE), resulting in a significant increase in antitumor activity. The MTT assay results showed that the inhibition rate of the VeA^OE mutant extract on A549 cancer cells was significantly higher than that of the WT extract, as the IC₅₀ decreased from 369.22 to 285.89 μg/mL, and the apoptosis ratio was significantly increased by approximately 4.86-fold. In VeA^OE, accumulation of alkaloids, terpenoids, carboxylic acid derivatives, phenols and flavonoid metabolites with potential antitumor activity was significantly increased compared with WT based on metabolomic analysis. Additionally, transcriptome analysis found that the expression patterns of 48 genes related to antitumor activity were significantly changed in VeA^OE, mainly involving glycosyl hydrolases, the Zn(2)-Cys(6) class, cytochrome P450 monooxygenase, 3-isopropylmalate dehydratase, and polyketide synthases. These results suggested that VeA mediated the antitumor activity of the metabolites in F. solani HB1-J1 by regulating multiple metabolic pathways.

Antimicrobial Potential of Endophytic Fungi From Artemisia argyi and Bioactive Metabolites From Diaporthe sp. AC1

Endophytic fungi of medicinal plants are important sources of active natural products. In this study, 26 fungi were isolated from Artemisia argyi, which were belonging to eight genera, namely, Alternaria, Fusarium, Chaetomium, Phoma, Diaporthe, Trichoderma, Gibberella, and Colletotrichum. The antimicrobial activities of all fungal extracts were tested by using the cup-plate method against Staphylococcus aureus, Salmonella enteritidis, and Fusarium graminearum. The results demonstrated that 25 extracts (96%) exhibited inhibitory activity against at least one of the tested pathogenic microorganisms. The strain Diaporthe sp. AC1, which showed good antimicrobial activity and high yield of crude extract from fermentation, was selected for the study of secondary metabolites. The crude extract of strain AC1 was purified by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and HPLC, and finally, a new compound phomopsolide G (1), together with three known phomopsolides (2–4) and four other known compounds (5–8), was obtained. The structures of the compounds were elucidated by NMR and/or HR-MS spectroscopy. Microdilution method and MTT colorimetry were used to determine the bioactivity of the compounds. The study demonstrated that the new compound 1 had moderate antifungal activity against F. graminearum, Fusarium moniliforme, and Botrytis cinerea and weak antibacterial activity against Staphylococcus aureus. Compound 1 also showed weak cytotoxicity against HepG2, A549, and MDA-MB-231, with IC50 values of 89.91, 107.65, and 53.97 μM. Additionally, other compounds also exhibited antimicrobial and/or cytotoxic activities. The findings provided the basis for searching drug and agricultural lead compounds from A. argyi-associated fungi resources.

Overhauling the Effect of Surface Sterilization on Analysis of Endophytes in Tea Plants

Increasing evidence shows that plant Endophytes play a crucial role in the fitness and productivity of hosts. Surface sterilization is an indispensable process before high-throughput sequencing (HTS) and tissue separation of plant endophytes, but its potential impact on the composition and diversity of endophytes has rarely been investigated. In the present work, the influence of sodium hypochlorite (NaClO) on the diversity of endophytic bacteria and fungi in leaves and stems of tea plants was investigated. We found that the diversity of bacterial endophytes was significantly affected by the concentration of NaClO as well as the pretreatment time. Pretreatment with 0.5% NaClO for 8 min and 2.0% NaClO for 3 min were suitable for the tea plant leaves and stems, respectively, but the effects of NaClO on the diversity of fungal endophytes were limited according to the results from HTS. Regardless of NaClO sterilization, most of the endophytes in tissues, such as the dominant taxa, could not be Isolated by using the regular culture-dependent approaches. Collectively, our results demonstrated that the pretreatment with NaClO should be modified to precisely understand the diversity of endophytes from different tissues of tea plants and also indicate that more attention should be paid to establish specific culture-dependent protocols for the isolation of plant endophytes.

Bioactive terpenoids derived from plant endophytic fungi: An updated review (2011-2020)

Plant endophytes have been considered as novel sources of naturally occurring compounds with various biological activities, including cytotoxic, antimicrobial, anti-inflammatory, anticancer, herbicides, antileishmanial and antioxidant. A variety of specialised products, comprising terpenoids, alkaloids, polyketides, phenolic compounds, coumarins, and quinone derivatives have been reported from various strains. An increasing number of products, especially terpenoids, are being isolated from endophytes. Herein, the isolated new terpenoids from plant endophytic fungi, their hosts, as well as biological activities, from January 2011 until the end of 2020 are reviewed. In this period, 516 terpenoids are classified into monoterpenes (5), sesquiterpenes (299), diterpenes (76), sesterterpens (22), meroterpenes (83), triterpenes (29), and other terpenoids (2), were isolated from different plant endophytic fungi species.

Exploring the Activity of Fungal Phenalenone Derivatives as Potential CK2 Inhibitors Using Computational Methods

Cancer represents one of the most prevalent causes of global death. CK2 (casein kinase 2) activation boosted cancer proliferation and progression. Therefore, CK2 inhibition can have a crucial role in prohibiting cancer progression and enhancing apoptosis. Fungi have gained vast interest as a wealthy pool of anticancer metabolites that could particularly target various cancer progression-linked signaling pathways. Phenalenones are a unique class of secondary metabolites that possess diverse bioactivities. In the current work, the CK2 inhibitory capacity of 33 fungal phenalenones was explored using computational studies. After evaluating the usefulness of the compounds as enzyme inhibitors by ADMET prediction, the compounds were prepared for molecular docking in the CK2-α1 crystal structure (PDB: 7BU4). Molecular dynamic simulation was performed on the top two scoring compounds to evaluate their binding affinity and protein stability through a simulated physiological environment. Compound 19 had a superior binding affinity to the co-crystallized ligand (Y49). The improved affinity can be attributed to the fact that the aliphatic chain makes additional contact with Asp120 in a pocket distant from the active site.

A target and efficient synthetic strategy for structural and bioactivity optimization of a fungal natural product

Drugs have been largely inspired from natural products, while enzymes underlying their biosynthesis have enabled complex structures and diverse bioactivities. Nevertheless, the high enzyme specificity and limited in vivo precursor types have restricted the natural product reservoir, but Nature has imprinted natural products with active sites, which can be readily modified by chemosynthesis with various functional groups for more favorable druggability. Here in the less exploited fungal natural products, we introduced CtvA, a polyketide synthase for a mycotoxin citreoviridin biosynthesis in Aspergillus, into an endophytic fungus Calcarisporium arbuscula to expand tetrahydrofuran (THF) into a dioxabicyclo-octane (DBO) ring moiety based on versatility and promiscuity of the aurovertin biosynthetic enzyme. Alternative acylations on the hydroxyl groups essential for cell toxicity by chemosynthesis produced compounds with improved anti-tumor activities and pharmacokinetics. Thus, we showed an effective strategic way to optimize the fungal natural product efficiently for more promising drug development.

Endophytic Fungi: Key Insights, Emerging Prospects, and Challenges in Natural Product Drug Discovery

Plant-associated endophytes define an important symbiotic association in nature and are established bio-reservoirs of plant-derived natural products. Endophytes colonize the internal tissues of a plant without causing any disease symptoms or apparent changes. Recently, there has been a growing interest in endophytes because of their beneficial effects on the production of novel metabolites of pharmacological significance. Studies have highlighted the socio-economic implications of endophytic fungi in agriculture, medicine, and the environment, with considerable success. Endophytic fungi-mediated biosynthesis of well-known metabolites includes taxol from Taxomyces andreanae, azadirachtin A and B from Eupenicillium parvum, vincristine from Fusarium oxysporum, and quinine from Phomopsis sp. The discovery of the billion-dollar anticancer drug taxol was a landmark in endophyte biology/research and established new paradigms for the metabolic potential of plant-associated endophytes. In addition, endophytic fungi have emerged as potential prolific producers of antimicrobials, antiseptics, and antibiotics of plant origin. Although extensively studied as a “production platform” of novel pharmacological metabolites, the molecular mechanisms of plant–endophyte dynamics remain less understood/explored for their efficient utilization in drug discovery. The emerging trends in endophytic fungi-mediated biosynthesis of novel bioactive metabolites, success stories of key pharmacological metabolites, strategies to overcome the existing challenges in endophyte biology, and future direction in endophytic fungi-based drug discovery forms the underlying theme of this article.

Potentials of Endophytic Fungi in the Biosynthesis of Versatile Secondary Metabolites and Enzymes

World population growth and modernization have engendered multiple environmental problems: the propagation of humans and crop diseases and the development of multi-drug-resistant fungi, bacteria and viruses. Thus, a considerable shift towards eco-friendly products has been seen in medicine, pharmacy, agriculture and several other vital sectors. Nowadays, studies on endophytic fungi and their biotechnological potentials are in high demand due to their substantial, cost-effective and eco-friendly contributions in the discovery of an array of secondary metabolites. For this review, we provide a brief overview of plant–endophytic fungi interactions and we also state the history of the discovery of the untapped potentialities of fungal secondary metabolites. Then, we highlight the huge importance of the discovered metabolites and their versatile applications in several vital fields including medicine, pharmacy, agriculture, industry and bioremediation. We then focus on the challenges and on the possible methods and techniques that can be used to help in the discovery of novel secondary metabolites. The latter range from endophytic selection and culture media optimization to more in-depth strategies such as omics, ribosome engineering and epigenetic remodeling.

The important role of P450 monooxygenase for the biosynthesis of new benzophenones from Cytospora rhizophorae

Benzophenones are polyketides with diverse biological activities. Novel cytotoxic benzophenones cytosporaphenones A-C and cytorhizins A-D, which contain a new skeleton, were previously extracted from endophytic fungus Cytospora rhizophorae A761. However, the mechanism for the biosynthesis of these compounds remains unknown. Cytosporaphenone A was assumed to be the precursor for the biosynthesis of cytorhizins A-D. In this study, we sequenced the genome of C. rhizophorae A761 and characterized a benzoate 4-monooxygenase cytochrome P450(BAM). CRISPR/Cas9-mediated gene knockout and overexpression studies in C. rhizophorae confirmed the vital function of BAM in the biosynthesis of cytosporaphenones and cytorhizins. Overexpression of BAM also enhanced the yield of cytosporaphenone A by 1.868 folds. The in vitro function and enzymatic properties of BAM were also described. This study demonstrates the important role of BAM for the biosynthesis of cytosporaphenone A and cytorhizins and is also the first to provide approaches for the CRISPR-Cas9-mediated gene deletion and gene overexpression studies in C. rhizophoarae, thus laying a foundation for the elucidation of the biosynthetic mechanism of cytorhizins and the discovery of new benzophenones mediated by BAM.Key points• The novel bam gene encoding BAM protein in C. rhizophorae was firstly deleted using CRIPSR/Cas9 system.• The in vitro oxidation function of novel BAM protein and enzymatic properties was characterized.• The over expression of bam gene enhanced the yield of cytosporaphone A in C. rhizophorae significantly.

The plant endosphere-hidden treasures: a review of fungal endophytes

The endosphere represents intracellular regions within plant tissues colonize by microbial endophytes without causing disease symptoms to host plants. Plants harbor one or two endophytic microbes capable of synthesizing metabolite compounds. Environmental factors determine the plant growth and survival as well as the kind of microorganisms associated with them. Some fungal endophytes that symbiotically colonize the endosphere of medicinal plants with the potential of producing biological products have been employed in traditional and modern medicine. The bioactive resources from endophytic fungi are promising; biotechnologically to produce cheap and affordable commercial bioactive products as alternatives to chemical drugs and other compounds. The exploration of bioactive metabolites from fungal endophytes has been found applicable in agriculture, pharmaceutical, and industries. Thus, fungal endophytes can be engineered to produce a substantive quantity of pharmacological drugs through the biotransformation process. Hence, this review shall provide an overview of fungal endophytes, ecology, their bioactive compounds, and exploration with the biosystematics approach.

Stingless Bee Propolis: New Insights for Anticancer Drugs

Natural products are important sources of biomolecules possessing antitumor activity and can be used as anticancer drug prototypes. The rich biodiversity of tropical and subtropical regions of the world provides considerable bioprospecting potential, including the potential of propolis produced by stingless bee species. Investigations of the potential of these products are extremely important, not only for providing a scientific basis for their use as adjuvants for existing drug therapies but also as a source of new and potent anticancer drugs. In this context, this article organizes the main studies describing the anticancer potential of propolis from different species of stingless bees with an emphasis on the chemical compounds, mechanisms of action, and cell death profiles. These mechanisms include apoptotic events; modulation of BAX, BAD, BCL2-L1 (BCL-2 like 1), and BCL-2; depolarization of the mitochondrial membrane; increased caspase-3 activity; poly (ADP-ribose) polymerase (PARP) cleavage; and cell death induction by necroptosis via receptor interacting protein kinase 1 (RIPK1) activation. Additionally, the correlation between compounds with antioxidant and anti-inflammatory potential is demonstrated that help in the prevention of cancer development. In summary, we highlight the important antitumor potential of propolis from stingless bees, but further preclinical and clinical trials are needed to explore the selectivity, efficacy, and safety of propolis.

Plant associated fungal endophytes as a source of natural bioactive compounds

Endophytes are a potent source of bioactive compounds that mimic plant-based metabolites. The relationship of host plant and endophyte is significantly associated with alteration in fungal colonisation and the extraction of endophyte-derived bioactive compounds. Screening of fungal endophytes and their relationship with host plants is essential for the isolation of bioactive compounds. Numerous bioactive compounds with antioxidant, antimicrobial, anticancer, and immunomodulatory properties are known to be derived from fungal endophytes. Bioinformatics tools along with the latest techniques such as metabolomics, next-generation sequencing, and metagenomics multilocus sequence typing can potentially fill the gaps in fungal endophyte research. The current review article focuses on bioactive compounds derived from plant-associated fungal endophytes and their pharmacological importance. We conclude with the challenges and opportunities in the research area of fungal endophytes.

New naphthoquinone derivatives from Fusarium napiforme of a mangrove plant

Two new naphthoquinone derivatives, 6-hydroxy-astropaquinone B (1) and astropaquinone D (2) as well as the known compound 3-O-methyl-9-O-methylfusarubin (3) were isolated from Fusarium napiforme, an endophytic fungus isolated from the mangrove plant, Rhizophora mucronata. The structures of 1 and 2 were determined by 1D and 2D NMR spectroscopic analyses. Compounds 1, 2 and 3 exhibited moderate antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, 1, 2 and 3 were phytotoxic action in lettuce seeding at a concentration of 30 μg · mL-1.

Natural Products That Changed Society

Until the end of the 19th century all drugs were natural products or minerals. During the 19th century chemists succeeded in isolating pure natural products such as quinine, morphine, codeine and other compounds with beneficial effects. Pure compounds enabled accurate dosing to achieve serum levels within the pharmacological window and reproducible clinical effects. During the 20th and the 21st century synthetic compounds became the major source of drugs. In spite of the impressive results achieved within the art of synthetic chemistry, natural products or modified natural products still constitute almost half of drugs used for treatment of cancer and diseases like malaria, onchocerciasis and lymphatic filariasis caused by parasites. A turning point in the fight against the devastating burden of malaria was obtained in the 17th century by the discovery that bark from trees belonging to the genus Cinchona could be used for treatment with varying success. However isolation and use of the active principle, quinine, in 1820, afforded a breakthrough in the treatment. In the 20th century the synthetic drug chloroquine severely reduced the burden of malaria. However, resistance made this drug obsolete. Subsequently artemisinin isolated from traditional Chinese medicine turned out to be an efficient antimalarial drug overcoming the problem of chloroquine resistance for a while. The use of synthetic analogues such as chloroquine or semisynthetic drugs such as artemether or artesunate further improved the possibilities for healing malaria. Onchocerciasis (river blindness) made life in large parts of Africa and South America miserable. The discovery of the healing effects of the macrocyclic lactone ivermectin enabled control and partly elimination of the disease by annual mass distribution of the drug. Also in the case of ivermectin improved semisynthetic derivatives have found their way into the clinic. Ivermectin also is an efficient drug for treatment of lymphatic filariasis. The serendipitous discovery of the ability of the spindle toxins to control the growth of fast proliferating cancer cells armed physicians with a new efficient tool for treatment of some cancer diseases. These possibilities have been elaborated through preparation of semisynthetic analogues. Today vincristine and vinblastine and semisynthetic analogues are powerful weapons against cancer diseases.

Optimal extraction, purification and antioxidant activity of total flavonoids from endophytic fungi of Conyza blinii H. Lév

Background

Flavonoids are widely used in the market because of their antibacterial, antiviral, and antioxidant activities. But the production speed of flavonoids is limited by the growth of plants. CBL9 (Chaetomium cruentum) is a flavonoid-producing endophytic fungi from Conyza blinii H. Lév, which has potential to produce flavonoids.

Methods

In this study, we isolated total flavonoids from endophytic fungus CBL9 of Conyza blinii H. Lév using macroporous resin D101. The process was optimized by response surface and the best extraction process was obtained. The antioxidant activities of total flavonoids were analyzed in vitro.

Results

It was found that the best parameters were 25 °C pH 2.80, 1.85 h, and the adsorption ratio reached (64.14 ± 0.04)%. A total of 60% ethanol was the best elution solvent. The elution ratio of total flavonoid reached to (81.54 ± 0.03)%, and the purity was 7.13%, which was increased by 14.55 times compared with the original fermentation broth. Moreover its purity could rise to 13.69% after precipitated by ethanol, which is very close to 14.10% prepared by ethyl acetate extraction. In the antioxidant research, the clearance ratio of L9F-M on DPPH, ABTS, •OH, •O²⁻, (96.44 ± 0.04)% and (75.33 ± 0.03)%, (73.79 ± 0.02)%, (31.14 ± 0.01)% at maximum mass concentration, was higher than L9F.

Conclusion

The result indicated using macroporous resin in the extraction of total flavonoid from endophytic fungus is better than organic solvents with higher extraction ratio, safety and lower cost. In vitro testing indicated that the flavonoid extracted by macroporous resin have good antioxidant activity, providing more evidence for the production of flavonoid by biological fermentation method.

Deep learning approaches for natural product discovery from plant endophytic microbiomes

Plant microbiomes are not only diverse, but also appear to host a vast pool of secondary metabolites holding great promise for bioactive natural products and drug discovery. Yet, most microbes within plants appear to be uncultivable, and for those that can be cultivated, their metabolic potential lies largely hidden through regulatory silencing of biosynthetic genes. The recent explosion of powerful interdisciplinary approaches, including multi-omics methods to address multi-trophic interactions and artificial intelligence-based computational approaches to infer distribution of function, together present a paradigm shift in high-throughput approaches to natural product discovery from plant-associated microbes. Arguably, the key to characterizing and harnessing this biochemical capacity depends on a novel, systematic approach to characterize the triggers that turn on secondary metabolite biosynthesis through molecular or genetic signals from the host plant, members of the rich 'in planta' community, or from the environment. This review explores breakthrough approaches for natural product discovery from plant microbiomes, emphasizing the promise of deep learning as a tool for endophyte bioprospecting, endophyte biochemical novelty prediction, and endophyte regulatory control. It concludes with a proposed pipeline to harness global databases (genomic, metabolomic, regulomic, and chemical) to uncover and unsilence desirable natural products.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s40793-021-00375-0.

Endophytic Microbial Diversity: A New Hope for the Production of Novel Anti-tumor and Anti-HIV Agents as Future Therapeutics

Cancer is a collective name for a variety of diseases that can begin in virtually every organ or body tissue as abnormal cells develop uncontrollably and ten million new cancer cases are diagnosed all over the world at present. Whereas HIV is a virus that makes people susceptible to infection and contributes to the condition of acquired immune deficiency syndrome (AIDS). Almost 37 million people are currently diagnosed with HIV and 1 million people die every year, which is the worst-case scenario. Potential medicinal compounds have played a crucial role in the production of certain clinically beneficial novel anti-cancer and anti-HIV agents that are produced from natural sources especially from plants. These include Taxol, Vinblastine, Podophyllotoxin, Betulinic acid, Camptothecin, and Vincristine, etc. In the past decades, bioactive compounds were extracted directly from the plant sources which was more time consuming, led to low yield productivity, high cost, and bad impact on biodiversity. Endophytes, the microorganisms that reside inside the host plant by not causing any kind of harm to them and have potential applications in agriculture, medicine, pollution, and food industries. Therefore, by isolating and characterizing novel endophytes from medicinal plants and extracting their secondary metabolites to produce useful bioactive compounds can be beneficial for well-being and society as a future therapeutics. This approach is not harmful to biodiversity economical, timesaving, low cost, and can lead to the discovery of various industrial and commercially important novel anti-tumor and anti-HIV agents in the future. The Himalayas are home to several medicinal plants and the endophytic microbial biodiversity of the Himalayan region is also not much explored yet. However, the effect of compounds from these endophytes on anticancer and antiviral activity, especially anti-HIV has been largely unexplored. Hence, the present review is designed to the exploration of endophytic microbial diversity that can give rise to the discovery of various novel potential industrially valuable bioactive compounds that can lessen the rate of such type of pandemic diseases in the future by providing low-cost future therapeutics in future.

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review

Endophytic microbes are microorganisms that colonize the intracellular spaces within the plant tissues without exerting any adverse or pathological effects. Currently, the world population is facing devastating chronic diseases that affect humans. The resistance of pathogens to commercial antibiotics is increasing, thus limiting the therapeutic potential and effectiveness of antibiotics. Consequently, the need to search for novel, affordable and nontoxic natural bioactive compounds from endophytic fungi in developing new drugs with multifunction mechanisms to meet human needs is essential. Fungal endophytes produce invaluable bioactive metabolic compounds beneficial to humans with antimicrobial, anticancer, antidiabetic, anti-inflammatory, antitumor properties, etc. Some of these bioactive compounds include pestacin, taxol, camptothecin, ergoflavin, podophyllotoxin, benzopyran, isopestacin, phloroglucinol, tetrahydroxy-1-methylxanthone, salidroside, borneol, dibenzofurane, methyl peniphenone, lipopeptide, peniphenone etc. Despite the aforementioned importance of endophytic fungal metabolites, less information is available on their exploration and pharmacological importance. Therefore, in this review, we shall elucidate the fungal bioactive metabolites from medicinal plants and their pharmacological potential.

DNA Repair Biosensor-Identified DNA Damage Activities of Endophyte Extracts from Garcinia cowa

Recent developments in chemotherapy focus on target-specific mechanisms, which occur only in cancer cells and minimize the effects on normal cells. DNA damage and repair pathways are a promising target in the treatment of cancer. In order to identify novel compounds targeting DNA repair pathways, two key proteins, 53BP1 and RAD54L, were tagged with fluorescent proteins as indicators for two major double strand break (DSB) repair pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). The engineered biosensor cells exhibited the same DNA repair properties as the wild type. The biosensor cells were further used to investigate the DNA repair activities of natural biological compounds. An extract from Phyllosticta sp., the endophyte isolated from the medicinal plant Garcinia cowa Roxb. ex Choisy, was tested. The results showed that the crude extract induced DSB, as demonstrated by the increase in the DNA DSB marker γH2AX. The damaged DNA appeared to be repaired through NHEJ, as the 53BP1 focus formation in the treated fraction was higher than in the control group. In conclusion, DNA repair-based biosensors are useful for the preliminary screening of crude extracts and biological compounds for the identification of potential targeted therapeutic drugs.

Implications of endophytic microbiota in Camellia sinensis: a review on current understanding and future insights

Endophytic fungi and bacteria are the most ubiquitous and representative commensal members that have been studied so far in various higher plants. Within colonization and interaction with their host plants, endophytic microbiota are reportedly to modulate not only the host's growth but also holobiont resilience to abiotic and biotic stresses, providing a natural reservoir and a promising solution for sustainable agricultural development challenged by global climate change. Moreover, possessing the talent to produce a wide array of high-value natural products, plant endophytic microbiota also serve as an alternative way for novel drug discovery. In this review, tea, one of the world's three largest nonalcoholic beverages and a worldwide economic woody crop, was highlighted in the context of endophytic microbiota. We explore the recent studies regarding isolation approaches, distribution characteristics and diversity, and also biological functions of endophytic microbiota in Camellia sinensis (L.) O. Kuntze. Profoundly, the future insight into interaction mechanism between endophytic microbiota and tea plants will shed light on in-depth exploration of tea microbial resources.