Bioactive Potential of Nepenthes miranda Flower Extracts: Antidiabetic, Anti-Skin Aging, Cytotoxic, and Dihydroorotase-Inhibitory Activities

Carnivorous plants have garnered attention as sources of pharmacologically active compounds, yet their floral tissues remain largely underexplored. In this study, we investigated the bioactive properties of Nepenthes miranda flower extracts prepared using water, methanol, ethanol, and acetone. Among these, the ethanol extract exhibited the highest total phenolic content (18.2 mg GAE/g), flavonoid content (68.9 mg QUE/g), and antioxidant activity (DPPH IC50 = 66.9 μg/mL), along with strong antibacterial effects against Escherichia coli and Staphylococcus aureus. Cosmetically relevant enzyme inhibition assays revealed significant activity against tyrosinase (IC50 = 48.58 μg/mL), elastase (IC50 = 1.77 μg/mL), and hyaluronidase (IC50 = 7.33 μg/mL), supporting its potential as an anti-skin aging agent. For antidiabetic evaluation, the ethanol extract demonstrated potent α-glucosidase inhibition (IC50 = 24.53 μg/mL), outperforming standard inhibitors such as acarbose and quercetin. The extract also displayed marked cytotoxicity against A431 epidermoid carcinoma cells (IC50 = 90.61 μg/mL), inducing dose-dependent apoptosis, inhibiting cell migration and colony formation, and causing significant DNA damage as shown by comet assay. Furthermore, the ethanol extract strongly inhibited the activity of purified human dihydroorotase (IC50 = 25.11 μg/mL), indicating that disruption of pyrimidine biosynthesis may underlie its anticancer activity. Overall, this study provides the first characterization of N. miranda flower extracts, particularly the ethanol fraction, as a promising source of multifunctional bioactive compounds with possible applications in cosmetics, antidiabetic therapy, and cancer treatment.