Fig. (1) Chemical structure and mass spectrometric analysis of madurahydroxylactone. Chemical structure of MHL (3,9,11,14,15-pentahydroxy-7-methoxy-10-methyl-1,3,5,6,8,13-hexahydronaphthaceno [1,2-f] isobenzofuran-1,8,13-trione) [28]. (A). Electrospray ionization mass spectrometry of the madurahydroxylactone preparation used throughout the described experiments (B) and the simulated mass spectrum for [C26H18O10Na]+ (C) corresponding to the structure depicted in (A).