This study systematically evaluated the potential of red rice extract as a biological ultraviolet (UV) filter and, for the first time, comprehensively validated its UV absorption characteristics, antioxidant properties, and SPF-enhancing effects in sunscreen formulations. Rich in phenolic acids, flavonoids, anthocyanins, and procyanidins, red rice extract demonstrated strong UV-absorbing capacity and free radical scavenging activity, indicating its ability to counteract UV-induced oxidative stress and inflammation.Comparative UV absorption analysis showed that the extract exhibited stable absorption peaks and favorable photothermal stability relative to three commonly used UV filters. When incorporated into oil-in-water (O/W) and water-in-oil (W/O) sunscreen formulations, red rice extract produced concentration-dependent SPF enhancement. Notably, adding 1% extract increased SPF values by more than 10% in both systems.
Importantly, the extract also showed the potential to partially replace traditional chemical UV filters. Formulations containing 1%, 3%, and 5% red rice extract were able to substitute approximately 12.82%, 19.05%, and 26.09% of chemical UV filters, respectively, without compromising SPF performance.
Overall, this work highlights red rice extract as a promising natural UV-filtering ingredient capable of boosting SPF efficacy while reducing chemical filter usage. The findings provide scientific support for its application in developing mild, safe, and environmentally friendly sunscreen products.
