Antibacterial and Antifungal Activities of Novel β-lactam-anthraquinone Hybrids

Background and Objectives: β-Lactam antibiotics are the most important antibacterial agents for human health and it began with the discovery of penicillin by Alexander Fleming in 1928. In addition, β-lactams are an important class of heterocyclic compounds due to their wide range of applications in other biological activities. Β-Lactam antibiotics interferes with the synthesis of peptidoglycan, the major component of the rigid cell wall that protects bacteria from osmotic lysis . With the alarming trends in bacterial resistance to many β-lactam antibiotics it has become necessary to synthesize some novel β-lactams for bioassay of antibacterial activity and the need for drugs with more specific antibacterial activity. In vitro antibacterial studies of all synthesized compound were carried out against three gram-positive strains Staphylococcus aureus (Methicillin-resistant strain), Enterococcus faecium (Vancomycin-resistant strain) and Bacillus subtilis, and two gram-negative strains Escherichia coli and Pseudomonas aeruginosa. These compounds were further evaluated for their in vitro antifungal activity against Candida albicans, Aspergillusniger and Trichophytonmentagrophytes. Therefore, the synthesis of the new β-lactams is the subject of extensive study. The anthraquinone and related compounds have been represented as a broad and growing family of bioactive molecules. Materials and Methods: Novel β-lactam-anthraquinone hybrids were synthesized by ketene-imine cycloaddition and characterized by spectral data. Antibacterial and antifungal activities of these compounds against some gram-positive, gram-negative bacteria and some fungal were investigated using MIC method.Results: β-lactam-anthraquinone hybrid compounds showed moderate to excellent antibacterial and antifungal activities. Surprisingly, among the tested compounds, some of them revealed equal antibacterialand antifungal properties and even better than standards .The results showed that the derivatives having methylthio substituent at C-3 of the β-lactam ring showed better antibacterial activity than other derivativesConclusion: All the synthesized β-lactam substituted anthraquinone showed good antibacterial activity. The overall antibacterial activity of the synthesized compounds may be attributed to the presence of β-lactam substituent in all the compounds. The variation in bioactivity may be due to the presence of anthraquinone moiety in the synthesized compounds.