Bioactives derived from Brazilian native flora with antimicrobial and anticancer activity.

Abstract

Background: The development of new drugs that act against multidrug-resistant microorganisms and malignant tumors is necessary owing to the limited therapeutic options and high mortality rates associated with these pathologies. In this study, we evaluated the phytochemical groups present in seven plants from the Brazilian Cerrado even as their antioxidant, antiproliferative and antimicrobial activities.

Methods: The extracts were obtained by the maceration technique and secondary metabolites were determined by phytochemical analysis. The antioxidant activity was assessed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging method. The antiproliferative activity of the extracts was assessed using human breast, kidney, and liver neoplastic cells. Cytotoxicity was evaluated in a non-neoplastic cell line - NIH/3T3. The antimicrobial activity of the plant extracts against resistant bacteria and yeasts was determined using disk diffusion assays, and the minimum inhibitory concentration (MIC) was determined by the broth microdilution technique.

Results: Phytochemical analysis revealed the presence of phenolic compounds, flavonoids, steroids, tannins, and saponins in all of the extracts, with Smilax fluminensis showing the highest levels of phenolic compounds and flavonoids. All tested extracts exhibited antioxidant activity above 50%, notably Tapiria obtusa (82.36 ± 0.44). The T. obtusa extract showed potent antiproliferative activity against the 786-0 cell line (GI₅₀ 10.16 ± 2.33 µg/mL) and a significantly greater SI (SI = 24.61) than the control (SI = 3.23, doxorubicin), indicating its selective cytotoxicity against cancer cells and its potential as a therapeutic agent against renal cancer. No cytotoxicity was observed in non-tumor cells. Extracts of S. fluminensis leaves showed fungicidal effects on Candida glabrata (MIC = 500 µg/mL). This study is the first to demonstrate the antibacterial activity of T. obtusa leaf ethanolic extract against MRSA (MIC = 1,000 µg/mL).

Conclusions: The ethanolic extract of T. obtusa demonstrated antioxidant activity, antiproliferative effects against the 786-0 cell line, and antibacterial activity against MRSA. The ethanolic extract of S. fluminensis leaves exhibited a fungicidal effect against C. glabrata. These findings may pave the way for more effective and safer treatments for managing oncological and infectious diseases.