Bioactive Fractions from Bougainvillea × buttiana Holtum & Standl (var. Rose): Antioxidant, Anti-Inflammatory, Enzyme Inhibitory and Cytoprotective Effects Against Oxidative Stress

Background: Bougainvillea species have been used in traditional Mexican medicine, but their bioactive compounds and mechanisms of action are insufficiently studied. This is the first comprehensive evaluation of fractions from the acetone extract of Bougainvillea × buttiana Holtum & Standl (var. Rose), combining phytochemical profiling with in vitro multitarget bioactivity assessment. Methods: Eleven fractions were analyzed for total phenolic (TPC) and flavonoid content (TFC) and antioxidant capacity using the DPPH assay. The most active fractions were further tested for nitric oxide (NO) scavenging, protection of erythrocytes and bovine serum albumin (BSA) from oxidative damage, inhibition of enzymes involved in inflammation (PLA2, COX, LOX) and carbohydrate metabolism (α-glucosidase, α-amylase, tyrosinase), cytoprotective effects in L929 fibroblasts exposed to hydrogen peroxide, and their main metabolites were qualitatively identified by HPLC-UV-Vis. Results: All fractions showed significant TPC and TFC and concentration-dependent antioxidant activity. The fractions with the highest antioxidant indices were F5, F7, and F9. These effectively scavenged NO, protected erythrocytes and L929 cells (maintaining viability at 82.0%, 75.6%, and 72.0%, respectively), and inhibited key enzymes. Seven major compounds, mainly flavonoids, were identified. Conclusions: These findings showed that flavonoid-enriched fractions from B. × buttiana exhibit coordinated antioxidant, anti-inflammatory, antidiabetic, and cytoprotective effects, suggesting potential to treat oxidative stress-related disorders.