Anti-inflammatory pregnane-type steroid derivatives clathroids A-B from the marine Microcionidae sponge Clathria (Thalysias) vulpina: Prospective duel inhibitors of pro-inflammatory cyclooxygenase-2 and 5-lipoxygenase

Two pregnane-type of steroid derivatives characterized as 5α-pregna-3β-methyl pent-3-enoate-12β, 16β diol-20-one (clathroid A) and 12β,15β- dihydroxypregna-4,6-diene-3,20-dione (clathroid B) were purified from the crude extract of the marine sponge, Clathria (Thalysias) vulpina (family Microcionidae) by extensive chromatographic fractionation. Spectroscopic methods including nuclear magnetic resonance spectroscopy were employed to characterize the purified clathroids A-B. The studied compounds exhibited duel inhibitory potentials against pro-inflammatory cyclooxygenase-2 and 5-lipoxygenase (median inhibitory concentration, IC₅₀ < 1 mM), whereas the attenuation property of clathroid A against 5-lipoxygenase (IC₅₀ 0.85 mM) was greater than the standard anti-inflammatory ibuprofen (IC₅₀ 4.51 mM, p < 0.05). Greater selectivity index (anti cyclooxygense-2/anti cyclooxygense-1) of the studied clathroids (>1) than ibuprofen (0.43) attributed the greater selective attenuation properties towards pro-inflammatory inducible cyclooxygenase-2 than its constitutive isoenzyme cyclooxygenase-1. The antioxidant potentials of clathroid A against 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (IC₅₀ 0.80 mM) and diphenyl-1-picrylhydrazyl (IC₅₀ 0.83 mM) free radicals were greater than those of clathroid B (IC₅₀ 0.86-0.96 mM). Structure-activity analyses showed that the bioactivities of the clathroids were directly related to their electronic parameters coupled with permissible hydrophobic properties. Clathroid A exhibited grater electronic parameter (topological polar surface area tPSA, 83.83) than clathroid B (74.60) and ibuprofen (37.30), which were found to be in agreement with the prospective anti-inflammatory profile of clathroid A. Clathroid A exhibited higher number of hydrogen bonding interactions with 5-lipoxygenase active site and lesser docking values, such as docking score (DS -12.90 kcal mol^-1) and inhibition constant (Ki 1.11 nM) than those recorded by clathroid B (DS -10.49 kcal mol^-1; Ki 13.88 nM). The molecular binding properties of clathroid A with 5-lipoxidase inferred that its docking score/ binding energy were positively correlated with their in vitro bioactivie potentilas. A putative biosynthetic pathway of the studied clathroids was proposed from a pregnenolone precursor. The present study recognized the potential of clathroid A isolated from C. (Thalysias) vulpina as prospective anti-inflammatory lead that could find its use in medicinal applications.

Clathriolide from marine demosponge Clathria (Thalysias) vulpina (Lamarck, 1814): previously undescribed macrocylic lactone with attenuating potential against angiotensin converting enzyme

Angiotensin-I converting enzyme catalyses the rate-determined step of the conversion of angiotensin-I to angiotensin-II that narrows the blood vessels, and angiotensin-I converting enzyme inhibitors were recognised as important medications for hypertension-related diseases. Chemical investigation of angiotensin-I converting enzyme inhibitors from marine demospongiae Clathria (Thalysias) vulpina (family Microcionidae), resulted in a previously undescribed 22-membered macrocyclic lactone derivative, named as clathriolide. The studied compound showed potential angiotensin converting enzyme attenuation property (IC₅₀ 0.41 mM), which was comparable with the standard captopril (IC₅₀ 0.36 mM). Clathriolide revealed significantly greater antioxidant potentials against free radical species (IC₅₀ < 1 mM) in comparison with the standard α-tocopherol (IC₅₀ > 1.5 mM). Superior electronic characteristics (topological polar surface area > 100) coupled with relatively smaller binding energy and docking score of clathriolide with the aminoacyl residues of angiotensin-I converting enzyme (-11.5 and -12.2 kcal/mol, respectively) described its potential inhibitory property against angiotensin-I converting enzyme.