Separation of ampicillin on polar-endcapped phase: Development of the HPLC method to achieve its correct dosage in cardiac surgery

The accurate, simple, and selective reversed phase high performance liquid chromatography (RP-HPLC) has been established and validated for the determination of an antibiotic ampicillin (AMP) in human blood plasma. The SPE extraction was used for the sample preparation. Chromatographic separation was accomplished by a mobile phase containing 15 mM monopotassium phosphate solution of pH 3.3 and methanol (75:25, v/v) in an isocratic mode at a flow rate of 1.4 mL min−1 at 30 °C. The separation was evaluated on a column with a new polar-endcapped C18 stationary phase Arion® Polar C18 or well-known phase Luna® Omega Polar C18. Excellent linearity (R 2 0.9998) was shown over range 10–300 mg L−1 with mean percentage recovery 90%. Peak shapes were symmetrical in both columns, Arion® Polar C18 and Luna® Omega Polar C18, with asymmetry factor of 1.0 and 1.4, tailing factor of 1.0 and 1.2, and retention factor of 4.6 and 5.6, respectively. The Arion® Polar C18 was almost 1.4-fold more effective than Luna® Omega Polar C18 phase. The LOQ for ampicillin was achieved 10 mg L−1 for Luna® Omega Polar C18 and 5 mg L−1 for Arion® Polar C18 using 20 µL of a solution containing 0.24 mg mL−1 of cephalexin as an internal standard.

A number of articles dealing with the determination of ampicillin is limited, therefore, this study showed the HPLC method suitable for the determination of AMP in human blood plasma from patient who underwent elective cardiac surgical revascularization. In addition, the determination of AMP was also performed for the first time using an Arion® Polar C18 column, which effectively separated AMP from other compounds present in human blood plasma. This new polar-endcapped phase can help in separation of polar antibiotics or other polar compounds, which are unsuccessfully separated on conventional C18 column, and thus can help during method development.

Prediction of Terpenoid Toxicity Based on a Quantitative Structure-Activity Relationship Model

Terpenoids, including monoterpenoids (C10), norisoprenoids (C13), and sesquiterpenoids (C15), constitute a large group of plant-derived naturally occurring secondary metabolites with highly diverse chemical structures. A quantitative structure-activity relationship (QSAR) model to predict terpenoid toxicity and to evaluate the influence of their chemical structures was developed in this study by assessing in real time the toxicity of 27 terpenoid standards using the Gram-negative bioluminescent Vibrio fischeri. Under the test conditions, at a concentration of 1 µM, the terpenoids showed a toxicity level lower than 5%, with the exception of geraniol, citral, (S)-citronellal, geranic acid, (±)-α-terpinyl acetate, and geranyl acetone. Moreover, the standards tested displayed a toxicity level higher than 30% at concentrations of 50-100 µM, with the exception of (+)-valencene, eucalyptol, (+)-borneol, guaiazulene, β-caryophellene, and linalool oxide. Regarding the functional group, terpenoid toxicity was observed in the following order: alcohol > aldehyde ~ ketone > ester > hydrocarbons. The CODESSA software was employed to develop QSAR models based on the correlation of terpenoid toxicity and a pool of descriptors related to each chemical structure. The QSAR models, based on t-test values, showed that terpenoid toxicity was mainly attributed to geometric (e.g., asphericity) and electronic (e.g., maximum partial charge for a carbon (C) atom (Zefirov's partial charge (PC)) descriptors. Statistically, the most significant overall correlation was the four-parameter equation with a training coefficient and test coefficient correlation higher than 0.810 and 0.535, respectively, and a square coefficient of cross-validation (Q2) higher than 0.689. According to the obtained data, the QSAR models are suitable and rapid tools to predict terpenoid toxicity in a diversity of food products.

Synthesis, potent anti-staphylococcal activity and QSARs of some novel 2-anilinobenzazoles

Synthesis and anti-staphylococcal activity of a number of substituted 2-anilinobenzimidazoles, benzothiazoles and benzoxazoles are reported. The anti-staphylococcal activities were evaluated in standard in vitro MIC assay method. While anilinobenzimidazole derivatives 11-45 showed very potent anti-staphylococcal activities (greatest activity with an MIC value of 0.095 microg/mL), none of the 2-anilinobenzothiazoles and benzoxazole derivatives exhibited inhibitory activity. QSAR analysis of the anilinobenzimidazoles was studied on the relationship between the anti-staphylococcal activity (MIC in mug/ml) and extrapolated log k(w) values.