Cyclooxygenase Enzyme and Lipid Peroxidation Inhibitory Terpenoids and Steroidal compounds as Major Constituents in...

Bioassay guided study of Cleome viscosa Linn. (Cleomaceae) leaves led to the isolation of a new cembrenoid diterpene (1: ) and three known compounds (2:  - 4: ) from the hexane extract. The chemical structures of these compounds were elucidated by spectroscopic methods such as NMR (1D and 2D), HRMS and IR and identified and afforded compound 1: , malabaric acid (2: ), stigmast-4-en-3-one (3: ) and stigmast-4-ene-3,6-dione (4: ). This is the first report of compounds 1: and 2: from C. viscosa Linn. Isolates were evaluated for anti-inflammatory activity using in vitro cyclooxygenase enzyme (COX-1 and -2) inhibitory assays. The novel cembrenoid diterpene (1: ) exhibited IC₅₀ values of 8.4 µM for COX-1 enzyme and 45.2 µM for COX-2 enzyme, respectively. Similarly, malabaric acid (2: ) exhibited IC₅₀ values of 11.5 µM for COX-1 enzyme and 46.9 µM for COX-2 enzyme, respectively. Their inhibitory activities were in par with non-steroidal anti-inflammatory drugs aspirin, ibuprofen and naproxen. Sterols 3: and 4: gave IC₅₀ values of 62.6 and 67.9 µM, respectively for COX-1 enzyme while indicating weak COX-2 enzyme inhibition. Lipid peroxidation inhibitory (LPO) and MTT assays were used to determine antioxidant activity of these compounds. Compounds 1:  - 4: showed LPO inhibition with IC₅₀ values between 82 and 100 µM and moderate antioxidant activity in the MTT assay. Biological activities reported for these compounds are for the first time and it support anecdotal medicinal claims of C. viscosa Linn. leaves.