Search Results (4)

Dizygostemon riparius is an endemic tropical Brazilian species whose physiological responses to salinity are poorly understood. This study evaluated the effects of NaCl (0, 50, and 100 mM) on in vitro-grown D. riparius by integrating growth, anatomical, photosynthetic, and biochemical analyses. Salinity significantly reduced biomass and growth parameters, indicating impaired development. Photosystem II efficiency declined, as evidenced by decreases in the performance index and chlorophyll content, while anatomical changes such as epidermal thickening and reduced vascular bundles reflected structural adjustments under stress. At the biochemical level, salinity altered polyamine metabolism, with reductions in total free polyamines, suggesting potential limitations in defense mechanisms. Hyperhydricity observed under high salinity indicated a non-adaptive response. Overall, D. riparius displayed limited tolerance to salt stress, with physiological and biochemical impairments outweighing structural plasticity. This study provides the first data-driven characterization of salinity effects in this species and highlights the value of in vitro culture as a tool to investigate stress responses. Full article

Background/Objectives: Endophytic fungi are valuable sources of bioactive compounds with potential therapeutic applications. This study aimed to evaluate the antifungal activity of secondary metabolites produced by Fusarium sp. isolated from Dizygostemon riparius, with particular focus on the impact of culture medium supplementation with halogenated and metallic additives on metabolite production. Methods: The fungus was cultivated in standard Czapek medium and media supplemented with NH₄Br or MnCl₂. Methanolic extracts were obtained, fractionated, and chemically characterised via LC-ESI-HRMS. In vitro antifungal assays, including MIC and MFC determinations and biofilm inhibition tests, were performed against Candida albicans strains. In vivo toxicity and efficacy were assessed using Tenebrio molitor larvae. Results: Fifteen metabolites were annotated, including known antifungals such as fusaric acid and cyclosporin A. Fractions EMBr4 and EMC5 demonstrated fungicidal activity with MIC values close to fluconazole and significantly inhibited biofilm formation and maturation. In vivo, these fractions displayed low acute toxicity and improved survival in infected larvae, comparable to fluconazole treatment. Conclusions: The results indicate that culture medium modulation enhances the production of bioactive metabolites by Fusarium sp., leading to extracts with notable antifungal efficacy and safety. EMBr4 and EMC5 are promising candidates for further development as antifungal agents, particularly for targeting biofilm-associated Candida infections. These findings support the potential of endophytic fungi as sources of novel therapeutics and warrant further mechanistic and pharmacological investigations. Full article

Background/Objectives: This study evaluates the effect of Mn(II) and Co(II) ions on the production of anti-Candida metabolites by the endophytic fungus Aspergillus sp., isolated from Dizygostemon riparius. The objective was to identify metal-induced secondary metabolites with antifungal potential against drug-resistant Candida species. Methods: Aspergillus sp. was cultivated in Czapek agar supplemented with MnCl₂ (400 µM) or CoCl₂ (200 µM). Metabolite profiles were analyzed using UHPLC-DAD and LC-ESI-HRMS, followed by structural elucidation via NMR. Antifungal and biofilm inhibition activities were tested against Candida albicans and Candida parapsilosis. Toxicity was assessed using Tenebrio molitor larvae. Results: Key metabolites, including pyrophen, penicillquei B, and fonsecinone B, demonstrated antifungal activity with MIC values of 4.37–280.61 µg/mL. Fonsecinone B exhibited superior biofilm inhibition, surpassing fluconazole in reducing biofilm biomass and viability. In vivo assays showed low toxicity, with survival rates above 80% at 2× MIC/kg. Conclusions: Mn(II) and Co(II) significantly modulated the production of antifungal metabolites in Aspergillus sp. Fonsecinone B emerged as a promising candidate for antifungal therapy due to its potent activity and low toxicity. These findings support further investigation into the therapeutic potential of metal-induced fungal metabolites for combating drug-resistant Candida infections. Full article

Salicylic acid (SA) is a bioregulator well-known for mitigating salinity damage in plants. However, no studies have examined the interaction between SA and salinity in Dizygostemon riparius, a species rich in bioactive molecules. Therefore, we aimed to evaluate the effect of SA application on Dizygostemon riparius under different salinity levels. A completely randomized experiment was conducted in a 2 × 3 factorial design (two SA concentrations of 0 and 100 µM and three salinity concentrations of 0, 200, and 400 mM NaCl) with five replicates. At 400 mM NaCl, leaf temperature increased by 11%, while relative water content and total soluble carbohydrates decreased by 30% and 35%, respectively, leading to reduced biomass accumulation. Notably, the SA application mitigated these effects by restoring relative water content under 400 mM NaCl and improving carboxylation efficiency and intrinsic water-use efficiency under 200 mM NaCl. Additionally, dry biomass was maintained under both 200 and 400 mM NaCl with SA treatment. These findings suggest that SA has a promising potential to alleviate salt stress in Dizygostemon riparius. Our results could inform cultivation practices, opening new perspectives on the use of SA as an attenuator of salinity stress. Full article