ABSTRACT
UiO-66 (University of Oslo 66) is a kind of promising material that can improve the release and bioavailability of poorly water-soluble bioactive compounds of traditional Chinese medicine. However, the loading of quercetin in raw UiO-66 was not ideal. In this study, UiO-66-BH (UiO-66-blend-heating) was obtained by heating UiO-66 and KOH solution following blended them. UiO-66-BH maintained the outline of octahedral structure of UiO-66 but with obvious rough and uneven pores on the surface. UiO-66-BH had good adsorption of quercetin with saturation adsorption was 138.92 mg·g-1, the adsorption process belonged to single molecular layer adsorption and was controlled by chemisorption. UiO-66-BH can control the release of quercetin in simulated gastrointestinal fluid, and the drug concentration was significantly higher than that of free quercetin after long-term release (36% vs 9%). Compared with quercetin, the ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt) radical scavenging activity of UiO-66-BH@quercetin drug delivery system decreased, while the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity remained almost unchanged. The drug delivery system showed a strong antioxidant effect similar to quercetin. The findings indicated that UiO-66-BH could control release of quercetin and was expected to be used as a drug carrier material for some insoluble active components of traditional Chinese medicine such as quercetin.
ABSTRACT
Poly(lactide-co-glycolide acid) (PLGA) is an extraordinary well-described polymer and has excellent pharmaceutical properties like high biocompatibility and good biodegradability. Hence, it is one of the most used materials for drug delivery and biomedical systems, also being present in several US Food and Drug Administration-approved carrier systems and therapeutic devices. For both applications, the quantification of the polymer is inalienable. During the development of a production process, parameters like yield or loading efficacy are essential to be determined. Although PLGA is a well-defined biomaterial, it still lacks a sensitive and convenient quantification approach for PLGA-based systems. Thus, we present a novel method for the fast and precise quantification of PLGA by RP-HPLC. The polymer is hydrolyzed into its monomers, glycolic acid and lactic acid. Afterwards, the monomers are derivatized with the absorption-enhancing molecule 2,4′-dibromoacetophenone. Furthermore, the wavelength of the deri-vatized monomers is shifted to higher wavelengths, where the used solvents show a lower absorption, increasing the sensitivity and detectability. The developed method has a detection limit of 0.1 μg/mL, enabling the quantification of low amounts of PLGA. By quantifying both monomers separately, in-formation about the PLGA monomer ratio can be also directly obtained, being relevant for degradation behavior. Compared to existing approaches, like gravimetric or nuclear magnetic resonance measure-ments, which are tedious or expensive, the developed method is fast, ideal for routine screening, and it is selective since no stabilizer or excipient is interfering. Due to the high sensitivity and rapidity of the method, it is suitable for both laboratory and industrial uses.
ABSTRACT
Objective: To prepare hydroxytyrosol (HT) by alkaline hydrolysis of oleuropein and to investigate its anti-oxidative property. Methods: According to single factor experiments, four variables: temperature, sodium hydroxide concentration, time, and the ratio of solid to liquid, were selected. On the basis of single factor experiments, orthogonal tests of L9(34) were carried out. HPLC-MS method was also further applied for the qualitative analysis on HT. Under the same conditions, contrast experiments on the acid and alkaline actions were made. Finally, anti-oxidative activity of HT was evaluated. Results: The results showed that the selected variables were all highly significant. Also, the descending influence orders on HT were temperature > sodium hydroxide concentration > time > the ratio of solid to liquid. Lastly, the optimal conditions on HT yield were obtained as follow: temperature 90°C, sodium hydroxide concentration 0.2 mol/L, time 45 min, and the ratio of solid to liquid 1:15. The HPLC retention time of HT was about 10.3 min, and its relative molecular weight of fragment ion by MS was 134.8. By comparison with the acid action, it was proved that the alkaline action was better in HT yield. In addition, the anti-oxidative activity of HT was carried out on scavenging DPPH radical. The results showed that DPPH scavenging capability of HT was 2.45 times of BHT. Conclusion: HT yield is well obtained under the alkaline condition and has a good anti-oxidation.
ABSTRACT
Hydrolysis studies of the two diterpene glycosides stevioside and rebaudioside A that were isolated from Stevia rebaudiana were performed using acid and alkaline conditions. Acid hydrolysis was carried out using H2SO4 whereas alkaline hydrolysis was performed using NaOH. Using these methods, partial hydrolyzed glycosides of stevioside and rebaudioside A and their sugar residues were identified from the alkaline and acid hydrolysis studies respectively. The structures of the acid and alkaline hydrolysis products were achieved on the basis of extensive NMR and high resolution mass spectral data, and in comparison with the data reported in the literature as well as TLC comparison with their corresponding standard compounds.
ABSTRACT
After alkaine hydrolysis, the body wall of Slicliopus varicyatus was fractionally pre-cipitatecd with alcohol, then oxidatively decoloured and purified with KAc, the elcctrophorelically pure polysaccharides SVI and SVIIwere obtained. The results of ultracentrifugal analysis showed that the sedimentation coefficients were S20w 3. 09 for SVI and S20w 2. 12 for SVII. The metachromatic reaction with reddish black I showed the metachromatic peaks of SVI and SVII were shifted to 514nm and 507nm, respectively. The molecule of SVI is composed of aminogalactose, glucuronic acid, fucose and sulfate (1:1. 21:1. 29:4. 62) and that of SVII is composed of fucose and sulfate (1.0. 99). And our results of Stichopus japonicus acidic mucopolysaccharide ultracentrifugation therefore suggests that the sedimentation coefficients is S20w 2. 12. The metachromatic reaction with reddish black I showed the metachromatic peak is 515nm. The molecule of Sjamp is also composed of aminogalactose, glucuronic acid, fucose and sulfate ( 1:1. 1:1. 20:4. 87)
ABSTRACT
98 %).Conclusions Saponins are the major active ingredients in Radix Polygalae.Tenuifolin as an alkaline hydrolysis product of total saponins can be used as a chemical reference substance for the quality control of Radix Polygalae.