Improvement of water solubility and antibacterial activity of Calophyllum inophyllum resin and calophylloidic acid A via inclusion complexation with cyclodextrins

Indonesian Calophyllum inophyllum resin and its main component, calophylloidic acid A (1), have potent antibacterial activity against foodborne pathogens such as Staphylococcus aureus and Escherichia coli. However, their low water solubility makes their practical use difficult. Here, we investigated the formation of inclusion complexes of C. inophyllum resin and 1 with cyclodextrins (CDs). The inclusion complexes of C. inophyllum resin or 1 with CDs exhibited enhanced water solubility and antibacterial activity against S. aureus and E. coli compared to those of uncomplexed C. inophyllum resin or 1. Among the analyzed samples, α-CD inclusion complexes exhibited the strongest antibacterial activity. Furthermore, 1 and α-CD formed inclusion complexes at a molar ratio of 1:1. The improved water-solubilities and good antibacterial activity of the inclusion complexes will allow for their future application against foodborne pathogens.