Isolation, Characterization and Antitrypanosomal Evaluation of a Proposed Pentaglycosylated-7,4’Dimethoxy Kaempferol Derivative from Ethanol Extract of Vernonia Perrottettii Promising Against Trypanosoma Parasite.

Abstract

Human African Trypanosomiasis (HAT) remains a significant public health challenge despite 
considerable progress in disease control and management. The continued emergence of drug
resistant Trypanosoma strains, coupled with the severe adverse effects associated with 
many existing chemotherapeutic agents, has limited the long-term effectiveness of current 
treatment strategies. Resistance mechanisms have been linked to mutations in P2 and AQP2 
transporters, deletion or modification of genes encoding these transport proteins, and, in 
some cases, enhanced drug efflux mechanisms. Consequently, the search for novel, safe, and 
effective antitrypanosomal agents from natural sources remains an important area of 
research. This study investigated the phytochemical composition and trypanocidal potential 
of Vernonia perrottettii leaf extract, a medicinal plant traditionally employed in Northern 
Nigeria for the treatment of HAT. Fresh leaves were collected, authenticated, air-dried, 
pulverized, and extracted by ethanol maceration. Qualitative phytochemical screening of the 
crude extract was conducted using standard analytical procedures. The results revealed the 
presence of alkaloids, flavonoids, terpenoids, phenols, tannins, saponins, and cardiac 
glycosides. Bioactive constituents were isolated through silica gel (200 mesh) column 
chromatography, leading to the purification of a compound structurally characterized and 
predicted as a pentaglycosylated-7,4′-dimethoxy kaempferol derivative. The isolated 
compound was subsequently evaluated for in vitro trypanocidal activity using the Nigerian 
Institute for Trypanosomiasis Research (NITR) assay protocol. The compound exhibited 
significant antitrypanosomal activity with an IC₅₀ value of 0.335 μM, demonstrating potency 
comparable to the reference drug, Diminazene diaceturate (IC₅₀ = 0.24 μM). These findings 
highlight the therapeutic potential of the isolated flavonoid derivative as a promising lead 
compound for HAT drug development and warrant further investigation through in vivo 
efficacy, toxicity, and cytotoxicity studies.