Quinoxaline and quinoxaline‐1,4‐di‐N‐oxides: An emerging class of antimycobacterials

Tuberculosis (TB) is a highly dreaded, infectious, chronic, airborne disease affecting more than two million people all around the world, with more than eight million cases every calendar year. TB is the second leading infectious cause of death after HIV/AIDS. Over the past few decades, numerous efforts have been undertaken to develop new anti‐TB agents. The current frontline therapy for TB consists of administering three or more different drugs (usually isoniazid, rifampin, pyrazinamide, and ethambutol) over an extended period of time. But these drugs will take 6–12 months to cure TB, along with many side effects; hence, there is an urgent need to explore new anti‐TB agents. Quinoxaline derivatives are a class of compounds that show a spectrum of biological properties and the interest in these compounds is exponentially growing within the field of medicinal chemistry. Quinoxaline‐1,4‐di‐N‐oxide derivatives have shown to improve the biological results and are endowed with anti‐viral, anti‐cancer, anti‐bacterial, and anti‐protozoal activities with application in many other therapeutic areas. Since quinoxaline derivatives are regarded as a new class of effective anti‐TB candidates, their 1,4‐di‐N‐oxide analogues may show promising in vitro and in vivo anti‐TB activities and might be able to prevent the drug resistance to a certain extent. Therefore, the main aim of this review is to focus on important quinoxaline and quinoxaline‐1,4‐di‐N‐oxide analogues that have shown anti‐TB activities, and their structure–activity relationships for designing anti‐TB agents with better efficacies. The present review will be helpful in providing insights for rational designs of more active and less toxic quinoxaline‐based anti‐TB prodrugs.

     

Design,synthesis, biological evaluations,molecular docking,and in vivo studies of novel phthalimide analogs

A series of novel phthalimide analogs containing an indole or brominated indole moiety were synthesized and their antimicrobial activity was evaluated. Compound 8 showed a broad spectrum activity, revealing 53–67% of erythromycin activity on the tested bacteria and 60–70% of miconazole activity on the tested fungi. Anticancer activity was evaluated on the cell lines HepG2, MCF‐7, A549, H1299, and Caco2. The results revealed that the new phthalimide analog 8 has broad‐spectrum anticancer activity toward all the tested cancer cell lines, followed by compound 11 , which showed good activity toward all the tested cell lines except for MCF‐7. The ability of the promising analogs 5 , 8 , and 11 to bind to topoisomerase II DNA gyrase was investigated. Caspase‐3 activation and Bcl‐2 assay of the best active derivatives 8 , 11 in addition to compound 5 were evaluated. The antifibrotic activity was studied in an in vivo model and the histopathological studies revealed that treatment with the new compound 8 improved the fibrotic liver tissues to normality.

     

气相色谱法测定复方樟脑搽剂中樟脑与薄荷脑含量及其不确定度评估

目的 建立测定复方樟脑搽剂中主要成分樟脑和薄荷脑含量的气相色谱（GC）法,并探讨不确定度评估方法。方法 采用GC法,以萘为内标物,Thermo TG-WAXMS毛细管柱（30.0 m×0.25 mm,涂层厚0.5 μm）,FID检测器;分析测量过程不确定度的来源,建立数学模型,计算合成标准不确定度和扩展不确定度。结果 樟脑和薄荷脑分别在8.56~85.6μg/ml、11.2~112.0 μg/ml质量浓度范围内线性关系良好,樟脑平均加样回收率100.20%、RSD为0.892%（n=9）,薄荷脑平均加样回收率99.65%、RSD为1.369%（n=9）;扩展不确定度分别为0.630 mg/ml （k=2）、0.656 mg/ml （k=2）,樟脑含量为（20.74±0.630） mg/ml、薄荷脑含量为（20.48±0.656） mg/ml。结论 气相色谱方法准确、灵敏、重现性好,可用于复方樟脑搽剂中樟脑和薄荷脑含量测定;不确定度评定有利于进一步提高含量测定的准确性。     

复方对乙酰氨基酚片溶出度方法研究及溶出行为评价

目的 建立复方对乙酰氨基酚片的溶出度方法并对不同样品进行溶出曲线评价。方法采用HPLC法,使用Sepax Amethyst C18-H(4.6×150mm,5μm)色谱柱,以磷酸盐缓冲液（取0.01mol/L磷酸二氢钾溶液,用磷酸调节pH值至2.6±0.1）-甲醇（70：30）;流速：1.0ml/min;柱温：35℃;检测波长：波长切换,0～12.5min,波长为275nm,12.5～16min,波长为303nm;溶出度试验采用桨法,以900ml盐酸溶液（稀盐酸24ml,加水至1000ml）为溶出介质,转速为50r?min-1。结果 在本文色谱条件下,阿司匹林和水杨酸分别在12.54～501.60μg?ml-1(r=1.0000)和0.99～39.76μg?ml-1(r=0.9999)范围内线性关系良好;低、中、高3种浓度的平均回收率分别为98.9%、96.7%、97.7%,RSD分别为0.46%、0.65%、0.31%;溶出度方法较好地反映了不同厂家复方对乙酰氨基酚片溶出行为的差异。结论 建立的HPLC溶出度测定方法简单方便,具有较好的专属性、精密度和准确度,溶出方法较好地体现了不同厂家样品间的差异。     

基于pH梯度载药技术的咪喹莫特脂质体的制备工艺研究

目的 根据咪喹莫特的理化性质,利用pH梯度主动载药技术制备脂质体,考察其性状、粒径、表面电荷及体外释药特征。方法 葡聚糖凝胶滤过法测定脂质体的包封率,以包封率与成型性为主要指标筛选制备方法,考察水化液的种类、pH值、离子强度及pH梯度载药、磷脂-胆固醇比例、脂药比、维生素E用量对包封率的影响;正交试验优化咪喹莫特脂质体的处方,考察脂质体样品在0~4℃下的稳定性。结果 按处方咪喹莫特50 mg、大豆卵磷脂400 mg、胆固醇130 mg、油酸10 mg、维生素E 5 mg、柠檬酸pH 2.5缓冲液5 mL,采用薄膜分散法工艺制备脂质体样品,并进行pH梯度主动载药,pH值调至7.0。制得的咪喹莫特脂质体呈白色均匀的混悬液,脂质体微粒圆整,分散性好,粒径（347±21）nm,包封率（81.2±1.9）%,Zeta电位（-12.19±1.7）mV。结论 pH梯度主动载药技术适于咪喹莫特脂质体的制备。     

补肝散不同分离组份抗抑郁活性筛选

目的 对补肝散醇提物不同分离组份的抗抑郁活性进行筛选。方法 采用慢性不可预知温和应激（chronicunpredictable mild stress,CUMS）对小鼠进行为期8周的造模,造模4周后,分别以盐酸帕罗西汀（paroxetine hydrochloride,PX）、补肝散醇提物、石油醚（A）、二氯甲烷（B）、乙酸乙酯（C）及正丁醇（D）4个分离组份进行为期4周的灌胃治疗,考察各组小鼠的行为学及脑内神经递质含量的变化。结果 连续给药4周（造模8周）后,PX组（0.026 g·kg^-1）、补肝散醇提物组（1.92 g·kg^-1）及其分离组份C（0.232 g·kg^-1）、D（1.04 g·kg^-1）和B（0.160 g·kg^-1）组均能明显逆转模型小鼠的抑郁表现如糖水偏好率下降、强迫游泳不动时间延长等抑郁症状。能不同程度地增加其脑内额叶皮质中5-羟色胺和多巴胺的含量,其中PX、醇提物及分离组份C的作用更为明显（与模型组比较,P<0.05或<0.01）。结论 补肝散醇提物的抗抑郁活性部位主要集中于乙酸乙酯和正丁醇分离组份,其次是二氯甲烷分离组份。     

Non-destructive profiling of volatile organic compounds using HS-SPME/GC–MS and its application for the geographical discrimination of white rice

The authenticity determination of white rice is crucial to prevent deceptive origin labeling and dishonest trading. However, a non-destructive and comprehensive method for rapidly discriminating the geographical origins of white rice between countries is still lacking. In the current study, we developed a volatile organic compound based geographical discrimination method using headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC–MS) to discriminate rice samples from Korea and China. A partial least squares discriminant analysis (PLS-DA) model exhibited a good classification of white rice between Korea and China (accuracy = 0.958, goodness of fit = 0.937, goodness of prediction = 0.831, and permutation test p-value = 0.043). Combining the PLS-DA based feature selection with the differentially expressed features from the unpaired t-test and significance analysis of microarrays, 12 discriminatory biomarkers were found. Among them, hexanal and 1-hexanol have been previously known to be associated with the cultivation environment and storage conditions. Other hydrocarbon biomarkers are novel, and their impact on rice production and storage remains to be elucidated. In conclusion, our findings highlight the ability to rapidly discriminate white rice from Korea and China. The developed method maybe useful for the authenticity and quality control of white rice.     

Multiseed liposomal drug delivery system using micelle gradient as driving force to improve amphiphilic drug retention and its anti-tumor efficacy

To improve drug retention in carriers for amphiphilic asulacrine (ASL), a novel active loading method using micelle gradient was developed to fabricate the ASL-loaded multiseed liposomes (ASL-ML). The empty ML were prepared by hydrating a thin film with empty micelles. Then the micelles in liposomal compartment acting as ‘micelle pool’ drove the drug to be loaded after the outer micelles were removed. Some reasoning studies including critical micelle concentration (CMC) determination, influencing factors tests on entrapment efficiency (EE), structure visualization, and drug release were carried out to explore the mechanism of active loading, ASL location, and the structure of ASL-ML. Comparisons were made between pre-loading and active loading method. Finally, the extended drug retention capacity of ML was evaluated through pharmacokinetic, drug tissue irritancy, and in vivo anti-tumor activity studies. Comprehensive results from fluorescent and transmission electron microscope (TEM) observation, encapsulation efficiency (EE) comparison, and release studies demonstrated the formation of ML-shell structure for ASL-ML without inter-carrier fusion. The location of drug mainly in inner micelles as well as the superiority of post-loading to the pre-loading method , in which drug in micelles shifted onto the bilayer membrane was an additional positive of this delivery system. It was observed that the drug amphiphilicity and interaction of micelles with drug were the two prerequisites for this active loading method. The extended retention capacity of ML has been verified through the prolonged half-life, reduced paw-lick responses in rats, and enhanced tumor inhibition in model mice. In conclusion, ASL-ML prepared by active loading method can effectively load drug into micelles with expected structure and improve drug retention.     

Can we estimate the critical micelle concentration of amphiphilic drug bases from molecular connectivity indices?

Self-aggregation of drugs is since many years an important topic in the pharmaceutical sciences. Drugs can aggregate similar to surfactants and thereby exhibit a critical micelle concentration (CMC). The present work focused on amphiphilic drug bases and it was aimed to predict log(CMC) based on chemical structure alone. A dataset of 35 compounds was gathered mostly form the literature and complemented with own measurements based on ultrasonic resonator technology. The hydrophilic–lipophilic balance (HLB) values of the protonated bases were calculated and provided a range of 22.9–27.4. Based on a hypothesis from surfactant sciences, it was tried to predict log(CMC) with connectivity and shape indices as well as molecular dipole moment. A fairly good model was obtained using the Randix index (RI), 3?D Wiener number (WN) and molecular dipole moment (DM) (R²?=?0.824). Interestingly, a simple linear regression of log(CMC) with the Randic index alone, resulted in an acceptable model (R²?=?0.755). The present work should help with early identification of drug bases that exhibit surfactant-like behavior and an estimation of log(CMC) values is proposed. An improved understanding of drug aggregation and prediction of log(CMC) helps to better cope with physical consequences like, for example, “anomalous” drug solubility in drug discovery and development.     

Synthesis,biological evaluation and in silico molecular docking of novel 1-hydroxy-naphthyl substituted heterocycles

The versatile precursor 2-acetyl-4-allyl-1-hydroxy naphthalene was synthesized efficiently via Claisen rearrangement 2-acetyl-1-allyloxynaphthalene. The Claisen-Schmidt condensation of latter precursor afforded the corresponding chalcones which were exploited to synthesize a series of potential heterocycles such as pyrazoline, isoxazoline, benzocoumarin and benzoflavone. The synthesized products showed potent antioxidant and antimicrobial activities. Chalcone 3c, naphthyl pyrazoline 6b and hydroxycoumarin 13 exhibited the highest activity as antioxidants. Their binding mode showed specialized recognition of hydroxycoumarin 13 with the triad key amino acids at the active site of the oxidoreductase enzyme (PDB code 1DXO). 1-Hydroxynaphth-2-yl pyrazoline (6b) revealed the highest efficacy against both Gram positive and negative bacterial species. In silico molecular docking of pyrazoline 6b endorsed its proper binding at the active site of the 2EX6 enzyme which explains its potent antibacterial activity in comparison with standard ampicillin.