Xuezhang Zhou

Antimycobacterial and Synergistic Effects of 18β-Glycyrrhetinic Acid or Glycyrrhetinic acid-30-piperazine in Combination with Isoniazid, Rifampicin or Streptomycin against Mycobacterium bovis

18ß‐Glycyrrhetinic acid (18ßGA) is a major bioactive component of liquorice with known activity. In this study, we found that both 18ßGA and its derivative glycyrrhetinic acid‐30‐piperazine (PGA), have potent antimycobacterial properties against the drug‐susceptible and drug‐resistant Mycobacterium bovis. More importantly, they exhibited synergistic effects with the first‐line drugs isoniazid (INH), rifampicin (RIF) and streptomycin (SM) against clinical M. bovis isolates, including drug‐resistant strains. In combination with a subinhibitory concentration of 18ßGA, the minimum inhibitory concentrations (MICs) of the anti‐tuberculosis agents decreased, ranging from 4‐ to 16‐, 4‐ to 8‐ and 4‐ to 8‐fold for INH (fractional inhibitory concentration index (FICI) 0.125–0.375), RIF (FICI 0.118–0.281) and SM (FICI 0.094–0.275), respectively. In the presence of PGA, MICs for the first‐line agents resulted in a 4–16‐fold decrease for INH (FICI 0.094–0.266, RIF (FICI 0.114–0.313) and SM (FICI 0.094–0.281). Additionally, the MICs of 18ßGA or PGA alone showed significant decreases ranging from 8‐ to 16‐, 8‐ to 64‐ and 8‐ to 128‐fold in the presence of INH, RIF and SM, respectively. These findings indicate that 18ßGA and its derivatives might serve as potential therapeutic compounds for future antimycobacterial drug development. Copyright

Azithromycin synergistically enhances anti-proliferative activity of vincristine in cervical and gastric cancer cells.

In this study, the anti-proliferative and anticancer activity of azithromycin (AZM) was examined. In the presence of AZM, cell growth was inhibited more effectively in Hela and SGC-7901 cancer cells, relative to transformed BHK-21 cells. The respective 50% inhibition of cell growth (IC50) values for Hela, SGC-7901 and BHK-21 were 15.66, 26.05 and 91.00 µg/mL at 72 h post incubation, indicative of a selective cytotoxicity against cancer cells. Cell apoptosis analysis using Hoechst nuclear staining and annexin V-FITC binding assay further demonstrated that AZM was capable of inducing apoptosis in both cancer cells and transformed cells. The apoptosis induced by AZM was partly through a caspase-dependent mechanism with an up-regulation of apoptotic protein cleavage PARP and caspase-3 products, as well as a down-regulation of anti-apoptotic proteins, Mcl-1, bcl-2 and bcl-X1. More importantly, a combination of AZM and a low dose of the common anti-cancer chemotherapeutic agent vincristine (VCR), produced a selectively synergistic effect on apoptosis of Hela and SGC-7901 cells, but not BHK-21 cells. In the presence of 12.50 μg/mL of VCR, the respective IC50 values of Hela, SGC-7901 and BHK-21 cells to AZM were reduced to 9.47 µg/mL, 8.43 µg/mL and 40.15 µg/mL at 72 h after the incubation, suggesting that the cytotoxicity of AZM had a selective anti-cancer effect on cancer over transformed cells in vitro. These results imply that AZM may be a potential anticancer agent for use in chemotherapy regimens, and it may minimize side effects via reduction of dosage and enhancing the effectiveness common chemotherapeutic drugs.

Association of the CD36 gene with impaired glucose tolerance, impaired fasting glucose, type-2 diabetes, and lipid metabolism in essential hypertensive patients.

Essential hypertension is a common disorder that can increase the risk of type 2 diabetes (T2D). CD36 has been studied in patients with diabetes and hypertension extensively; however, few studies have focused on the relationship of the CD36 gene with impaired fasting glucose (IFG)/impaired glucose tolerance (IGT) or T2D in essential hypertension patients. To identify rs1049673 and rs1527483 in the CD36 gene conferring susceptibility to IFG/IGT and T2D, we conducted a case-control study in 1257 essential hypertension patients among the Han Chinese population (control: 676; IGT/IFG: 468; T2D: 113). We also evaluated the impact of two loci on insulin sensitivity, glucose tolerance and serum lipid. The major findings of this study were that rs1049673 was found associated with IFG/IGT and T2D in essential hypertension patients (Pco = 0.028; Pdom = 0.015). The rs1049673 G carriers showed significant higher Glu0 (βdom = 0.08 (0.01~0.16), Pdom = 0.045) and Lp(a) (βco = 0.04 (0.002~0.07), Pco = 0.041; βdom = 0.06 (0.01~0.12), Pdom = 0.032), and lower HDL by the linear regression with the adjustment for gender, age, BMI, and mean blood pressures. These findings provided evidence that the CD36 gene may play some role in the pathogenesis of IFG/IGT and T2D in essential hypertension patients.

Total Alkaloids of Sophorea alopecuroides‐induced Down‐regulation of AcrAB‐ToLC Efflux Pump Reverses Susceptibility to Ciprofloxacin in Clinical Multidrug Resistant Escherichia coli isolates

In this report, total alkaloids extracted from the seeds of Sophorea alopecuroides (TASA) was evaluated against clinical Escherichia coli isolates resistant to four tested antibiotics, ampicillin (AM), amikacin (AN), cefotaxime (CTX) and ciprofloxacin (CIP). The TASA showed an antibacterial activity against the multidrug resistant (MDR) isolates. In combination with TASA, synergistic effects on the tested antibiotics against the MRD isolates were observed. Similarly, the isolates pretreated with a lower dose of TASA yielded increased and stable susceptibilities to CIP by 16–32‐fold determined by a microbroth dilution checkerboard method. Moreover, quantitative reverse transcription–polymerase chain reaction (qRT‐PCR) analysis revealed a constitutive overexpression of the AcrAB‐TolC pump system in the tested MDR isolates. The pretreatment of MDR isolates with TASA resulted in a statistically down‐regulated expression of acrA and acrB genes, and an up‐regulated expression of acrR gene (p < 0.05). But the expression of tolC gene was not significantly altered (p > 0.05). These results suggested that the TASA‐induced reversal resistance to CIP might be partially through a mechanism of inhibition of the AcrAB‐TolC pump activity in these isolates, implying that the TASA can be used as a potential natural source to develop efflux pump inhibitors (EPI) against AcrAB‐TolC pump mediated MDR in E. coli isolates. Copyright

In Vitro synergistic interaction of 5-O-methylglovanon and ampicillin against ampicillin resistant Staphylococcus aureus and Staphylococcus epidermidis isolates

Abstract5-O-methylglovanon (5-O-MG) is a bioactive compound that was first isolated and characterized from Glycosmis plants. In this study, we found that chemically synthesized 5-O-MG has antimicrobial ability against eleven clinical ampicillin resistant Staphylococcus aureus and S. epidermidis isolates. The MICs of 5-O-MG against the S. aureus and S. epidermidis isolates were 12.5–50 μg/mL and 25–50 μg/mL, respectively. In combination with ampicillin, a synergistic interaction between 5-O-MG and ampicillin against the eleven resistant Staphylococcus isolates was observed, with fractional inhibitory concentration indices of 0.03–0125. Moreover, the anti-staphylococcal activity of 5-O-MG in combination with ampicillin was comparable with that of clavulanic acid in combination with ampicillin. The drug combination had no antagonistic effects when tested against any of the strains. Time-killing assays confirmed the synergy between 5-O-MG and ampicillin (p < 0.01). The combination of these two agents yielded greater than a 2 log10 cfu/mL decrease in comparison with 5-O-MG or ampicillin alone. These findings suggest that 5-O-MG is a promising compound with the potential for future anti-staphylococcal drug development.

Effects of Total Alkaloids of Sophora alopecuroides on Biofilm Formation in Staphylococcus epidermidis.

Staphylococcus epidermidis (S. epidermidis) is an opportunistic pathogen with low pathogenicity and a cause of the repeated outbreak of bovine mastitis in veterinary clinical settings. In this report, a biofilm model of S. epidermidis was generated and the minimal inhibitory concentration (MIC) and sub-MIC (SMIC) on bacterial cultures were assessed for the following agents: total alkaloids of Sophora alopecuroides (TASA), ciprofloxacin (CIP), and erythromycin (ERY). The formation and characteristic parameters of biofilm were analyzed in terms of XTT assay, silver staining, and confocal laser scanning microscope (CLSM). Results showed that a sub-MIC of TASA could inhibit 50% biofilm of bacterial activity, while 250-fold MIC of CIP and ERY MICs only inhibited 50% and 47% of biofilm formation, respectively. All three agents could inhibit the biofilm formation at an early stage, but TASA showed a better inhibitory effect on the late stage of biofilm thickening. A morphological analysis using CLSM further confirmed the destruction of biofilm by these agents. These results thus suggest that TASA has an inhibitory effect on biofilm formation of clinic S. epidermidis, which may be a potential agent warranted for further study on the treatment prevention of infection related to S. epidermidis in veterinary clinic.

Potential of berberine to enhance antimicrobial activity of commonly used antibiotics for dairy cow mastitis caused by multiple drug-resistant Staphylococcus epidermidis infection.

Berberine is a plant alkaloid with antimicrobial activity against a variety of microorganisms. In this study, the antimicrobial properties of berberine against multi-drug resistant field isolates of Staphylococcus epidermidis were investigated using berberine alone or in combination with a commonly used antibiotics in veterinary clinics, including penicillin, lincomycin, and amoxicillin. The results indicated that the minimum inhibitory concentrations of berberine, penicillin, lincomycin, and amoxicillin against field S. epidermidis isolates were 2-512, 0.8-213, 0.4-1024, and 0.4-256 mg/mL, respectively. Furthermore, the synergistic effects of antimicrobial activity against these multi-drug resistant isolates were observed when the berberine was combined with penicillin, lincomycin, or amoxicillin; no antagonistic effect of the combination was detected in any of the clinical isolates. These observations were further confirmed using a time-killing assay, in which a combination of 2 agents yielded a greater than 2.03-2.44 log10 decrease in colony-forming unit/mL compared with each agent alone. These findings suggest that berberine is a promising compound for preventing and treating multi-drug resistant S. epidermidis infected mastitis in dairy cows either alone or in combination with other commonly used antibiotics, such as penicillin, lincomycin, and amoxicillin.

Total alkaloids from Sophora alopecuroides L. increase susceptibility of extended-spectrum β-lactamases producing Escherichia coli isolates to cefotaxime and ceftazidime

ObjectiveTo evaluate the antimicrobial activity of total alkaloids extracted from Sophorea alopecuroides L. (TASA) against clinical isolated extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli (E. coli) strains.MethodsThe antibacterial activity of TASA either itself or in combination with cefotaxime (CTX) or ceftazidime (CAZ) was investigated by using the microbroth dilution method and phenotypic confirmatory disk diffusion test against three clinical isolated ESBLs-producing E. coli strains; the interactions of TASA and CTX or CAZ were ascertained by evaluating the fractional inhibitory concentration index (FICI).ResultsThe antibacterial activity of either TASA itself or in combination with CTX or CAZ was found. The minimum inhibitory concentration (MICs) of TASA against the ESBLs producing isolates was 12.5 mg/mL. In the combinations with a sub-inhibitory concentration of TASA, a synergistic effect on CTX and CAZ against the ESBLs producing isolates was observed. Similarly, the isolates exposed to lower dose of TASA yielded an increased susceptibility to CTX and CAZ by 8–16 folds determined by microdilution assay. Moreover, enzymatic detection of ESBLs demonstrated that TASA induced reversal resistance to CTX and CAZ partially by a mechanism of inhibition of ESBLs activity in these isolates. Additionally, in the tested isolates following the exposure of TASA, molecular analysis verified the SHV-type beta-lactamase encoding ESBL gene in these isolates, and no mutation was introduced into the ESBL gene.ConclusionsThese results suggest that TASA could be used as a source of natural compound with pharmacological activity of reversal resistance to antimicrobial agent. These findings also indicated that the application of the TASA in combination with antibiotics might prove useful in the control and treatment of infectious diseases caused by the ESBLs producing enterobacteriaceae.

Association of KCNJ11 with impaired glucose regulation in essential hypertension.

KCNJ11 is one of the candidate genes for type 2 diabetes, confirmed by genome wide association study, but there are little data on the relationship between KCNJ11 and impaired glucose regulation in essential hypertension patients. To identify the effect of E23K and I337V in the KCNJ11 gene on susceptibility to impaired glucose regulation, we conducted a case control study in 1125 essential hypertension patients with or without impaired glucose regulation among a Han Chinese population. We also evaluated the impact of two SNPs on insulin sensitivity and glucose tolerance estimated through an oral glucose tolerance test. In our case control study, no association of E23K and I337V with impaired glucose regulation was found using any genotypic models. However, lysine carriers of E23K showed a significant association with decreased insulin (30 min) and Cederholm index, and valine carriers of I337V showed association with a lower Cederholm index. All the quantitative tests were performed by linear regression, with adjustment for gender, age, body mass index, blood pressure, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker treatment. These findings provided evidence that the KCNJ11 gene plays a role in the pathogenesis of decreased insulin sensitivity in essential hypertension patients.

Global Transcriptome Changes of Biofilm-Forming Staphylococcus epidermidis Responding to Total Alkaloids of Sophorea alopecuroides

Abstract Transcriptome changes of biofilm-forming Staphylococcus epidermidis response to total alkaloids of Sophorea alopecuroides was observed. Bioinformatic analyses were further used to compare the differential gene expression between control and the treated samples. It was found that 282 genes were differentially expressed, with 92 up-regulated and 190 down-regulated. These involved down-regulation of the sulfur metabolism pathway. It was suggested that inhibitory effects on Staphylococcus epidermidis and its biofilm formation of the total alkaloids of S. alopecuroides was mainly due to the regulation of the sulfur metabolism pathways of S. epidermidis.