First report of spiro-compounds from marine macroalga <i>Gracilaria salicornia</i>: prospective natural anti-inflammatory agents attenuate 5-lipoxygenase and cyclooxygenase-2

The inflammation pathology is an orchestrated biological process and the dual inhibition of pro-inflammatory enzymes 5-lipoxygenase and cyclooxygenase-2 has been found to be an effective approach against inflammation. This study involves the characterisation of two previously undescribed spiro[5.5]undecanes, 3-(hydroxymethyl)-7-(methoxymethyl)-3,11-dimethyl-9-oxospiro[5.5]undec-4-en-10-methylbutanoate (1) and 4-ethoxy-11,11-dimethyl-7-methylene-8-(propionyloxy)spiro[5.5]undec-2-en-104,106-dihydroxytetrahydro-2H-pyran-10-carboxylate (2) with potential anti-inflammatory properties, from seaweed Gracilaria salicornia by extensive-spectroscopic-experiments. These metabolites recorded prospective bioactivities against 5-lipoxygenase (IC50 p 4,106-dihydroxytetrahydro-2H-pyran-10-carboxylate analogue (2) against oxidants, 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid were found to be greater (IC50 α-tocopherol (IC50 1.42–1.79 mM). The greater hydrogen-bonding interactions and binding affinity of 2 (−10.13 kcal/mol) with 5-LOX appropriately corroborated its prospective anti-inflammatory activity.