Partial prevention of long-term femoral bone loss in aged ovariectomized rats supplemented with choline-stabilized orthosilicic acid.

Silicon (Si) deficiency in animals results in bone defects. Choline-stabilized orthosilicic acid (ch-OSA) was found to have a high bioavailability compared to other Si supplements. The effect of ch-OSA supplementation was investigated on bone loss in aged ovariectomized (OVX) rats.

Antiviral activity of Rwandan medicinal plants against human immunodeficiency virus type-1 (HIV-1).

Selected plants used in Rwandan traditional medicine for the treatment of infections and/or rheumatoid diseases were investigated for antiviral activity in vitro against human immunodeficiency virus type-1 (HIV-1). Of the 38 tested 80% ethanolic extracts, belonging to plants of 21 different families only the extracts from the leaves of Aspilia pluriseta (Asteraceae) and Rumex bequaertii (Polygonaceae) had interesting selectivity indices (SI = ratio of the 50% cytotoxic concentration to the 50% effective antiviral concentration) higher than 1. Further fractionation of the initially antivirally inactive ethanolic extract of Tithonia diversifolia, however, led to an aqueous fraction with a high anti-HIV-1 activity (SI > 461), indicating that the cytotoxicity of some plant components may mask the antiviral properties of the active plant substances in total plant extracts.

Complement modulating activity of Rwandan medicinal plants.

Forty-two ethanolic extracts of thirty-six Rwandan medicinal plants were investigated for their influence on complement-mediated hemolysis. The plants were selected on the base of their ethnomedicinal use in infections and autoimmune diseases. Eight plant extracts showed an inhibitory activity against the classical pathway of the complement system and ten plant extracts against the alternative pathway.

Further evaluation of Rwandan medicinal plant extracts for their antimicrobial and antiviral activities.

A total of 45 Rwandan plant extracts, belonging to 37 different plant species out of 21 families, were investigated for their antibacterial, antifungal, and antiviral properties. The plants were selected on the base of their ethnomedicinal use against infections and autoimmune diseases. From all the plant extracts tested, only Clematis hirsuta (leaves) showed a pronounced antifungal activity against Candida albicans and the dermatophytes Trichophyton rubrum, Epidermophyton floccosum, and Microsporum canis.

Antiviral, haemolytic and molluscicidal activities of triterpenoid saponins from Maesa lanceolata: establishment of structure-activity relationships.

Ten saponins isolated from the leaves of Maesa lanceolata were tested for their antiviral, haemolytic and molluscicidal activities. The influence of the substitution pattern of these acylated triterpenoid saponins on their biological activities was investigated and structure-activity relationships were established. Maesasaponin VI(2) (3 beta-O-[[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-galactopyranosyl-(1 --> 3)]-[beta-D-galactopyranosyl-(1 --> 2)]-beta-D-glucopyranuronyl]-21 beta,22 alpha-diangeloyloxy-13 beta,28-epoxyolean-16 alpha,28 alpha-diol), the most potent molluscicidal compound (LC(50) 0.

Cytotoxicity and lipid peroxidation-inhibiting activity of flavonoids.

Thirty-five flavonoids of seven different types, namely isoflavonoids, chalcones, dihydroflavonols, flavanols, flavanones, flavones, and flavonols were investigated for their ability to inhibit ascorbate-induced microsomal lipid peroxidation and their cytotoxicity. For each activity a structure-activity relationship was established. Subsequently, an antioxidant selectivity index, i.

Screening of seven selected Rwandan medicinal plants for antimicrobial and antiviral activities.

Aqueous EtOH (80%) extracts of seven plants used by Rwandan traditional healers to treat infections, were screened for antibacterial, antifungal, and antiviral activities. Only two of the selected plants showed a true antiviral activity against herpes simplex virus type 1, while all of them exhibited virucidal properties against several enveloped viruses including herpes simplex, measles, Semliki forest, and vesicular stomatitis viruses. Four plants were diversely active against gram-positive bacteria, two of these showing bactericidal effect against the acid-fast Mycobacterium fortuitum.

Separation of a triterpenoid saponin mixture from Maesa lanceolata: semipreparative reversed-phase wide pore high performance liquid chromatography with temperature control.

A mixture of triterpenoid saponins derived from the dried leaves of Maesa lanceolata was separated, without structure deterioration, in its components. Seven fractions (I-VII) of high molecular weight (1234-1358) saponins were obtained on a semipreparative scale using wide pore reversed-phase high performance liquid chromatography with an acetonitrile trifluoroacetic acid (500:0.3 w/w)-water-trifluoroacetic acid (391:0.

Evaluation of biological activities of triterpenoid saponins from Maesa lanceolata.

From a bioassay-guided fractionation procedure using Herpes simplex virus type 1 as the target model, a virucidal saponin mixture (maesasaponin mixture B) was isolated from the MeOH extract of leaves of Maesa lanceolata. The maesasaponin mixture B consisted of six homologous oleanane-type triterpenoid saponins 1-6, identified by 1H, 13C, and 2D NMR spectroscopy and mass spectrometry. The maesasaponin mixture B (1-6) showed several biological activities expected for saponins.

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.