A set of studies performed by Sabinsa Corporation revealed that Tetrahydrocurcuminoids is a potent antioxidant than the commonly used synthetic antioxidant, Butylated Hydroxytoluene (BHT)

In the DPPH radical scavenging method, the ability of an antioxidant to bind the 1:1 diphenyl-2-picrylhydrazyl-radical (a very stable free radical species) is measured using various concentrations of the selected antioxidants.

The role of curcuminoids as topical antioxidants has been validated in laboratory experiments. Curcuminoids are reported to protect normal human keratinocytes from hypoxanthine/xanthine oxidase injury in in vitro experiments. It was surmised in this study that since curcuminoids synergistically inhibit nitroblue tetrazolium reduction, a decrease in superoxide radical formation leading to lower levels of hydrogen peroxide could be their probable mode of action. The authors of this study propose that lower levels of hydrogen peroxide, leading to decreased cytotoxic effects, may be responsible for the protective effects of curcuminoids¹¹. This study suggests that curcuminoids and THC offer protection to the skin and could be included in antioxidant topical preparations.

A recent study further validated the well-known superior antioxidant properties of THC and explained the mechanism of antioxidant action⁵. The inhibitory effects of curcumin and tetrahydrocurcumin on lipid peroxidation of the erythrocyte membrane induced by tertbutylhydroperoxide were studied. The results demonstrated that THC showed a greater inhibitory effect than curcumin. The authors concluded that THC must scavenge free radicals such as the tert-butoxyl radical and peroxyl radical efficiently. They attempted to explain the mechanism of antioxidant action of THC on the basis of the molecular structure (Figure 9). They concluded that the beta-diketone moiety of THC must exhibit antioxidant activity by cleavage of the C-C bond at the active methylene carbon between two carbonyls in the beta-diketone moiety. Since THC is one of the major metabolites of curcumin, the authors propose that this compound may exhibit the observed physiological and pharmacological properties in vivo by means of the beta-diketone moiety as well as phenolic hydroxyl groups (Figure 9).