Anti-diabetic activities of phenolic compounds of Alternaria sp., an endophyte isolated from the leaves of desert plants growing in Egypt

Phthalate-related metabolites from an endophytic Alternaria sp. YUD24001 associated with Aconitum hemsleyanum

Seven undescribed phthalate-related compounds, designated alternyxtiols A-G (1-7), were isolated from the endophytic fungus Alternaria sp. YUD24001, which was found in Aconitum hemsleyanum. The structures of alternyxtiols A and B feature a benzofuran ring instead of the typical benzofuran ketone structure. Alternyxtiol C is identified as a penta-substituted phenol derivative, whereas alternyxtiols D-G comprise two rare penta-substituted phenol dimers. The chemical structures of these compounds were elucidated through spectral data analysis. Their absolute configurations were determined using TDDFT-ECD calculations and DP4+ probability analysis, which relied on NMR chemical shift calculations. Notably, the structures of alternyxtiols F and G possess highly functionalized penta-substituted benzene ring cores, differing from other benzene ring dimer compounds in their alkyl substitution patterns. Alternyxtiols B, F and G exhibited antimicrobial activity against pathogenic fungi Fusarium solani, Alternaria panax and Epicoccus nigrum, respectively.

Talaromyketides A-I: Nine polyketides with anti-inflammatory activity from a soil fungus Talaromyces sp. KYS-41

A chemical investigation into fermentation product of Talaromyces sp. KYS-41, a fungus isolated from Kunyu Mountain soil, resulted in the discovery and identification of 27 polyketides. Notably, talaromyketides A-I (1-9) are reported for the first time, with talaromyketides A-C (1-3) being three pair of enantiomers. Talaromyketides A-D (1-4) display novel frameworks and are regarded as products resulting from oxidative ring-opening and/or subsequent rearrangement of the bibenzyl derivatives. Talaromyketide A (1) exhibits a scaffold comprising an isochroman-1,4-dione, whereas talaromyketide B (2) showcases the structural backbone of a naphthalen-1(4H)-one. Talaromyketides C (3) and D (4) are the outcomes of oxidative ring-opening of one of the phenyl rings in bibenzyl derivatives. Biological evaluations demonstrated that compounds 2b, 9, and 18-21 show significant anti-inflammatory activity with IC50 values within 10 μM. By inhibiting the activation of NF-κB/MAPK signaling pathways, (-)-1S-talaromyketide B (2b) is involved in suppression of inflammatory response and shows significant pharmacological effects in vivo on zebrafish model.

Biocontrol potential of the active substance isolated from the endophytic fungus Aa-Lcht against apple Valsa canker

Apple Valsa canker (AVC), primarily caused by the pathogenic fungus Valsa mali, is a devastating disease of apple. The development and application of high efficiency and low toxicity fungicides are of great significance for disease control. Natural active substances serve as a vital foundation for the development of novel green fungicides. In previous studies, the endophytic fungus Aa-Lcht was confirmed to contain specific inhibitory effect against V. mali. This study confirmed that Aa-Lcht fermentation broth (FB)'s suppression of V. mali growth and conidial germination, exhibiting AVC prevention. Through extraction, isolation, and purification, one active substance with high inhibitory effect on V. mali was obtained and identified as altenusin. Its concentration value for 50 % of maximal effect (EC50 values) against V. mali mycelium growth was 3.118 μg/mL. Before V. mali infection, the lesion length of apple twigs and lesion area of fruits pretreated with altenusin decreased by 47.27 % and 80.52 %, respectively. Further research revealed that the hyphae of V. mali treated with altenusin exhibited irregular thickening of cell walls, severe vacuolation within the cells, and protoplasmic exudation. Meanwhile, transcriptome analysis indicated that altenusin primarily inhibited V. mali by interfering with the normal hyphal cell metabolism, substance degradation, peptidase activity, and proteolysis functions. Additionally, altenusin could also significantly up-regulate the expression of immunity resistance-related genes MdCYP81F2, MdPR2, MdPR4, and MdPR5 in apple. Summarizing the above, the altenusin provides valuable insights for the development of novel green fungicides for controlling AVC disease, contributing to the safe and healthy development of apple production.

Structural characterization, in-silico studies, and antifungal activity of 5-methylmellein isolated from endophytic Alternaria burnsii

The present investigation focused on exploring the potential of fungal endophytes as a valuable source of bioactive compounds with diverse applications. The phenolic compound 5-methylmellein was isolated for the first time from Alternaria burnsii, an endophytic fungus associated with Morus alba Linn. The compounds were structurally characterized using comprehensive spectral analysis, including 1H-, 13C, and 2D-NMR, as well as HRESI-MS. The study investigated the antifungal activity of 5-methylmellein against several plant pathogenic fungi, including Botrytis cinerea, Colletotrichum gloeosporioides, Cercospora beticola, and Rhizoctonia solani. In vitro assays showed significant inhibition of various plant pathogenic fungi, and the IC50 values ranging from 34.59 ± 1.03a µg/mL to 44.76 ± 1.03b µg/mL against the tested fungi. In vivo experiments on apples and grapes revealed that 5-Methylmellein significantly reduced fruit decay caused by Botrytis cinerea. The wound incidence in the control group reached 95.78%, while the treated groups exhibited a reduction of 37.54% after 15 days. These findings underscore the potential of 5-methylmellein as a potent antifungal agent, suggesting its eco-friendly application in agriculture for managing fruit decay.

Natural resorcylic lactones derived from alternariol

In this overview, naturally occurring resorcylic lactones biosynthetically derived from alternariol and almost exclusively produced by fungi, are discussed with view on their isolation, structure, biological activities, biosynthesis, and total syntheses. This class of compounds consists until now of 127 naturally occurring compounds, with very divers structural motifs. Although only a handful of these toxins (i.e., alternariol and its 9-O-methyl ether, altenusin, dehydroaltenusin, altertenuol, and altenuene) were frequently found and isolated as fungal contaminants in food and feed and have been investigated in significant detail, further metabolites, which were much more rarely found as natural products, similarly show interesting biological activities.

Altenuene derivatives produced by an endophyte Alternaria alternata

Two novel aromatic polyketides 1 and 3 and five known compounds, (4S,10S)-talaroflavone (2), altenuene (4), isoaltenuene (5), alternariol (6), and altenusin (7), were isolated from an endophytic strain of Alternaria alternata SI-694. The structures of the new compounds, including their absolute configurations, were elucidated by NMR, IR, UV, and ECD spectroscopies, and the phytotoxicities of the isolated compounds were also evaluated. Altenusin (7) showed moderate cytotoxicity against HL-60 cells, with an IC50 of 6.65 µM, whereas 5, 6, and 7 were phytotoxic against Lactuca sativa, Brassica campestris L., Stellaria aquatica (L.) Scop. and Digitaria ciliaris.

Investigation the biological activities and the metabolite profiles of endophytic fungi isolated from Gundelia tournefortii L

Endophytic fungi are microorganisms that are considered as a potential source of natural compounds, and can be applied in various industries. The aims of this research were molecular identification of endophytic fungi isolated from the Gundelia tournefortii stems, and investigation their biological activities as well as phenolic and fatty acid profile. Surface sterilized stems of G. tournefortii were placed on potato dextrose agar (PDA) to isolate the fungal endophytes. Genomic DNA was extracted by CTAB method, and PCR amplification was performed by ITS 1 and ITS 4 as primers. The enzyme production of endophytic fungi was determined based on the formation of a clear zone that appeared around the colonies of fungus. The anti-oxidant activity was evaluated by measuring the amount of free radicals DPPH. Also, the total phenol and flavonoid contents were measured obtained by Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. Moreover, the separation and identification of phenolic acids and fatty acids were done by HPLC and GC, respectively. Phylogenetic analysis was done based on the Internal Transcribed Spacer (ITS) region, and five isolates were identified as following: Aspergillus niger, Penicillium glabrum, Alternaria alternata, A. tenuissima, and Mucor circinelloides. Evaluation of the enzymatic properties showed that P. gabrum (31 ± 1.9 mm), and A. niger (23 ± 1.7) had more ability for producing pectinase and cellulase. The anti-oxidant activity of isolates showed that A. alternata extract (IC50 = 471 ± 29 µg/mL) had the highest anti-oxidant properties, followed by A. tenuissima extract (IC50 = 512 ± 19 µg/mL). Also, the extract of A. alternata had the greatest amount of total phenols and flavonoids contents (8.2 ± 0.4 mg GAL/g and 2.3 ± 0.3 mg QE/g, respectively). The quantification analysis of phenolic acid showed that rosmarinic acid, para-coumaric acid, and meta-coumaric acid (42.02 ± 1.31, 7.53 ± 0.19, 5.41 ± 0.21 mg/g, respectively) were the main phenolic acids in the studied fungi. The analysis of fatty acids confirmed that, in all fungi, the main fatty acids were stearic acid (27.9-35.2%), oleic acid (11.3-17.3%), palmitic acid (16.9-23.2%), linoleic acid (5.8-11.6%), and caprylic acid (6.3-10.9%). Our finding showed that endophytic fungi are a source of bioactive compounds, which could be used in various industries. This is the first report of endophytic fungi associated with G. tournefortii, which provides knowledge on their future use on biotechnological processes.

Altenusin, a fungal metabolite, alleviates TGF-β1-induced EMT in renal proximal tubular cells and renal fibrosis in unilateral ureteral obstruction

Renal fibrosis is a pathological feature of chronic kidney disease (CKD), progressing toward end-stage kidney disease (ESKD). The aim of this study is to investigate the therapeutic potential of altenusin, a farnesoid X receptor (FXR) agonist derived from fungi, on renal fibrosis. The effect of altenusin was determined (i) in vitro using the transforming growth factor β1 (TGF-β1)-induced epithelial to mesenchymal transition (EMT) of human renal proximal tubular cells and (ii) in vivo using mouse unilateral ureteral obstruction (UUO). The findings revealed that incubation of 10 ng/ml TGF-β1 promotes morphological change in RPTEC/TERT1 cells, a human renal proximal tubular cell line, from epithelial to fibroblast-like cells. TGF-β1 markedly increased EMT markers namely α-smooth muscle actin (α-SMA), fibronectin, and matrix metalloproteinase 9 (MMP-9), while decreased the epithelial marker E-cadherin. Co-incubation TGF-β1 with altenusin preserved the epithelial characteristics of the renal epithelial cells by antagonizing TGF-β/Smad signaling pathway, specifically a decreased phosphorylation of Smad2/3 with an increased level of Smad7. Interestingly, the antagonizing effect of altenusin does not require FXR activation. Moreover, altenusin could reverse TGF-β1-induced fibroblast-like cells to epithelial-like cells. Treatment on UUO mice with 30 mg/kg altenusin significantly reduced the expression of α-SMA, fibronectin, and collagen type 1A1 (COL1A1). The reduction in the renal fibrosis markers is correlated with the decreased phosphorylation of Smad2/3 levels but does not improve E-cadherin protein expression. Collectively, altenusin reduces EMT in human renal proximal tubular cells and renal fibrosis by antagonizing the TGF-β/Smad signaling pathway.

Exploration of Polyphenols Extracted from Cytisus Plants and Their Potential Applications: A Review

The increasing world population means an increased demand for sustainable processes and products related to foods, particularly those with added health benefits. Plants can be an alternative source of nutritional and biofunctional ingredients. Cytisus plants are an underexploited bioresource, currently prevalent in the Mediterranean Basin and western Asia. This manuscript addresses the processing potential of Cytisus plants for the development of added-value products, including food formulations, food packaging, cosmetics, and therapeutic applications. Most research has reported that Cytisus spp. are a promising source of inexpensive bioactive polyphenol compounds. Cytisus flowers should be considered and exploited as raw materials for the development of new food ingredients (antioxidants, preservatives, additives, etc.), nutraceuticals, or even direct therapeutic agents (anticancer, antibacterial, etc.). In order to evaluate the socioeconomic effect of these underutilized plants, more research is needed to assess their valorization for therapeutic and dietary possibilities, as well as the economic impact.

Chemical and Biological Properties of Three Poorly Studied Species of Lycium Genus-Short Review

The genus Lycium belongs to the Solanaceae family and comprises more than 90 species distributed by diverse continents. Lycium barbarum is by far the most studied and has been advertised as a “superfood” with healthy properties. In contrast, there are some Lycium species which have been poorly studied, although used by native populations. L. europaeum, L. intricatum and L. schweinfurthii, found particularly in the Mediterranean region, are examples of scarcely investigated species. The chemical composition and the biological properties of these species were reviewed. The biological properties of L. barbarum fruits are mainly attributed to polysaccharides, particularly complex glycoproteins with different compositions. Studies regarding these metabolites are practically absent in L. europaeum, L. intricatum and L. schweinfurthii. The metabolites isolated and identified belong mainly to polyphenols, fatty acids, polysaccharides, carotenoids, sterols, terpenoids, tocopherols, and alkaloids (L. europaeum); phenolic acids, lignans, flavonoids, polyketides, glycosides, terpenoids, tyramine derivatives among other few compounds (L. schweinfurthii), and esters of phenolic acids, glycosides, fatty acids, terpenoids/phytosterols, among other few compounds (L. intricatum). The biological properties (antioxidant, anti-inflammatory and cytotoxic against some cancer cell lines) found for these species were attributed to some metabolites belonging to those compound groups. Results of the study concluded that investigations concerning L. europaeum, L. intricatum and L. schweinfurthii are scarce, in contrast to L. barbarum.