Anti-aging effects of Alpinia galanga rhizome extracts via modulation of oxidative stress in Drosophila melanogaster

Aging is a biological process characterized by progressive functional decline caused by cellular and molecular damage. Free radicals contribute to oxidative stress, which negatively affects longevity, while antioxidant defenses can delay aging. This study investigated the antioxidant and anti-aging potential of Alpinia galanga rhizome extracts in Drosophila melanogaster. Phytochemical analysis revealed a rich diversity of metabolites, with the ethanolic extract showing the highest phenolic (197.92 mg GAE/g) and flavonoid (23.32 mg QE/g) contents and the strongest DPPH radical scavenging activity (89.61%; IC₅₀ = 65.23 μg/mL) relative to the aqueous and hydromethanolic extracts. Toxicological assays revealed a clear dose- and time-dependent mortality, reaching 100% after 15 days at 50–100 mg/mL. At 7 days, LC₅₀ and LC₉₀ values ranged between 31.2–57.8 mg/mL and 65.9–108.9 mg/mL depending on extract type (R² = 0.93–0.97; p < 0.05). Conversely, sublethal concentrations (LC₂₅) markedly prolonged lifespan, up to 39% (60 days for ethanolic, 55 days for hydro-methanolic and aqueous extracts), and improved resistance to H₂O₂-induced oxidative stress by 31.6% versus controls. A. galanga also enhanced antioxidant defenses, with the ethanolic extract producing the strongest enzymatic response after 10 days (CAT: 0.934 μM/min/mg protein; GST: 0.701 μM/min/mg protein), which remained significantly higher than controls after 35 days (p < 0.001). These results highlight A. galanga as a potent source of bioactive compounds capable of sustaining redox balance, mitigating oxidative stress, and promoting longevity.