Chemical Composition, Antimicrobial, and Drug-Potentiating Activities of Extracts From Tocoyena formosa (Cham. & Schltdl.) K.Schum. (Rubiaceae).

Tocoyena formosa is a medicinal species used to treat gastrointestinal disorders, which may include infections. This study analyzed the hexane (HETF) and ethanolic (EETF) extracts of T. formosa to identify their chemical composition and antimicrobial potential. Gas chromatography-mass spectrometry revealed that HETF is mainly composed of n-alkanes, especially n-nonacosane (70.02%), while EETF contains pentacyclic triterpenes, such as ursolic acid (72.08%) and oleanolic acid (16.30%). Antimicrobial activity was evaluated against multidrug-resistant bacteria and Candida species. HETF showed activity against Escherichia coli and Staphylococcus aureus (minimum inhibitory concentrations [MICs] of 128 and 256 µg/mL, respectively), while EETF was active against E. coli (MIC 256 µg/mL). When combined with imipenem, both extracts enhanced their efficacy against S. aureus (MIC = 20-32 µg/mL). EETF exhibited strong antifungal activity against Candida albicans (IC₅₀ = 57.0 µg/mL), and both extracts reduced fungal growth in C. albicans and C. tropicalis, also inhibiting morphogenesis of C. tropicalis at 512 µg/mL. Thus, T. formosa extracts proved to be an important source of bioactive compounds, especially n-alkanes and triterpenes, acting either alone or potentiating the action of conventional drugs against infectious microorganisms, making them a promising source for the development of pharmaceutical products targeting bacteria and fungi.