Harzianum A (HA), a trichothecene produced by Trichoderma arundinaceum, has recently been described to have antagonistic activity against fungal plant pathogens and to induce plant defence genes. In the present work, we have shown that a tri5 gene-disrupted mutant that lacks HA production overproduces two polyketides, aspinolides B and C, which were not detected in the wild-type strain. Furthermore, four new aspinolides (D-G) were characterized. These compounds confirm that a terpene-polyketide cross-pathway exists in T. arundinaceum, and they may be responsible for the antifungal activity and the plant sensitization effect observed with the tri5-disrupted mutant. In addition, the molecular changes involving virulence factors in the phytopathogenic fungus Botrytis cinerea 98 (Bc98) during interaction with T. arundinaceum were investigated. The expression of genes involved in the production of botrydial by Bc98 was relatively repressed by HA, whereas other virulence genes of this pathogen were induced by the presence of T. arundinaceum, for example atrB and pg1 which encode for an ABC transporter and endopolygalacturonase 1 respectively. In addition, the interaction with Bc98 significantly repressed the production of HA by T. arundinaceum, indicating that a bidirectional transcriptional regulation is established between these two antagonistic fungi.
The sequencing of the genomes of the B05.10 and T4 strains of the fungus Botrytis cinerea revealed an abundance of novel biosynthetic gene clusters, the majority of which were unexpected on the basis of the previous analyses of the fermentation of these and closely related species. By systematic alteration of easy accessible cultivation parameters, using chemical induction with copper sulfate, we have found a cryptic sesquiterpenoid family with new structures related to eremophil-9-ene, which had the basic structure of the sesquiterpene (+)-5-epiaristolochene ((+)-4-epieremophil-9-ene). An expression study of the sesquiterpene cyclase genes present in the Botrytis cinerea genome, under culture conditions, is reported. In general, a 3 day delay and a higher BcSTC genes expression were observed when copper (5 ppm) was fed to the fermentation broth. In addition, to the observed effect on the BcBOT2 (BcSTC1) gene, involved in the biosynthesis of the botrydial toxin, a higher expression level for BcSTC3 and BcSTC4 was observed with respect to the control in the strain B05.10. Interestingly, under copper conditions, the BcSTC4 gene was the most expressed gene in the Botrytis cinerea UCA992 strain. In vitro evaluation of the biological role of these metabolites indicates that they contributed to the conidial development in B. cinerea and appear to be involved in self-regulation of the production of asexual spores. Furthermore, they promoted the formation of complex appressoria or infection cushions.
The COVID-19 pandemic has led to the search for new molecules with antiviral activity against SARS-CoV-2. The entry of the virus into the cell is one of the main targets for inhibiting SARS-CoV-2 infection. Natural products are an important source of new therapeutic alternatives against diseases. Pseudotyped viruses allow the study of SARS-CoV-2 viral entry inhibitors, and due to their simplicity, they allow the screening of a large number of antiviral candidates in Biosafety Level 2 facilities. We used pseudotyped HIV-1 with the D614G SARS-CoV-2 spike glycoprotein to test its ability to infect ACE2-expressing HEK 293T cells in the presence of diverse natural products, including 21 plant extracts, 7 essential oils, and 13 compounds from plants and fungi. The 50% cytotoxic concentration (CC50) was evaluated using the resazurin method. From these analyses, we determined the inhibitory activity of the extract of Stachytarpheta cayennensis, which had a half-maximal inhibitory concentration (IC50) of 91.65 µg/mL, a CC50 of 693.5 µg/mL, and a selectivity index (SI) of 7.57, indicating its potential use as an inhibitor of SARS-CoV-2 entry. Moreover, our work indicates the usefulness of the pseudotyped-virus system in the screening of SARS-CoV-2 entry inhibitors.
Trichothecene mycotoxins are recognized as highly bioactive compounds that can be used in the design of new useful bioactive molecules. In Trichoderma brevicompactum, the first specific step in trichothecene biosynthesis is carried out by a terpene cyclase, trichodiene synthase, that catalyzes the conversion of farnesyl diphosphate to trichodiene and is encoded by the tri5 gene. Overexpression of tri5 resulted in increased levels of trichodermin, a trichothecene-type toxin, which is a valuable tool in preparing new molecules with a trichothecene skeleton. In this work, we developed the hemisynthesis of trichodermin and trichodermol derivatives in order to evaluate their antimicrobial and cytotoxic activities and to study the chemo-modulation of their bioactivity. Some derivatives with a short chain at the C-4 position displayed selective antimicrobial activity against Candida albicans and they showed MIC values similar to those displayed by trichodermin. It is important to highlight the cytotoxic selectivity observed for compounds 9, 13, and 15, which presented average IC50 values of 2 μg/mL and were cytotoxic against tumorigenic cell line MCF-7 (breast carcinoma) and not against Fa2N4 (non-tumoral immortalized human hepatocytes).
Trichoderma arundinaceum (Ta37) and Botrytis cinerea (B05.10) produce the sesquiterpenoids harzianum A (HA) and botrydial (BOT), respectively. TaΔTri5, an HA non-producer mutant, produces high levels of the polyketide compounds aspinolides (Asp) B and C. We analyzed the role of HA and Asp in the B. cinerea-T. arundinaceum interaction, including changes in BOT production as well as transcriptomic changes of BcBOT genes involved in BOT biosynthesis, and also of genes associated with virulence and ergosterol biosynthesis. We found that exogenously added HA up-regulated the expression of the BcBOT and all the virulence genes analyzed when B. cinerea was grown alone. However, a decrease in the amount of BOT and a down-regulation of BcBOT gene expression was observed in the interaction zone of B05.10-Ta37 dual cultures, compared to TaΔTri5. Thus, the confrontation with T. arundinaceum results in an up-regulation of most of the B. cinerea genes involved in virulence yet the presence of T. arundinaceum secondary metabolites, HA and AspC, act separately and together to down-regulate the B. cinerea genes analyzed. The present work emphasizes the existence of a chemical cross-regulation between B. cinerea and T. arundinaceum and contributes to understanding how a biocontrol fungus and its prey interact with each other.
ABSTRACT:The antibacterial activity of the alkaloid extract from the leaves of Croton bonplandianum Baill. and its main compounds, sparsiflorine and crotsparine, was tested against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa by the resazurin microtitre-plate method. Pure compounds were identified by spectroscopic techniques, mainly 1D and 2D NMR. The alkaloid extract showed activity particularly against the S. aureus and P. aeruginosa. Regarding the pure compounds, the crotsparine was inactive against the microorganisms assayed, whereas the sparsiflorine indicated a moderate activity similar to the alkaloid extract. The Pseudomonas aeruginosa was the most sensitive of the tested microorganisms with MIC of 0.141 mg/mL. The results suggest that the activity of the extract may be credited mainly to the presence of the sparsiflorine. Although the activity of the sparsiflorine does not get close to the antimicrobial drugs in clinical use, it still could be a lead compound for the development of new antibacterial substances.Keywords: alkaloids, sparsiflorine, crotsparine, antibacterial activity, Croton bonplandianum, Euphorbiaceae. RESUMO: Atividade anti-bacteriana do extrato alcaloide e de compostos isolados de Croton bonplandianum Baill. (Euphorbiaceae).A atividade antibacteriana do extrato alcaloidal das folhas de Croton bonplandianum Baill., além dos principais compostos isolados, esparsiflorina e crotsparina, foi testada contra Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae e Pseudomonas aeruginosa. Foi utilizado o método de microdiluição em placa empregando resazurina como indicador da viabilidade celular. Os compostos isolados foram identificados por técnicas espectroscópicas, principalmente RMN 1D e 2D. O extrato alcaloidal foi ativo principalmente contra S. aureus e P. aeruginosa. Crotsparina mostrou-se inativa contra todos os micro-organismos testados, enquanto esparsiflorina apresentou atividade moderada, a qual foi similar à do extrato bruto. Pseudomonas aeruginosa foi a mais sensível das bactérias testadas, com CIM de 0,141 mg/mL. Os resultados sugerem que a atividade do extrato pode ser devida em grande medida pela presença de esparsiflorina. Apesar de a CIM da esparsiflorina não ter se aproximado daquela apresentada pelos agentes antimicrobianos em uso clínico, tal composto ainda pode compor um protótipo interessante para o desenvolvimento de novas substâncias antibacterianas.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.