A.M. Baldé

A-type Proanthocyanidins from stem-bark of Pavetta owariensis

Abstract In a chemical investigation on the stem-bark of Pavetta owariensis , a new proanthocyanidin A-type, ent -epicatechin (4α→8,2α→ O →7)- ent -catechin designated as pavetannin A1, was isolated as second representative of a (2α,4α) A-type proanthocyanidin. Additionally, the occurrence of (+)-catechin, (−)-epicatechin, ent -epicatechin, proanthocyanidin A-2 and proanthocyanidin A-4 was demonstrated, the latter being reported from a natural source for the second time.

Ferulic acid esters from stem bark of Pavetta owariensis

Abstract Three major and two minor ferulic acid esters were identified in a hexane extract of Pavetta owariensis stembark. Their structures were elucidated using mass, 1 H and 13 C NMR spectroscopy.

Triterpenoid saponins from Maesa lanceolata

Six new homologous triterpenoid saponins were isolated from the methanol extract of the leaves of Maesa lanceolata and characterized as 3 beta-O-[alpha-L-rhamnopyranosyl(1 --> 2)-beta-D-galactopyranosyl (1 --> 3)]-[beta-D-galactopyranosyl(1 --> 2)]-beta-D-glucuronopyranosides alpha-diol, 22 alpha-angeloyloxy-16 alpha-butanoyloxy-13 beta,28-oxydoolean-21 beta,28 alpha-diol, 16 alpha,22 alpha-diangeloyloxy-13 beta,28-oxydoolean-21 beta,-28 alpha-diol, 22 alpha-angeloyloxy-13 beta,28-oxydo-16 alpha-(2-methyl-butanoyloxy)-olean-21 beta,28 alpha-diol, 21 beta-acetoxy-22 alpha-angeloyloxy-13 beta,28-oxydo-16 alpha-propanoyloxyolean-28 alpha-ol, 21 beta-acetoxy-22 alpha-angeloyloxy-16 alpha-butanoyloxy-13 beta,28-oxydoolean-28 alpha-01. The structures were established on the basis of chemical and spectral evidence.

Ethnobotanical survey on medicinal plants used by Guinean traditional healers in the treatment of malaria.

ETHNOPHARMACOLOGICAL RELEVANCEnThe objective of the present study was to collect and document information on herbal remedies traditionally used for the treatment of malaria in Guinea.nnnMATERIALS AND METHODSnThe survey was carried out from May 2008 to September 2010 and targeted traditional medical practitioners and herbalists. The questionnaire and oral interviews were based on the standardized model which was prepared by the Centre de Recherche et de Valorisation des Plantes Médicinales (CRVPM) - Dubréka.nnnRESULTS AND DISCUSSIONnA total of 258 people (141 males and 117 females) from which 150 traditional healers and 108 herbalists were interviewed. The age of informants ranged from 28 to 82 years old. 57% (149/258) of the interviewees were more than 50 years old. The respondents had good knowledge of the symptoms of malaria, and a fairly good understanding of the causes. One hundred thirteen plant species were recorded, out of which 109 were identified. They belonged to 84 genera and 46 families. The most frequently cited plants were Vismia guineensis, Parkia biglobosa, Nauclea latifolia, Harungana madagascariensis, Terminalia macroptera, Crossopteryx febrifuga, Terminalia albida, Annona senegalensis, and Nauclea pobeguinii. The leaves were most frequently used (80/113 species), followed by stem bark (38/113 species) and roots (4/113 species). The remedies were mostly prepared by decoction (111 species), followed by maceration (seven species). Only one species was prepared by infusion.nnnCONCLUSIONnThe present study showed that traditional healers in Guinea have a consistent knowledge of antimalarial plants. Further research should be carried out to compare the anti-malarial activity of the different species, and to check if their use against malaria can be scientifically validated.

Dimeric and trimeric proanthocyanidins possessing a doubly linked structure from Pavetta owariensis

Abstract Pavetannin A-2, a new A-type proanthocyanidin, along with the trimers cinnamtannin B-1, pavetannin B-1, B-2, B-3, B-5 and B-6 have been isolated in their free phenolic form from the stem bark of Pavetta owariensis. Spectral data and partial acid-catalysed degradation established their structures as ent-epicatechin-(4α→8,2α→O→7)-catechin, epicatechin-(4β→8,2β→O→7)-epicatechin-(4α→8)-epicatechin, epicatechin-(4β→8,2β→O→7)-epicatechin-(4β→8)-ent-epicatechin, epicatechin-(4β→8,2β→O→7)-epicatechin-(4β→8)-epicatechin, epicatechin-(4β→6,2β→O→7)-epicatechin-(4β→8)-epicatechin, epicatechin-(4β→6,2β→O→7)-catechin-(4β→8)-epicatechin, epicatechin-(4β→8,2β→O→7)-epicatechin-(4α→8)-catechin, respectively.

Management of diabetes in Guinean traditional medicine: An ethnobotanical investigation in the coastal lowlands

ETHNOPHARMACOLOGICAL RELEVANCEnThis survey was carried out in the coastal lowlands of Guinea-Conakry in order to make an inventory of plants used by traditional healers, herbalists and diabetic patients for the management of diabetes mellitus.nnnMATERIALS AND METHODSnFrequent ethnomedical and ethnobotanical investigations were conducted from June 2008 to December 2009 in Conakry, Kindia, Forécariah, Dubréka, Boke, Fria and Boffa. It is a cross-sectional survey and data collection is based on the interactive method. During this period a total of 112 people aged from 39 to 76 years old were interviewed.nnnRESULTSnDuring this investigation 146 plant species belonging to 55 families were collected. The most cited plants were Anacardium occidentale L. and Ficus spp., while the Fabaceae family was the most represented, followed by the Euphorbiaceae and Rubiaceae. The most frequently plant parts used by the traditional healers and the herbalists were the stem-bark and decoctions the most common preparation mode.nnnCONCLUSIONSnIt is clear that a variety of plants is used in the management and treatment of diabetes. Due to the increasing prevalence of type 2 diabetes, there is an urgent need for scientific investigations to rationalise the use of these traditional remedies, which could represent accessible alternative medicines for the Guinean populations.

Oligomeric proanthocyanidins possessing a doubly linked structure from Pavetta owariensis

Abstract Pavetannins B7 and B8, two new trimeric proanthocyanidins, have been isolated from the stem bark of Pavetta owariensis , along with the known tetramers cinnamtannin B2 and its positional isomer, pavetannin C1, and the pentamer pavetannin D1. NMR and mass spectral data established the structure of the pavetannins as epicatechin-(4 β → 8, 2 β → O → 7)- ent -epicatechin-(4 α → 8, 2 α → O → 7)- ent -catechin, epicatechin-(4 β → 8, 2 β → O → 7)-epicatechin-(4 β → 8, 2 β → O → 7)- ent -catechin, epicatechin-(4 β → 6)-epicatechin-(4 β → 8, 2 β → O → 7)-epicatechin-(4 β → 8)-epicatechin and epicatechin-(4 β → 8)-epicatechin-(4 β → 8, 2 β → O → 7)-epicatechin-(4 β → 8)-epicatechin-(4 β → 8)- epicatechin, respectively. The naming of cinnamtannin B2 is revised to epicatechin-(4 β → 8)-epicatechin-(4 β → 8,2 β → O → 7)-epicatechin-(4 β → 8)-epicatechin, according to its structural presentation.

Herbal Medicines and Infectious Diseases: Characterization by LC‑SPE‑NMR of Some Medicinal Plant Extracts Used against Malaria

The extracts of two medicinal plants used in traditionalmedicine against malariawere characterized by means of an LC‑SPE‑NMR and LC‑MS platform. The structure of a series of major constituents from Bafodeya benna, as well as minor constituents from Ormocarpum kirkii, was determined. Bafodeya benna was found to contain (2R,3R)-taxifolin-3-O-α-L-rhamnoside or astilbin, and its isomers neoastilbin, neoisoastilbin, and isoastilbin, as well as quercetin-3-O-α-L-rhamnoside. From Ormocarpum kirkii, a series of known flavonoids and biflavonoids was obtained, as well as three new compounds, i.e., 7,7′′-di-O-β-D-glucosyl-(−)-chamaejasmin, 7-O-β-D-glucosyl-(I-3,II-3)-biliquiritigenin, and isovitexin-(I-3,II-3)-naringenin. The isolated constituents may explain, at least in part, the traditional use against malaria. LC‑SPE‑NMR, in combination with LC‑MS, is a powerful tool for the fast characterization of plant extracts, in order to define priorities at an early stage of a fractionation procedure. In addition, herbal medicinal products can completely be characterized, both with regard to their major as well as their minor constituents.

In vitro antiprotozoal, antimicrobial and antitumor activity of Pavetta crassipes K. Schum leaf extracts.

AIM OF THE STUDYnTo study the potential benefit of the traditional medicinal plant Pavetta crassipes K. Schum (Rubiaceae), which is widely distributed throughout West Africa, the methanol and dichloromethane extracts were isolated from the plant leaves to determine if they exhibited antiprotozoal, antibacterial, antifungal or antitumor activity in vitro.nnnMATERIALS AND METHODSnThe methanol and dichloromethane extracts and their specific fractions were obtained using bioassay-guided fractionation and investigated for antiproliferative activity in vitro in microorganisms (Staphylococcus aureus, Escherichia coli and Candida albicans), protozoans (Trypanosoma cruzi, Trypanosoma brucei, Leishmania infantum and Plasmodium falciparum), and cancer (U373, PC3, MXT and A549) and normal cell lines (NHDF and MRC-5).nnnRESULTSnMost of the alkaloid fractions investigated exhibited antiproliferative activity in all the cancer cell lines, microorganisms and protozoans studied.nnnCONCLUSIONSnThe benefit of Pavetta crassipes as a traditional medicinal remedy was confirmed using antiprotozoal and cytotoxicity assays in vitro. These analyses revealed that the components present in the alkaloid extract of Pavetta crassipes are responsible for its antiprotozoal and cytotoxic efficacy.

Spermacoceine, a bis-indole alkaloid from Borreria verticillata

Abstract A new bis -indole alkaloid, spermacoceine, was isolated from the aerial parts of Borreria verticillata . Its structure was established from spectroscopic data. In addition, the known indole alkaloids, borrerine, borreverine and isoborreverine, were obtained.