Polysaccharides of marine algae exhibit different structural characteristics and interesting biological functions. In this study, crude polysaccharides (CP) of eleven Sri Lankan marine algae obtained through hot water extraction and ethanol precipitation were investigated for DPPH, alkyl, and hydroxyl radical scavenging activities using electron spin resonance spectrometry and for intracellular reactive oxygen species scavenging activity in the Chang liver cell line. Characterization of CPs was done by Fourier transform infrared (FTIR) spectroscopy and by analysis of the monosaccharide composition. Time-dependent density functional theory quantum-chemical calculations at the RB3LYP/6-31G(d,p) level for constructed dimeric units of the corresponding polysaccharides were used to resolve the FTIR spectra. CPs from Chnoospora minima showed the highest DPPH and alkyl radical scavenging activities and higher intracellular reactive oxygen species scavenging effects for both AAPH and H 2 O 2 induced ROS production in "Chang" cells. The major polysaccharide constituent in C. minima CP was identified as fucoidan and it displayed a higher sulfate content. The degree of sulfation of these polysaccharides suggests a positive correlation with the observed antioxidant properties.

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This study determined the oral hypoglycaemic effect of suspensions of freeze dried and powdered (SFDP) Pleurotus ostreatus (P.o) and Pleurotus cystidiosus (P.c), using healthy human volunteers and Type 2 diabetic patients on diet control at a dose of 50 mg/kg/body weight, followed by a glucose load. The possible hypoglycaemic mechanisms were evaluated using rats, by examining intestinal glucose absorption and serum levels of insulin, glucokinase (GK) and glycogen synthase kinase (GSK). The P.o and P.c showed a significant reduction (P < 0.05) in fasting and postprandial serum glucose levels of healthy volunteers and reduced the postprandial serum glucose levels and increased the serum insulin levels (P < 0.05) of Type 2 diabetic patients. The P.o and P.c increased the intestinal absorption of glucose but simultaneously reduced the serum glucose levels (P < 0.05) in rats. Both mushrooms reduced the serum GSK and promoted insulin secretion while P.c increased serum GK (P < 0.05). The hypoglycaemic activity of P.o and P.c makes mushrooms beneficial functional foods in diabetes mellitus. The mechanism of hypoglycaemic activity of P.o and P.c is possibly by increasing GK activity and promoting insulin secretion and thereby increasing the utilization of glucose by peripheral tissues, inhibiting GSK and promoting glycogen synthesis.

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This study involves enzymatic extraction of fucoidan from Sargassum swartzii and further purification via ion-exchange chromatography. The chemical and molecular characteristics of isolated fucoidan is evaluated concerning its anti-inflammatory potential in RAW 264.7 macrophages under LPS induced conditions. Structural properties of fucoidan were assessed via FTIR and NMR spectroscopy. NO production stimulated by LPS was significantly declined by fucoidan. This was witnessed to be achieved via fucoidan acting on mediators such as iNOS and COX-2 including pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β), with dose dependent down-regulation. Further, the effect is exhibited by the suppression of TLR mediated MyD88, IKK complex, ultimately hindering NF-κB and MAPK activation, proposing its therapeutic applications in inflammation related disorders. The research findings provide an insight in relation to the sustainable utilization of fucoidan from marine brown algae S. swartzii as a potent anti-inflammatory agent in the nutritional, pharmaceutical, and cosmeceutical sectors.