Functional food property of honey locust (Gleditsia triacanthos) flowers

The use of honey locust in food prompted us to study its flowers for functional food constituents. Bioassay-guided purification of hexane, ethyl acetate and methanolic extracts of its flowers afforded three new betulinic acid esters (1-3), one new linalool carboxylic acid ester (4), known terpenoids (5-7) and known polyphenols (8-11), as elucidated by spectroscopic methods. The extracts and terpenoids 1-7 were tested for antiinflammatory and antioxidant activities against cyclooxygenase enzymes (COX-1 and -2) and lipid peroxidation (LPO), respectively. Compounds 1-7 at 25 µg/mL showed antiinflammatory activity as indicated by COX-1 and -2 enzymes inhibition at a range of 40-50% and 33-37%, respectively. The antiinflammatory activity of extracts at 100 and compounds at 25 µg/mL was superior to aspirin and comparable to other over the counter non-steroidal antiinflammatory drugs (NSAIDs) naproxen and ibuprofen. Compounds 1-7 did not show LPO activity.