Comparative Analysis of Temperature Effects on the Free Radical Scavenging Activity of Moringa oleifera Leaves

Temperature plays an important role in influencing the radical scavenging activity of bioactive compounds. Generally, an increase in temperature can enhance the solubility and diffusion rate of antioxidants, leading to higher activity in some cases. Free radicals, particularly reactive oxygen species (ROS), are highly reactive molecules that can cause oxidative damage to lipids, proteins, and DNA. Antioxidants are compounds that scavenge free radicals, thereby protecting biological systems from oxidative stress. The present study evaluated the effect of temperature on the free radical scavenging activity of Moringa oleifera leaf extracts, with butylated hydroxyanisole (BHA) serving as a standard antioxidant. Moringa oleifera, commonly referred to as the drumstick tree, is widely recognized for its rich phytochemical and nutritional profile, particularly its antioxidant constituents such as flavonoids, tannins, and phenolics. Moringa oleifera leaves, known for their high content of phenolics, flavonoids, and vitamins, were subjected to thermal treatments at raw, 40°C, 60°C, 80°C, and 100°C, extracted with aqueous and ethanol solvents, and analyzed using the DPPH radical scavenging assay. The results revealed a concentration-dependent increase in antioxidant activity across all samples. Among the treatments, the extract heated at 60 °C exhibited the strongest activity, reflected by the lowest EC₅₀ value (~500 µg/ml), while the 80 °C sample showed the weakest activity despite higher RSA values at some concentrations. The raw and 100 °C extracts displayed intermediate performance. BHA maintained the highest overall scavenging activity, but moringa extracts, particularly at 60 °C, showed comparable efficiency. These findings indicate that moderate heating enhances the release and stability of antioxidant phytochemicals in Moringa oleifera, whereas excessive heat reduces activity. The study concludes that controlled thermal processing optimizes the antioxidant potential of moringa leaves, supporting their application in nutraceuticals, functional foods, and as natural alternatives to synthetic antioxidants.