Hypoglycemic and hypolipidemic effects of the total triterpene acid fraction from Folium Eriobotryae.

For seeking the good natural material to develop new agent to treat diabetes, the total triterpene acid (TTA) fraction extracted from Folium Eriobotryae [leaves of Eriobotrya japonica (Thunb.) Lindl.] was evaluated for its hypoglycemic and hypolipidemic potential through normal, alloxan and streptozotocin-induced diabetic mice administered with graded oral doses (100, 200, 300 mg/(kg day)) for 7 or 14 days. The results showed that a dose of 300 mg/kg of TTA is the most effective dose to cause significant (p<0.01) hypoglycemic and/or hypolipidemic effects on normal, alloxan and streptozotocin-induced diabetic mice. This dose also significantly (p<0.01) lowered the glycosylated serum protein (GSP), total cholesterol (TC) and triglyceride (TG) level in severely diabetic mice. Furthermore, TTA increased the superoxide dismutase activity (SOD) and the serum insulin level of diabetic mice. These evidences indicated that the total triperpene acid fraction from Folium Eriobotryae has a high anti-diabetic potential along with a good hypolipidemic profile.

Influence of bleaching by ultrasound on fatty acids and minor compounds of olive oil. Qualitative and quantitative analysis of volatile compounds (by SPME coupled to GC/MS).

The effects of bleaching using high power ultrasound (20 kHz) on the quality of olive oil were considered in this study, in order to verify the modifications that can occur in fatty acid composition and minor compounds. During the treatment of olive oil under ultrasonic waves, a rancid odour has been detected. Treated olive oils show no significant changes in their chemical composition but the presence of some volatile compounds, due to ultrasonic treatment. Some off-flavour compounds (hexanal, hept-2-enal and 2(E),4(E)-decadienal) resulting from the sonodegradation of olive oil have been identified. A wide variety of analytical techniques (GLC, HPLC and GC/MS) were used to follow the quality of bleached olive oils with ultrasonic waves by the determination of the amounts of certain minor compounds such as sterols and tocopherols. Steradienes, resulting from the dehydration of sterols, were detected with small quantities especially in severe conditions of sonication. Solid phase micro-extraction (SPME) coupled to gas chromatography was known to be a sensitive technique to follow changes in the oxidative state of vegetable oils by measuring the amount of volatile materials produced during the refining process.

Evaluation of the mutagenic and antimutagenic effects of South African plants.

Dichloromethane and 90% methanol extracts of 42 South African plants were screened for mutagenicity and antimutagenicity using the Salmonella/microsome mutagenicity assay (Ames) against Salmonella typhimurium TA98 and TA100 bacterial strains in the presence and absence of metabolic activator S9. The methanol extracts from whole plants of Helichrysum simillimum, Helichrysum herbaceum and Helichrysum rugulosum indicated mutagenicity. These are the first reported tests on the mutagenicity of Helichrysum species. Six species indicated antimutagenic properties, all in the presence of S9: methanol leaf extract of Bauhinia galpinii, and dichloromethane leaf extracts of Bauhinia galpinii, Clerodendrum myricoides, Datura stramonium, Buddleja saligna, Millettia sutherlandii and Sutherlandia frutescens.

Natural medicines used in the traditional Chinese medical system for therapy of diabetes mellitus.

The rapidly increasing diabetes mellitus is becoming a serious threat to mankind health in all parts of the world. The control and treatment of diabetes and its complications mainly depend on the chemical or biochemical agents, but the fact is that it has never been reported that someone had recovered totally from diabetes. With the distinctive traditional medical opinions and natural medicines mainly originated in herbs, the traditional Chinese medicine performed a good clinical practice and is showing a bright future in the therapy of diabetes mellitus and its complications. Based on a large number of chemical and pharmacological research work, numerous bioactive compounds have been found in Chinese medicinal plants for diabetes. The present paper reviews 86 natural medicines with regards to their origin, anti-diabetic active principles and/or pharmacological test results, which are commonly used in the traditional Chinese medical system and have demonstrated experimental or/and clinical anti-diabetic effectiveness. Among these natural medicines, 82 originate from plants and 4 from animals or insects, which covers 45 families. It is strongly significant to pay close attention to traditional Chinese medical therapeutics and natural medicines for treatment of diabetes mellitus and its complications.

Investigation of the antimutagenic effects of selected South African medicinal plant extracts.

Dichloromethane extracts from different parts of Rhamnus prinoides, Ornithogalum longibracteatum, Gardenia volkensii, Spirostachys africana, Diospyros whyteana, Syzigium cordatum and Prunus africana were investigated for mutagenic and antimutagenic effects in Salmonella/microsome and micronucleus tests. None of the extracts tested in the Ames test were found to induce mutations or to modify the effect of the mutagen 4-nitroquinoline-oxide (4NQO). In the micronucleus test, extracts from twigs/bark of R. prinoides, twigs of D. whyteana, P. africana and S. cordatum significantly lowered the effect of the mutagen mitomycin C (MMC). Extracts from twigs/bark of G. volkensii and S. africana were genotoxic in the micronucleus test, while extracts of O. longibracteatum leaves potentiated the genotoxicity of MMC. This preliminary investigation shows that plant extracts used in traditional medicine may have particular effects with regard to mutagenicity and antimutagenicity indicating careful use in some instances and the need to isolate their active principles for further research.

Phytotoxins from the leaves of Laggera decurrens.

Upon biological screening of a series of African medicinal plants, substantial phytotoxic activity was found in the leaves of Laggera decurrens (Vahl.) Hepper & Wood (Asteraceae), using a Lemna minor bioassay. Bioassay-guided fractionation of the leaves led to the isolation of two physiologically active compounds: 3-hydroxythymoquinone and 5-acetoxy-2-hydroxythymol, causing death of Lemna minor in the 25-100 microM range. Symptoms were a rapidly developing chlorosis, followed by necrosis of fronds. The compounds also inhibited growth and germination of the grass weed Agrostis capillaris down to 250 microM. The mode of action of both compounds could not be elucidated, but they do not appear to be photosystem II inhibitors.

The hepatoprotective principle of Hypoestes triflora leaves.

Hypoestes triflora is frequently used in Rwandese native medicine to treat hepatic diseases. Premedication with a water extract of the leaves prevented the prolongation of the barbiturate sleeping time associated with carbon tetrachloride-induced liver damage in mice. The compound responsible for this protective activity was benzoic acid. Mice previously treated with benzoic acid also showed a significant diminution of the increased GOT and GPT levels seen after carbon tetrachloride administration.

Isolation of flavonoids and a chalcone from Helichrysum odoratissimum and synthesis of helichrysetin.

3,5-Dihydroxy-6,7,8-trimethoxyflavone, 3-O-methylquercetin, and helichrysetin were isolated from the flowers of the Rwandese medicinal plant, Helichrysum odoratissimum. Because of inconsistencies of the mp of the latter chalcone, a synthesis of helichrysetin was developed. 3-O-Methylquercetin was shown to be an active principle as it displayed antimicrobial activity.

Wheat rootlet growth inhibition test of Rwandese medicinal plants: active principles of Tetradenia riparia and Diplolophium africanum.

A series of 50 medicinal plants of Rwanda (121 plant samples) has been screened for wheat rootlets inhibition activity. The minimum inhibitory concentration (MIC) of the active principle of Tetradenia riparia, i.e. 8(14),15-sandaracopimaradiene-7 alpha, 18-diol (7.81 micrograms/ml), and of the active principle of Diplolophium africanum, i.e. scoparone (62.5 micrograms/ml), in this test was determined.

Active principles of Tetradenia riparia. I. Antimicrobial activity of 8(14),15-sandaracopimaradiene-7 alpha,18-diol.

Tetradenia riparia is one of the most popular medicinal plants in Rwanda. Previously, several new substances have been isolated from the leaves of this plant, including a new diterpene diol, i.e. 8(14),15-sandaracopimaradiene-7 alpha,18-diol. This new diterpene diol exhibits significant antimicrobial activity against several bacteria and fungi. The minimum inhibitory concentration (MIC) of the substance for microorganisms which were inhibited ranged from 6.25 to 100 micrograms/ml.