Effect of Uncaria tomentosa aqueous extract on the response to palmitate-induced lipotoxicity in cultured skeletal muscle cells.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is frequently associated with dyslipidemia, which corresponds to the increase in the triglycerides and fatty acid concentrations in tissues, such as the skeletal muscle. Also, T2DM molecular mechanism involves increasing in reactive oxygen species (ROS) production and oxidative stress. The use of herbal medicines such as Uncaria tomentosa (Ut) has been proposed as an auxiliary treatment for patients with T2DM. In this study, it was evaluated the effect of Ut aqueous extract on cell viability and ROS production, in skeletal myoblasts from C2C12 lineage exposed to the free fatty acid palmitate (PA). METHODS: Cells were incubated with PA in different concentrations ranging from 10 to 1000 µM, for 24 or 48 h, for cytotoxicity assay. Cell death, DNA fragmentation and ROS production assays were performed in cell cultures incubated with PA for 24 h, in the pre (preventive condition) or post treatment (therapeutic condition) with 250 µg/ml Ut aqueous extract, for 2 or 6 h. Cell death was evaluated by MTT method or flow cytometry. ROS generation was measured by fluorescence spectroscopy using the DCFDA probe. RESULTS: Cell viability was reduced to approximately 44% after the incubation with PA for 24 h from the concentration of 500 µM. In the incubation of cells with 500 µM PA and Ut extract for 6 h, in both conditions (preventive or therapeutic), it was observed an increase of 27 and 70% in cell viability respectively, in comparison to the cultures incubated with only PA. Also, the incubation of cultures with 500 µM PA, for 24 h, increased 20-fold the ROS formation, while the treatment with Ut extract, for 6 h, both in the preventive or therapeutic conditions, promoted decrease of 21 and 55%, respectively. CONCLUSION: The Ut extract was efficient in promoting cell protection against PA lipotoxicity and ROS generation, potentially preventing oxidative stress in C2C12 skeletal muscle cells. Since T2DM molecular mechanism involves oxidative stress condition and it is often associated with dyslipidemia and fatty acid accumulation in muscle tissue, these results open perspectives for the use of Ut as an auxiliary strategy for T2DM management.

Lipopeptides from an isolate of Bacillus subtilis complex have inhibitory and antibiofilm effects on Fusarium solani.

Bacillus subtilis species complex is known as lipopeptide-producer with biotechnological potential for pharmaceutical developments. This study aimed to identify lipopeptides from a bacterial isolate and evaluate their antifungal effects. Here, we isolated and identified a lipopeptide-producing bacterium as a species of Bacillus subtilis complex (strain UL-1). Twenty lipopeptides (six iturins, six fengycins, and eight surfactins) were identified in the crude extract (CE) and fractions (F1, F2, F3, and F4), and the highest content of total lipopeptides was observed in CE and F2. The chemical quantification data corroborate with the hemolytic and antifungal activities that CE and F2 were the most hemolytic and inhibited the fungal growth at lower concentrations against Fusarium spp. In addition, they caused morphological changes such as shortening and/or atypical branching of hyphae and induction of chlamydospore-like structure formation, especially in Fusarium solani. CE was the most effective in inhibiting the biofilm formation and in disrupting the mature biofilm of F. solani reducing the total biomass and the metabolic activity at concentrations ≥ 2 µg/mL. Moreover, CE significantly inhibited the adherence of F. solani conidia on contact lenses and nails as well as disrupted the pre-formed biofilms on nails. CE at 100 mg/kg was nontoxic on Galleria mellonella larvae, and it reduced the fungal burden in larvae previously infected by F. solani. Taken together, the lipopeptides obtained from strain UL-1 demonstrated a potent anti-Fusarium effect inducing morphological alterations and antibiofilm activities. Our data open further studies for the biotechnological application of these lipopeptides as potential antifungal agents. KEY POINTS: • Lipopeptides inhibit Fusarium growth and induce chlamydospore-like structures. • Lipopeptides hamper the adherence of conidia and biofilms of Fusarium solani. • Iturins, fengycins, and surfactins were associated with antifungal effects.