METABOLISM OF BENZOPHENONE-3 IN RATS

Benzophenone-3 [2-hydroxy-4-methoxybenzophenone (HMB), oxybenzone, Spe ctra-Sorb UV-9 light absorber(R)] is used in many cosmetics and sunscr eens as a UV absorber. This study was conducted to investigate the met abolism of HMB (100 mg/kg body weight administered orally). 2,4-Dihydr oxybenzophenone (DHB), 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), an d 2,3,4-trihydroxy-benzophenone (THB) metabolites were identified as f ree and conjugated forms by HPLC analysis. HMB was rapidly absorbed, m etabolized, and detected in plasma (as free and protein bound) at 5 mi n postadministration. The parent compound and metabolites (free and co njugated) were detected at 6 hr in most tissues. DHB was present in mo st tissues with the highest concentration in the liver. DHMB was only detected as the conjugated form in liver, spleen, and heart. Trace amo unts of THB were also detected in biological samples. Urine was the pr imary route, whereas feces was the secondary route of elimination of H MB and its metabolites. This study revealed O-dealkylation as the majo r pathway of HMB metabolism.