Six new metabolites produced byColletotrichum aotearoa09F0161, an endophytic fungus isolated fromBredia oldhamii

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.

Diversity of Mycotoxins and Other Secondary Metabolites Recovered from Blood Oranges Infected by Colletotrichum, Alternaria, and Penicillium Species

This study identified secondary metabolites produced by Alternaria alternata, Colletotrichum gloeosporioides, and Penicillium digitatum in fruits of two blood orange cultivars before harvest. Analysis was performed by UHPLC-Q-TOF-MS. Three types of fruits were selected, asymptomatic, symptomatic showing necrotic lesions caused by hail, and mummified. Extracts from peel and juice were analyzed separately. Penicillium digitatum was the prevalent species recovered from mummified and hail-injured fruits. Among 47 secondary metabolites identified, 16, 18, and 13 were of A. alternata, C. gloeosporioides, and P. digitatum, respectively. Consistently with isolations, indicating the presence of these fungi also in asymptomatic fruits, the metabolic profiles of the peel of hail-injured and asymptomatic fruits did not differ substantially. Major differences were found in the profiles of juice from hail-injured and mummified fruits, such as a significant higher presence of 5,4-dihydroxy-3,7,8-trimethoxy-6C-methylflavone and Atrovenetin, particularly in the juice of mummified fruits of the Tarocco Lempso cultivar. Moreover, the mycotoxins patulin and Rubratoxin B were detected exclusively in mummified fruits. Patulin was detected in both the juice and peel, with a higher relative abundance in the juice, while Rubratoxin B was detected only in the juice. These findings provide basic information for evaluating and preventing the risk of contamination by mycotoxins in the citrus fresh fruit supply chain and juice industry.

Undescribed alkyne-geranylcyclohexenetriols from the endophyte Diaporthe caulivora 09F0132 and their anti-melanogenic activity

To explore valuable endophytic fungus from Formosan Lauraceous plants as natural medicinal products, the fungus, Diaporthe caulivora isolated from leaves of Neolitsea daibuensis, was investigated. Through a thorough investigation of the ethanolic extract of the solid fermentation of D. caulivora 09F0132, six undescribed alkyne-geranylcyclohexenetriols, caulivotrioloxins A-F, one undescribed trichopyrone, diapopyrone, two undescribed sesquiterpenes, caulibysins A-B, one compound firstly isolated from the natural source, 3-O-desmethyl phomentrioloxin, and eight known compounds have been successfully identified. The absolute configuration of caulibysin A was confirmed by single-crystal X-ray diffraction, and those of (3R,8S)-5,7-dihydroxy-3-(1-hydroxyethyl)phthalide and (3S,8S)-5,7-dihydroxy-3-(1-hydroxyethyl)phthalide were determined by circular dichroism (CD) spectra. Among the isolated compounds, caulivotrioloxin A concentration-dependently decreased the cellular melanin contents and tyrosinase activities in mouse melanoma B16-F10 cells, suggesting the anti-melanogenic potentials. The anti-melanogenic effects of caulivotrioloxin A involved the decrease in the protein expressions of melanogenic enzymes, including tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2. Taken together, these results suggested that the isolates from D. caulivora could be served as natural melanogenesis inhibitors for cosmeceutical applications.

Fungal Naphthalenones; Promising Metabolites for Drug Discovery: Structures, Biosynthesis, Sources, and Pharmacological Potential

Fungi are well-known for their abundant supply of metabolites with unrivaled structure and promising bioactivities. Naphthalenones are among these fungal metabolites, that are biosynthesized through the 1,8-dihydroxy-naphthalene polyketide pathway. They revealed a wide spectrum of bioactivities, including phytotoxic, neuro-protective, cytotoxic, antiviral, nematocidal, antimycobacterial, antimalarial, antimicrobial, and anti-inflammatory. The current review emphasizes the reported naphthalenone derivatives produced by various fungal species, including their sources, structures, biosynthesis, and bioactivities in the period from 1972 to 2021. Overall, more than 167 references with 159 metabolites are listed.

New cytotoxic ergosterols from a plant-associated fungus Colletotrichum magnisporum

Three new ergosterols, colletosterols A-C (1-3), together with two known analogues 4 and 5, were isolated from the endophytic fungus Colletotrichum magnisporum associated with the leaves of Rauvolfia verticillata by a bioassay-guided fractionation method. The new structures were elucidated on the basis of extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. All the ergosterols were evaluated for their cytotoxic activities against A549 and HeLa cell lines. Compounds 1-3 exhibited notable cytotoxicity with the IC₅₀ values of 3.76-11.18 μM.

Naturally Occurring Isocoumarins Derivatives from Endophytic Fungi: Sources, Isolation, Structural Characterization, Biosynthesis, and Biological Activities

Recently, the metabolites separated from endophytes have attracted significant attention, as many of them have a unique structure and appealing pharmacological and biological potentials. Isocoumarins represent one of the most interesting classes of metabolites, which are coumarins isomers with a reversed lactone moiety. They are produced by plants, microbes, marine organisms, bacteria, insects, liverworts, and fungi and possessed a wide array of bioactivities. This review gives an overview of isocoumarins derivatives from endophytic fungi and their source, isolation, structural characterization, biosynthesis, and bioactivities, concentrating on the period from 2000 to 2019. Overall, 307 metabolites and more than 120 references are conferred. This is the first review on these multi-facetted metabolites from endophytic fungi.

Recent advances in the chemistry and biology of azaphilones

Recent advances in the chemistry and biology of structurally diverse azaphilones from 2012 to 2019.

The fungus Colletotrichum as a source for bioactive secondary metabolites

Colletotrichum sp. is a widely distributed fungal genus, which is mainly known to cause anthracnose on cereals, legumes, fruit trees, and vegetables. Even though many of the Colletotrichum sp. are plant pathogens, a variety of secondary metabolites with diverse bioactivities have been reported to be produced by this fungus. At least 109 secondary metabolites from the fungus Colletotrichum have been reported to date. They mostly include nitrogen-containing metabolites, sterols, terpenes, pyrones, phenolics, and fatty acids. Herein, the authors review the structurally interesting secondary metabolites produced by Colletotrichum and their biological activities.

Lathyroxins A and B, Phytotoxic Monosubstituted Phenols Isolated from Ascochyta lentis var. lathyri, a Fungal Pathogen of Grass Pea ( Lathyrus sativus)

Ascochyta lentis var. lathyri has recently been reported to be the causal agent of Ascochyta blight of grass pea ( Lathyrus sativus), a disease characterized by the appearance of necrotic lesions of leaves and stems. Considering the novelty of the pathogen and the possible involvement of secondary metabolites in symptom appearance, a study was carried out to ascertain the capability of this fungus to produce bioactive metabolites. Some phytotoxic phenols were isolated from the culture filtrates of the fungus. In particular, two new phytotoxic metabolites, named lathyroxins A and B, were characterized by spectroscopic methods as 4-(2-hydroxy-3,3-dimethoxypropyl)phenol and 3-(4-hydroxyphenyl)propane-1,2-diol, respectively, and the R absolute configuration of C-2 of their 2-dimethoxy- and 2,3-diol-propyl side chain was assigned. Moreover, other well-known fungal metabolites, namely, p-hydroxybenzaldehyde, p-methoxyphenol, and tyrosol, were also identified. Lathyroxins A and B showed interesting phytotoxic properties, being able to cause necrosis on leaves and to inhibit seed germination and rootlet elongation. Moreover, both of the new metabolites had no effect against bacteria, arthropods, and nematodes.

Secondary metabolites from Colletotrichum capsici, an endophytic fungus derived from Siegesbeckia pubescens Makino

A rare new tremulane sesquiterpenoid analogue, 11,12-epoxy-5,6-seco-1,6(13)-tremuladien-5,12-olide (1), together with five known altenuene derivatives (2-6) was isolated from the cultures of Colletotrichum capsici, which was isolated as an endophytic fungus from fresh leaves of Siegesbeckia pubescens Makino (Compositae). Their structures were elucidated by means of spectroscopic methods and comparison with literature data. All compounds isolated were reported for the first time from the fungus C. capsici.