Latest ArticlesIn order to determine the differences in structure and optimum isolation conditions of Glycyrrhiza uralensis endophytes from different habitats, plate-separation method was used to identify endophytes in G. uralensis from Gansu, Ningxia, Inner Mongolia, Xinjiang, and Beijing. The isolation parameters were defined by investigating various concentrations and sterilization time of NaClO solution. The strains were identified by morphological and molecular biological methods. The results showed that 5% NaClO solution and sterilization time of 5 min were the optimal surface sterilization conditions. Among 129 strains of G. uralensis from 5 producing areas, 438 strains of endophytic fungi were isolated and belonged to 5 orders, 7 genera, and 11 species. Among them, 4 taxa were firstly isolated from the licorice in China. Fusarium was a common genus among the 5 regions. There were differences in the composition and structure of the endophytic fungi of G. uralensis from different habitats. Diversity analysis showed that the endophytic fungi diversity in Gansu was the highest and that of Beijing was the lowest. The comprehensive analyses indicated that the endophytic fungi of G. uralensis are diverse, and there were differences among the number, composition and population of endophytic fungi in five producing areas of Gansu, Ningxia, Inner Mongolia, Xinjiang and Beijing.
Hypophosphatemia is a common metabolism disease in humans. Fibroblast growth factor 23 (FGF23) inhibits phosphate reabsorption by targeting on the renal tubules. FGF23C-tail contains 73 amino acids from C-terminus of FGF23, serves as an inhibitor of FGF23, and can increase phosphate reabsorption. Therefore, FGF23C-tail is an important drug for hypophosphatemia. In this paper, we constructed a fusion protein of FGF23C-tail with HSA, and investigated the expression of the fusion protein in the Pichia pastoris system. The recombinant gene was constructed by fusion PCR. A high-yield strain was selected by G418 resistance and fermentation yield, and the expression yield was 43.7 mg·L-1 in flask. In 5 L fermenters, the highest expression yield could reach 265.6 mg·L-1. FGF23C-tail-HSA could be used as an inhibitor for FGF23, and could significantly increase blood phosphorus levels in rats. The procedures for care and use of animals were approved by the Ethics Committee of YiChun University. This paper provided a basis research for further studying physiological activity of FGF23C-tail-HSA.
BCS Ⅱ drugs are characterized by low solubility and high permeability. Improving their solubility is considered an important approach to improve its oral absorption. Recent strategies to increase the solubility of poorly-soluble drugs may unexpectedly result in greatly depressed permeability, ultimately leading to failure in improving oral absorption. Based on the mathematics of membrane permeability coefficient of a drug, the membrane/aqueous partition coefficient is dependent on the drug's solubility in the gastrointestinal milieu, suggesting a unique interplay between the solubility and permeability of the drug, and treating the one irrespectively of the other may be insufficient. When we focus on the increase of drug solubility and overlook the efficacy of drug permeability, the positive effect of increased solubility to drug oral absorption might be traded off by depressed permeability. To provide rational formulary designs, by optimizing excipients and evaluation, this review summarizes solubility-permeability interplay for different types of solubilizing techniques, such as cyclodextrin, surfactants-based vehicle, cosolvent, amorphous solid dispersions, other infectors such as P-gp transporters and new techniques for simultaneous evaluation of drug solubility and permeability.
The solubilization and protection of curcumin (Cur) by mixed surfactants were studied through the determination about the critical micellar concentration (CMC) of the mixed surfactants of Tween 80 and dodecyl trimethyl ammonium bromide (DTAB), molar solubilization ratio (MSR), degradation rate (k) of Cur in pH 13 solution and mixed surfactant solutions prepared at pH 13. The results showed that when Tween 80 was used alone, it exhibited high solubilization ability but poor stability. DTAB was used alone, it showed strong stability but poor solubilization ability. When DTAB was mixed with Tween 80 at different mole fractions, the stability of Cur was enhanced, and the best stability was observed when the mole fraction of DTAB was 0.4, although the solubilization ability was not the best at this mole fraction, but MSR was increased by 1.7 times compared to DTAB used alone. Mixed surfactant not only increased the solubility but also improved the stability of Cur. In addition, mixed surfactant has the advantages of less dosage and low toxicity, which is worth popularizing in application.
Spironolactone, a class Ⅱ drug of the biopharmaceutics classification system, has low oral bioavailability due to poor solubility. Spironolactone solid dispersions were prepared using the solvent method in order to improve its aqueous solubility. Optimization studies of spironolactone solid dispersions were performed using in vitro dissolution tests. Differential scanning calorimetry, X-ray diffraction and Fourier transform infrared were used to investigate the physical state of the drug in carrier materials and to detect the possible interactions between the drug and carrier materials in the solid dispersions. In addition, stress tests were employed to elucidate the key factors which have influence on the stability of the spironolactone solid dispersions. Results showed that spironolactone in the solid dispersions formulated with Soluplus and HPMC-E5 were both in amorphous state and the hydrogen bonds between the drug and carrier materials were formed in the solid dispersion. Therefore, the in vitro dissolution of spironolactone was also significantly enhanced. Stress tests demonstrated that the physical stability of spironolactone solid dispersions prepared with Soluplus was greatly improved compared to those formulated with HPMC-E5. Thus, spironolactone solid dispersion formulated with Soluplus using the solvent method could be used to improve the in vitro dissolution and stability of poorly soluble drugs.
The poor solubility of cyclosporine A (CsA) in water limits its oral absorption. We prepared CsA/Soluplus/SDS complex, which can form CsA/Soluplus/SDS supersaturated micelles (CSS-SM) after hydration. Then, We further prepared CSS-SM osmotic pump tablets (CSS-SM-T). CSS-SM had a particle size of 156 nm, where in encapsulation efficiency and drug loading efficiency of CsA were 89.0% and 17.5%, respectively. CSS-SM-T achieved zero-level drug release in vitro. Pharmacokinetic data from Beagle dogs (all animal experiments were conducted under the guidelines approved by the Institutional Animal Care and Use Committee of the Shanghai Institute of Materia Medica, Chinese Academy of Sciences) indicated that CsA in the ordinary osmotic pump tablets was hardly absorbed after orally administered; despite slightly lower bioavailability[relative bioavailability:(85.1 ±47.4)%] than that of Sandimmum Neoral, CSS-SM-T displayed lower fluctuations in CsA plasma concentration and obvious sustained-release characteristics in vivo, implying lower toxicity. Therefore, CSS-SM-T provides a new research idea for the design and development of oral sustained-and controlled-release preparations of poorly water-soluble drugs.
The aim of this study is to prepare porous γ-cyclodextrin metal-organic framework (CD-MOF) with good biocompatibility to improve the in vitro release properties of water-insoluble drugs. Different sizes of CD-MOF were obtained by controlling the self-assembly of γ-cyclodextrin and potassium ion and the rate of crystal growth. The poorly water-soluble diflunisal (DIF) was selected as the model drug and loaded into the interior of porous CD-MOF by the impregnation method. The DIF loaded CD-MOF (DIF-MOF) was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), nitrogen adsorption and desorption, Fourier infrared spectrometer and thermogravimetric analysis. In addition, in vitro cytotoxicity and solubilizing capability of CD-MOF were investigated. It revealed that the obtained CD-MOF was cubic-like with a narrow size distribution and high porosity. Negligible cytotoxicity was found after incubation with RAW264.7 cells. Compared with the pure CD-MOF carrier, the morphology and crystal form of DIF-MOF was not damaged during the drug loading process. Moreover, the solubility and release rate of water-insoluble DIF from the DIF-MOF were significantly increased.
Artemisinin and its derivatives have been proved for their anti-tuberculosis activities, despite its low water solubility which hampered its efficacy and corresponding formulation development. In this study we designed and synthesized a novel artemisinin analog by conjugating an arginine through a succinic acid linker. This design not only enhanced the water solubility of the artemisinin, but also increased the efficacy of the molecule towards tuberculosis bacteria due to disruption by arginine. The results showed that the solubility of the synthesized derivatives A-2 and A-3 increased 19.8-27.8 folds compared to artemisinin. In vitro cytotoxicity experiment showed that compound A-3 had negligible toxicity to THP-1 cells up to 1 mg·mL-1, the minimal inhibitory concentration (MIC) of A-2 and A-3 was 20 and 10 μg·mL-1, respectively, which was 5 or 10 times lower than that of artemisinin. Intracellular bacteria inhibition experiment showed that compound A-3 at lower concentrations such as 100 or 200 μg·mL-1 significantly inhibited the growth of tuberculosis bacteria (P < 0.05 or P < 0.01), which efficacy was stronger than artemisinin at the concentration of 100 μg·mL-1. These results strongly suggested that compound A-3 was a potential anti-tuberculosis lead compound.
The aim of this study is to investigate the effect of nicotinamide (NIC) on the solubility/dissolution of a poorly soluble drug ibuprofen (IBU), and to explore the mechanism of the formed soluble complex by complexation model, fluorescence quenching and Raman spectroscope. The results showed that NIC could significantly improve the solubility of IBU, and exhibited an Ap type complexation profile. The calculated complexation constants of K1:1 and K1:2 were 0.24 and 4.00, respectively. In the solution, the fluorescent intensity of IBU gradually decreased with the increase of NIC, exhibiting the typical fluorescence-quenching phenomenon. The Raman spectrum showed stretching vibrations, bending vibrations, and rocking vibrations ascribed to benzene ring of IBU and pyridine ring of NIC disappeared or significantly shifted, suggested that the soluble complex was formed by dipole-dipole interaction force between the benzene group on IBU and pyridine group on NIC, resulting in the aqueous solubility enhancement of IBU. In comparison to IBU alone, the physical mixture of IBU and NIC showed significantly higher dissolution rate (1.6-fold) and extent.
The aim of this study is to investigate the influence of flufenamic acid (FFA) on the solubility, dissolution and bioavailability of sorafenib (SFN) in the combined administration of the MSNM@SFN and FFA. The MSNM@SFN&FFA was prepared by mixing the MSNM@SFN with FFA. The solubility, dissolution and bioavailability of SFN in the MSNM@SFN&FFA complex was investigated in comparison with those of the MSNM@SFN. This study was performed following the National Institutes of Health guidelines for the use of experimental animals; all care and handling of animals were performed with the approval of the Experimental Animal Center of Peking University Health Science Center. The MSNM@SFN&FFA showed no significant influence on the solubility, dissolution and bioavailability of SFN when compared with the MSNM@SFN. These data indicated that FFA had almost no influence on the solubility, dissolution and bioavailability of SFN in the combined administration of MSNM@SFN and FFA, thus providing an experimental foundation for the subsequent formulation research on the combined usage of drugs.
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