α,β-DIBROMOCHALCONE DERIVATIVES--SYNTHESIS AND ANTIMICROBIAL ACTIVITY

AIM

To obtain some chalcones and their dibrominated analogues and to evaluate their antimicrobial potential.

MATERIAL AND METHODS

Eight chalcones were synthesized using the Claisen-Schmidt condensation of acetophenone/4-bromo-acetophenone and different benzaldehyde derivatives. These chalcones were further brominated using two different bromination agents: molecular bromine and pyridinium tribromide. The antimicrobial activity was tested using the disk diffusion method.

RESULTS AND DISCUSSIONS

The classical bromination technique was compared to the eco-friendly one using pyridinium tribromide. Pyridinium tribromide bromination did not improve the reaction yields (except for one compound), but it had the advantage of being a stable, non-corrosive and non-toxic salt. The results of the antimicrobial assessment indicated that the bromination of the double bond slightly increased the antimicrobial potential in some cases, but the results obtained during the antimicrobial evaluation were modest, some of the derivatives being active especially on Sarcina lutea ATCC 9341 and Bacillus cereus ATCC 14579.

CONCLUSIONS

In this study, eight chalcones and their dibrominated analogues were synthesized, four of the α,β-dibromochalcones being reported for the first time. Pyridinium tribromide was used as an alternative for liquid bromine, the main advantage of this method being related to the reduced toxicity of the reagents. The synthesized compounds did not exhibit a very good antimicrobial potential.

[Antimicrobial activity of some cinnamic acid derivatives]

Due to drug-resistance phenomenon, there is a constant need for discovering new antiinfectious agents. A series of cinnamic acid derivatives was synthesized and then brominated with bromine in the presence of chloroform or acetic acid. The structure of the new compounds was confirmed by elemental and spectral data. Their antimicrobial activity was tested by disc-diffusion method. The tested compounds had mainly antifungal activity and were moderately active against Gram-positive bacteria. Bromination of the double bond determined the enhancement of the antimicrobial activity for all the tested compounds.

Characterization of some extractive fractions isolated from raw Allium cepa L. bulbs

Many recent studies have showed that onion (Allium cepa L.) has antioxidant effect which could be of great importance for prevention and treatment of different diseases: diabetes, cancer, cardiovascular and neurodegenerative disorders. The aim of this study was to investigate the antioxidant capacity of two extracts isolated from fresh onion bulbs: an hydroalcoholic extract (codified EC1) and an aqueous extract (codified EC2).

METHODS

Antioxidant capacity was evaluated by three different assays: DPPH scavenging assay, H2O2, scavenging assay and reducing power assay.

RESULTS

Both investigated extracts possess interesting antioxidant properties which are significantly influenced by their chemical composition.

Synthesis and characterization of some new bishydrazones derived from isatin

The scientific literature states that isatin and its derivatives exhibit antibacterial, antifungal, anticonvulsant, cytotoxic and anti-HIV activities. The aim of our study was to enlarge the number of isatin derivatives.

MATERIAL AND METHOD

We synthesized some new hydrazones and then, the corresponding bishydrazones using salicylaldehyde. By condensing isatin and its derivatives (methyl-, nitro-, brom-) with hydrazine, corresponding hydrazones were obtained. The bishydrazones were synthesized by refluxing the obtained hydrazones with salicylaldehyde in methanolic solution. The structure of new compounds was confirmed by elemental and spectral analysis. The lipophilicity of the synthesized derivatives was expressed by clog P values. The antibacterial and antifungal activities of the compounds were determined using disk-diffusion method against Gram positive, Gram negative bacteria, and Candida albicans.

RESULTS

New bishydrazines derived from isatin have been synthesized; their structures have been confirmed by elemental and spectral analysis.

[Research concerning the characterization of Allium cepa based ointments]

Three topical formulae with Allium cepa L. extract 30% (w/w) were studied for the evaluation of their release profiles of flavonoids and for their potency on experimental wounds on mice. The rates of release were performed under occluded conditions using cellulose acetate membrane. Data obtained from the in vitro release show that the gel formula F1 is the most efficient in the membrane diffusion process. The rate of wound healing was assessed by the contracting ability and the period of epithelization. The most important effect in the contracting ability was noticed in the case of F2 formula.

[Phytochemical and microbiological characterization of two Allium cepa L. extracts in order to include in dermo-cosmetics]

We have obtained two Allium cepa extracts (C1 and C2) which were characterized from chemical and microbiological point of view. The C1 extract is the richest concerning the content in flavonoids, triterpenic acids, amino acids, compounds recognized for their beneficial effects in wound healing. All this data shows us the possibility of using the Allium cepa extracts in the treatment of wounds, scars. As well, the antimicrobial activity of the two extracts was evaluated. The C2 extract was efficient as antimicrobial agent, but there are necessary special preserving conditions.