ISOLATION OF FOUR FUROQUINOLINE ALKALOIDS FROM TECLEA NOBILIS AND THEIR ACTIVITY AGAINST SCHISTOSOMA MANSONI MIRACIDIA

Abstract

Schistosomiasis is one of the neglected diseases affecting approximately 200 million people worldwide. In this research, we isolated and evaluated the antimiracidial activity of secondary metabolites from Teclea nobilis (Rutaceae) which has been used ethnomedicinally against helminthes. Ethyl acetate extract was fractionated over silica gel column chromatography yielding four furoquinoline alkaloids which were identified through analysis of their 1D and 2D NMR, mass spectrometry data and comparison with literature data as; tecleoxine A, methylnkolbisine B, kokusaginine C and nkolbisine D. Serial dilutions of these compounds were exposed to Schistosoma mansoni miracidia. Compounds A, B and C were tested for bioassay and analyzed as a mixture because they were not resolved individually into purified forms due to their minimal amounts and close Rf values. Miracidial mortality was determined after 30 minutes under a dissecting microscope. Log probit regression analysis at 95% confidence level was used to calculate LC₅₀ and LC₉₀ using IBM SPSS version 21.0 software. Compounds A, B and C mixture were the most potent with LC₅₀ and LC₉₀ values of 270.2 and 690.9 ppm, respectively. Synergism could have been the reason for the high potency. Compound B was the least potent with mortality recorded LC₅₀ and LC₉₀ values of 287.9 and 631.7 ppm, respectively. These findings indicate that these compounds could be useful as lead compounds for the development of schistosomicide. Also, considering that a large number of human populations, mostly from poor backgrounds, suffer chronic schistosomiasis, the discovery of plant compounds that may control schistosomiasis could be of great value.

Key words: alkaloids, miracidial activity, Schistosoma mansoni and Teclea nobilis