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Consumption of marine alga-based polysaccharides as additional functional foods can endow with health benefits by diminishing the risk of chronic diseases. A polygalacto-fucopyranose characterized as [→1)-2, 4-SO 3 -α-Fucp-(3 → 1)-{2-SO 3 -α-Fucp-(3→}] with [(4 → 1)-6-OAc-β-Galp-(4→] side chain isolated from marine alga Sargassum wightii exhibited potential antihypertensive activity. Upon treatment with studied polygalactofucan (50 mg/kg BW), serum hypertension biomarkers troponin-T (1.3 pg/mL), troponin-I (1.2 μg/dL) and angiotensin-II converting enzyme (0.18 pg/mL) were significantly recovered in hypertensive rats compared to disease control. Serum cardiovascular risk indices of diseased rats were significantly decreased (< 10%, p < 0.05) after administration of the studied galactofucan (50 mg/kg BW) related to hypertension group (> 17%), and were comparable with standard antihypertensive agent telmisartan (8.3-10.2% at 2 mg/kg BW). The studied compound was safe for consumption as obvious from the high LD 50 value (>5 g/kg), and could be developed as a prospective functional food ingredient attenuating the pathophysiological attributes causing hypertension-related conditions., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Four previously undescribed antioxidative O-heterocyclic analogues, characterized as 3″-isopropyl-3c-{3b-[(2-oxo-3,4-dihydro-2H-chromen-3-yl) methyl] butyl}-2″-butenyl-3'-hydroxy-2'-(2'b-methoxy-2'-oxoethyl)-3', 4'-dihydro-2H-pyran-4'-carboxylate (1), 2c-methylbutyl-6-[6c-(benzoyloxy)propyl]-6-methyl-tetrahydro-2H-pyran-2-carboxylate (2), 6-{6b-[3'-(5'a-methyl propyl)-3', 4'-dihydro-2H-pyran-6'-yl] ethyl}-tetrahydro-2H-pyran-2-one (3) and 7-(7c-methylpentyl)-hexahydro-2H-chromen-2-one (4) were isolated from the ethylacetate:methanol fraction of the brown seaweed Sargassum wightii. Nuclear magnetic resonance and mass spectroscopic experiments unambiguously attributed their structural identities. Antihypertensive activities of the studied compounds were determined in terms of their angiotensin converting enzyme (ACE) inhibitory potential. The 2H-pyranylcarboxylate derivative (1) displayed comparable activity (IC 50 0.08 mg/mL) with standard antihypertensive agent captopril (IC 50 0.07 mg/mL). The O-heterocyclic derivatives bearing 2H-pyran-4'-carboxylate (1) and 2H-pyran-2-carboxylate (2) frameworks showed significantly greater (p < 0.05) 1, 1-diphenyl-2-picryl-hydrazil radical quenching potential {IC 50 (1) 0.34 and IC 50 (2) 0.45 mg/mL} compared to the standard antioxidant α-tocopherol (IC 50 0.63 mg/mL). Structure-activity relationship analyses demonstrated that the electronic and lipophilic descriptors might significantly contribute towards the target bioactivities of 2H-pyranylcarboxylates (1 and 2). Molecular docking simulations were carried out for ACE inhibition, and the binding energy obtained for the compounds (~7.04-8.48 kcal/mol) demonstrated their potential enzyme-ligand interactions. The potential of hitherto undescribed O-heterocyclic derivatives as natural antioxidant and antihypertensive functional food supplements and their utilization as therapeutic leads in the antihypertensive management were described in the present study., (Copyright © 2018. Published by Elsevier Ltd.)