STRUCTURE-ACTIVITY-RELATIONSHIPS OF SOME ANTIMICROBIAL 5-SUBSTITUTED 2-(3-PYRIDYL) BENZOXAZOLES USING QUANTUM-CHEMICAL CALCULATIONS


SENER E., TURGUT H., YALCIN I., OREN I., TURKER L., CELEBI N., ...More

INTERNATIONAL JOURNAL OF PHARMACEUTICS, vol.110, no.2, pp.109-115, 1994 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 110 Issue: 2
  • Publication Date: 1994
  • Doi Number: 10.1016/0378-5173(94)90148-1
  • Title of Journal : INTERNATIONAL JOURNAL OF PHARMACEUTICS
  • Page Numbers: pp.109-115
  • Keywords: 5-SUBSTITUTED 2-(3-PYRIDYL)BENZOXAZOLES, ANTIBACTERIAL ACTIVITY, ANTIMYCOTIC ACTIVITY, QUANTUM-CHEMICAL CALCULATIONS, STRUCTURE-ACTIVITY RELATIONSHIP, BENZIMIDAZOLES, OXAZOLO(4,5-B)PYRIDINES, BENZOTHIAZOLES, ANTIFUNGAL, AGENTS

Abstract

The synthesis and in vitro antimicrobial activity of 5-substituted 2-(3-pyridyl)benzoxazoles (3-7) is described for some Gram-positive and Gram-negative bacteria and the yeast Candida albicans. The compounds 3-7 exhibited significant activity against the screened microorganisms, having MIC values between 25 and 12.5 mu g/ml. Quantum-chemical calculations were performed for the compounds 1-10, in order to observe some feasible structure-activity relationships. These theoretical observations, calculated for the description of the mechanism of interactions at the molecular level, revealed that the electrophilic superdelocalizability of the nitrogen atom (S-N(E)) in the oxazolo moiety of the benzoxazole ring is related to the activity. The results obtained from the theoretical calculations and the observed MIC values shaw that 2-(3-pyridyl)- and 2-phenylbenzoxazole derivatives exhibit bio-isosteric effects for antimicrobial activity. Additionally, substituents at position 5 on the fused heterocyclic system contribute to the activity constructively or destructively depending on the type of microorganism screened.