2,4,8-trihydroxybicyclo [3.2.1]octan-3-one scavenges free radicals and protects against xenobiotic-induced cytotoxicity

Currently, there is a great deal of interest in the study of natural compounds with free-radical-scavenging activity because of
their potential role in maintaining human health and preventing diseases. In this paper, we report the antioxidant and cytoprotective
properties of 2,4,8-trihydroxybicyclo [3.2.1]octan-3-one (TBO) isolated from the aqueous extract of Decalepis
hamiltonii roots. Our results show that TBO is a potent scavenger of superoxide (O 2 · - ), hydroxyl ( · OH), nitric oxide ( · NO)
and lipid peroxide (LOO · ) – physiologically relevant free radicals with IC 50 values in nmolar (42 – 281) range. TBO also
exhibited concentration-dependent secondary antioxidant activities such as reducing power, metal-chelating activity and
inhibition of protein carbonylation. Further, TBO at nmolar concentration prevented CuSO 4 -induced human LDL oxidation.
Apart from the in vitro free-radical-scavenging activity, TBO demonstrated cytoprotective activity in primary hepatocytes
and Ehrlich ascites tumour (EAT) cells against oxidative-stress-inducing xenobiotics. The mechanism of cytoprotective
action involved maintaining the intracellular glutathione (GSH), scavenging of reactive oxygen species (ROS) and inhibiting
lipid peroxidation (LPO). Based on the results, it is suggested that TBO is a novel bioactive molecule with implications in
both prevention and amelioration of diseases involving oxidative stress as well as in the general well-being.