The Genus Diospyros: A Review of Novel Insights into the Biological Activity and Species of Mozambican Flora.

Species of the Diospyros L. genus (Ebenaceae family) have been largely used in traditional medicine for the treatment of several diseases, especially infectious ones. To date, active major compounds such as naphthoquinones, triterpenoids, and tannins have been isolated and pharmacologically validated from Diospyros species. The present study summarizes the information available in the literature on the species described in the Flora of Mozambique. To do so, scientific databases (e.g., PubMed, Scopus, Web of Science, and Google Scholar) were searched using various keywords and Boolean connectors to gather and summarize the information. Of the 31 native and naturalized species in the Flora of Mozambique, 17 are used in different regions of Africa and were described for their traditional uses. They were reported to treat more than 20 diseases, mostly infectious, in the gastrointestinal and oral cavity compartments. This work provides an overview of the therapeutical potential of Diospyros species and explores novel insights on the antimicrobial potential of extracts and/or isolated compounds of these Mozambican species.

Diospyros villosa Root Monographic Quality Studies.

Diospyros villosa L. (De Winter) (Ebenaceae) is a shrub whose root (DVR) is used as a toothbrush and to treat oral infections in Mozambique. The present work aims at establishing monographic quality criteria to allow the sustainable and safe development of pharmaceutical preparations with this herbal drug. This includes setting botanical (qualitative and quantitative) and chemical identification parameters, purity tests (loss on drying and total ash), quantifying the major classes of constituents identified, and particle size characterization of the powdered drug. DVR samples are cylindrical and microscopically characterized by: a periderm, with six layers of flattened phellem cells, with slightly thickened walls and few layers of phelloderm; cortical parenchyma with brachysclereids with a short, roughly isodiametric form (13.82-442.14 µm2 × 103), surrounded by a ring of prismatic calcium oxalate crystals; uniseriate medullary rays and prominent vessels of the xylem with single or double shape; numerous single and clustered starch grains, within the cortical parenchyma, medullar parenchyma, and ray cells. Polyphenols, mainly hydrolyzable tannins (212.29 ± 0.005 mg gallic acid equivalent/g of dried DVR), are the main marker class of constituents. Furthermore, the average diameter of the particles of the powder, 0.255 mm, allows its classification as a fine powder.

Contribution of Light and Electron Microscopy to Identification of Bark from Frangula azorica, an Azorean Medicinal Plant.

Frangula azorica V. Grubow is a Macaronesian flora medicinal plant, endemic from Azores islands and inscribed on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. This species, known as "sanguinho," belongs to the family Rhamnaceae, the same as Frangula alnus Mill. and Frangula purshiana (DC.) J. G. Cooper, two widely used official laxative herbal medicines of the western Pharmacopoeias constituted by the dried barks of each species. Morphological and chemical studies on F. azorica dried bark are scarce although it is potentially recognized as a Portuguese laxative herbal medicine. Macroscopically, the bark occurs in quills or nearly flat pieces. A channeled external surface with transversely elongated lenticels is characteristic. When the outer phellem layer is removed, a bright purple inner phellem layer is disclosed. Light and electron microscopy observations revealed flattened phellem cells with slightly thickened walls, cortical parenchyma with secretory ducts and groups of sclereids, phloem with groups of fibers and sheaths of parenchymatous cells containing druses or more frequently prismatic crystals of calcium oxalate, and parenchymatous medullary rays one to three cells wide with spherical starch grains. Observation of these botanical characteristics must be included in quality monographs of F. azorica bark herbal medicine.

Anti-Helicobacter pylori activity of Terminalia macroptera root.

The root of Terminalia macroptera Guill. & Perr. (Combretaceae) is widely used in African traditional medicine to treat various infectious diseases, including stomach-associated diseases. This study investigates the in vitro activity of T. macroptera root extract against reference strains and clinical isolates of H. pylori and attempts to localize the extract bioactivity. T. macroptera hydroethanol (80% V/V) root extract (Tmr) activity was tested against three standard strains and sixty two clinical strains of H. pylori. Tmr liquid-liquid partition fractions were screened against twenty H. pylori strains. Qualitative analysis of Tmr and its fractions was performed by HPLC-UV/DAD. The antibiotic characterization of the H. pylori strains revealed that 20% of the tested clinical isolates were resistant to at least two of the three antibiotics belonging to the main groups of antibiotics used in multi-therapy to eradicate H. pylori infections. In contrast, Tmr showed anti-H. pylori activity against the majority (92%) of the tested strains (MIC(50) and MIC(90)=200 µg/ml). The Tmr water liquid-liquid fraction (Tmr-3) and the precipitate obtained from this fraction (Tmr-5) were the most active tested samples, showing a MIC(50) of 100 µg/ml. The present work proves the in vitro activity of T. macroptera against H. pylori, thus confirming the utility of this traditional medicinal plant to treat stomach complaints due to H. pylori infection. The main compounds of Tmr and of Tmr-3 were the ellagitannins terchebulin and punicalagin. These compounds can be considered as markers of T. macroptera root active extracts against H. pylori.

Guieranone A, a naphthyl butenone from the leaves of Guiera senegalensis with antifungal activity.

A new methoxylated naphthyl butenone, guieranone A (1), was isolated from the leaves of Guiera senegalensis. Its structure was elucidated as (2E)-1-(1,3,6,8-tetramethoxy-2-naphthyl)but-2-en-1-one, on the basis of spectroscopic data. Also isolated were two known naphthopyrones, 5-methyldihydroflavasperone (2) and 5-methylflavasperone (3). Guieranone (1) exhibited potent antifungal activity against Cladosporium cucumerinum and is the first naphthyl ketone derivative to have been isolated from the family Combretaceae.

In vitro anti-Neisseria gonorrhoeae activity of Terminalia macroptera leaves.

We used the agar dilution method to evaluate the antibacterial effect of Terminalia macroptera leaf (Tml) extract against nine reference and clinical Neisseria gonorrhoeae strains, including penicillin- and tetracycline-resistant and -susceptible strains. Tml possesses anti-N. gonorrhoeae activity against all of the strains and the minimum inhibitory concentrations (MIC) were between 100 and 200 microg ml(-1). We then used a liquid-liquid partition method to divide the Tml extract into five fractions and determined the anti-N. gonorrhoeae activity of each of the fractions. All of the fractions showed antibacterial activity. The most active one was identified as the diethyl ether fraction and had MIC values of between 25 and 50 microg ml(-1) against all of the strains.

In vitro anti-Neisseria gonorrhoeae activity of Terminalia macroptera leaves.

We used the agar dilution method to evaluate the antibacterial effect of Terminalia macroptera leaf (Tml) extract against nine reference and clinical Neisseria gonorrhoeae strains, including penicillin- and tetracycline-resistant and -susceptible strains. Tml possesses anti-N. gonorrhoeae activity against all of the strains and the minimum inhibitory concentrations (MIC) were between 100 and 200 microg ml(-1). We then used a liquid-liquid partition method to divide the Tml extract into five fractions and determined the anti-N. gonorrhoeae activity of each of the fractions. All of the fractions showed antibacterial activity. The most active one was identified as the diethyl ether fraction and had MIC values of between 25 and 50 microg ml(-1) against all of the strains.