Bioactive, antioxidant and antimicrobial potential of the aqueous extract from the Croton blanchetianus Baill leaf essential oil extraction process

Abstract

Croton blanchetianus Baill, known as marmeleiro, is rich in secondary metabolites, such as alkaloids and terpenes, which can have biological effects. Thus, this study aimed to evaluate the bioactive, antioxidant and antimicrobial potential of aqueous extracts, resulting of the essential oil extraction process from fresh and dry leaves of C. blancheticianus. The essential oil was extracted by hydrodistillation and then the aqueous extract was collected and lyophilized, being submitted to analysis. The determination of the Minimum Inhibitory Concentration and Minimum Bactericidal Concentration against pathogenic bacteria of interest in foods (Staphylococcus aureus, Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli) was carried out by the microdilution method. The effect of aqueous extracts on bacterial cells was evaluated by transmission electron microscopy images. Evaluation of antioxidant activity provided by the ABTS and DPPH method. The aqueous extract from fresh leaves has higher levels of flavonoids and antioxidant activity by ABTS than the extract from dry leaves. The phenolic compounds, tannins and the antioxidant activity by the DPPH method did not differ significantly in both types of samples. Both aqueous extracts showed antimicrobial activity only against Gram-positive bacteria (S. aureus and L. monocytogenes). Cellular alterations were observed in S. aureus and L. monocytogenes under the action of the aqueous extract of fresh and dry leaves. The results indicate the possibility of using the aqueous extract of dried C. blanchtianus leaves as a bioactive additive and to improve food safety, regarding Gram-positive bacteria