Anti-plasmodial flavonoids from the stem bark of Erythrina abyssinica

Medicinal plants are an important local resource for the Washambaa of the Western Usambara Mountains in Tanzania. In this study the Washambaa medicinal plants are inventoried. It is based on ethnobotanical fieldwork carried out over 15 months. This study presents for the first time an analysis of medicinal plants used in Africa with a ranking of these taxa by the frequency of their reported use. A total of 328 taxa were collected and yielded 2260 individual use reports. The most popular species are Myrica salicifolia and Toddalia asiatica. Subsequently, the use reports were arranged into 9 groups of medicinal uses based on the types of illness treated. The Factor of Informant Consensus (FIC) is used in order to evaluate the ethnobotanical importance of the plants. The largest number of plants and of use reports are in the group of gastrointestinal disorders. For the most commonly used taxa, an ethnopharmacological evaluation was performed. Studies to evaluate the Washambaa therapeutic claims as well as toxicological data are still lacking for many of the species. This study will form the basis for pharmacological and phytochemical research on selected Washambaa medicinal plants.

Medicinal Plants of the Washambaa (Tanzania): Documentation and Ethnopharmacological Evaluation

Inhibition of protein tyrosine phosphatase-1B (PTP1B) has been proposed as a therapy for treatment of type-2 diabetes and obesity. Bioassay-guided fractionation of an EtOAc-soluble extract of the root bark of Erythrina mildbraedii, using an in vitro PTP1B inhibitory assay, resulted in the isolation of three new isoprenylated flavonoids, abyssinone-IV-4'-O-methyl ether (2), 7-hydroxy-4'-methoxy-3'-(3-hydroxy-3-methyl-trans-but-1-enyl)-5'-(3-methylbut-2-enyl)flavanone (3), and abyssinone-VI-4-O-methyl ether (6), along with six known flavonoids, abyssinone-V-4'-O-methyl ether (1), abyssinone-V (4), abyssinone-IV (5), sigmoidin E (7), 4'-hydroxy-5,7-dimethoxyisoflavone (8), and alpinumisoflavone (9). Compounds 1 and 2, 4-7, and 9 inhibited PTP1B activity, with IC50 values ranging from 14.8 +/- 1.1 to 39.7 +/- 2.5 microM. On the basis of the data obtained, flavanones and chalcones with isoprenyl groups may be considered as a new class of PTP1B inhibitors.

Protein tyrosine phosphatase-1B inhibitory activity of isoprenylated flavonoids isolated from Erythrina mildbraedii.

The antibacterial activity of the stem bark of Erythrina caffra Thunb. was investigated against different bacterial strains. The antibacterial activity was determined by a micro broth dilution assay. Antibacterial compounds were isolated and identified using a Bruker Avance III LPO NMR spectrometer. Four known flavonoids, abyssione-V 4'-O-methyl ether, 6,8-diprenylgenistein, alpinumisoflavone and burttinone, were isolated. All the compounds were active against both Gram-negative and Gram-positive bacteria. The minimum inhibitory concentration values obtained (MIC) ranged from 3.9 μg/mL to 125 μg/mL. This is the first report of antibacterial activity of burttinone and the isolation of these compounds from E. caffra.

Antibacterial activity of flavonoids from the stem bark of Erythrina caffra thunb.

Comprehensive review on flavonoids biological activities of Erythrina plant species

Four new prenylated flavanones, abyssinone-V 4'-methyl ether (1) and abyssinoflavanones IV (2), V (3), and VI (4), have been isolated as minor flavanones from the African medicinal plant, Erythrina abyssinica, together with a known flavanone, sigmoidin D. The structure elucidation of compounds 1-4 by spectroscopic studies is described.

Minor flavanones from Erythrina abyssinica

Eight brands of antacid tablets commonly available in the private market in Kenya were subjected to in-vitro tests for neutralizing capacity. The neutralizing capacity per gram and per tablet of the products was compared. The neutralizing capacity in millilitres of 0.1 M HC1 per gram ranged from 103.10 for Gelusil to 225.13 for Maalox, with others ranging between +/- 18.1% and -12% about the average. The neutralizing capacity per tablet ranged from 64.90 ml for Magnesium trisilicate Co tablets B.P. to 263.15 ml for Maalox, with the others ranging between +/- 24.9% and -33.1% about the average. This shows high variation in the neutralizing capacities of the different brands available especially in relations to the neutralizing capacities per tablet due to the high variation in the tablet weight.

Joseph N. Nganga

Papers

Minor flavanones from Erythrina abyssinica

A comparative study of the neutralising capacity of eight brands of antacids.