Bentonite Reinforced Chitosan Scaffold: Effect of Bentonite Exfoliation on Scaffold Properties

Chitosan is under investigation as biodegradable scaffolding material for tissue engineering. Crosslinked chitosan alone cannot form a self-supporting scaffold hence it needs reinforcement. The group reported fabrication of chitosan scaffolds reinforced by exfoliated and non-exfoliated bentonite and compared their properties. Scaffolds were fabricated by freeze-drying technique. Bentonite was exfoliated by allowing it to swell in water for a certain time interval. XRD profile showed that swelling reduced the crystallinity of bentonite. Both types of bentonite dispersed well in the chitosan matrix and imparted structural stability to the scaffolds. Scaffolds had interconnected pores, apparent porosity of scaffold with exfoliated bentonite was higher than of scaffold with unexfoliated bentonite. The scaffolds swelled almost 35% in 3 days without losing the structural integrity. The scaffolds could be compressed to 50% of their original height. Compression modulus of scaffold with exfoliated bentonite was higher than that of unexfoliated bentonite scaffold

Previously undescribed antioxidative and anti-inflammatory chromenyls bearing 3H-isochromenone and furanyl-2H-chromenyl skeletons from the venerid clam, Paphia malabarica

Previously undescribed chromenyl derivatives, characterized as 7-(2′-ethyl-1′-hydroxynonan-2′-yl)-6,7,8, 8a-tetrahydro-3H-isochromen-1-(5H)-one (1) and 61-(3- ((E)-31b-(furan-2′-yl)-prop-31b-en-31-yl)-4a,5,6,8a-tetrahydro- 8-methyl-2H-chromen-6-yl)-ethyl-5′′-methyl-hexanoate (2) were isolated from ethyl acetate-methanol extract of yellowfoot bivalve clam, Paphia malabarica. Their structures have skeletons composed of isochromen-(5H)-one and furanyl-2Hchromenyl moieties, which are reported for the first time in marine organism. These were characterized by extensive one and two-dimensional nuclear magnetic resonance, infrared, and high-resolution mass spectroscopic experiments. The title compounds were evaluated for therapeutic potentials with regard to anti-inflammatory and antioxidant properties compared to known standards. These compounds exhibited comparable 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′- azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) radical scavenging activities with α-tocopherol (IC50 ~0.6–0.7mg/mL). The significantly higher anti-5- lipoxygenase activity of the title compounds (IC50 0.76–0.82mg/mL) than ibuprofen (IC50 0.93 mg/mL) indicated their potential anti-inflammatory properties. The selectivity indices (IC50 anti-cyclooxygenase-1/IC50anticyclooxygenase- 2) of compounds 1 (1.19) and 2 (1.31) well established its safety profiles as an anti-inflammatory when compared to known drug, ibuprofen (0.44). The target bioactivities of chromenyl derivatives were guided by hydrophobic and electronic parameters. These compounds can be used as potential bioactive leads in functional food and medicinal applications

Nutritional qualities of common edible cephalopods at the Arabian Sea

Nutritional composition of the edible portions of five commercially important species of cephalopods in the Arabian Sea was evaluated. The selected species included Amphioctopus neglectus, Cistopus indicus, Uroteuthis duvauceli, Sepia pharaonis and Sepiella inermis. The cephalopods were demonstrated to contain protein with balanced proportions of essential to non-essential amino acids (~ 1.2). A. neglectus was found to contain greater quantities of sulfur containing amino acids (23 mg/100 g) and lysine (36 mg/100 g) than other cephalopods, which indicated that the protein can effectively complement the limiting amino acids in our daily diets. The C20–C22 long chain n-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, vital for human health, were found to be predominant in the edible part of the cephalopod species (119-360 mg/100g and 595-1211 mg/100g respectively). The n-3/n-6 polyunsaturated fatty acid ratio of U. duvauceli was significantly greater (~10, P < 0.05) than other cephalopods, and may consequently serve as a substitute to balance the greater admission of n-6 fatty acids in our standard utilization of vegetable oil. Fatty acid based atherogenicity and thrombogenicity indices (<0.8 and <0.3, respectively) were found to be ideal in cephalopods ensuring that they can be consumed without any risk for health

Bioactive Marine Natural Products - A Review

The marine flora and fauna remain largely unexplored. Approximately 71% of the molecular entities listed in the Dictionary of Marine Natural Products have novel molecular structures compared to ~40% of those in the Dictionary of Natural Products. In NCI preclinical cytotoxicity screen, marine organisms show higher incidence of anti-tumor potential: 1% vs. 0.1% for terrestrial organisms. Number of new marine compounds reported each year is increasing >1000 compounds

First report of a lactonic disecosteroid from the buccinid gastropod Babylonia spirata

A lactonic steroid with an unprecedented 1, 10: 8, 9-disecoergostane framework was identified from the ethyl acetate-methanol extract of buccinid gastropod mollusk, Babylonia spirata collected from the southwestern coast of Indian peninsular region. The compound was characterized as 1, 10: 8, 9-disecoergosta-8-en-A-homo-6a-oxa-1-one by exhaustive spectroscopic methods including two-dimensional nuclear magnetic resonance and mass spectroscopic investigations. The disecosteroid displayed moderate carbolytic enzyme inhibition activity as distinguished by its inhibitive effects against α-amylase and α-glucosidase (IC50 0.40 and 0.54 mg/mL, respectively). The anti-inflammatory (5-lipoxidase inhibitory) activity of the titled secondary metabolite was found to be superior (IC50 0.85 mg/mL). However, significantly greater antioxidant property was recorded for the studied disecosteroid as evaluated by in vitro 2, 2-diphenyl-1-picrylhydrazyl radical inhibition potential (IC50 0.30 mg/mL) than that of standard, α-tocopherol (IC50 > 0.50 mg/mL). The in silico molecular docking studies were conducted to explain the anti-5-lipoxidase and anti-α-amylase properties of the isolated compound. The molecular binding interactions of the ligands with the pro-inflammatory 5-lipoxidase and the carbolytic enzyme α-amylase, demonstrated that their binding energies/docking scores were positively associated with their in vitro bioactivies. A plausible pathway for the biosynthetic origin of lactonic disecosteroid in B. spirata was proposed from an ergosterol precursor. Structure-activity correlation study demonstrated that the biological activities of the disecosteroid were directly proportional to their electronic properties allied with lesser steric restrictions

Macrocyclic lactones from seafood Amphioctopus neglectus: Newly described natural leads to attenuate angiotensin-II induced cardiac hypertrophy

Amphioctopus neglectus (Family: Octopodidae) is recognised as culinary delicacy in many cultures and a common sea food item on the Mediterranean and Asian coasts. Bioassay-directed fractionation of ethyl acetate/methanol extract of A. neglectus ensued in the characterisation of four previously undescribed macrocyclic lactones (1-4). These compounds exhibited potential radical-scavenging capacities (IC50 0.95–1.73 mM) along with anti-hypertensive activities (IC50 1.12–2.34 mM) against angiotensin converting enzyme (ACE). The optimum binding affinity of compound 2 (−9.84 kcal mol−1) bearing furo[1,4,8]trioxacyclohexadecine-12,19-dione moiety with ACE, along with its permissible hydrophobic-hydrophilic balance, manifested towards its greater anti-hypertensive activity compared to other analogues. The compound 2, with lesser values of the inhibitory constant (Ki = 1.0 mM) towards ACE, was found to bind more effectively to the enzyme in a non-competitive manner, and could describe the greater inhibitory ramifications than those displayed by other compounds (Ki >1.1 mM). The ex-vivo studies revealed that compound 2 imparted protective effects against angiotensin-II induced cardiac hypertrophy at 25 μg mL−1 on H9C2 cell lines, wherein about 34 percent decrease in cell area with increase in viability could be attributed to anti-hypertrophic effects of the compound administrated. These results confirmed that the protective effect of the isolated macrocyclic lactones is mediated by enhancement of anti-oxidant defense systems, which subsequently attenuates the hypertensive related disorders

First report of chromenyl derivatives from spineless marine cuttlefish Sepiella inermis: Prospective antihyperglycemic agents attenuate serine protease dipeptidyl peptidase‐IV

Spineless marine cuttlefish Sepiella inermis has been considered as a popular dietary cephalopod species in Asian and Mediterranean coasts. Bioassay‐directed purification of organic extract of S. inermis ensued in the characterization of two chromenyl derivatives. The studied compounds exhibited significantly greater antioxidant potencies (IC50 ≤ 0.5 mg/ml) when compared with α‐tocopherol. The substituted 1H‐ isochromenyloxy‐11‐hydroxyethyl pentanoate isoform (compound 1) efficiently inhibited the carbolytic enzymes along with key regulator of insulin secretion dipeptidyl peptidase‐IV (IC50 0.16 mg/ml). The molecular docking simulations displayed optimum binding affinity of the compound 1 (−10.01 kcal/mol) with dipeptidyl peptidase‐IV and lesser inhibition constant (Ki 46.41 nM), which along with its permissible hydrophobic‐hydrophilic balance (log Pow ~ 2) appeared to play significant roles in its greater antihyperglycemic activity compared to other studied chromenyl isoform. The greater antioxidant and antidiabetic properties of compound 1 could be utilized as an important natural lead against hyperglycemic‐related disorders

Spectroscopic Methods to Characterize Bioactive Compounds: Nuclear Magnetic Resonance Spectroscopy

It is a spectroscopic technique that gives us information about the number and types of atoms in a molecule, for example, about the number and types o

Prospective natural anti-inflammatory drimanes attenuating proinflammatory 5-lipoxygenase from marine macroalga Gracilaria salicornia

The 5-lipoxygenase-associated cascade has appeared as potential therapeutic target in attenuating inflammatory pathologies. Progression and pathophysiology of inflammation have also shown potential involvement of oxidative stress and inflammatory pathways. Three drimane sesquiterpene quinols, characterised as 3-(hept-36- enyloxy)-decahydro-4,6a,12a,12b-tetramethyl-1H-benzo[a]xanthene-4,10,12-triol (1), 13-[[2-(hexyloxy)- 2,5,5,8a-tetramethyldecahydro-1-naphthalenyl](methoxy)methyl]benzenol (2), and 1-butoxy-4,4,11b,11c-tetramethyl- decahydrobenzo[kl]xanthen-10-ol (3) were purified from the organic extract of intertidal marine macroalga Gracilaria salicornia, obtained from the southeast coastal regions of Indian peninsular. The 1H-benzo [a]xanthene-triol derivative (1) registered potential activities against pro-inflammatory 5-lipoxygenase (IC50 1.7 mM) and free radicals (IC50 1.3–1.6 mM). The in silico molecular modelling studies to designate 5-lipoxygenase inhibitory mechanism of the studied analogues and the comparison of docking parameters attributed that the drimane sesquiterpene 1 exhibited least binding energy of −12.30 kcal mol−1, and showed effective hydrogen bonding interactions with the catalytic site of the enzyme. The higher electronic parameters and permissible hydrophobic-hydrophilic balance of the drimane sesquiterpene bearing 1H-benzo[a]xanthene-triol moiety (1) appeared to constitute significant roles towards the attenuation of pro-inflammatory 5-lipoxygenase. Putative biosynthetic pathway of the studied compounds involving cyclisation of farnesyl diphosphate and carbocationic rearrangement through a battery of enzyme-mediated cascade validated their structural attributions. These results demonstrated that the drimane-type sesquiterpenoids with 1H-benzo[a]xanthene-triol framework could be used as a potential therapeutic agent for the treatment of 5-lipoxygenase-mediated inflammatory pathologies