COMPARATIVE ANTIOXIDANT AND PROTECTIVE EFFECTS OF GINGER AND TUMERIC EXTRACTS AGAINST ALUMINUM AND MANGANESE-INDUCED HEPATOTOXICITY IN VITRO

Heavy metal exposure, particularly to aluminum and manganese, poses serious risks to liver health by triggering oxidative stress. This study assessed the antioxidant and hepatoprotective effects of ginger and turmeric extracts against aluminum and manganese-induced liver toxicity in vitro. Two species of ginger(Zingiber officinale, Zingiber zerumbet) and two species of turmeric( Curcuma longa and Curcuma zedoaria) were examined using three extraction methods: conventional maceration, microwave-assisted maceration, and sonication-assisted maceration. Dried and authenticated rhizomes were processed into powders, extracted with ethanol, and analyzed for phytochemical composition. Total phenolic and flavonoid contents were quantified, while antioxidant activities were assessed through (1,1-diphenyl-2-picrylhydrazyl) DPPH, nitric oxide, hydrogen peroxide scavenging, and iron chelation assays. Antioxidant potential of the extracts were evaluated by measuring malondialdehyde (MDA) and reduced glutathione (GSH) levels in liver homogenates exposed to aluminum and manganese salts. Results showed that advanced extraction methods, particularly sonication, yielded significantly higher levels of phenolics and flavonoids compared to maceration. Curcuma longa sonicated extract (CLS) recorded the highest phenolic (68.21 ± 0.17 mg GAE/g) and flavonoid (68.83 ± 0.28 mg QE/g) contents. Phytochemical screening confirmed the presence of alkaloids, flavonoids, saponins, and terpenoids, with variations linked to extraction technique. In antioxidant assays, CLS consistently outperformed other extracts, displaying strong DPPH scavenging (IC₅₀ = 36.50 ± 0.34 µg/mL) and nitric oxide scavenging (IC₅₀ = 12.58 ± 0.21 µg/mL) activities, approaching standard antioxidant levels. Notably, Zingiber officinale microwave extract (ZOM) showed metal-chelating activity (IC₅₀ = 46.33 ± 3.23 µg/mL) comparable to ascorbic acid. Hepatoprotective studies revealed that extracts dose-dependently lowered MDA levels and restored GSH, indicating reduced lipid peroxidation and preserved antioxidant defenses. Overall, Curcuma longa emerged as the most effective species across assays, while Zingiber officinale offered distinct benefits in metal detoxification. The strong link between extraction efficiency, phytochemical content, and biological activity underscores the importance of optimizing processing methods.