Studies on acridone derivatives with and without inclusion complex formation with β-cyclodextrin

Using keto group of acridone pharmacophore, three important acridone derivatives namely thiosemicarbazone, semicarbazone and oxime have been synthesised which have significant antimicrobial activity. In order to increase the bio-accessibility of these compounds, inclusion complexes have been prepared with a non-toxic oligosaccharide, beta-cyclodextrin. The synthesis of derivatives and their inclusion complexes have been ascertained from the changes in spectral characteristics and melting point data. The aqueous phase solubility studies reveal 1:1 stoichiometry between the compound and beta-cyclodextrin in the inclusion complex. The calculation of thermodynamic parameters Delta G (change in free energy), Delta H (change in enthalpy) and Delta S (change in entropy) of the complexes indicates the inclusion complex formation to be spontaneous and exothermic in nature. The determination of thermodynamic stability constants suggests existence of weak intermolecular forces in between host and guest in the inclusion complex. The study of antimicrobial activity indicates that the microbes like E. coli and P. aeruginosa are susceptible to acridone and its derivatives and the susceptibility increases further after the formation of inclusion complexes.