ABSTRACT
@#The poorly water-soluble drug curcumin was prepared into oral nanocrystalline solid preparation by nanocrystal technology to improve the solubility, dissolution rate, and bioavailability. Curcumin nanocrystals were prepared by media grinding technology, and two types of stable curcumin nanocrystal suspension formulations were developed. The stabilizers in the two formulations were polyvinylpyrrolidone (PVP K30)/sodium lauryl sulfate (SDS)(1∶1) and Tween 80, respectively. The prepared curcumin nanocrystal suspension was loaded onto microcrystalline cellulose pellets through fluidized bed coating technology, and the nanocrystalline capsules were obtained after filling. The results of nanocrystal redispersion stability and scanning electron microscope (SEM) showed that the morphology of drug-loaded pellets was uniform when PVP K30 and SDS were used as stabilizers, and the diameter of nanocrystals before and after redispersion was about 200 nm, which was determined as the optimal formulation. In vitro dissolution study showed that curcumin nanocrystals at the size of 200 nm exhibited significantly promoted dissolution. The results of X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) showed that the curcumin crystalline partly turned amorphous during the preparation of nanocrystals.Pharmacokinetic studies in rats showed that the bioavailability of curcumin nanocrystals was 9.3 times higher than that of the bulk drug. The curcumin nanocrystalline capsules developed in this research can significantly improve the dissolution rate and bioavailability, which is of great significance in improving the poor solubility of drugs, and is expected to become a new dosage form for clinical treatment.
ABSTRACT
Sichuan basin, situated in the west of China, is the fourth biggest basin in China. In order to describe a systematic study of the cry2-type genes resources from Bacillus thuringiensis strains of Sichuan basin, a total of 791 Bacillus thuringiensis strains have been screened from 2650 soil samples in different ecological regions. The method of PCR-restriction fragment length polymorphism (PCR-RFLP) was used to identify the type of cry2 genes. The results showed that 322 Bacillus thuringiensis strains harbored cry2-type genes and four different RFLP patterns were found. The combination of cry2Aa/cry2Ab genes was the most frequent (90.4 percent), followed by cry2Aa (6.8 percent) and cry2Ab alone (2.5 percent), and only one novel type of cry2 gene was cloned from one isolate (JF19-2). The full-length of this novel gene was obtained by the method of thermal asymmetric interlaced PCR (Tail-PCR), which was designated as cry2Ag1 (GenBank No. ACH91610) by the Bt Pesticide Crystal Protein Nomenclature Committee. In addition, the result of scanning electron microscopic (SEM) observation showed that these strains had erose, spherical, bipyramidal, and square crystal. And the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that these strains harbored about one to three major proteins. These strains exhibited a wide range of insecticidal spectrum toxic to Aedes aegypti (Diptera) and Pieris rapae Linnaeus, 1758 (Lepidoptera). Particularly, JF19-2 contained cry2Ag gene had the highest insecticidal activity. All these researches mentioned above revealed the diversity and particularity of cry2-type gene resources from Bacillus thuringiensis strains in Sichuan basin.