Journal of Ethnopharmacology 80 (2002) 25 – 35 Screening of African medicinal plants for antimicrobial and enzyme inhibitory activity Jeannette Ndaya Tshibangu a , Kusamba Chifundera b , Ronald Kaminsky c , Anthony David Wright a , Gabriele Maria Ko ¨ nig a, * a Institute for Pharmaceutical Biology, Nussallee 6, D-53115 Bonn, Germany b Centre de Recherches en Sciences Naturelles Lwiro, Bukau, Congo c Swiss Tropical Institute, Socinstrasse 57, CH-4002 Basel, Switzerland Received 20 May 2001; received in revised form 10 November 2001; accepted 23 November 2001 Abstract Seven plant species, belonging to different families, were collected in the eastern part of the Republic of Congo (Kivu) based on ethnopharmacological information. Their dichloromethane and methanolic extracts were tested for biological activity. Five of the seven collected plants exhibited antiplasmodial activity with IC 50 values ranging from 1.1 to 9.8 g/ml. The methanolic extract of Cissampelos mucronata was the most active one showing activity against chloroquine sensitive (D6) and chloroquine resistant (W2) Plasmodium falciparum strains with IC 50 values of 1.5 and 1.1 g/ml, respectively. Additionally, this extract significantly inhibited the enzyme tyrosine kinase p56 lck (TK). The dichloromethane extract of Amorphophallus bequaertii inhibited the growth of Mycobacterium tuberculosis with a MIC of 100 g/ml and the methanolic extract of Rubus rigidus inhibited the activity of both enzymes HIV1-reverse transcriptase (HIV1-RT) and TK p56 lck . © 2002 Published by Elsevier Science Ireland Ltd. Keywords: Antimicrobial; Medicinal plants; Inhibitory activity; Malaria www.elsevier.com/locate/jethpharm 1. Introduction Plant materials remain an important resource to combat serious diseases in the world. Pharmacognostic investigations of plants are carried out to find novel drugs or templates for the development of new thera- peutic agents (Ko ¨ nig, 1992). Among the more than 250 000 species of higher plants, only about 5–10% are chemically investigated (Nahrstedt, 1996). Since many drugs, e.g. quinine and artemisinin (Wright and Phillip- son, 1990), taxol and camptothecin (Debernardis et al., 1996) were isolated from plants, and because of in- creased resistance of many microorganisms, e.g. malaria parasites, towards established drugs, investiga- tion of the chemical compounds within traditional plants is necessary (Phillipson, 1991). Malaria is still one of the most important parasitic diseases of mankind. The yearly statistics of the World Health Organization, concerning mortality caused by tropical diseases, particulary from malaria, is frighten- ing. It is estimated that there are more than a million deaths and up to 500 million clinical cases of malaria each year (Bulletin of the World Health Organization, 1999). The Republic of Congo is a country entirely situated in the high risk zone of endemic malaria. Many plants in Congo are used traditionally to heal different dis- eases (Wome, 1982, 1985) including malaria; they play an important role in the medical system of the country. Generally, the traditional use of medicinal plants is accompanied with certain rituals and incantations. Man is considered to be part of an intriguing system com- posed of the community he is living in, the nature surrounding him and the ancestors. Thus, sickness is considered as the destruction of balance in a person, and between the person and nature, community and ancestors. Similarly, as in ayuverdic medicine (Mazars, 1998), the psychical and corporeal state of a person is taken into account. These considerations make the accompanying rituals of treatment understandable. Some people (healers or not healers), however, simply use medicinal plants, without ritual. The knowledge concerning traditional plants and remedies is mostly handed down orally. Efforts to collect and write down * Corresponding author. 0378-8741/02/$ - see front matter © 2002 Published by Elsevier Science Ireland Ltd. PII:S0378-8741(01)00409-3