Antiprotozoal and Anthelmintic Naphthoquinones from Three Unexplored Species of Diospyros

Abstract

The genus Diospyros is a rich source for napthols and naphthoquinones. During the study, we have chemically examined the roots of three unexplored species of Diospyros, D. oocarpa, D. nigresence and D. candolleana for their chemical profile and biological activities. The plant materials on conventional extractions with organic solvents and sequential chromatography yielded seven naphthoquinone derivatves, habibone [1], 8'-hydroxyisodiospyrin [2], diospyrin [3], 4-hydroxy-5-methoxy-2-naphthaldehyde [4], 5-hydroxy-4-methoxy-2-naphthaldehyde [5], 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde [6], and 2-methyl anthraquinone [7]. These isolates were characterized by spectral data (2D NMR, ¹H-¹H COSY and ¹³C-¹H COSY). In addition, these compounds were evaluated for their potential to inhibit parasitic protozoa belonging to the genera Trypanosoma, Leishmania and Plasmodium using in vitro antiprotozoal assay and anthelmintic activity against adult earth worms, Pheretima posthuma. The study showed that the isolates enjoy significant anthelmintic and antiprotozoal activity and supports its use in folk medicine.