Antibacterial evaluation of novel organoarsenic compounds by the microcalorimetric method

A spectrum-effect based method for screening antibacterial constituents in Niuhuang Shangqing Pill using comprehensive two-dimensional liquid chromatography

To investigate and screen the active antibacterial constituents of Niuhuang Shangqing Pill (NSP), the current study developed a two-dimensional liquid chromatography (2DLC) method combining microcalorimetry technique. 60% ethanol extracts from 10 batches of different commercial NSP samples were analyzed and their chemical fingerprint were developed by the comprehensive 2DLC system of Shimadzu Nexera X2. Anti-streptococcus pneumoniae (SP) constituents were determined by microcalorimetry. Thermal kinetic parameters of the SP thermogram affected by 60% ethanol extracts from 10 NSP samples were analyzed by principal component analysis. Spectrum-effect correlation between comprehensive 2DLC fingerprint and the antibacterial activity were analyzed by orthogonal partial least squares (OPLS) and orthogonal partial least squares discriminant analysis (OPLS-DA). Findings showed that peak X1 (unknown), X9 (aloe-emodin), X10 (baicalein), X11 (unknown), X14 (wogonin), X15 (glycyrrhizic acid) and X17 (unknown) are the relevant components that are in positive correlation with inhibitory rate. Regarding inhibitory rate, X17 is the most powerful one, followed by X14, X15, X10, X11, X1 and X9, suggesting that compound X17, wogonin, glycyrrhizic acid and baicalein are the major active antibacterial components of NSP. The current method employing 2DLC with microcalorimetry technique proposes a new insight for screening and identifying antibacterial components in complex herbal formula.

Antibacterial evaluation of Salvia miltiorrhizae on Escherichia coli by microcalorimetry coupled with chemometrics

For seeking novel antibacterial agents with high efficacy and low toxicity to deal with drug resistance, the effects of Salvia miltiorrhizae from various sources on Escherichia coli were evaluated by microcalorimetry coupled with chemometrics. Firstly, the heat-flow power-time curves of E. coli growth affected by different S. miltiorrhizae samples were recorded. Then, some crucial quantitative thermo-kinetic parameters including growth rate constant, heat-flow power and heat output, etc. were obtained from theses curves and were further investigated by some powerful chemometric techniques including similarity analysis, multivariate analysis of variance, hierarchical clustering analysis and principle component analysis. By analyzing the principle parameters, growth rate constant of the second exponential phase (k 2) and the heat-flow output powers of the second highest peak (P 2), together with the derived parameter inhibitory ratio (I,  %), it could be quickly concluded that the tested S. miltiorrhizae samples from different sources in China exhibited strong antibacterial effects on E. coli and the samples from Beijing city exhibited the strongest anti-E. coli effects, which might be used as novel and underlying antibacterial candidates for the resistance of E. coli to the existing drugs in practice. This study provides a useful tool and helpful idea to accurately and rapidly evaluate the antibacterial effects of some complex matrices, offering some references for exploring new antibacterial agents.

Phenylarsine oxide (PAO) induces apoptosis in HepG2 cells via ROS-mediated mitochondria and ER-stress dependent signaling pathways

Arsenic trioxide (As₂O₃) is an old drug that has recently been reintroduced as a therapeutic agent for acute promyelocytic leukemia (APL). Although As₂O₃ is also applied to treat other types of cancer in vitro and in vivo, it has been reported that single agent As₂O₃ has poor efficacy against non-hematologic malignant cancers in clinical trials. Recently, a few reports have indicated that organic arsenic compounds can be a possible alternative for the treatment of As₂O₃-resistant cancers. In this study, we aimed to investigate whether the organic arsenic compound phenylarsine oxide (PAO) has potent cytotoxic effects against human hepatocellular carcinoma (HCC) HepG2 cells. Our results showed that PAO not only had a potent inhibitory effect on the proliferation of HepG2 cells but also activated apoptosis-related proteins (e.g., caspase-3 and -9 and poly-ADP ribose polymerase) in a dose- and time-dependent manner. Furthermore, intracellular ROS were specifically accumulated in the mitochondria and endoplasmic reticulum (ER) after exposure to PAO, implying that they are the target organelles for PAO-induced cytotoxicity. Additionally, when the cells were pretreated with antioxidant N-acetylcysteine (NAC), apoptosis and ER-stress were attenuated significantly, suggesting that induction of apoptosis and cell death probably occurs through the ROS-mediated mitochondria and ER-stress dependent signaling pathways.

Rat Liver Mitochondrial Dysfunction Induced by an Organic Arsenical Compound 4-(2-Nitrobenzaliminyl) Phenyl Arsenoxide

Arsenic is successfully used in cancer chemotherapy and several cancer treatments on account of its apoptogenic effects. However, it is environmentally hazardous with potential for toxicity when distributed in the soil, water, and food, and long exposure to water contaminated with Arsenic may induce cancers. Some research studies have reported that liver is the storage site and an important target organ for Arsenic toxicity. In the present work, a new kind of organic arsenic compound, 4-(2-nitrobenzaliminyl) phenyl arsenoxide (NPA), was synthesized, and its potential involvement of mitochondria was explored. The results presented that the toxicology of NPA, at least in part, mediated mitochondrial function and may thoroughly destroy mitochondrial membrane physiological functions. NPA induced mitochondrial permeability transition pore (mtPTP) opening that induces mitochondrial biochemical abnormalities as evidenced by mitochondrial swelling, mitochondrial membrane potential breakdown, membrane fluidity alterations, and the strikingly remarkable protection of CsA. Meanwhile, both the decreased respiration rate of state 4 and the increased inner membrane H(+) permeabilization revealed that the inner membrane function regarding important energy production chain was destroyed. The toxicity of NPA is due to its interaction with mitochondrial membrane thiol protein. This conclusion is based on the protective effects of RR, DTT, and MBM(+).