The prevalence of chronic diseases has increased steadily over the last 20 years. The side effects of drugs used to treat chronic disease have always been a problem, owing to the need for long-term medication. Many studies have attempted to discover drugs from natural sources with fewer side effects. In this study, we investigated the possibility of using jujube leaf as a potential anti-diabetic drug source or food supplement. The IC50 values of acarbose and jujube leaf extract on a-glucosidase were 2.59 and 0.37 mg/mL, respectively. In vitro tests showed that the inhibition of a-glucosidase was maintained after the jujube extract was passed through a simulated digestive system, but no inhibition of a-amylase was observed either before or after the in vitro digestion. The jujube leaf extract showed mixed non-competitive inhibition. Jujube leaf extract is expected to be safer and cheaper than synthetic inhibitors.

The glucosidase inhibitors are currently interested owing to their promising therapeutic potential in the treatment of disorders such as diabetes, human immunodeficiency virus (HIV) infection, metastatic cancer, and lysosomal storage diseases. Among them, β-d-glucosidase inhibitors can be used to elucidate the mechanisms of various biochemical reactions and to treat the Gaucher disease as potential therapeutics. In this study, the natural β-glucosidase inhibitor was isolated from jujube leaf extract. The isolation and purification are vital for the structure analysis. The jujube leaf was extracted with hot water (95°C, 15 min). Then the natural β-glucosidase inhibitor was isolated using size exclusion chromatography and semi-preparative HPLC. In the first purification process, the 35 fractions were collected according to molecular size using PD-10 column packed with Sephadex G-25 medium. The strongest inhibition on the activity of β -glucosidase was observed at 6 and 7 fractions. The chromatogram of these samples showed that 3 peaks were observed comparing with baseline. For further purification, the strongest inhibitory activity peak was isolated using semi-preparative HPLC with VDS C18 column. Highly purified inhibitor, which can be used for structure analysis and characterization, was obtained. Further study is necessary to identify the natural β-glucosidase inhibitor in the jujube leaf extract.

To enhance the oral bioavailability (BA) of curcumin (CUR), we applied 1 wt% CUR-loaded lipid nanoparticle (LNP) system prepared with tristearin (TS) and short (Brij S10) / long (Brij S100) PEGylated surfactants. All LNPs were colloidally stable under high ion strength and pH 3 conditions regardless of the PEG chain length. However, the long-chained PEGylation prevented LNP surface better than the short-chained PEGylation from the lipase/bile salt adsorption according to ζ potential results after treatment of lipase and bile solutions. Actually, the short-chained LNPs were digested rapider than the long-chained one in the simulated small intestinal condition due to the faster displacement of PEGylated surfactants on LNP surface by bile salts. Furthermore in the rat model pharmacokinetics for oral administration of CUR, the long-chained LNP group had 10.62-fold BA of native CUR group due to the coabsorption of CUR with the mixed micelles made after gastrointestinal digestion, and had 4.57-fold BA of the short-chained LNP group despite the same molarity use (17.058 mM) of both emulsifiers due to the reduced digestion rate by long-chained PEG on LNP surface. In conclusion, since CUR incorporated in LNPs was improved in the bioavailability, the designed LNP system may serve as an encapsulation strategy to enhance the bioavailability of non-bioavailable nutraceuticals in foods.

An importance of food allergen detection has been growing in food industry. Here, we developed a rapid and easy-to-use detection system for Ara h1, a major allergen in peanut, using gold nanoparticles and switchable linkers. The detection system was performed by two steps. In the first step, Ara h1 was mixed with various concentrations (0.2 - 1.0μg/mL) of biotinylated anti-Ara h1 antibody (i.e., switchable linker, SLs) solutions for 20 min. After mixing, streptavidin coated gold nanoparticle (Abs. 4.0) was added to the mixture solutions with agitation for10 min. Without Ara h1(control), the region of aggregation caused by quantitative relationship between SLs and gold nanoparticle was observed at more than 0.4 μg/mL of SLs. However, under presence of Ara h1, SLs covered with Ara h1 had less ability to react with gold nanoparticles than naked SLs. This resulted in a change of the quantitative relationship mentioned above, which led to shift of the aggregation region. When 10 nM and 40 nM of Ara h1 were added, the aggregation region was appeared from 0.5and 0.8 μg/mLof switchable linkers, respectively. Ara h1 in peanut sample was also detected with this system. 0.4 μg/mL of switchable linkers are mixed with serially diluted peanut extract solutions. As a result, the shift of the aggregation region was observed from undiluted extract to 10 -2 diluted solution. This system could be adapted to detect other harmful/useful bio materials in food.