Ethnobotanical, phytochemical and biological investigations on medicinal plants used by the Nkundo (Bandundu, DR Congo)

Date: 16 January 2017

Venue: UAntwerp, Campus Drie Eiken, Building S - Universiteitsplein 1 - 2610 Antwerp (Wilrijk) (route: UAntwerpen, Campus Drie Eiken)

Time: 3:00 PM - 5:00 PM

PhD candidate: Crispin-Désiré Musuyu Muganza

Principal investigator: Luc Pieters

Co-principal investigator: Cimanga Kanyanga - Barbara Fruth

Short description: Phd defence Crispin-Désiré Musuyu Muganza - Department of Pharmaceutical Sciences



The present study was carried out to evidence the efficacy and safety of extracts from some selected medicinal plants used in traditional treatment of infectious and parasitic diseases by the Nkundo people of Bandundu, one of the DR Congo provinces, where malaria and sleeping sickness are both prevailing. Antiprotozoal and larvicidal tests were used to estimate the activity of selected plant extracts.

Results showed that aqueous extracts from Quassia africana (root bark and stem bark) were most active (IC50 0.46 and 1.27 µg/ mL; selectivity indices SI 13.7 and 13.6, respectively) towards Plasmodium falciparum K1 (PfK1), whereas Isolona hexaloba stem bark extract was most potent against Trypanosoma brucei brucei (IC50 1.95 µg/ mL, SI 16.5). Many interesting fractions were obtained from 80% EtOH extracts of different parts of Greenwayodendron suaveolens and Isolona hexaloba. The root bark alkaloid fraction of G. suaveolens exhibited pronounced activities (IC50 ≤0.75 µg/ mL) against all tested protozoa without cytotoxicity on a mammalian cell line. The stem bark alkaloid fraction showed a similar activity towards PfK1 (IC50 0.27 µg/ mL; SI >237), as well as the polyphenolic fraction from I. hexaloba leaves. These results can justify at least in part the use of these plant species in ethnomedicine e.g. against malaria.

Four constituents were isolated from the 90% MeOH fraction of the G. suaveolens root bark extract: polycarpol, dihydropolycarpol (a new compound), polyalthenol, and N-acetyl-polyveoline (highest activity against PfK1, IC50 2.8 µM, SI 10.9). In general, it appeared that any of the isolated compounds could reach the activity and the level of selectivity displayed by most active extracts and fractions.

With regard to the larvicidal activity as a contribution to vector control, globally the sensitivity of the tested larvae towards plants extracts was ranged as follows: Culex quinquefasciatus > Anopheles gambiae > Aedes aegypti. The 80% EtOH extracts were more active than the corresponding aqueous ones. The most active extracts came from Crossopteryx febrifuga, Penianthus longifolius, Piper guineense and Quassia africana.

As a contribution to the field of zoopharmacognosy, self-medication behavior in Bonobos using swallowed unchewed hispid leaves and stemstrips of Manniophyton fulvum, a valuable medicinal plant, was explored and confirmed with the fulfillment of four Huffman’s criteria indicative of self-medication in animals. By exploring self-medication behavior in animals, in complement to the ethnomedicinal approach, it is possible to discover novel medical benefits, and apply them towards modern medicine.