Phenolic composition and antioxidant, anticholinesterase and antibiotic-modulating antifungal activities of Guazuma ulmifolia Lam. (Malvaceae) ethanol extract

Tea from the bark and leaves of Guazuma ulmifolia Lam. (Malvaceae) are used in several countries in South and Central America in cases of gastrointestinal and skin problems, among other diseases. The aim of this study was to characterize the chemical composition and its antioxidant, anticholinesterase and antifungal activity to correlate these with the popular use of this plant. The antioxidant activity was evaluated by DPPH method and the anticholinesterase action by inhibiting the acetylcholinesterase enzyme, with an adaptation to thin layer chromatography. In the antifungal assay, the minimum inhibitory concentration (MIC) was determined by the microdilution broth method at concentrations ranging from 1024 to 1 μg/mL, moreover a modulated test on the antibiotic fluconazole was performed at concentrations from 1024 to 8 μg/mL. Assays were performed in triplicates and plate readings were performed in an ELISA spectrophotometer. The ethanol extract showed antioxidant activity (EC50: 119.85 ± 2.42 μg/mL), significant anticholinesterase activity (growth inhibition zone of 1.0 cm, near the physostigmine standard), and low antifungal activity was observed against standard strains of Candida. Nevertheless, the extract showed a significant fluconazole modulatory effect, with potentiation of the antifungal action against Candida tropicalis. The chemical study of the ethanol extract from Guazuma ulmifolia leaves revealed the presence of flavonoids and phenolic acids with recognized antioxidant potential. The antioxidant activity combined with anticholinesterase potential corroborates, in part, with the use of G. ulmifolia in the treatment of gastrointestinal disorders.