One therapeutic approach for preventing diabetes mellitus is to retard the absorption of glucose via inhibition of α-glucosidase. In this study, 2 fatty acids with strong α-glucosidase-inhibitory activity, 7(Z)-octadecenoic acid and 7(Z),10(Z)-octadecadienoic acid, were purified and identified from sea cucumber. Therefore, sea cucumber fatty acids can potentially be developed as a novel natural nutraceutical for the management of type-2 diabetes.

Summary Edible mushrooms contain considerable amounts of the potent natural antioxidant 2‐thiol‐l‐histidine‐betaine (l‐ergothioneine, ESH). The objective of this study was to evaluate the effects of extraction solvents, common cooking methods and storage conditions on the ESH content, total phenols (TPs) and antioxidant capacity of the edible mushroom Flammulina velutipes fruiting body and its hot water extract that had been stored at different temperatures. Regarding cooking procedures, boiling in water resulted in the highest losses of antioxidant activity of both ESH and TPs. Most of the losses of ESH and TPs were detected in the cooking water. The ESH contents in the raw mushroom fruiting bodies significantly decreased after 8 days of refrigerated storage under both dark and fluorescent lighting conditions. However, the TP content in the raw mushroom stored under fluorescent lighting significantly increased during 10 days of refrigeration. In contrast, the ESH and TP contents as well as DPPH radical scavenging ability of the fruiting bodies remained unchanged for up to 15 days of frozen storage at −18 °C. The same behaviour was obtained with the mushroom extract packed in plastic tubes. The correlation between DPPH radical scavenging activity and ESH contents was higher than that for TP compounds.

α-Glucosidase inhibitory activities of the various solvent fractions (n-hexane, CHCl3 , EtOAc, BuOH, and water) of sea cucumber internal organ were investigated. 1,3-Dipalmitolein (1) and cis-9-octadecenoic acid (2) with potent α-glucosidase inhibitory activity were purified from the n-hexane fraction of sea cucumber internal organ. IC50 values of compounds 1 and 2 were 4.45 and 14.87 μM against Saccharomyces cerevisiae α-glucosidase. These compounds mildly inhibited rat-intestinal α-glucosidase. In addition, both compounds showed a mixed competitive inhibition against S. cerevisiae α-glucosidase and were very stable at pH 2 up to 60 min. The KI values of compounds 1 and 2 were 0.48 and 1.24 μM, respectively. Therefore, the internal organ of sea cucumber might be a potential new source of α-glucosidase inhibitors suitably used for prevention of obesity and diabetes mellitus.

The physicochemical and biofunctional properties of crab chitosan nanoparticles of two different sizes (Nano A and B) manufactured by dry milling method were evaluated for commercialization. The deacetylation degrees (DD) of Nano A, B and the control chitosan were 90.9, 93.0, and 92.7% respectively whereas their molecular weights (M(w)) were 43.9, 44.7 and 208.8 kDa. The average sizes of the dispersed Nano A, B and the control chitosan in cetyltrimethylammonium chloride were 735.9, 849.4 and 2,382.4 nm, respectively, which were lower than 1441.7, 2935.6 and 6832.9 nm of the intact chitosans. Chitosan nanoparticles had mild tyrosinase, antioxidant and angiotensin I converting enzyme (ACE), but weak collagenase, elastase and beta-glucuronidase inhibitory activity. However, Nano A had strong alpha-glucosidase inhibitory activity, which was comparable to that of acarbose, a commercial alpha-glucosidase inhibitor. In addition, the minimum inhibitory concentrations (MICs) of chitosan and its nanoparticles ranged from 30 to > 200 microg/mL against each four gram-positive and gram-negative bacteria. Therefore, crab chitosan nanoparticles could be used as a nutraceutical, cosmeceutical or pharmaceutical product.

This study aimed to determine the optimum ultrasound-assisted extraction (UAE) conditions for obtaining the highest yields of phenolics and antioxidants from Padina australis. The effects of extraction variables including temperature (40-60°C), extraction time (50-80 min), ethanol concentration (0%-60%) and sample-to-solvent ratio (1-5 g/100 mL) on the total phenolic content (TPC), DPPH radical scavenging activity (DRSA) and ferric reducing antioxidant power (FRAP) were determined and optimized using Box-Behnken design in conjunction with response surface methodology (RSM). The extraction temperature, ethanol concentration and sample-tosolvent ratio significantly affected TPC and DRSA, while extraction time had no impact on TPC and antioxidant activity of P. australis within the tested ranges. The optimal UAE conditions were determined to be ultrasonic temperature of 60°C, ultrasonic time of 60 min, solvent concentration of 60% (v/v) aqueous ethanol and sample-to-solvent ratio of 1 g/100 mL. The developed mathematical models were found to be reliable predictors for TPC, DRSA and FRAP, and the predicted values fit well with the experimental data (R 2 = 0.86-0.96). The extract was then fractionated to generate n-hexane, ethyl acetate and aqueous fractions. Of these fractions, ethyl acetate fraction was found to possess the highest values of TPC (807.20 mg GAE/g), DPPH (1,417.01 mg TE/g), FRAP (615.07 mg TE/g dry fraction) and the strongest tyrosinase inhibitory activity (29.90 mg AAE/g). Practical applicationsThe study employed ultrasound-assisted extraction technique, an advanced extraction method, and RSM method for maximizing the yields of phenolics and antioxidants from P. australis. In addition, the tyrosinase inhibitory activity of P. australis extract and its fractions, for the first time, was also investigated. The results suggested the optimal UAE conditions to recover phenolics and bioactive compounds with high antioxidant and tyrosinase inhibitory properties from P. australis. Moreover, this study establishes that the ethyl acetate fraction derived from P. australis was a rich source of phenolics and antioxidants; thus, it could be further isolated and purified to obtain individual bioactive compounds for the utilization in the food and cosmeceutical industries.