A new antimicrobial anthrone from the leaf latex of Aloe trichosantha

Phytochemical investigation of the leaf latex of Aloe trichosantha by preparative TLC gave two closely related anthrones, aloin A/B (1) and aloin-6'-O-acetate A/B (2). The identity of the compounds was established from HRESI-MS, 1H, 13C, DEPT, HMQC and HMBC spectral and chemical data. Whilst aloin A/B occurs in several Aloe species, aloin-6'-O-acetate A/B was isolated for the first time. The isolated compounds inhibited growth of several bacterial and fungal pathogens with minimum inhibitory concentration (MIC) from 10 to 400 microg/mL and 800 to 1000 microg/mL, respectively.