Evidence for metabolism of capsaicin by liver homogenate of rats and evidence for the metabolic product being a hydroxylated product were presented previously. The fact that the metabolising enzyme is induced by prior treatment of rats with sodium phenobarbital (intraperitoneal injection) and that the enzyme action can be inhibited by addition of orthophenanthroline suggests that the system is involved in mixed function oxygenase. The degree of enzyme induction by sodium phenobarbital injection to rats was several times greater for the mixed strain rats than that for the pure strain (Sprague Dowley). Thus mired- strain rats obtained from the local supplier were bred and used in all the experiments. The structural analogs of capsaicin and zingerone were synthesized and were tested for metabolism by 10,000xg supernatant of rat liver homogenate. The supernatant was supplemented with NADPH regenerating system. The substrate dissolved in smallest possible amount of methanol was added to the incubation mixture. Incubation was carried out at 37℃, in presence of air, for 35 minutes and terminated by addition of dilute hydrochloric acid. After extraction with ethylacetate and drying under reduced pressure, the sample was tested by running a TLC plate in a solvent system (ethylacetate: isooctane: acetic acid: water=110: 50: 20: 100), and the diazotized sulfanilic acid as spraying agent. Analog: thus tested and results obtained are as following: 1. Capsaicin - Complete metabolism 2. Vanoyl vanillyl amide - Complete metabolism 3. Isobutyl vanillyl amide - Metabolised 4. Vanillyl acetamide - Not metabolised. 5. Methyl capsaicin - Not metabolised 6. Zingerone - Slight metabolism 7. Dehydrozingerone - Not metabolised Experiment was repeated for capsicin metabolism by using the microsomal enzyme pellet obtained from 10,000xg supernatant after centrifuging at 2℃ fir one hour at 100,000xg. The microsome suspended in phosphate buffer (pH 7.4) was supplemented with NADPH, and the rest experimental details were the same as for the earlier experiments. Microsomal enzyme metabolised capsaicin. In another experiment the microsomal suspension was supplemented with 100,000xg supernatant and with NADPH regenerating system. There was metabolism of capsaicin on a greater scale. The future experiments will be designed to isolate pure metabolite and identify the structure.