Ab initio study of the Trinem antibiotic Sanfetrinem GV104326

Quantum mechanical calculations of the cephalosporin nucleus

A computational study using several ab initio methods, HF, DFT and MP2 at different basis set levels (6-31G*, 6-31G**, 6-311G** and 6-311++G**) has been performed to determine the possible stable conformations attained by the cephalosporin nucleus. The calculations were carried out in three stages by studying the conformational analysis of the 3-cephem nucleus, the 3-cephem-4-carboxylic acid nucleus and the acetylamino group of the 7-acetylamino-3cephem-4-carboxylic acid. In the first two stages, the potential energy surfaces indicated two minima that correspond to the S1-up and C2-up conformations, with the S1-up being more stable. The energy required for the interconversion of the S1-up to the C2-up is around 7 kcal/mol, indicating the feasibility of interconversion between the two conformers. In the third stage, the acetylamino group attained two conformations with respect to the 3-cephem nucleus. All the geometric parameters obtained in this study were found to be in reasonably good agreement with available X-ray diffraction data, even upon using a simple basis set.

Vibrational spectra study on quinolones antibiotics

In order to be able to fully understand and easily identify the quilonoles, we collected IR and Raman spectra of six quinolones, and attempted to assign the attribution of the observed frequencies and their association with specific modes of vibration. According to the structure, the compounds were divided into the groups, and the similarities and differences were further studied by comparing. The result of the study shows that the frequency and intensity are comparable to the corresponding structure. The spectra not only have the commonness but also the individualities.

Molecular Modeling and Chemical Reactivity of Sanfetrinem and Derivatives

The indiscriminate use of beta-lactams has considerably diminished their efficiency as a result of bacteria developing effective defense mechanisms against them. Recent pharmaceutical research has led to the synthesis of tricyclic beta-lactam antibiotics known as "tricyclic carbapenems" or "trinems". In this work, we studied the chemical reactivity, an essential property for antibiotic action, of trinems and found it to be similar to that of cephalosporins. Also, we elucidated the interaction pattern for sanfetrinem and 4beta-methoxy trinem and compared it to that for classical beta-lactams. The behavior of both trinems was found to be similar to that of penicillin G toward Staphylococcus aureus PC1, and that of cephalothin and imipenem toward Enterobacter cloacae P99.