Two previously undescribed furanyl compounds, characterized as 5-(7-(5-ethyl-3,4-dimethoxycyclooctyl) benzofuran-6-yl)-7-methyl-3,4,7,8-tetrahydro-2H-oxocin-2-one (compound 1) and 2-(3-ethyl-9-(2-methoxyethoxy)-1-oxo-2,3,4,9-tetrahydro-1H-xanthen-2-yl) ethyl-5-hydroxy-9-methoxy-7,8-dimethyl-8-(5-methylfuran-2-yl) nona-3,6-dienoate (compound 2) were derived from the ethyl acetate–methanol (EtOAc:MeOH) crude extract of red seaweed Gracilaria opuntia. The isolated compounds are the first furanyl natural products featuring methoxycyclooctyl benzofuran with tetrahydro-2H-oxocin framework and tetrahydro-1H-xanthenyl methoxy methylfuran skeletons. These compounds were assessed for anti-inflammatory activities against pro-inflammatory cyclooxygenase-2/5-lipoxygenase (COX-1, 2, and 5-LOX) and antioxidative effects in various in vitro models. The methylfuran derivative exhibited comparable inhibitory activities towards 5 LOX (IC50 0.209 × 10−2 M) with synthetic non-steroidal anti-inflammatory drugs (NSAID) ibuprofen (IC50 0.451 × 10−2 M, P < 0.05), which indicated its potential anti-inflammatory properties. The antioxidative properties of the furanyl derivatives as resolved by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2ʹ-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical scavenging activities were found to be significantly greater (IC50 ~0.051–0.055 × 10−2 M) than those exhibited by α-tocopherol (IC50 > 0.146 × 10−2 M), and were similar to those displayed by the synthetic antioxidants (butylated hydroxytoluene (BHT)/ butylated hydroxyanisole (BHA) (IC50 ~0.144–0.189 × 10−2 M, P < 0.05). The anti-inflammatory selectivity indices of the isolated compounds recorded significantly greater values (SI: anti-COX-1IC50/anti-COX-2IC50 ~1.08–1.09) than NSAIDs (aspirin, and ibuprofen, SI: 0.02 and 0.44, respectively, P < 0.05), and consequently, appeared to be safer. The isolated compounds showed significant anti-diabetic properties as determined by α-amylase/α-glucosidase (IC50 < 0.052 × 10−2 M) and dipeptidyl peptidase-4 (DPP-4, IC50 < 0.002 × 10−2 M) inhibitory activities. The angiotensin converting enzyme-I (ACE-I) inhibitory activity of the compounds (IC50 0.023–0.024 × 10−2 M) was found to be comparable with that recorded by commercial ACE inhibitor, captopril (IC50 0.037 × 10−2 M).

Phytochemical investigation of the thalli of ethyl acetate-methanol extract of the red seaweed Gracilaria opuntia led to isolation of a substituted 2H-chromen derivative of unusual structure possessing highly oxygenated carbon skeleton, characterised as 2-acetoxy-2-(5acetoxy- 4-methyl-2-oxotetrahydro-2H-pyran-4-yl) ethyl 4-(3-methoxy2-( methoxymethyl)-7-methyl-3,4,4a, 7,8,8a-hexahydro-2H-chromen-4yloxy)- 5-methylheptanoate, which have not been reported in nature. The chemical structure was resolved by detailed spectroscopic analysis. The anti-inflammatory activity of the newly reported metabolite was determined by pro-inflammatory cyclooxygenase and 5-lipoxygenase inhibitory assays. The anti-inflammatory selectivity index of the title compound recorded greater value (SI: anti-cycloxygense-1 IC 50 /anti-cycloxygense-2 IC 50 similar to 1.26) than synthetic NSAIDs (aspirin and ibuprofen, SI: 0.02 and 0.44, respectively), and consequently, appeared to be safer. The antioxidative activity of the title compound was significantly greater as determined by 2, 2-diphenyl-1-picrylhydrazyl and 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activities (IC 50 0.26-0.32 mg/mL) compared to a-tocopherol (IC 50 > 0.6 mg/mL), and was comparable to the synthetic antioxidants butylated hydroxytoluene and butylated hydroxyanisole (IC 50 similar to 0.25-0.34 mg/mL). [GRAPHICS] .

Three antioxidant and anti-inflammatory oxygenated meroterpenoids, 1-(3-methoxypropyl)-2-propylcyclohexane (C-13) (1), 3-(methoxymethyl)heptyl 3-(cyclohex-3-enyl) propanoate (C-18) (2), and 2-ethyl-6-(4-methoxy-2-((2-oxotetrahydro-2H-pyran-4-yl)methyl)butoxy)-6-oxohexyl 5-ethyloct-4-enoate (C-29) (3) were purified from the methanol:ethyl acetate fraction of red seaweed Kappaphycus alvarezii (family Solieriaceae) collected from the Gulf-of-Mannar on the southeast coast of peninsular India. The highly oxygenated C-29 meroterpenoid 3 displayed potential antioxidative activities (IC50 < 0.35 mg/mL) as evaluated by 2, 2'-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid and 1, 1-diphenyl-2-picryl-hydrazil free radical scavenging assays. The compound 3 displayed potential in vitro inhibitory activities towards pro-inflammatory 5-lipoxidase (IC50 1.04 mg/mL), which indicated its potential anti-inflammatory properties against inducible inflammatory mediators causing an inflammatory response. Structure-activity relationship analyses displayed the functional roles of lipophilic-hydrophobic characteristics and electronic parameter to determine its potential anti-inflammatory activity in terms of inhibiting inducible inflammatory cyclooxygenase and lipoxidase.

Antioxidant and antihypertensive potential of the sulphated polygalactans isolated from the marine macroalgae Kappaphycus alvarezii and Gracilaria opuntia were assessed by utilising different in vitro systems. The galactans isolated from K. alvarezii possessed significantly greater antioxidative properties as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH IC90 0.97mg/mL) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS(.+) IC90 0.72mg/mL) scavenging activities than those isolated from G. opuntia (DPPH IC90 1.2mg/mL and ABTS 0.86mg/mL). The sulphated polygalactan 4)-4-O-sulphonato-(2-O-methyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-methyl)--D-galactopyranan from K. alvarezii showed greater angiotensin-I-converting enzyme (ACE) inhibitory activity (IC50 0.02g/mL) than 3)-4-O-sulphonato-(6-O-acetyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-sulphonato)--D-galactopyranosyl-(13)-4-O-sulphonato-(6-O-acetyl)--D-xylosyl-(13)-4-O-sulphonato-(6-O-acetyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-sulphonato)--D-galactopyranan motif extracted from G. opuntia (IC50 0.70g/mL). Structure activity correlation studies displayed that the ACE inhibitory properties of titled polygalactans were directly proportional to their electronic properties and inversely with the steric and hydrophobic characteristics. Putative ACE inhibitory mechanism of action of sulphated galactans from marine macroalgae corroborated the structure bioactivity correlation analysis. [GRAPHICS]

Two previously undescribed furanyl compounds, characterized as 5-(7-(5-ethyl-3,4-dimethoxycyclooctyl) benzofuran-6-yl)- 7-methyl-3,4,7,8-tetrahydro-2H-oxocin-2-one (compound 1) and 2-(3-ethyl-9-(2-methoxyethoxy)-1-oxo-2,3,4,9-tetrahydro1H-xanthen-2-yl) ethyl-5-hydroxy-9-methoxy-7,8-dimethyl-8-(5-methylfuran-2-yl) nona-3,6-dienoate (compound 2) were derived from the ethyl acetate–methanol (EtOAc:MeOH) crude extract of red seaweed Gracilaria opuntia. The isolated compounds are the first furanyl natural products featuring methoxycyclooctyl benzofuran with tetrahydro-2H-oxocin framework and tetrahydro-1H-xanthenyl methoxy methylfuran skeletons. These compounds were assessed for antiinflammatory activities against pro-inflammatory cyclooxygenase-2/5-lipoxygenase (COX-1, 2, and 5-LOX) and antioxidative effects in various in vitro models. The methylfuran derivative exhibited comparable inhibitory activities towards 5 LOX (IC50 0.209 × 10−2 M) with synthetic non-steroidal anti-inflammatory drugs (NSAID) ibuprofen (IC50 0.451 × 10−2 M, P < 0.05), which indicated its potential anti-inflammatory properties. The antioxidative properties of the furanyl derivatives as resolved by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2ʹ-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid (ABTS) free radical scavenging activities were found to be significantly greater (IC50 ~0.051–0.055 × 10−2 M) than those exhibited by α-tocopherol (IC50 > 0.146 × 10−2 M), and were similar to those displayed by the synthetic antioxidants (butylated hydroxytoluene (BHT)/ butylated hydroxyanisole (BHA) (IC50 ~0.144–0.189 × 10−2 M, P < 0.05). The anti-inflammatory selectivity indices of the isolated compounds recorded significantly greater values (SI: anti-COX1IC50/anti-COX-2IC50 ~1.08–1.09) than NSAIDs (aspirin, and ibuprofen, SI: 0.02 and 0.44, respectively, P < 0.05), and consequently, appeared to be safer. The isolated compounds showed significant anti-diabetic properties as determined by α- amylase/α-glucosidase (IC50 < 0.052 × 10−2 M) and dipeptidyl peptidase-4 (DPP-4, IC50 < 0.002 × 10−2 M) inhibitory activities. The angiotensin converting enzyme-I (ACE-I) inhibitory activity of the compounds (IC50 0.023–0.024 × 10−2 M) was found to be comparable with that recorded by commercial ACE inhibitor, captopril (IC50 0.037 × 10−2 M).

Two halogen derivatives, characterized as 2-butyl-7-4-(chloromethyl) cyclooct-1-enyl) hept-5-en-1-ol (compound 1) and 4-(2-chloroethyl)-5-7-(methoxymethyl) undec-3-enyl) cyclooct-4-enone (compound 2) were isolated from the ethyl acetate-methanol extract of the intertidal red seaweed Kappaphycus alvarezii. The studied compounds were evaluated for their inhibitory effects towards pro-inflammatory 5-lipoxygenase along with cyclooxygenases, and also were determined the free radical scavenging potential. The halogenated cyclooctenone (compound 2) displayed greater 5-lipoxygenase (IC50 0.90 mg mL−1) inhibitory activity when compared to the non steroidal anti-inflammatory drug ibuprofen (IC50 0.93 mg mL−1). Similarly selectivity indices of the studied compounds were higher (anti-cyclooxygense-1 IC50/anti-cyclooxygense-2 IC50 ~1.06–1.07) when compared to those displayed by ibuprofen (0.44) and aspirin (0.02). The antioxidative activities of the halogen derivatives were found to be greater (IC50 < 0.30 mg mL−1) in comparison with that exhibited by α-tocopherol (IC50 > 0.50 mg mL−1). This is the first report on structural characterization of unusual halogen analogues from K. alvarezii with dual cyclooxygenase-2 and 5-lipoxygenase inhibitory activities.

In vitro antioxidative and anti-inflammatory bioassay-guided fractionation of the methanol: ethyl acetate crude extract of the thalli of red seaweed Gracilaria opuntia collected from the Gulf of Mannar led to the isolation of a new morpholine alkaloid 3-(2-ethyl-6-((3Z,7Z)-1,2,5,6-tetrahydroazocin-5-yl)hexyl) morpholin-6-one. The substituted azocinyl morpholinone recorded significant 1,1-diphenyl-2-picryl-hydrazil free radical scavenging activities (IC50 ~ 0.086 mg/mL) compared to the commercially available antioxidants, butylated hydroxyanisole, butylated hydroxytoluene, and α-tocopherol (IC50 > 0.20 mg/mL). The title compound showed greater cyclooxygenase-2 (COX-2) inhibitory activity (IC50 0.84 mg/mL) in conjunction with in vitro 5-lipoxidase inhibitory activity (IC50 0.85 mg/mL) than non-steroidal anti-inflammatory drugs (NSAIDs). The test compound had better selectivity index (COX-1/COX-2 ratio) (1.17 mg/mL) compared to aspirin (0.02 mg/mL), Na salicylate (0.73 mg/mL) and ibuprofen (0.44 mg/mL). The animals challenged with the substituted azocinyl morpholinone significantly mitigated the carrageenan-induced paw edema in time-dependent manner till the end of 6 h.

Antioxidant potential of three brown seaweeds, Anthophycus longifolius, Sargassum plagiophyllum, and Sargassum myriocystum, obtained from the Gulf of Mannar region of India were evaluated utilizing different in vitro systems. Ethyl acetate (EtOAc) fraction of Anthophycus longifolius registered significantly greater hydroxyl radical scavenging ability (IC50 0.19 mg/mL) and was effective in stabilizing the 2,2'-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid (IC50 1.23 mg/mL) and 1,1-diphenyl-2-picryl-hydrazil (DPPH) radicals (IC50 0.48 mg/mL) (p < 0.05). No significant differences in hydrogen peroxide (H2O2) scavenging and ferrous ion chelating properties of the EtOAc extracts of the seaweeds were apparent. The utilities of the reverse-phase high-performance liquid chromatography (RP-HPLC) method hyphenated to diode-array detection for analyzing the fingerprints of phenolic constituents in the solvent extracts and fractions of the seaweeds were denoted. High-performance liquid chromatographic analysis indicated the presence of phenolic acids in the solvent extracts of seaweeds. This study demonstrated the potential use of A. longifolius as candidate species to be used as a nutritional food supplement/functional foods to increase the shelf life of food items for human consumption.

Objective: To study the anti-diabetic activity of marine macroalgae extracts (n = 31), purification and characterization of sulphated galactopyran (SGP) from Gracilaria opuntia (FM4) in diabetic rats.Methods: The animals were separated into groups and STZ (55 mg/kg body weight) was used to induce diabetics.Glucose, HbA1c, insulin, C-peptide levels and in vivo antioxidant levels were estimated and histopathological studies were done in STZ-induced diabetic and marine macroalgae treated rats.Results: Based on glucose and HbA1c levels and in vivo antioxidant levels, among the 31 marine macroalgae extracts, FM4 has showed high anti-diabetic activity.Hence, FM4 was purified and characterized by 1 H-NMR spectra and FT-IR as sulphated galactopyran.During the survival analysis, SGP at dose of 100 mg/kg showed significant (P < 0.05) survival rate and elevations in C-peptide and insulin levels.The histopathological modulations of SGP were observed in diabetic rat tissues such as liver, kidney and brain.Hence obtained results reveal that SGP treated diabetic rats has significant changes in C-peptide and insulin levels which regulates the blood glucose levels and recovered the histopathological changes.Conclusions: Marine macroalgae have significant anti-diabetic activity.Hence, they could be used as nutraceutical supplement or natural green remedy against diabetes mellitus.

Antidiabetic and anti-inflammatory potential of sulphated polygalactans isolated from the red seaweeds Kappaphycus alvarezii and Gracilaria opuntia were acquired by employing different in vitro systems. The sulphated galactopyran motif derived from G. opuntia possessed significant antidiabetic properties as identified by -amylase (IC50 0.04 mg/mL), -glucosidase (IC50 0.09 mg/mL) and dipeptidyl peptidase-4 (DPP-4, IC50 0.09 mg/mL) inhibitory activities. Based on the detailed nuclear magnetic resonance spectroscopy experiments the sulphated galactopyran motif of G. opuntia was designated as 3)-4-O-sulfonato-(6-O-acetyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-sulfonato)--D-galactopyranosyl-(13)-4-O-sulfonato-(6-O-acetyl)--D-xylosyl-(13)-4-O-sulfonato-(6-O-acetyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-sulfonato)--D-galactopyranan, while the one from K. alvarezii was demonstrated to be 4)-4-O-sulfonato-(2-O-methyl)--D-galactopyranosyl-(14)-3,6-anhydro-(2-O-methyl)--D-galactopyranan. The sulphated galactans from G. opuntia showed greater anti-inflammatory inhibitory activities as determined by cyclooxygenase-1 (COX-1, IC50 0.01 mg/mL), cyclooxygenase-2 (COX-2, IC50 0.03 mg/mL), and 5-lipoxygenase inhibitory activities (5-LOX, IC50 0.24 mg/mL). This study revealed that the sulfated polygalactan enriched concentrate from G. opuntia can be used as potential therapeutic candidate to suppress the hyperglycemic response in diabetic conditions and inflammatory activity. They can be used to develop functional food ingredient in nutraceutical products.

Inter-annual and seasonal variability in the nutritional parameters of the edible portion of skipjack tuna (Katsuwonus pelamis) collected from the Arabian Sea were determined for a period of 4 years. Greater levels of long chainn-3 fatty acids (35% during pre-monsoon), critical in the human diet for their anti-inflammatory properties with greatern-3:n-6 fatty acid ratio (8:12) demonstrated that this species may serve as an alternative to balance the greater amount ofn-6 fatty acids. The present study demonstrated skipjack tuna as a significant source of protein, amino acids, minerals and vitamins. A balanced essential to non-essential amino acid ratio (1.2:1.4) in the fillets indicated that this species could provide well-balanced protein depositions. Vitamins A and K1demonstrated post-monsoon maxima, whilst vitamins D3and E showed pre-monsoon maxima. Greater calcium (172 mg 100 g−1) and phosphorus contents (923 mg 100 g−1) were recorded in the fillets of skipjack tuna during the pre-monsoon season. The chlorophyll-a concentration and sea surface temperature of its habitat were considered to understand their effect on the nutritional composition of skipjack tuna all through the study period. Significant correlation between long chainn-3 polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid (r2~ 0.99) of skipjack tuna alongside chlorophyll-a concentration was observed, particularly during the monsoon. The lesser atherogenic/thrombogenicity indices (<1), greater hypocholesterolaemic/hypercholesterolaemic ratio (>1.0), and lesser cholesterol contents (<50 mg 100 g−1) of the fillets in skipjack tuna contributed towards its parameters to be qualified as a high value, balanced nutritional source.

In vitro antioxidant assays of FM4 were estimated by DPPH, ABTS, hydroxyl free radical and Nitric oxide free radical activities. FM4 was purified and characterized by 1H-NMR spectra and FTIR as sulphated galactopyran. Diabetes was induced intraperitonially by single dose of STZ (55 mg/kg body weight). FM4 was administrated orally (80, 100, 125 mg/kg BW) to diabetic rats for 60 days. The enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione-S-transferase (GST), lipid peroxidase (LPx), glutathione reduced (GSH), vitamin-C (VIT-C) and vitamin-E (VIT-E) levels were estimated. Glibenclamide was used as standard drug.

Recently a great deal of interest has been developed towards natural bioactive components from seaweeds as functional food ingredients. Antioxidant, anti-inflammatory, antidiabetic, and antihypertensive activities of ethyl acetate:methanol and chloroform solvent fractions of the brown seaweed Sargassum wightii were evaluated using different in vitro systems. The ethyl acetate:methanol fraction registered greater Fe2+ ion chelating ability (IC50 0.52 mg/ml), and were effective in stabilizing the 2,2-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid (IC50 0.82 mg/mL), and 1,1-diphenyl-2-picryl hydrazil radicals (IC50 0.32 mg/mL) than those derived from chloroform solvent fractions. The chloroform solvent fraction showed greater angiotensin converting enzyme-I inhibitory activity (IC50 0.084 mg/mL), while the ethyl acetate:methanol fraction exhibited greater anti-COX-1, 2, and 5-LOX (IC50 0.03-0.05 mg/mL) and DPP-4 inhibitory (IC50 similar to 0.013 mg/mL) properties. A significant co-linearity was recorded between target bioactive properties and the electronegative groups appeared in the downfield space of the nuclear magnetic resonance spectra of the ethyl acetate:methanol and chloroform solvent fractions from S. wightii.

An unprecedented non-isoprenoid oxocine carboxylate cyclic ether characterised as (3S, 4R, 5S, 6Z)-3-((R)-hexan-2-yl)-3,4,5,8-tetrahydro-4-methyl-2H-oxocin-5-yl acetate was isolated from the ethyl acetate-methanol extract of the red seaweed Kappaphycus alvarezii. The structure, as well as its relative stereochemistry, was proposed on the basis of extensive spectral data. The antioxidative activity of the isolated metabolite was found to have significantly greater as determined by 1, 1-diphenyl-2-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid radical scavenging activities (IC50 similar to 0.3mg/mL) compared to -tocopherol (IC50>0.6mg/mL) and was comparable to the synthetic antioxidants butylated hydroxytoluene and butylated hydroxyanisole (IC50 similar to 0.35-0.34mg/mL). The compound exhibited greater activity against COX-2 (cyclooxygenase-2) than COX-1 (cyclooxygenase-1) isoform, and therefore, the selectivity index remained significantly lesser (anti-COX-1(IC50): anti-COX-2(IC50) 0.87) than synthetic anti-inflammatory drugs (0.02-0.44). No significant difference of in vivo 5-lipoxidase activity (IC50 0.95mg/mL) than ibuprofen (IC50 0.93mg/mL) indicated the potential anti-inflammatory properties of the title compound.

Antioxidant and antihypertensive potential of ethyl acetate-methanol (EtOAc-MeOH) extract of cephalopods, Amphioctopus marginatus, Uroteuthis duvaucelii, Sepia pharaonis, Sepiella inermis and Cistopus indicus were evaluated using different in vitro systems. EtOAc-MeOH fractions of S. inermis, A. marinates and C. indicus showed greater ferrous ion chelating ability (IC90 5.01-5.8 mg/mL), and were effective in neutralizing the ABTS (IC90 3.5-4.01 mg/mL), and DPPH radicals (IC90 4.69-5.8 mg/mL). The utilities of deconvolated H-1 and C-13-NMR spectroscopy for analyzing the signature peaks and abundance of bioactive functional groups in the extracts of cephalopods were illustrated. The EtOAc-MeOH extract derived from S. inermis showed greater angiotensin-converting enzyme-I (ACE-I) inhibitory activity (IC90 0.45 mg/mL) than other cephalopods (IC90 > 0.50 mg/mL). A significant colinearity was found between the electronegative groups present in the downfield position of NMR spectra vis-a-vis antioxidative and ACE-inhibitory activities of EtOAc-MeOH extracts from C. indicus and S. inermis.

Dietary fats are used to build every cell in the body and cell membranes are made of a variety of individual fatty acids which are carboxylic acids with long hydrocarbon chains (usually C12-22). The essential fatty acids from marine fish have protective mechanisms against coronary heart disease, which became apparent in the investigations of the health status of Greenland Eskimos who consumed diets very high in fat from seals,whales, fish etc, and yet had a low rate of coronary heart disease.