Trichoderma spp. are filamentous fungi generally observed in nature, which are widely marketed as biocontrol agents. The secondary metabolites produced have obtained special attention since they possess attractive chemical structures with a broad spectrum of biological activities. In Cuba, the species of Trichoderma have been commercially applied for the control of several phytopathogens to protect agricultural crops, but few studies have been carried out to detect and characterize the production of metabolites with biological activity. The strain Trichoderma harzianum LBAT-53 was subjected to an antifungal in vitro assay against Fusarium oxysporum f.sp. cubense by dual culture and volatile metabolite assays and fermented in PDB under constant agitation conditions. The ethyl acetate crude extract was obtained by liquid–liquid extraction. The fungal extract was investigated for the composition of secondary metabolites through chemical screening and ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in negative ionization mode. As a result, LBAT-53 showed antagonistic activity in vitro (Class 2) against the pathogen evaluated in direct confrontation (76.9% of inhibition in 10 days) and by volatile metabolites (<40% in 7 days). Furthermore, seven low-molecular-weight phenolic compounds, including chrysophanol, phomarin, endocrocin, and trichophenol A, among others, were identified using UHPLC-ESI-MS/MS. This study is the first work on the characterization of secondary metabolites produced by the commercially applied strain LBAT-53, which is a promising source of bioactive compounds. These results provide a better understanding of the metabolism of this fungus, which is widely used in Cuba as biopesticides in agriculture pest control.

In this study, the characteristic growth of Cladobotryum virescens on nine culture media was analyzed. The growing behavior of this fungus was dependent on the culture medium. In vitro analysis showed that oat agar was better than other media tested with the highest conidia production. The antifungal activity against Fusarium chlamydosporum and Alternaria brassicicola was evaluated by the Dual Culture method. C. virescens displayed high activity against both pathogens acting through antibiosis and mycoparasitism. This effect was increased by a higher competitiveness of the strain for the substrate. Furthermore, the crude ethyl acetate extract of the culture broth was tested in vitro against Botrytis cinerea and Septoria tritici, as well as the hemibiotrophic oomycete Phytophthora infestans using a microtiter plate assay at different concentrations. The extract showed excellent inhibition even below 5 ppm. According to these results, we concluded that C. virescens can be considered as a potential biological control agent in agriculture. To the best of our knowledge, this is the first study to investigate C. virescens as a biocontrol agent for different diseases caused by five relevant pathogens that affect cereals and vegetables.

Phaseolus vulgaris L. is one of the most important legumes for human consumption due to its contents of proteins, antioxidants, minerals, and bioactive compounds. In the last decade, there has been a growing research interest in increasing yields while reducing or replacing the use of chemical fertilizers. This has led to a focus on plant growth-promoting Rhizobacteria (PGPR) as biofertilizers in sustainable agricultural practices. The aim of this study was to determine the growth-promoting activity of a culture broth of the Gram-negative soil bacteria Rhizobium sp. (F7), which is conserved in the Collection of Beneficial Bacteria at the Institute of Fundamental Research in Tropical Agriculture (INIFAT), and to identify the main secondary metabolites present in the ethyl acetate crude extract using high-resolution liquid chromatography coupled with mass spectrometry (UHPLC-ESI-MS/MS). The growth-promoting activity of the culture broth on Phaseolus vulgaris L. seeds was evaluated. The ethyl acetate extract was obtained by liquid–liquid extraction with ethyl acetate from the culture broth, and UHPLC-ESI-MS/MS was used to identify secondary metabolites. The results indicated that the culture broth of Rhizobium sp. exhibited an in vitro growth-stimulating effect. Furthermore, ten secondary metabolites were identified in the ethyl acetate extract (p-coumaric acid, indole-3-lactic acid, naringenin, and siderophores B and C, among others). These findings highlight the bioactive metabolites produced by Rhizobium sp., a bacterial strain of the INIFAT collection, which have a positive effect as growth promoters in plants. They reveal the potential of Rhizobium sp. as a promising candidate for inclusion in agricultural management practices.

Cecropia peltata L., commonly known as "yagruma," is one of the most renowned plants in Cuba for its traditional uses. This study aimed to evaluate the impact of drying and extraction methods on the chemical composition and antioxidant activity of yagruma leaves. Two drying methods, traditional drying and advanced multifunctional solar dryers, were employed. Aqueous extracts (LOYT001 and LOYC002) were prepared by infusion from each dried sample, while hydroalcoholic extracts (LOYT001_H and LOYC002_H) were obtained through maceration. The crude extracts were analyzed for chlorogenic acid (CA) and isoorientin content using UHPLC, and their antioxidant activity was assessed via DPPH and FRAP assays. LOYC002 and LOYC002_H exhibited higher concentrations of CA and isoorientin compared to their counterparts (LOYT001 and LOYT001_H). Isoorientin levels were highest in hydroalcoholic extracts, while aqueous extracts contained more CA. Among the extracts, LOYC002 demonstrated the strongest antioxidant activity, with the highest DPPH scavenging ability (IC50 = 39.72 ± 3.9 µg/mL) and Fe3⁺ reducing power. These findings suggest that aqueous infusions of yagruma leaves dried using CONA technology may serve as a potent natural antioxidant due to their enriched metabolite profile.

Cecropia peltata L., commonly known as “yagruma,” is used in Cuba for traditional medicinal applications. This study aimed to evaluate the impact of drying and extraction methods on the chemical composition and antioxidant activity of yagruma leaves. Two drying methods, traditional drying and advanced multifunctional solar dryers, were employed. Aqueous extracts (LOYT001 and LOYC002) were prepared by infusion from each dry sample, while hydroalcoholic extracts (LOYT001_H and LOYC002_H) were obtained through maceration. The crude extracts were analyzed for chlorogenic acid (CA) and isoorientin content using UHPLC, and their antioxidant activity was assessed via DPPH and FRAP assays. Additionally, the total phenolic and total flavonoid contents were evaluated for the aqueous extracts. LOYC002 and LOYC002_H exhibited higher concentrations of CA and isoorientin compared to their counterparts (LOYT001 and LOYT001_H). Isoorientin levels were highest in hydroalcoholic extracts, while aqueous extracts contained more CA. Among the extracts, LOYC002 (49.41 ± 0.99 mg GAE/g and 3.07 ± 0.06 mg QE/g) demonstrated the strongest antioxidant activity, with the highest DPPH scavenging ability (IC50 = 39.72 ± 3.9 μg.mL-1) and Fe3+ reducing power. These findings suggest that aqueous infusions of yagruma leaves dried using the CONA technology may serve as a natural antioxidant.