Análise fitoquímica e avaliação da actividade antioxidante e antimicrobiana dos extractos de Solanum linnaeanum

Abstract

Solanum linnaeanum belongs to the Solanaceae family and is used in traditional medicine for the treatment of various ailments, including inflammatory diseases, but scientific investigations aiming to determine its therapeutic potencial are scarce. The present study aimed to evaluate the phytochemical profile and assess the in vitro antioxidant and antimicrobial activity of the crude hydroethanolic extract and the respective chloroform, ethyl acetate, n-butanol and residual aqueous fractions of leaves, stem bark, and root bark of S. linnaeanum. Qualitative and quantitative phytochemical analyses were performed using standard methods, whereas the antioxidant activity was estimated using DPPH, Phosphomolybdenum, and Ferric Reducing Antioxidant Power (FRAP) assays. Antimicrobial activity was determined by the agar disk diffusion method against Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, and Candida albicans. Qualitative phytochemical analysis revealed the presence of condensed tannins, coumarins, flavonoids, and phenols in all extracts. The ethyl acetate fraction of the leaves showed the highest contents of total phenols (49.527 ± 0.178 mgGAEg -¹ ), total flavonoids (28.743 ± 0.145 mgQEg -¹ ), and condensed tannins (12.133 ± 0.036 mgCyaEg -¹ ). The ethyl acetate fraction of the leaves demonstrated also the highest DPPH radical scavenging power (IC 50 = 347.533 ± 4.219 μgmL -¹ ), highest reduction of the phosphomolybdenum complex (35.091 ± 0.150%) and the highest ferric reducing antioxidant power (322.070 ± 3.375 μMFe 2+ g -¹ ). S. linnaeanum extracts and fractions did not show significant antimicrobial activity against the studied microbial strains. The results contributed to reveal some phytochemical characteristics of this species, and suggest that S. linnaeanum is a promising plant that deserves further studies for its exploration as a new source of compounds with antioxidant activity