The value of central-African traditional medicine for lead finding: Some case studies.

Unlabelled: Ethnoparmaological relevance: One of the possible methodologies for the discovery of novel drugs is the screening of selected plant extracts for a broad array of pharmacological activities.

Materials And Methods: The selection based on enthnomedicinal uses, combined with a follow-up of existing literature on the plants' chemotaxonomic properties, would seem to be the most cost-effective strategy for finding active plant extracts. A bioassay-guided fractionation of the active extracts should subsequently lead to the isolation and identification of the active lead constituent(s).

Antimalarial efficacy of a quantified extract of Nauclea pobeguinii stem bark in human adult volunteers with diagnosed uncomplicated falciparum malaria. Part 2: a clinical phase IIB trial.

According to the promising results of the Phase I and Phase IIA clinical trials with the herbal medicinal product PR 259 CT1 consisting of an 80 % ethanolic extract of the stem bark of Nauclea pobeguinii containing 5.6 % strictosamide, a Phase IIB study was conducted as a single blind prospective trial in 65 patients with proven Plasmodium falciparum malaria to evaluate the effectiveness and safety of this herbal drug. The study was carried out simultaneously using an artesunate-amodiaquine combination (Coarsucam®) as a positive control.

Antimalarial efficacy of a quantified extract of Nauclea pobeguinii stem bark in human adult volunteers with diagnosed uncomplicated falciparum malaria. Part 1: a clinical phase IIA trial.

The aim of this phase IIA clinical trial was to assess the efficacy of an 80 % ethanolic quantified extract (containing 5.6 % strictosamide as the putative active constituent) from Nauclea pobeguinii stem bark denoted as PR 259 CT1 in a small group of adult patients diagnosed with uncomplicated falciparum malaria. Results obtained from a phase I clinical trial on healthy male volunteers indicated that the oral administration during meals of two 500 mg capsules three times daily (each eight hours) during seven days was well tolerated and showed only mild and self-resolving adverse effects.

Assessment of the short-term safety and tolerability of a quantified 80 % ethanol extract from the stem bark of Nauclea pobeguinii (PR 259 CT1) in healthy volunteers: a clinical phase I study.

The aim of this study was to evaluate the short-term safety and tolerability of an antimalarial herbal medicinal product (PR 259 CT1) consisting of a quantified 80 % ethanol extract from the stem bark of Nauclea pobeguinii when given orally to healthy adult male volunteers. The amount of the major alkaloid strictosamide in the extract was determined by a validated HPLC method and was shown to be 5.6 %.

Development and validation of an HPLC-method for the determination of alkaloids in the stem bark extract of Nauclea pobeguinii.

A new method was developed and validated for the quantification of strictosamide in the extract of the stem bark of Nauclea pobeguinii. This plant belongs to the Rubiaceae family and is widely used in the African traditional medicine against malaria and malaria-like symptoms. Alkaloids are suspected to be responsible for the antimalarial activity.

Complement-Inhibiting Constituents of Bridelia ferruginea Stem Bark.

A bioassay-guided fractionation of an 80% acetone extract from BRIDELIA FERRUGINEA stem bark showing a dose-dependent inhibitory effect towards both the classical and the alternative pathways of the complement system resulted in the isolation of a biflavanol (gallocatechin-(4'- O-7)-epigallocatechin) ( 1), 3,5-dicaffeoylquinic acid ( 2), 1,3,4,5-tetracaffeoylquinic acid ( 3), and a series of 3-methoxyflavone derivatives, including quercetin 3-methyl ether ( 4), quercetin 3,7,3',4'-tetramethyl ether ( 5), myricetin 3',4',5'-trimethyl ether ( 6; new compound) named ferrugin, myricetin 3,3',4',5'-tetramethyl ether ( 7), myricetin ( 8), and quercetin 3- O-glucoside ( 9) as the active constituents. Especially the biflavanol 1 and the caffeoyl esters of quinic acid 2 and 3 showed a strong inhibitory effect (IC (50) < 10 microM) on the classical pathway, compared to rosmarinic acid. Also on the alternative pathway, the biflavanol 1, the quinic acid derivatives 2 and 3, and some of the 3-methoxyflavones 5, 7 and 8 were more active than rosmarinic acid.

Antiamoebic activity of iridoids from Morinda morindoides leaves.

An aqueous decoction (dried extract), an 80 % methanolic extract from Morinda morindoides (Rubiaceae) leaves, and five iridoids isolated from the 80 % methanolic extract were evaluated in vitro for their activity against Entamoeba histolytica and their cytotoxicity. The aqueous decoction and the 80 % methanolic extract exhibited a promising antiamoebic activity with IC (50) values of 3.1 +/- 1.

Cytotoxicity and in vitro susceptibility of Entamoeba histolytica to Morinda morindoides leaf extracts and its isolated constituents.

An aqueous decotion (dried extract), an 80% MeOH extract from Morinda morindoides leaves, and 10 flavonoids and 4 iridoids isolated from the 80% MeOH extract were evaluated in vitro for their potential antiamoebic activity and their cytotoxic effect against MT-4 cells. Results indicated that the aqueous decoction and the 80% MeOH extract exhibited an interesting antiamoebic activity with IC(50) values of 3.1 +/- 1.

In vitro antiplasmodial activity of callus culture extracts and fractions from fresh apical stems of Phyllanthus niruri L. (Euphorbiaceae): part 2.

The ethanolic extracts from fresh apical stems of Phyllanthus niruri L. (Euphorbiaceae) cultured on Murashige and Skoog (MS) medium supplemented with IBA/BAP/Coco nucifera L. milk for 1, 2, 4 and 6 months were phytochemically and biologically investigated and compared with intact plant part and whole plant extracts.

In vitro antiplasmodial activity of extracts and fractions from seven medicinal plants used in the Democratic Republic of Congo.

The in vitro antiplasmodial activity of seven EtOH extracts and twenty fractions from the partition of the initial ethanolic extracts from seven African medicinal plants used in the Democratic Republic of Congo (DR Congo) for the treatment of malaria was evaluated. The most active EtOH extracts (IC50 < 3 microg/ml) were those from Cassia occidentalis leaves, Euphorbia hirta whole plant, Garcinia kola stem bark and Phyllanthus niruri whole plant. Their respective petroleum ether soluble fractions also exhibited an antiplasmodial activity with IC50 < 3 microg/ml.

Correlation between chemical composition and antibacterial activity of essential oils of some aromatic medicinal plants growing in the Democratic Republic of Congo.

The chemical composition of essential oils from 15 aromatic medicinal plant species growing in the Democratic Republic of Congo have been studied. More than 15 constituents in an amount higher than 0.1% were identified in each essential oil.

Radical scavenging and xanthine oxidase inhibitory activity of phenolic compounds from Bridelia ferruginea stem bark.

Bridelia ferruginea Benth. (Euphorbiaceae) is a subtropical medicinal plant widely used in traditional African medicine against various diseases, including rheumatic pains. Seven of its constituents (3-O-methylquercetin (1), 3,7,3',4'-tetra-O-methylquercetin (rutisin, 2), myricetin (3), 3',4',5'-tri-O-methylmyricetin (ferrugin, 4), 3,3',4',5'-tetra-O-methylmyricetin (5), quercetin 3-O-glucoside (6), and a biflavanol gallocatechin-[4'-O-7]-epigallocatechin (7)) have been evaluated in-vitro in the xanthine-xanthine oxidase enzymatic system for inhibition of xanthine oxidase and radical scavenging activity.

In-vivo antimalarial activity of Cassia occidentalis, Morinda morindoides and Phyllanthus niruri.

The ethanolic, dichloromethane and lyophilized aqueous extracts of Cassia occidentalis root bark, Morinda morindoides leaves and whole plants of Phyllanthus niruri were evaluated for their antimalarial actvity in vivo, in 4-day, suppressive assays against Plasmodium berghei ANKA in mice. No toxic effect or mortality was observed in mice treated, orally, with any of the extracts as a single dose, of 500 mg/kg body weight, or as the same dose given twice weekly for 4 weeks (to give a total dose of 4 g/kg). No significant lesions were observed, by eye or during histopathological examinations, in the hearts, lungs, spleens, kidneys, livers, large intestines or brains of any mouse.

Antiamoebic and spasmolytic activities of extracts from some antidiarrhoeal traditional preparations used in Kinshasa, Congo.

Three major extracts from some traditional preparations, based on medicinal plants, used as antidiarrhoeal agents were investigated for their putative antiamoebic and spasmolytic activities in vitro. Results indicated that both biological activities are concentrated in the polyphenolic fraction, and not in the saponin or alkaloid containing fractions. The most active polyphenolic extracts were those from Euphorbia hirta whole plant, leaves of Alchornea cordifolia, Crossopteryx febrifuga, Nauclea latifolia, Psidium guajava, Tithonia diversifolia, stem bark of Harungana madagascariensis, Mangifera indica, Maprounea africana and Psidium guajava, inhibiting Entamoeba histolytica growth with MAC < 10 micrograms/ml.

Antimalarial activity of 20 crude extracts from nine African medicinal plants used in Kinshasa, Congo.

Twenty extracts including ten EtOH and ten CH2Cl2 from different parts of nine African medicinal plants used in Congolese traditional medicine for the treatment of malaria, were submitted to a pharmacological test in order to evaluate their effect on P. falciparum growth in vitro. Of these plant species, 14 (70%) extracts including EtOH and CH2Cl2 from Cassia occidentalis leaves, Cryptolepis sanguinolenta root bark, Euphorbia hirta whole plant, Garcinia kola stem bark and seeds, Morinda lucida leaves and Phyllanthus niruri whole plant produced more than 60% inhibition of the parasite growth in vitro at a test concentration of 6 microg/ml.

Biological screening of traditional preparations from some medicinal plants used as antidiarrhoeal in Kinshasa, Congo.

Forty six aqueous extracts from 38 medicinal plant species belonging to different families were selected on the basis of their traditional medicinal use as antidiarrhoeic agents. They were submitted in a broad biological screening including antibacterial, antiamoebic and antispasmodic activities. The results of the testing have indicated that 37 extracts (80.

Antiamoebic and phytochemical screening of some Congolese medicinal plants.

Results from the in vitro antiamoebic activity of some Congolese plant extracts used as antidiarrhoeic in traditional medicine indicated that of 45 plant extracts tested, 35 (77.78%) exhibited an antiamoebic activity and 10 (22.22%) were inactive.

Antibacterial and antifungal activities of neocryptolepine, biscryptolepine and cryptoquindoline, alkaloids isolated from Cryptolepis sanguinolenta.

From the 80% EtOH extract of Cryptolepis sanguinolenta (Lindl.) Schlechter (Periplocaeae) root bark, a cryptolepine isomer named neocryptolepine, and two dimeric alkaloids named biscryptolepine and cryptoquindoline were isolated. These compounds were tested for their putative antibacterial and antifungal activities.

Complement-modulating properties of a kaempferol 7-O-rhamnosylsophoroside from the leaves of Morinda morindoides.

A kaempferol 7-O-rhamnosylsophoroside isolated from the leaves of Morinda morindoides showed dose-dependent complement-modulating properties towards both the classical (inhibiting effect) and alternative (activating effect) pathways of the complement system. Its structure was elucidated by chemical and spectroscopic methods as kaempferol 7-O-[alpha-L-rhamnopyranosyl-(1-->6)]-[beta-D-glucopyranosyl-(1-->2)]-be ta-D-glucopyranoside, a new natural product which was named morindaoside.

In vitro biological activities of alkaloids from Cryptolepis sanguinolenta.

In our biological screening of higher plants, an aqueous and an 80% EtOH extract from the root bark of Cryptolepis sanguinolenta showed potent antibacterial, anticomplementary, and moderate antiviral activities, but no antifungal effect could be detected. Bioassay-guided fractionation of the 80% EtOH extract led to the isolation of three alkaloids: quindoline (1), hydroxycryptolepine (2), cryptolepine.HCl (3), and the corresponding base cryptolepine (4).

In vitro anticomplementary activity of constituents from Morinda morindoides.

In a screening program for complement classical pathway modulation, an 80% MeOH extract of the leaves of Morinda morindoides showed potent dose-dependent anticomplementary activity. Bioassay-guided chromatographic separation of the active constituents led to the isolation of ten flavonoids of which two were aglycones. The compounds were tested in vitro for their putative complement-inhibiting properties on the classical (CP) and the alternative (AP) pathways of the complement system.

[In vitro study of the adsorption of chloroquine by an antidiarrheal remedy traditionally used in Africa].

Mouboumou is a traditional medicine prepared from the inner part of termitarium and is used in traditional medicine in Zaire. In tropical diseases, antimalarial drugs are often used simultaneously with antidiarrheal absorbent drugs, which might, by their adsorbent properties, compromise the efficacy of the antimalarial treatment. The present in vitro study has allowed to determine the adsorption characteristics of chloroquine on Mouboumou; kaopectate was used a reference adsorbent.

Depressant effects of chloroquine on the isolated guinea-pig heart.

Some anti-malarials have deleterious effects upon the heart. The actions of two of these, chloroquine and quinacrine, were compared on isolated guinea-pig atria and Langendorff preparations to assess their effects on several calcium pools. Both compounds decreased developed tension in a concentration (chloroquine 10-100 microM; quinacrine 3-100 microM) and time-dependent manner, with quinacrine being twice as potent as potent as chloroquine.

[Antibacterial activity of extracts from plants used in preparation as antidiarrheals at Kinshasa, Zaire].

A preliminary and anterior bacteriological study about 38 plant antidiarrheic traditional preparations, has demonstrated that 35 of them have bactericidal activity. Thirty inhibit the growth of all select germs and 5 exert this bactericidal effect on some germs. Some extracts proceeding of these possess a bactericidal activity, specially if they contain polyphenols (flavonoids, catechics tanins), saponins and alkaloids.