Toosendanin relatives, trypanocidal principles from Meliae Cortex

Abstract

Africa Trypanosomiasis remains a serious health problem, but the approved drugs for this disease are so few that novel trypanocidal compounds are demanded. In search for trypanocidal principles from medicinal plants, we found MeOH extracts of Meliae Cortex with potent activity through the screening from about 300 kinds of methanolic extract. By bioassay-guided fractionation from this extract through the liquid-liquid partition and subsequent chromatographic technique using silica gel and ODS, finally we disclosed toosendanin (1) and its relatives as active principles. These active congeners showed not only potent trypanocidal activity but also little cytotoxicity to display the excellent selective index. Taking the isolated amount as well as trypanocidal activity into consideration, 1 was disclosed to be the responsible active principle in Meliae Cortex. Additionally, the derivatives of 1 were chemically prepared from 1 and bioactivity of them were also evaluated. Through the comparison with their trypanocidal activity among the isolated relatives and the synthesized derivatives of 1, the epoxide moiety was revealed to be essential for their potent trypanocidal activity. Furthermore, 3-O-acetyl group and 7-hydroxyl group were presumed to be important functional groups and introduction of methylpropionyl group into hemiacetal hydroxy moiety was clarified to enhance their typanocidal activity.

Fexinidazole: First Global Approval

Abstract

Fexinidazole Winthrop (hereafter referred to as fexinidazole) is a DNA synthesis inhibitor developed by the Drugs for Neglected Diseases initiative (DNDi), in collaboration with Sanofi, for the oral treatment of human African trypanosomiasis (HAT) [commonly known as 'sleeping sickness'] and Chagas' disease. The drug is a 5-nitroimidazole derivative first discovered by Hoechst AG (now part of Sanofi) and was identified by the DNDi in 2005 as having activity against Trypanosoma brucei gambiense and T. b. rhodesiense. Under Article 58 of Regulation (EC) no. 726/2004 (a regulatory mechanism for reviewing new medicines destined for use outside of the EU), fexinidazole has been granted a positive opinion by the EMA for the treatment of both the first-stage (haemo-lymphatic) and second-stage (meningo-encephalitic) of HAT due to T. b. gambiense (g-HAT) in adults and children aged ≥ 6 years and weighing ≥ 20 kg. This approval will facilitate and support marketing authorization application in endemic countries in 2019; following registration, fexinidazole will be distributed via the WHO to endemic countries for g-HAT. Phase 3 evaluation of fexinidazole for g-HAT is ongoing in the Democratic Republic of the Congo and Guinea and the drug is also in development for Chagas' disease, with a study currently ongoing in Spain. Clinical development for visceral leishmaniasis is discontinued. This article summarizes the milestones in the development of fexinidazole leading to this first approval for g-HAT.