Byung Soo Chun

Biological Properties of Fucoxanthin in Oil Recovered from Two Brown Seaweeds Using Supercritical CO2 Extraction.

The bioactive materials in brown seaweeds hold great interest for developing new drugs and healthy foods. The oil content in brown seaweeds (Saccharina japonica and Sargassum horneri) was extracted by using environmentally friendly supercritical CO2 (SC-CO2) with ethanol as a co-solvent in a semi-batch flow extraction process and compared the results with a conventional extraction process using hexane, ethanol, and acetone mixed with methanol (1:1, v/v). The SC-CO2 method was used at a temperature of 45 °C and pressure of 250 bar. The flow rate of CO2 (27 g/min) was constant for the entire extraction period of 2 h. The obtained oil from the brown seaweeds was analyzed to determine their valuable compounds such as fatty acids, phenolic compounds, fucoxanthin and biological properties including antioxidant, antimicrobial, and antihypertension effects. The amounts of fucoxanthin extracted from the SC-CO2 oils of S. japonica and S. horneri were 0.41 ± 0.05 and 0.77 ± 0.07 mg/g, respectively. High antihypertensive activity was detected when using mixed acetone and methanol, whereas the phenolic content and antioxidant property were higher in the oil extracted by SC-CO2. The acetone–methanol mix extracts exhibited better antimicrobial activities than those obtained by other means. Thus, the SC-CO2 extraction process appears to be a good method for obtaining valuable compounds from both brown seaweeds, and showed stronger biological activity than that obtained by the conventional extraction process.

Molecular modification of native coffee polysaccharide using subcritical water treatment: Structural characterization, antioxidant, and DNA protecting activities

Polysaccharides are an abundant resource in coffee beans and have proved to show numerous bioactivities. Despite their abundance, their activities are not always satisfactory mostly due to their structure and large molecular size. Molecular modifications of native polysaccharides can overcome this problem. In this study, we used a novel and green method to modify native coffee polysaccharides using subcritical water (SCW) treatment. The SCW treatment was used at the temperature of 180°C-220°C and pressure of 30-60bar. The molecular and structural modification of the polysaccharides was confirmed using several techniques such as FT-IR, UV spectroscopy, XRD, and TGA. The antioxidant activity of the modified polysaccharides was evaluated using several chemical and Saccharomyces cerevisiae-based high throughput assays. The modified polysaccharides showed high antioxidant activities in all tested assays. Moreover, the polysaccharides showed high DNA protection activities. Therefore, SCW could be employed as a green solvent for molecular modification of polysaccharides.

Impact of extraction conditions on bergapten content and antimicrobial activity of oils obtained by a co-extraction of citrus by-products using supercritical carbon dioxide

Citrus oils obtained from citrus by-products are widely used in many areas because of their bioactive nature. However, their use in products has been restricted due to phototoxicity and other health problems of some of the non-volatile compounds, especially bergapten. We studied the effect of supercritical carbon dioxide (SC-CO2) extraction conditions on the minimization of bergapten content for the oils obtained from a combination of citrus peels and seeds. The influence of combined citrus by-products on cytotoxicity, antimicrobial activity, and other quality characteristics was studied so that those by-products can be used effectively. A second-order polynomial model showed a suitable fitting of the experimental value for the bergapten content (R2 = 0.977, p < 0.05). Optimization (minimization of bergapten content) and validation were performed. The optimum conditions were 200.54 bar, 46.28°C and 34.98 g/min for pressure, temperature, and flow rate, respectively. The corresponding predicted value was 37.82 μg/g oil, which agreed well with the experimental value (38.36 ± 0.44 μg/g oil), affirming the adequacy and validity of the predicted model. The oil displayed higher antimicrobial activity and was less susceptible to fungi than bacteria. The cytotoxicity of the oil on HaCaT cells was low (84.59 ± 1.24% cell viability) for a concentration of 500 μg/mL. SC-CO2 extraction of a mixture of citrus by-products can yield oils with low bergapten content, low toxicity, and higher antimicrobial activity, which could have a variety of applications.

Optimization of polysaccharides extraction from Pacific oyster (Crassostrea gigas) using subcritical water: Structural characterization and biological activities

Bioactive polysaccharide was extracted from Pacific oyster Crassostrea gigas using subcritical water (SW) and the extraction process was optimize by response surface methodology (RSM). The optimum condition was found to be temperature 125.01 °C, extraction time 14.93 min, and liquid to solid ratio of 44.69:1 (ml:g). At this condition, the yield of the C. gigas polysaccharides (CGPs) was found to be 18.66%. The polysaccharide was characterized for its chemical, physical, thermal, and structural properties using HPLC, GPC, XRD, FTIR, TGA, UV-Vis spectroscopy, and NMR and the results of this characterization showed a characteristic feature of a typical polysaccharide. The CGPs was found to be a d-glucan with α-(1 → 4) configuration. The CGPs was also evaluated for its antioxidant, antihypertensive, and hypoglycemic activity and the IC50 (mg/ml) values were found to be 2.06 ± 0.33, 1.58 ± 0.03, and 2.77 ± 0.01 respectively. The current study demonstrated that SWE could be used as an effective process to extract bioactive polysaccharides from C. gigas.

Effect of pretreatments on isolation of bioactive polysaccharides from spent coffee grounds using subcritical water

In this study, we used a novel approach to recover polysaccharide from spent coffee ground (SCG) by combining pretreatments and subcritical water hydrolysis (SCWH). The independent variables which affect SCWH were optimized using response surface methodology. The highest yield of SCG polysaccharides (SCGPSs) (18.25 ± 0.21%) was obtained using ultrasonic pretreatment and SCWH conditions of temperature (178.85 °C), pressure (20 bar), and extraction time (5 min). The extracted SCGPSs showed high antioxidant activity as measured using ABTS+ and DPPH radical scavenging assay with IC50 values of 1.83 ± 0.03 and 2.66 ± 0.13 mg/ml respectively. SCGPSs also showed in vitro hypoglycemic activities. The structural and thermal characterization of the polysaccharide showed that the extracted polysaccharide has a typical carbohydrate features. The results of this study suggested that the extracted polysaccharide could have a potential application in food and related industries.

Seaweed Polysaccharide Isolation Using Subcritical Water Hydrolysis

Abstract Seaweed contains several important polysaccharides. The major polysaccharides are agar, carrageenan, and alginates, while the minor polysaccharides comprise of fucose, cellulose, laminarin, floridean, and xylan. To obtain these compounds with the principle of green chemistry, subcritical water extraction (SWE) is the most promising technique. SWE of biomass presents several advantages as compared with traditional technologies (acid, alkali, and enzymatic hydrolysis). Its main advantage is that, it does not use solvents, which is a factor of major importance in any process. In the current chapter, the extraction and characterization of polysaccharides from seaweeds using SWE are discussed.

Green synthesis of silver nanoparticles from deoiled brown algal extract via Box-Behnken based design and their antimicrobial and sensing properties

Abstract The aim of this work was to acquire even and sphere-shaped silver nanoparticles (AgNPs) using statistical design of experiment. AgNPs were produced by green synthesis method using deoiled Saccharina japonica powder obtained after supercritical carbon dioxide (Sc-CO2) extraction. Based on the Box-Behnken design, three variables influencing the size of AgNPs produced were identified as silver nitrate (AgNO3) concentration, temperature, and reaction time. Optimum conditions were determined using response surface methodology for synthesis of AgNPs. We found that increasing reaction time at low concentration of AgNO3 resulted in smaller particle size, and conversely increasing reaction time at high concentration of AgNO3 resulted in bigger particles. The obtained AgNPs were characterized by transmission electron microscopy, energy dispersive X-ray, X-ray diffraction analysis, and ultraviolet-visible and Fourier transform infrared spectroscopy techniques for particle size, distribution, aggregation, and anisotropy. The optimum operating conditions are 1 mm of AgNO3, 40°C, and 45 min with the smallest AgNPs size being 14.77 nm. The optimized AgNPs showed good antimicrobial activity and excellent sensing behavior towards hydrogen peroxide. The polyphenols present in aqueous AgNPs were evaluated by high-pressure liquid chromatography, which revealed the existence of chlorogenic acid and rutin.