Abstract

ASSESSMENT OF ACUTE AND SUBACUTE TOXICITY OF AQUEOUS EXTRACT AND IN VITRO SUSCEPTIBLITY OF EXTRACTS AND ISOLATED INDOLOQUINOLINE ALKALOIDS FROM CRYPTOLEPIS SANGUINOLENTA (LINDL.) SCHLECHTER (PERIPLOCACEAE) ROOT BARK TO ENTAMOEBA HISTOLYTICA

Cimanga K. R.*, Makila B. M. F., Kambu K. O., Tona L. G., Vlietinck A. J.3 and Pieters L.

ABSTRACT

Aqueous and 80% methanol extracts from Cryptolepis sanguinolenta root bark and their alkaloids were submitted to an evaluation for their potential amoebicidal activity against Entamoeba histolytica. Results indicated that aqueous and 80% methanol extracts exhibited pronounced amoebicidal activity with minimal amoebicidal concentrations (MAC) of 6.25 and 4.15 μg/ml respectively and with inhibitory concentrations 50 (IC50) of 4.02 and 2.87 μg/ml respectively. Among isolated indoloquinoline alkaloids, cryptolepine, the major alkaloid of this plant part and its isomer neocryptolepine showed pronounced amoebicidal activity with MAC values of 3.12 and 1.87 μg/ml, and IC50 values of 3.27 and 2.07 μg/ml respectively. Other monomeric alkaloids such as cryptolepine HCl, hydrocryptolepine and quindoline displayed this activity with MAC and IC50 values ranging from 4.25 to 10.68 μg/ml with quindoline exhibing weak activity (MAC = 10.68 and IC50 =.8.65±0.03 μg/ml. The dimeric alkaloids biscryptolepine and cryptoquindoline also exhibited pronounced amoebicidal activity with MAC and IC50 values < 10 μg/ml, but their amoebicidal effect was weak compared to monomer alkaloids except quindoline which showed weak activity. The aqueous extract did not significantly modify the concentrations of haematological, biochemical parameters and weights of some vital organs. It increased the concentrations of some electrolytes in treated animals compared to untreated. The extract was found to be non-toxic, safe and well tolerated. These reported results constitute a irrefutable scientific base supporting and justifying the traditional use of C. sanguinolenta root bark for the treatment of amoebiasis in traditional medicine without signficant toxic effects.

Keywords: Cryptolepis sanguinolenta, root bark, amoebiasis, acute and sub-acute toxicity, indoloquinolinique alkaloids.