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Natural Products from Cameroonian Medicinal Plants

Tsopmo, Apollinaire LU (2002)
Abstract
Natural product chemistry is a main research area in Cameroon, as well as for the division of Bioorganic Chemistry at Lund Institute of Technology. A review of the results obtained recently with Cameroonian medicinal plants shows that a large number of compounds, many with complex structures, have been isolated and characterised, and the work presented in this thesis is part of this effort. Based on empirical, ethnodietary, and ethnomedicinal information obtained from medicine men who use the plants to treat various diseases, several species were collected for study. Extraction, fractionation and purification using various chromatographic techniques led to the isolation and characterisation of a large number of compounds including several... (More)
Natural product chemistry is a main research area in Cameroon, as well as for the division of Bioorganic Chemistry at Lund Institute of Technology. A review of the results obtained recently with Cameroonian medicinal plants shows that a large number of compounds, many with complex structures, have been isolated and characterised, and the work presented in this thesis is part of this effort. Based on empirical, ethnodietary, and ethnomedicinal information obtained from medicine men who use the plants to treat various diseases, several species were collected for study. Extraction, fractionation and purification using various chromatographic techniques led to the isolation and characterisation of a large number of compounds including several novel derivatives. Structure elucidation was achieved by a combination of spectroscopic techniques (NMR, UV, IR, MS).



Biological tests performed on some of the isolated compounds showed some promising results. Sesquiterpenes obtained from Reneilmia cincinnata were tested against two Plasmodium falciparum clones; the Indochina W-2 clone, resistant to chloroquine, pyrimethamine, sulfadoxine, and quinine; and the Sierra Leone D-6 resistant to mefloquine. Plasmodium species are parasites that cause life-threatening diseases, four related species, P. falciparum, P. malariae, P. ovale, and P. vivax, are responsible for human malaria. P. falciparum, the most virulent malaria parasite, is responsible for more than one million deaths per year while hundreds of millions of cases of malaria occur annually. R. cincinnata was identified in a preliminary screening as a potential antimalarial plant. The isolated sesquiterpenes were then tested against the most virulent parasite. Inhibition concentrations (IC50) of the range 1.5-1.6 ug/ml for D-6 and 1.9-31.9 ug/ml for W-2 were determined. Similar activities were noted with diarylheptanoids isolated from Aframomum letestuianum when tested against three major strains of Trypanosoma brucei, a causative agent of African trypanosomiasis or sleeping sickness. The three strains were Lab 110 EATRO, a drug sensitive strain of Trypanosoma brucei brucei; KETRI 243, an uncloned clinical isolate of Trypanosoma brucei rhodesiense; and KETRI 243 As-10-3 a pentamidine and melarsol-resistant clone of Trypanosoma brucei rhodesiense.



In addition, chemical studies were performed with aframodial, an alpha,beta-unsaturated dialdehyde and major component of some Aframomum species. It turned out to be very reactive toward amines and amino acids, and several pyrrole and oxazolidine derivatives were prepared. (Less)
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author
supervisor
opponent
  • Prof. Appendino, Giovanni, University of Torino, Italy
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Växtbiokemi, Plant biochemistry, antiplasmodial., antitrypanosomal, diarylheptanoids, terpenoids, flavonoids, aframodial, Aframomum, Reneilmia cincinnata, Dorstenia, Euphorbia, Lepidobotrys staudtii, Pentadiplandra brazzeanea, Vernonia guineensis, Natural products, Myrica arborea
pages
75 pages
publisher
Department of Bioorganic Chemistry, Lund University
defense location
Chemical Center, Lund, Sal K:B
defense date
2002-06-06 13:15:00
external identifiers
  • other:ISRN: LUTKDH/(TEKOK-1053)/1-75/(2002)
ISBN
91-628-5266-3
language
English
LU publication?
yes
additional info
Article: Mathieu Tene, Hyppolite Kamdem Wabo, Pierre Kamnaing, Apollinaire Tsopmo, Pierre Tane, Johnson Foyere Ayafor, Olov Sterner. Diarylheptanoids from Myrica arborea. Phytochemistry 2000, 54, 975-978. Article: Alembert T. Tchinda, Apollinaire Tsopmo, Pierre Tane, Johnson F. Ayafor , Joseph D. Connolly, Olov Sterner. Vernoguinosterol and vernoguinoside, trypanocidal stigmastane derivatives from Vernonia guineensis (Asteraceae). Phytochemistry 2002, 59, 371-374. Article: Apollinaire Tsopmo, David Ngnokam, Dieudonné Ngamga, Johnson F. Ayafor, Olov Sterner. Urea Derivatives from Pentadiplandra brazzeana J. Nat. Prod. 1999, 62, 1435-1436 Article: Pierre Tane, Apollinaire Tsopmo, David Ngnokam, Johnson F. Ayafor, Olov Sterner. New Friedelanes Triterpenes from Lepidobotrys staudtii. Tetrahederon 1996, 52, 14989-14994. Article: Apollinaire Tsopmo, Mathieu Tene, Pierre Kamnaing, David Ngnokam, Johnson F. Ayafor, Olov Sterner. Geranylated Flavonoids from Dorstenia poinsettifolia. Phytochemistry 1998, 48, 345-348. Article: Apollinaire Tsopmo, Mathieu Tene, Pierre Kamnaing, Johnson F. Ayafor, Olov Sterner. A New Diels-Alder-Type Adduct Flavonoid from Dorstenia barteri. J. Nat. Prod. 1999, 62, 1432-1434. Article: Maguerite H.K. Tchuendem, James A. Mbah, Apollinaire Tsopmo, J. Foyere Ayafor, Olov Sterner, Christopher C. Okunjic, Maurice M. Iwu, Brian M. Schuster. Anti-plasmodial sesquiterpenoids from the African Reneilmia cincinnata. Phytochemistry 1999, 52, 1095-1099. Article: Apollinaire Tsopmo, Godfred A. Ayimele, Pierre Tane, Johnson Foyere Ayafor, Joseph D. Connolly, Olov Sterner. Bisnorladane and other diterpenes from Aframomum sulcatum. Tetrahedron 2002, 58, 2725-2728. Article: Pierre Kamnaing, Apollinaire Tsopmo, Eric A. Tanifum, Marguerite H.K. Tchuendem, Pierre Tane, Johnson F. Ayafor, Olov Sterner, Donna Rattendi, Maurice M. Iwu, Brian Schuster, Cyrus Bachii. Trypanocidal Diarylheptanoids from Aframomum letestuianum (Zingiberaceae). In Manuscipt Article: Apollinaire Tsopmo, Johnson F. Ayafor, and Olov Sterner. Terpenoids Constituents of Euphorbia kinnii. In Manucript. Article: Apollinaire Tsopmo, Johnson F. Ayafor, and Olov Sterner. A Spirotriterpenoid and an Anhydride from Euphorbia prostrata. In Manuscipt. The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Organic chemistry (S/LTH) (011001240)
id
1bf74631-d4f7-4e5a-9ce3-b1a51a306411 (old id 464742)
date added to LUP
2016-04-04 11:11:00
date last changed
2018-11-21 21:03:11
@phdthesis{1bf74631-d4f7-4e5a-9ce3-b1a51a306411,
  abstract     = {Natural product chemistry is a main research area in Cameroon, as well as for the division of Bioorganic Chemistry at Lund Institute of Technology. A review of the results obtained recently with Cameroonian medicinal plants shows that a large number of compounds, many with complex structures, have been isolated and characterised, and the work presented in this thesis is part of this effort. Based on empirical, ethnodietary, and ethnomedicinal information obtained from medicine men who use the plants to treat various diseases, several species were collected for study. Extraction, fractionation and purification using various chromatographic techniques led to the isolation and characterisation of a large number of compounds including several novel derivatives. Structure elucidation was achieved by a combination of spectroscopic techniques (NMR, UV, IR, MS).<br/><br>
<br/><br>
Biological tests performed on some of the isolated compounds showed some promising results. Sesquiterpenes obtained from Reneilmia cincinnata were tested against two Plasmodium falciparum clones; the Indochina W-2 clone, resistant to chloroquine, pyrimethamine, sulfadoxine, and quinine; and the Sierra Leone D-6 resistant to mefloquine. Plasmodium species are parasites that cause life-threatening diseases, four related species, P. falciparum, P. malariae, P. ovale, and P. vivax, are responsible for human malaria. P. falciparum, the most virulent malaria parasite, is responsible for more than one million deaths per year while hundreds of millions of cases of malaria occur annually. R. cincinnata was identified in a preliminary screening as a potential antimalarial plant. The isolated sesquiterpenes were then tested against the most virulent parasite. Inhibition concentrations (IC50) of the range 1.5-1.6 ug/ml for D-6 and 1.9-31.9 ug/ml for W-2 were determined. Similar activities were noted with diarylheptanoids isolated from Aframomum letestuianum when tested against three major strains of Trypanosoma brucei, a causative agent of African trypanosomiasis or sleeping sickness. The three strains were Lab 110 EATRO, a drug sensitive strain of Trypanosoma brucei brucei; KETRI 243, an uncloned clinical isolate of Trypanosoma brucei rhodesiense; and KETRI 243 As-10-3 a pentamidine and melarsol-resistant clone of Trypanosoma brucei rhodesiense.<br/><br>
<br/><br>
In addition, chemical studies were performed with aframodial, an alpha,beta-unsaturated dialdehyde and major component of some Aframomum species. It turned out to be very reactive toward amines and amino acids, and several pyrrole and oxazolidine derivatives were prepared.},
  author       = {Tsopmo, Apollinaire},
  isbn         = {91-628-5266-3},
  language     = {eng},
  publisher    = {Department of Bioorganic Chemistry, Lund University},
  school       = {Lund University},
  title        = {Natural Products from Cameroonian Medicinal Plants},
  year         = {2002},
}