Characterization of a bioactive derivative of calophyllolide by 2D NMR and LC-MS/MS

This study details the characterization of a novel and an unexpected cyclization reduction product of Calophyllolide (I), by using sodium borohydride. The structure of the derivative (II) was established as 6,10,11-tetramethyl-4-phenyl-6, 10-dihydro-2H-dipyrano [2, 3-f: 2′, 3′-h] chromen-2-one by 2D NMR experiments such as 1H-1H gCOSY, gHSQC, gHMBC, and LC-MS/MS along with 1H and 13C NMR spectra. A reversed-phase HPLC method and a chiral HPLC method were developed to evaluate the purity and chirality. A reaction mechanism for II was proposed. The synthesized compound was showing significant antimicrobial activity than the parent compound (I) when tested against various pathogenic bacteria and fungus.