Isolation and physico-chemical studies on some alkaloids of cryptolepis sanguinolenta (periplocaceae)

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The root and stem extract of Cryptolepis sanguinolenta has long been used for the treatment of various ailments in the West African sub-region. This research piece seeks to investigate and establish certain physic-chemical properties of these alkaloids after their isolation. The alkaloids were isolated by both column and preparative thin layer chromatography. The structures of both cryptolepine and quindoline were confirmed by comparison of data obtained to those obtained by earlier workers. The structure of the third alkaloid CSA—3 was elucidated for the first time. The dissociation constant (pKa) of cryptolepine, was determined both spectrophotometrically and titrimetrically. The pKa of CSA-3 and quindoline were determined titriinetrically. The partition coefficients of the alkaloids were determined in octanol-buffer and octanol-water systems. The solubilities of cryptolepine and quindoline in octanol were determined. That of cryptolepine heptane and hexane was also investigated. However, cryptolepine was found to be insoluble in the non-polar solvents. The indicator properties of cryptolepine was investigated and established. Boric acid was successfully assayed using cryptolepine indicator. In non-aqueous titrations, the use of cryptolepine as an indicator was not feasible.
A thesis submitted to the Department of Pharmaceutical Chemistry, College of Health Sciences, in partial fulfilment of the requirements for the degree of Master of Science, 1993