Enhanced production of unusual triterpenoids from Kadsura angustifolia fermented by a symbiont endophytic fungus, Penicillium sp. SWUKD4.1850

Six undescribed 23-norursane triterpenoids from the biotransformation of ilexgenin a by endophytic fungi and their vascular protective activity

Biotransformation of ursane-type triterpenoid ilexgenin A by endophytic fungi Lasiodiplodia sp. MQD-4 and Pestalotiopsis sp. ZZ-1, isolated from Ilex pubescences and Callicarpa kwangtungensis respectively, was investigated for the first time. Six previously undescribed metabolites (1-6) with 23-norursane triterpenoids skeleton were isolated and their structures were unambiguously established by the analysis of spectroscopic data and single-crystal X-ray crystallographic experiments. Decarboxylation, oxidation, and hydroxylation reactions were observed on the triterpenoid skeleton. Especially, the decarboxylation of C-23 provided definite evidence to understand the biogenetic process of 23-norursane triterpenoids. Moreover, the qualitative analysis of the extract of I. pubescences showed metabolites 1, 3, 4, and 6 could be detected in the originated plant, indicating biotransformation by endophytic fungi is a practical strategy for the isolation of novel natural products. Finally, all isolates were evaluated for the protective activities against H2O2-induced HUVECs dysfunction in vitro. Compound 5 could improve the viability of endothelial cells and decrease the level of intracellular ROS.

Multi-Level Optimization and Strategies in Microbial Biotransformation of Nature Products

Continuously growing demand for natural products with pharmacological activities has promoted the development of microbial transformation techniques, thereby facilitating the efficient production of natural products and the mining of new active compounds. Furthermore, due to the shortcomings and defects of microbial transformation, it is an important scientific issue of social and economic value to improve and optimize microbial transformation technology in increasing the yield and activity of transformed products. In this review, the aspects regarding the optimization of fermentation and the cross-disciplinary strategy, leading to the microbial transformation of increased levels of the high-efficiency process from natural products of a plant or microbial origin, were discussed. Additionally, due to the increasing craving for targeted and efficient methods for detecting transformed metabolites, analytical methods based on multiomics were also discussed. Such strategies can be well exploited and applied to the production of more efficient and more natural products from microbial resources.

Fungal Endophytes: an Accessible Source of Bioactive Compounds with Potential Anticancer Activity

Endophytes either be bacteria, fungi, or actinomycetes colonize inside the tissue of host plants without showing any immediate negative effects on them. Among numerous natural alternative sources, fungal endophytes produce a wide range of structurally diverse bioactive metabolites including anticancer compounds. Considering the production of bioactive compounds in low quantity, genetic and physicochemical modification of the fungal endophytes is performed for the enhanced production of bioactive compounds. Presently, for the treatment of cancer, chemotherapy is majorly used, but the side effects of chemotherapy are of prime concern in clinical practices. Also, the drug-resistant properties of carcinoma cells, lack of cancer cells-specific medicine, and the side effects of drugs are the biggest obstacles in cancer treatment. The interminable requirement of potential drugs has encouraged researchers to seek alternatives to find novel bioactive compounds, and fungal endophytes seem to be a probable target for the discovery of anticancer drugs. The present review focuses a comprehensive literature on the major fungal endophyte-derived bioactive compounds which are presently been used for the management of cancer, biotic factors influencing the production of bioactive compounds and about the challenges in the field of fungal endophyte research.

Endophytic Fungi: An Effective Alternative Source of Plant-Derived Bioactive Compounds for Pharmacological Studies

Plant-associated fungi (endophytic fungi) are a biodiversity-rich group of microorganisms that are normally found asymptomatically within plant tissues or in the intercellular spaces. Endophytic fungi promote the growth of host plants by directly producing secondary metabolites, which enhances the plant's resistance to biotic and abiotic stresses. Additionally, they are capable of biosynthesizing medically important "phytochemicals" that were initially thought to be produced only by the host plant. In this review, we summarized some compounds from endophyte fungi with novel structures and diverse biological activities published between 2011 and 2021, with a focus on the origin of endophytic fungi, the structural and biological activity of the compounds they produce, and special attention paid to the exploration of pharmacological activities and mechanisms of action of certain compounds. This review revealed that endophytic fungi had high potential to be harnessed as an alternative source of secondary metabolites for pharmacological studies.

Endophytic Fungal Terpenoids: Natural Role and Bioactivities

Endophytic fungi are a highly diverse group of fungi that intermittently colonize all plants without causing symptoms of the disease. They sense and respond to physiological and environmental changes of their host plant and microbiome. The inter-organism interactions are largely driven by chemical networks mediated by specialized metabolites. The balance of these complex interactions leads to healthy and strong host plants. Endophytic strains have particular machinery to produce a plethora of secondary metabolites with a variety of bioactivities and unknown functions in an ecological niche. Terpenoids play a key role in endophytism and represent an important source of bioactive molecules for human health and agriculture. In this review, we describe the role of endophytic fungi in plant health, fungal terpenoids in multiple interactions, and bioactive fungal terpenoids recently reported from endophytes, mainly from plants used in traditional medicine, as well as from algae and mangroves. Additionally, we highlight endophytic fungi as producers of important chemotherapeutic terpenoids, initially discovered in plants. Despite advances in understanding endophytism, we still have much to learn in this field. The study of the role, the evolution of interactions of endophytic fungi and their terpenoids provide an opportunity for better applications in human health and agriculture.

Pezicula endophytica sp. nov., endophytic in Dendrobium in Thailand

A new species, Pezicula endophytica, was isolated from roots and stems of two Dendrobium species in northern Thailand. Evidence to support the new species is based on morphology and phylogenetic analysis of the combined ITS, LSU, and RPB2 DNA sequence dataset. Pezicula endophytica, which constituted a clade independent from other Pezicula species, has 4% distinct base pair differences in all genes. Pezicula endophytica has larger macroconidia and longer conidiophores compared with phylogenetically neighboring species. This is the first report of an endophytic Pezicula species from Dendrobium in Thailand.

Biotransformation ability of endophytic fungi: from species evolution to industrial applications

Increased understanding of the interactions between endophytic fungi and plants has led to the discovery of a new generation of chemical compounds and processes between endophytic fungi and plants. Due to the long-term co-evolution between fungal endophytes and host plants, endophytes have evolved special biotransformation abilities, which can have critical consequences on plant metabolic processes and their composition. Biotransformation or bioconversion can impact the synthesis and decomposition of hormones, sugars, amino acids, vitamins, lipids, proteins, and various secondary metabolites, including flavonoids, polysaccharides, and terpenes. Endophytic fungi produce enzymes and various bioactive secondary metabolites with industrial value and can degrade or sequester inorganic and organic small molecules and macromolecules (e.g., toxins, pollutants, heavy metals). These fungi also have the ability to cause highly selective catalytic conversion of high-value compounds in an environmentally friendly manner, which can be important for the production/innovation of bioactive molecules, food and nutrition, agriculture, and environment. This work mainly summarized recent research progress in this field, providing a reference for further research and application of fungal endophytes. KEY POINTS: •The industrial value of degradation of endophytes was summarized. • The commercial value for the pharmaceutical industry is reviewed.

Endophytic Fungi-Mediated Biocatalysis and Biotransformations Paving the Way Toward Green Chemistry

Catalysis is a process carried out in the presence of a heterogenous catalyst for accelerating the rate of a chemical reaction. It plays a pivotal role in transition from take, make, and dispose technology to sustainable technology via chemo- and biocatalytic processes. However, chemocatalyzed reactions are usually associated with copious amounts of perilous/hazardous environmental footprints. Therefore, whole-cell biotransformations or enzyme cocktails serve as cleaner biocatalytic alternatives in replacing the classical chemical procedures. These benchmark bioconversion reactions serve as important key technology in achieving the goals of green chemistry by eliminating waste generation at source. For this, nature has always been a driving force in fuelling natural product discovery and related applications. The fungal endophytic community, in particular, has undergone co-evolution with their host plant and has emerged as a powerful tool of genetic diversity. They can serve as a treasure trove of biocatalysts, catalyzing organic transformations of a wide range of substances into enantiopure compounds with biotechnological relevance. Additionally, the biocatalytic potential of endophytic fungi as whole-intact organisms/isolated enzyme systems has been greatly expanded beyond the existing boundaries with the advancement in high-throughput screening, molecular biology techniques, metabolic engineering, and protein engineering. Therefore, the present review illustrates the promising applications of endophytic fungi as biocatalysts for the synthesis of new structural analogs and pharmaceutical intermediates and refinement of existing proteins for novel chemistries.

Resorcylic Acid Lactones Produced by an Endophytic Penicillium ochrochloron Strain from Kadsura angustifolia

Four new β-resorcylic acid lactones, including penochrochlactone A (2: ), 4-O-desmethyl-aigialomycin B (4: ), and penochrochlactones C and D (5: and 6: ), two compounds isolated from a natural source for the first time, 5α, 6β-acetonide-aigialomycin B (1: ) and penochrochlactone B (3: ), together with six known compounds, aigialomycin F (7: ), aigialomycins A, B, and D (8: -10: ), zeaenol (11: ), and oxozeaenol (12: ), were isolated from a mycelial solid culture of the endophytic fungus Penicillium ochrochloron SWUKD4.1850 from the medicinal plant Kadsura angustifolia by sequential purification over silica gel, Sephadex LH-20 column chromatography, and preparative HPLC. Their structures were elucidated by extensive spectroscopic analysis and chemical conversions. In addition, all the new compounds were evaluated for their cytotoxic and antibacterial activities in vitro. Penochrochlactone C (5: ) displayed moderate cytotoxicity against the HeLa tumor cell line with an IC₅₀ value of 9.70 µM. In the antibacterial assays, compounds 4:  - 6: exhibited moderate activities against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa with MIC values between 9.7 and 32.0 µg/mL.

Biological Activities of Some New Secondary Metabolites Isolated from Endophytic Fungi: A Review Study

Secondary metabolites isolated from plant endophytic fungi have been getting more and more attention. Some secondary metabolites exhibit high biological activities, hence, they have potential to be used for promising lead compounds in drug discovery. In this review, a total of 134 journal articles (from 2017 to 2019) were reviewed and the chemical structures of 449 new metabolites, including polyketides, terpenoids, steroids and so on, were summarized. Besides, various biological activities and structure-activity relationship of some compounds were aslo described.

Progress on Terpenoids With Biological Activities Produced by Plant Endophytic Fungi in China Between 2017 and 2019

Plant endophytic fungi are an important part of plant microecosystems and a natural resource for human survival and development. Various bioactive natural products produced by plant endophytic fungi show promising prospects in biopharmacy, agricultural production, and industrial fermentation. Terpenoids, the most numerous and structurally diverse natural products from endophytic fungi, possess a broad range of biological activities and huge potential for drug development. It is critically significant for ecological and economic benefits to develop their activities. This paper utilized literature analysis to summarize 200 terpenoids with biological activities that are derived from plant endophytic fungi in China between 2017 and 2019. Among them, sesquiterpenoids were the most important kind of terpenoids, and Trichoderma and Aspergillus species were main terpenoid-producing plant endophytic fungi. Furthermore, these terpenoids displayed multifarious biological activities, including antimicrobial, antipathogenic, and anti-inflammatory activities, as well as cytotoxicity, antitumor agents, and enzyme inhibition.

Kadanguslactones A-E, further oxygenated terpenoids from Kadsura angustifolia fermented by a symbiotic endophytic fungus, Penicillium ochrochloron SWUKD4.1850

The fermentation of Kadsura angustifolia with an endophytic fungus, Penicillium ochrochloron SWUKD4.1850 yielded five additional undescribed oxygenated terpenoids, kadanguslactones A-E, together with ten known compounds. Their structures were established by the extensive 1D, 2D-NMR, HR-ESI-MS, CD and X-ray crystallography data analysis. Kadanguslactone A is the first example of 1,30-cyclo-3,4; 9,10-disecocycloartanes that combine a five-membered lactone ring A with a cyclopentane ring B consisting of C-1, C-4, C-5, C-10, C-30. Kadanguslactone B was a rare highly oxygenated 18-norschiartane-type bisnortriterpenoid with spirocyclis rings F and G, whereas kadanguslactone C was an uncommon henrischinin-type schitriterpenoid containing a unique 3-one-2-oxabicyclo [3,2,1]-octane motif. The cytotoxicity against HepG2 cell line of all compounds were evaluated. Except nigranoic acid, all other metabolites have been first found in unfermented K. angustifolia, suggesting that main functional ingredients from K. angustifolia may be converted by P. ochrochloron SWUKD4.1850 into highly oxygenated terpenoids. This study provided a fascinating prospective for setting up alternative processing techniques to enhance the functionality and utility of Chinese herbal medicine.

Biological Activity of Endophytic Fungi from the Roots of the Medicinal Plant Vernonia anthelmintica

Endophytic fungi were first isolated from the fresh root of the Chinese medicinal plant Vernonia anthelmintica collected from the Hotan Prefecture within the Xinjiang Autonomous region of the People’s Republic of China. This plant has been used in Uyghur traditional medicine to treat vitiligo, a skin condition characterized by patches of the skin losing their pigment. In total, fifteen fungal strains were isolated. Among these, four endophytic fungi were identified by their DNA sequences and registered to GenBank with accession numbers. The isolates were identified as Schizophyllum commune XJA1, Talaromyces sp. XJA4, Aspergillus sp. XJA6, Aspergillus terreus XJA8. Ethyl acetate extracts of all fungal strains were used to quantify melanin content and to identify in vitro biological activity assays including antimicrobial, antioxidant, cytotoxic, antidiabetic and tyrosinase activity on B16 cells. Among the extracts of all four identified strains, the ethyl acetate extract of the Aspergillus sp. XJA6 was chosen for further characterization because it presented the highest biological activity against these tests. In addition, twenty four volatile compounds from the petroleum ether fraction were characterized by GC–MS.

Endophytic Penicillium species and their agricultural, biotechnological, and pharmaceutical applications

Penicillium genus constituted by over 200 species is one of the largest and fascinating groups of fungi, particularly well established as a source of antibiotics. Endophytic Penicillium has been reported to colonize their ecological niches and protect their host plant against multiples stresses by exhibiting diverse biological functions that can be exploited for countless applications including agricultural, biotechnological, and pharmaceutical. Over the past 2 decades, endophytic Penicillium species have been investigated beyond their antibiotic potential and numerous applications have been reported. We comprehensively summarized in this review available data (2000-2019) regarding bioactive compounds isolated from endophytic Penicillium species as well as the application of these fungi in multiple agricultural and biotechnological processes. This review has shown that a very large number (131) of endophytes from this genus have been investigated so far and more than 280 compounds exhibiting antimicrobial, anticancer, antiviral, antioxidants, anti-inflammatory, antiparasitics, immunosuppressants, antidiabetic, anti-obesity, antifibrotic, neuroprotective effects, and insecticidal and biocontrol activities have been reported. Moreover, several endophytic Penicillium spp. have been characterized as biocatalysts, plant growth promoters, phytoremediators, and enzyme producers. We hope that this review summarizes the status of research on this genus and will stimulate further investigations.

Improving the acetylcholinesterase inhibitory effect of Illigera aromatica by fermentation with Clonostachys rogersoniana

Illigera aromatica was fermented by Clonostachys rogersoniana. The acetylcholinesterase (AChE) inhibitory effects of unfermented and fermented I. aromatica revealed that C. rogersoniana-fermented I. aromatica (CFIA) induced significantly more AChE inhibitory activity (IC₅₀: 35.4 ± 2.1 μg/mL). The biotransformation of actinodaphnine (1) into (4R,6aS)-4-hydroxyactinodaphnine (2) was found during the fermentation, which played an important role in the improvement of the AChE inhibitory activity of I. aromatica. Subsequently, the fermentation conditions-including the solid-liquid ratio, fermentation temperature, and fermentation time-were optimized. I. aromatica immersed in 100-200% water and fermented with C. rogersoniana at ambient temperature for 30 days was conducive to the biotransformation of actinodaphnine (1) and improved the AChE inhibitory activity of I. aromatica. The present study provides a novel approach for improving the pharmacological effect of I. aromatica and suggests that CFIA may be used as an alternative AChE inhibitor.