Phytochemical Profile and Bioactive Potential of Erythroxylum nummularium Peyr: Evaluation of Antioxidant, Antimicrobial, and Antinociceptive Properties

Erythroxylum nummularium is a native Brazilian species with limited phytochemical and pharmacological characterization. This study aimed to investigate the chemical composition and biological properties of methanolic extracts and fractions obtained from the leaves, branches, stem bark, and stem of the plant. Total phenolic content (TPC), total flavonoid content (TFC), total alkaloid content (TAT), and GC–MS profiling were combined with antioxidant (DPPH, β-carotene bleaching, TAC), antimicrobial, toxicological, and antinociceptive assays. The extracts exhibited substantial variation in TPC, TFC, and metabolite profiles, which strongly influenced their biological activities. The ethyl acetate fraction from the leaves (ELEN) showed the highest TPC and TFC, correlating with superior antioxidant performance, antimicrobial activity against Staphylococcus aureus, low toxicity in Artemia salina, and significant antinociceptive effects in mice, with an LD50 above 2000 mg/kg. In the antioxidant assays, the ethyl acetate fraction from the stem bark (ESBEN) exhibited the highest overall activity, likely due to its elevated levels of highly polar phenolics and flavonoids. Among the fractions characterized by GC–MS, DSBEN, DLEN, and DBEN were the most active, with phenolic acids, their methylated derivatives, and low-molecular-weight organic acids contributing synergistically to antioxidant activity. These findings identify E. nummularium as a promising source of structurally diverse metabolites with antioxidant, antimicrobial, and antinociceptive potential and support further investigation toward the development of natural bioactive agents.