Investigations on antimycobacterial activity of some Ethiopian medicinal plants.

Fifteen crude extracts prepared from seven Ethiopian medicinal plants used to treat various infectious diseases were assessed for their ability to inhibit the growth of Mycobacterium tuberculosis. A preliminary screening of the crude extracts against M. tuberculosis typus humanus (ATCC 27294) was done by dilution assay using Löwenstein-Jensen medium. None of the tested extracts except the acetone fraction obtained from the stem bark of Combretum molle (R. Br. ex G. Don.) Engl & Diels (Combretaceae) showed significant inhibitory action against this strain. The acetone fraction of the stem bark of C. molle caused complete inhibition at concentrations higher than 1 mg/mL. Phytochemical analysis of the bioactive fraction led to the isolation of a major tannin and two oleanane-type pentacyclic triterpene glycosides. The tannin was identified as the ellagitannin, punicalagin, whilst the saponins were characterized as arjunglucoside (also called 4-epi-sericoside) and sericoside. All the pure compounds were further tested against the ATCC strain. Punicalagin was found to inhibit totally growth of the ATCC and also of a patient strain, which was fully sensitive to the standard antituberculosis drugs, at concentrations higher than 600 microg/mL and 1.2 mg/mL, respectively. On the other hand, the saponins failed to show any action on the ATCC strain. It appears that our findings are the first report of tannins exhibiting antimycobacterial activity.

Antiviral activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) of ethnobotanically selected Ethiopian medicinal plants.

Ethiopian medicinal plants used for the treatment of a variety of ailments including infectious diseases were screened for activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2). Seventy-one polar and nonpolar extracts derived from 21 plants belonging to 14 families were tested for inhibition of viral replication using HIV-1 (III(B)) and HIV-2 (ROD) strains. Selective inhibition of viral growth was assessed by the simultaneous determination of the in vitro cytotoxicity of each of the extracts against MT-4 cells. Six extracts made from the root bark of Bersama abyssinica Fresen, the leaves of Combretum paniculatum Vent., and Dodonaea angustifolia L.f., and the stem bark of Ximenia americana L. displayed antiviral activity at concentrations that were nontoxic to MT-4 cells. The highest selective inhibition of HIV-1 replication was observed with the acetone fraction of C. paniculatum and the methanol fraction of D. angustifolia which showed selectivity indices (ratio of 50% cytotoxic concentration to 50% effective antiviral concentration) of 6.4 and 4.9, and afforded cell protection of viral induced cytopathic effect of 100% and 99%, respectively, when compared with control samples. The greatest degree of antiviral activity against HIV-2 was achieved with the acetone extract of C. paniculatum (EC(50): 3 microg/mL), which also showed the highest selectivity index (32). The 50% cytotoxic concentration ranged from 0.5 microg/mL for the hexane extract of D. angustifolia L.f., the most cytotoxic of the extracts tested, to >250 microg/mL for some extracts such as the methanol fraction of Alcea rosea L., the least toxic tested. Only the polar extracts that were obtained by extraction with hydroalcohol, methanol or acetone exhibited inhibition of viral growth at subtoxic concentrations. The results obtained in this study enable the selection of extracts which show some specificity of action and support the further investigation of these extracts for their potential as new lead antiretroviral compounds.

Antiinflammatory activity of extracts of Biophytum sensitivum in carrageenin-induced rat paw oedema.

The antiinflammatory activity of aqueous and methanol extracts of aerial parts, an aqueous extract of roots as well as ultrafiltration fractions of a methanol extract of roots of Biophytum sensitivum were evaluated in the carrageenin induced rat paw oedema model. All the extracts except the methanol extract of aerial parts exhibited antiinflammatory activity, but inhibition of oedema was found to be maximum with aqueous extracts.

Quantitative phytochemical analyses of six hypericum species growing in slovenia.

The 74 samples of six HYPERICUM species (H. PERFOROTUM, H. HIRSUTUM, H. MACULATUM, H. TETRAPTERUM, H. MONTANUM, AND H. HUMIFUSUM) were collected around Slovenia and analysed for the content of ten substances (rutin, hyperoside, isoquercetin, quercitrin, quercetin, I3,II8-biapigenin, amentoflavone, pseudohypericin, hypericin, and hyperforin). The flowers were analysed separately from the green parts of the plants (herbs). The highest content of most of the substances was found in the flowers of H. PERFOROTUM. Among the herbal samples (without flowers), H. MONTANUM and H. HIRSUTUM contained significantly higher levels of amentoflavone (average 3-fold and 2.5-fold higher, respectively), than the herbs of H. PERFOROTUM. In the herbal part of H. PERFOROTUM the contents of all constituents strongly correlate with the contents of the same compound in flowers, except for the content of amentoflavone, which is independent in these two parts. Rutin and hyperoside are in positive correlation, and quercitrin is in negative correlation with the altitude of the growing site.

Amentoflavone from Biophytum sensitivum and its effect on COX-1/COX-2 catalysed prostaglandin biosynthesis.

Amentoflavone (I3', II8-biapigenin) was isolated from the roots of Biophytum sensitivum DC. (Oxalidaceae) and proved to be a selective inhibitor of cyclooxygenase (COX)-1 catalysed prostaglandin biosynthesis when tested in vitro with an IC (50) value of 12.4 microM (standard: indomethacin, IC (50) = 1.1 microM). Doses of up to 37 microM showed only a slight inhibition in the corresponding COX-2 assay. Quantification of amentoflavone was carried out by reversed phase HPLC in methanolic and aqueous extracts of the roots, stems and leaves. Highest amounts of amentoflavone were detected in methanolic extracts of roots and stems (0.26-0.35%), while considerably lower amounts were detected in the corresponding water extracts.

Production of hypericin, pseudohypericin and flavonoids in cell cultures of various Hypericum species and their chemotypes.

Suspension cultures were established from the shoots of sterile germinated seeds of various provenances of seven Hypericum (H.) species in a half strength modified Murashige and Skoog liquid medium. In most strains of H. perforatum (18 provenances) and all strains of H. maculatum (6 provenances) as well as in the cultures of H. tomentosum, H. bithynicum, H. glandulosum and H. balearicum, hypericin and pseudohypericin could be proven, however, in extremely varying amounts. In general, the pseudohypericin content was significantly higher than that of hypericin. The flavonoid patterns, comprising monomeric quercetin derivatives and dimeric apigenin derivatives, varied among strains over a wide range.

Flavone glucuronides of Lycopus virginicus.

From the ethanolic extract of the aerial parts of Lycopus virginicus (L.) Michx. (Lamiaceae) the 7- O-beta- D-glucuronides of apigenin, acacetin, and luteolin as well as the methyl ester of apigenin 7- O-beta- D-glucuron-ide could be isolated. Quantification of luteolin 7- O-beta- D-glucuronide by HPLC in crude methanolic extracts from L. virginicus, L. europaeus, and L. exaltatus showed contents of 0.017-0.22%.

Investigations on the adsorption of quercetin on a medicinal carbonic absorbent--controlled release and stability.

The process of adsorption/desorption of quercetin (which is therapeutically used in the Ukraine owing to its antioxidant and radical scavenging activities) on the surface of the medicinal carbonic adsorbent "Dnieper" was studied. Owing to a high adsorption capacity, the adsorbent could be used as a carrier for immobilised drugs. On the basis of desorption data, liberation of quercetin from the complex quercetin-adsorbent can be characterized as rapid initial with subsequent sustained release. On the surface of the adsorbent, quercetin does not loose its antioxidative activity. However, adsorption leads to instability of quercetin as well as of kaempferol and rutin caused mainly by oxidation during storage.

[The application of microwave energy in preparation of herbal drugs. 2]. / Der Einsatz von Mikrowellenenergie zur Aufbereitung von Arzneidrogen. 2. Mitteilung.

On the basis of various plant organs the relation between the used microwave energy and the drying processes, temperatures of the surface and the interior of the drying materials as well as the remaining moisture in the drugs was investigated. Leaf, flower and herb drugs showed a similar drying behaviour. Plant material of high humidity, e.g. meaty fruits or roots, should be dried by means of pulsed microwave application to avoid too high temperatures. In almost all investigated drugs microwave drying resulted in a lower remaining moisture than air drying. The effect of microwave irradiation on carbohydrates, fats and proteins in plant materials was preliminarily investigated.

[The application of microwave energy in preparing medicinal plant drugs. 1]. / Der Einsatz von Mikrowellenenergie zur Aufbereitung von Arzneidrogen. 1. Mitteilung.

Using a specially constructed microwave device, containing a steady-state-broadcasting magnetron that is infinitely adjustable within a range of 100 to 1200 W, the applicability of microwave energy for drying medicinal plants was investigated. When optimising the drying parameters (e.g. microwave power, time of irradiation, mass of plant material, thickness of layer) most of the obtained leave, flower, herb and root drugs showed a significant better appearance (colour) than the air dried drugs.

Production of Flavonoids in Cell Cultures of Crataegus monogyna.

Callus and suspension cultures were established from shoot tips of CRATAEGUS MONOGYNA L. in Murashige and Skoog (MS) medium and a modified MS medium. The flavonoid glycosides vitexin, vitexin 2- O-rhamnoside, rutin, and hyperoside, as well as the aglycones apigenin, luteolin, and quercetin, could be detected by TLC and HPLC in, however, varying amounts. Additionally, the contents of procyanidins were determined. The ratio between the contents of flavonoids and procyanidins is discussed.

Antimicrobial activity of the essential oil of young pine shoots (Picea abies L.).

The antimicrobial activity of the essential oil of young pine shoots was investigated and compared with that of a commercial pine needle oil and chloramphenicol. The correlation between the antimicrobial activity of the essential oils and their compositions, analysed by gas chromatography, is discussed.