A new stilbene-type polyphenol and other phenolics with anti-inflammatory activities from Coleus esculentus (N.E.Br.) G.Taylor

A new stilbene-type polyphenol (S,E)-2-(3,6-dihydroxyphenyl)-3-((3-(3,4-dihydroxyphenyl)acryloyl)oxy)propanoic acid (1) has been isolated from Coleus esculentus (N.E.Br.) G.Taylor. In addition, a flavonoid lactate, 7-O-lactoyl-luteolin (2); and two flavonoids, caryatin (3) and dillenetin (4); were also isolated. All compounds are reported for the first time in Coleus esculentus. Characterisation of the isolated compounds was done using NMR (1D and 2D), MS, FTIR and UV Spectroscopy. Anti-inflammatory activities of the compounds were determined using ROS inhibitory, Nitric oxide (NO) and TNF-α inhibitory assays. Compounds 3 and 4 showed the highest ROS inhibition, (IC₅₀ 1.10 ± 0.06 and 9.80 ± 1.00 µg/mL respectively). Compound 3 had no activity in NO and TNF-α inhibition assays while 4 had a high NO inhibitory activity (IC₅₀, 7.10 ± 1.90), but did not inhibit TNF-α. Compounds 1 and 2 showed moderate ROS inhibitory activities. Anti-inflammatory activities of the compounds are being reported for the first time in literature.