Min Lang Tsai

In vitro antioxidant activities of low-molecular-weight polysaccharides with various functional groups.

The objectives of this study were to evaluate the effect of different functional groups of sulfate, amine, and hydroxyl and/or their ionized groups on in vitro antioxidant capacities of low-molecular-weight polysaccharides (LMPS) prepared from agar (LMAG), chitosan (LMCH), and starch (LMST), respectively, and to elucidate their structure-activity relationship. Ascorbic acid and ethylenediaminetetraacetic acid (EDTA) were used as positive controls. The in vitro antioxidant capacities of LMAG and LMCH were higher than that of LMST in the DPPH radical, superoxide radical, hydrogen peroxide, and nitric oxide radical scavenging and ferrous metal-chelating capacities. The different scavenging capacities may be due to the combined effects of the different sizes of the electron-cloud density and the different accessibility between free radical and LMPS, which, in turn, depends upon the different hydrophobicities of the constituent sugars.

Effect of Different Parts (Leaf, Stem and Stalk) and Seasons (Summer and Winter) on the Chemical Compositions and Antioxidant Activity of Moringa oleifera

Moringa oleifera, Lam. (Moringaceae) is grown world-wide in the tropics and sub-tropics of Asia and Africa and contains abundant various nutrients. This study describes the effect of different parts (leaf, stem and stalk) and seasons (summer and winter) on the chemical compositions and antioxidant activity of M. oleifera grown in Taiwan. The results showed that the winter samples of Moringa had higher ash (except the stalk part), calcium and phenolic compounds (except the leaf part) and stronger antioxidative activity than summer samples. The methanolic extract of Moringa showed strong scavenging effect of DPPH radicals and reducing power. The trend of antioxidative activity as a function of the part of Moringa was: leaf > stem > stalk for samples from both seasons investigated. The Moringa extract showed strong hydrogen peroxide scavenging activity and high Superoxide Dismutase (SOD) activity except the stalk part.

Development of a new type of multifunctional fucoidan-based nanoparticles for anticancer drug delivery

Fucoidan, a sulfated marine polysaccharide, has many potential biological functions, including anticancer activity. Recently, fucoidan has been reported to target P-selectin expressed on metastatic cancer cells. Increasing research attention has been devoted to the developments of fucoidan-based nanomedicine. However, the application of traditional chitosan/fucoidan nanoparticles in anticancer drug delivery may be limited due to the deprotonation of chitosan at a pH greater than 6.5. In this study, a mutli-stimuli-responsive nanoparticle self-assembled by fucoidan and a cationic polypeptide (protamine) was developed, and their pH-/enzyme-responsive properties were characterized by circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), and zeta potential analysis. Enzymatic digestion and acidic intracellular microenvironment (pH 4.5-5.5) in cancer cells triggered the release of an anticancer drug (doxorubicin) from the nanoparticles. The protamine/fucoidan complex nanoparticles with P-selectin mediated endocytosis, charge conversion and stimuli-tunable release properties showed an improved inhibitory effect against a metastatic breast cancer cell line (MDA-MB-231).

Structural alterations, pore generation, and deacetylation of α- and β-chitin submitted to steam explosion.

The purpose of this study was to use an environmentally friendly steam explosion method to achieve α- and β-chitin structural alterations, pore generation, and deacetylation, enhancing the degree of deacetylation (DD) in chitin and extending its applications. The samples of α- and β-chitin possessing various moisture contents that were exploded at 9 kg/cm(2) exhibited higher DDs, lower densities, lower crystallinity and more porous structures compared to unexploded chitin. After explosion, β-chitin exhibited a larger expansion ratio, lower crystallinity and contained a larger proportion of small-sized particles compared to α-chitin. The highest DD values of exploded α- and β-chitin with 75% moisture content were 42.9% and 43.7%, respectively. The exploded chitin samples with lower moisture content exhibited lower DDs, densities, crystallinity indices, smaller particle sizes, and higher expansion ratios than the chitin samples with higher moisture content. The chitin samples with lower moisture content also contained larger and more numerous pores.

Selective isolation of trypsin inhibitor and lectin from soybean whey by chitosan/tripolyphosphate/genipin co-crosslinked beads.

Selective isolation of Kunitz trypsin inhibitor (KTI) and lectin from soybean whey solutions by different types of chitosan beads was investigated. The chitosan beads were co-crosslinked with tripolyphosphate/genipin in solutions at pH 5, 7 or 9 (CB5, CB7, CB9). The maximum adsorption ratios of chitosan beads to KTI and lectin were observed at pH 4.4 and 5.4, respectively; highly selective separation was also demonstrated at these pHs. The adsorption ratios increased with temperature, rising between 5 and 25 °C. CB9 produced the best adsorption ratio, followed by CB7 then CB5. The critical interaction governing absorption of chitosan beads to KTI and lectin could be hydrogen bonding. At pH 9, KTI and lectin desorbed efficiently from CB7 with desorption ratios of 80.9% and 81.4%, respectively. The desorption was most likely caused predominantly by electrostatic repulsion. KTI and lectin can effectively be selectively isolated from soybean whey using this novel separation technique.

Inhibition of Oxidative Stress by Low-Molecular-Weight Polysaccharides with Various Functional Groups in Skin Fibroblasts

The aim of this study was to evaluate the in cellulo inhibition of hydrogen-peroxide-induced oxidative stress in skin fibroblasts using different low-molecular-weight polysaccharides (LMPS) prepared from agar (LMAG), chitosan (LMCH) and starch (LMST), which contain various different functional groups (i.e., sulfate, amine, and hydroxyl groups). The following parameters were evaluated: cell viability, intracellular oxidant production, lipid peroxidation, and DNA damage. Trolox was used as a positive control in order to allow comparison of the antioxidant efficacies of the various LMPS. The experimentally determined attenuation of oxidative stress by LMPS in skin fibroblasts was: LMCH > LMAG > LMST. The different protection levels of these LMPS may be due to the physic-chemical properties of the LMPS’ functional groups, including electron transfer ability, metal ion chelating capacities, radical stabilizing capacity, and the hydrophobicity of the constituent sugars. The results suggest that LMCH might constitute a novel and potential dermal therapeutic and sun-protective agent.

Effect of Grape Seed Proanthocyanidin–Gelatin Colloidal Complexes on Stability and in Vitro Digestion of Fish Oil Emulsions

The colloidal complexes composed of grape seed proanthocyanidin (GSP) and gelatin (GLT), as natural antioxidants to improve stability and inhibit lipid oxidation in menhaden fish oil emulsions, were evaluated. The interactions between GSP and GLT, and the chemical structures of GSP/GLT self-assembled colloidal complexes, were characterized by isothermal titration calorimetry (ITC), circular dichroism (CD), and Fourier transform infrared spectroscopic (FTIR) studies. Fish oil was emulsified with GLT to obtain an oil-in-water (o/w) emulsion. After formation of the emulsion, GLT was fixed by GSP to obtain the GSP/GLT colloidal complexes stabilized fish oil emulsion. Menhaden oil emulsified by GSP/GLT(0.4 wt %) colloidal complexes yielded an emulsion with smaller particles and higher emulsion stability as compared to its GLT emulsified counterpart. The GSP/GLT colloidal complexes inhibited the lipid oxidation in fish oil emulsions more effectively than free GLT because the emulsified fish oil was surrounded by the antioxidant GSP/GLT colloidal complexes. The digestion rate of the fish oil emulsified with the GSP/GLT colloidal complexes was reduced as compared to that emulsified with free GLT. The extent of free fatty acids released from the GSP/GLT complexes stabilized fish oil emulsions was 63.3% under simulated digestion condition, indicating that the fish oil emulsion was considerably hydrolyzed with lipase.

Drug release and antioxidant/antibacterial activities of silymarin-zein nanoparticle/bacterial cellulose nanofiber composite films

Bacterial cellulose (BC) is a biopolymer composed of nanofibers which has excellent film-forming ability. However, BC do not have antibacterial or antioxidant activity, thus limiting the applicability of BC for food and biomedical applications. In this study, flavonoid silymarin (SMN) and zein were assembled into spherical SMN-Zein nanoparticles that could be effectively adsorbed onto BC nanofibers. SMN-Zein nanoparticles greatly changed the wettability and swelling property of BC films due to the formation of nanoparticles/nanofibers nanocomposites. SMN-Zein nanoparticles enhanced the release of sparingly soluble silymarin from the nanocomposite films. The active films showed more effective antioxidant and antibacterial activities as compared with pure BC films and thus were able to protect salmon muscle from deterioration and lipid oxidation. These findings suggest that the nanoparticle/nanofiber composites may offer a suitable platform for modification of BC films with improved drug release properties and biological activities.

Effect of the Characters of Chitosans Used and Regeneration Conditions on the Yield and Physicochemical Characteristics of Regenerated Products

The objective of this study was to explore the effect of the character of chitosans used, and the regeneration conditions employed on, the yield and physicochemical characteristics of regenerated products. Different concentrations of acetic acid were used to dissolve chitosans of 61.7% and 94.9% degree of deacetylation (DD), and weight-average molecular weight (Mw) of 176 and 97 kDa, respectively; they were then precipitated with an 8 N NaOH solution, followed by washing and neutral and freeze drying to get the regenerated products. Yields of regenerated products and their physicochemical properties, such as ash content, bulk density, Mw, polydispersity index (PDI), DD, and crystallinity were measured. A higher concentration of acetic acid used resulted in a higher yield. The purity of the regenerated product increased significantly, whereas the bulk density and crystallinity decreased significantly after regeneration. The regeneration process showed its merits of narrowing down the PDI of regenerated products. The DD and structure of chitosan was changed insignificantly after the regeneration process.

Enrichment desired quality chitosan fraction and advance yield by sequential static and static-dynamic supercritical CO2.

This study aimed to establish the sequential static and static-dynamic supercritical carbon dioxide (SDCO2) fractionation conditions to obtain a higher yield and desired chitosan with lower polydispersity index (PDI) and higher degree of deacetylation (DD). The yield increased with increasing DD of used chitosan and amount of cosolvent. The yield of acetic acid cosolvent was higher than those of malic and citric acid cosolvents. SDCO2, compared to static supercritical carbon dioxide, has higher yield. The yield of extracted chitosan was 5.82-14.70% by SDCO2/acetic acid, which increases with increasing pressure. The DD of fractionated chitosan increased from 66.1% to 70.81-85.33%, while the PDI decreased from 3.97 to 1.69-3.16. The molecular weight changed from 622kDa to 412-649kDa, which increased as density of supercritical carbon dioxide increases. Hence, higher DD and lower PDI extracted chitosan can be obtained through controlling the temperature and pressure of SDCO2.