Cytotoxic Mannich bases of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones

A series of 12 new Mannich bases with chalcone core structure were synthesized as potential antineoplastic agents, via N-aminomethylation of two parent 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones. The newly synthesized compounds as well as the chalcone prototypes were evaluated for cytotoxicity in the human pre-B-cell leukemia cell line BV-173 using the MTT-dye reduction assay. The tested compounds exhibited concentration-dependent cytotoxic effects at low micromolar concentrations. Ten of the Mannich bases characterized by significant activity in BV-173 were further evaluated against the chronic myeloid leukemia cell line K-562 and were found to suppress the growth of these cells at relatively higher concentrations as compared to the former tumor model. Selected Mannich bases induced programmed cell death in BV-173 at a concentration of 2.5muM as evidenced by the encountered DNA-laddering. Taken together our data suggest that the presented heterocyclic chalcone derived Mannich bases necessitate detailed pharmacological evaluation in order to define further the structure activity relationships, in a larger spectrum of tumor models and to elucidate the mechanisms implicated in the observed cytotoxic effects.

Matrix-assisted laser desorption/ionization, fast atom bombardment and plasma desorption mass spectrometry of polyethylene glycol esters of (2-benzothiazolon-3-yl)acetic acid

Fast atom bombardment (FAB), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and plasma desorption (PD) mass spectra of newly synthesized polyethylene glycols (PEGs), (M(w) 600-4000 Da) chemically modified with biologically active (2-benzothiazolon-3-yl)acetyl end-groups are described (products 1-6). The spectra were also used for the determination of the molecular mass characteristics (number average (M(n)) and weight average (M(w)) molecular masses) of the initial and modified PEGs. As expected, M(n) and M(w) of the modified samples are higher than those of the non-modified samples. However, it is shown that molecular mass dispersity (determined by the comparison of the polydispersity indices (PDI = M(w)/M(n)) of both types of PEGs) essentially do not change during this modification. The FAB mass spectra, together with molecular species, show the presence of abundant [M + Na](+) ions of product 1 and [M + Na + H](+) species of 2 and 3, and [M + Na + 2H](+) of product 4. Two main series of fragment ions, derived from the cleavage of the ether bonds, are observed. The number fractions of the molecular adduct ions and fragment adduct ions, determined from the FAB and PD mass spectra of the modified PEGs, are compared. The MALDI-TOF mass spectra of compounds 1-6 show the presence of two series of polymers. The most abundant peaks are due to [M + Na](+) and [M + K](+) ions originating from the polymers, in which the two terminal hydroxyl groups of PEGs are esterified with (2-benzothiazolon-3-yl)acetic acid. The less abundant peaks are due to the monosubstituted polymers.

Penicillin amidase-catalysed transfer of low specific acyl moiety. Synthesis of 7-benzoxazolonylacetamido desacetoxycephalosporanic acid

The methyl ester of 2-benzoxazolon-3-yl-acetic acid was used as an acyl donor in the penicillin amidase-catalysed transfer reaction to 7-aminodesacetoxycephalosporanic acid. The synthesis of 7-(2-benzoxazolon-3-yl-acetamido)-desacetoxycephalosporanic acid was carried out as a kinetically controlled reaction. A characteristic feature of this system is that the benzoxazolone derivatives are very low specific substrates for penicillin amidase (the kcat/Km values for their hydrolysis were shown to be 10(5)-fold lower compared to the corresponding values for phenylacetyl derivatives). Nevertheless, penicillin amidase proved to be an effective catalyst for the synthesis of these new cephem derivatives (50% yield for 6 h). The reason is the observed unusually high value for the transferase-hydrolase activity ratio. The determined value for (k3'/k3)app = 120,000 implies that in this case of low specific acyl moiety, penicillin amidase acts more like a transferase than a hydrolase. The maximum yield has been increased up to 70% by lowering the reaction temperature and stepwise feeding of the reaction medium with the acyl component. The results obtained extend the potential of the penicillin amidase as a catalyst for the synthesis of a new group of biologically active cephem derivatives.

Synthesis and antimicrobial evaluation of some cephem derivatives

Two novel cephem derivative series were synthesized: 7-(D-alpha-aminophenyl-acetamido-)-3-methyl-3-cephem-4-carboxylic acid monohydrate (Cephalexin) derivatives and those of 7-amino-3-(1-methyl-1H-tetrazol-5-yl)-thio methyl-3-cephem-4-carboxylic acid (7-AMTCA). The antimicrobial activity of the prepared compounds was studied and compared to that of known cephalosporin antibiotics of the first generation against 12 standard strains and 189 clinical isolates of Gram-positive and Gram-negative microorganisms. The Cephalexin derivatives 4a-f show a narrow activity spectrum and are inactive while 5c and 5d are more active than the Cephalexin and Cephazolin antibiotics against clinically isolated S. aureus and S. epidermidis strains.

Synthesis and in vitro activity of new cephalosporin derivatives containing a benzoxazolone ring

New cephalosporin derivatives containing a benzoxazolone ring in the side acylamino chain are synthesized using chlorides of non-substituted and halogen substituted (2-benzoxazolone-3-yl) acetic acids for the acylation of the 7-aminodesacetoxy-cephalosporanic acid and 7-amino-cephalosporanic acid amino group. Some of these new compounds exhibit a biological activity higher than that of cephalexin and cephazolin against clinical strains of Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus group A and B.