Investigation of antidiabetic properties, mechanisms of action and toxicology of Strychnos Henningsii (GILG) bark
- Authors: Oyewole, Oyedemi Sunday
- Date: 2011
- Subjects: Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Diabetics -- Alternative treatment -- South Africa , Loganiaceae , Lamiaceae , Diabetes , Proteins
- Language: English
- Type: Thesis , Doctoral , PhD (Biochemistry)
- Identifier: vital:11254 , http://hdl.handle.net/10353/d1001070 , Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape , Diabetics -- Alternative treatment -- South Africa , Loganiaceae , Lamiaceae , Diabetes , Proteins
- Description: The apparent reversal of trend from modern drugs to herbal medicine is partly due to the fact that synthetic drugs have always shown adverse reactions and other undesirable side effects. Hence, the use of medicinal plants for the treatment of diseases such as diabetes is very common especially in the rural areas. Majority of these plants are used based on the experience and indigenous knowledge without identification of the therapeutic agents. There is enormous wealth of medicinal plants in the world yet many of them have not been discovered or studied scientifically to substantiate their ethno-medicinal usages. Ethnobotanical study has been the method often used to search for locally important plant species for the discovery of crude drugs with low side effects. An ethnobotanical survey was conducted on the medicinal plants commonly used for the management of diabetes mellitus in Nkonkobe Municipality, Eastern Cape of South Africa. Information was obtained through structured questionnaire administered to traditional healers and herbalists in the region. The study revealed 15 species of plants belonging to 13 families. Strychnos henningsii and Leonotis leonorus among others were repeatedly mentioned by the traditional healers as the two mostly used plants for the management of diabetes mellitus. The infusion and decoction of the roots, leaves and barks of these plants are the methods of preparation. The antioxidant potential of aqueous bark extract of S. henningsii was investigated both in vivo and in vitro using spectroscopic method. The antioxidant activity of the extract against hydrogen peroxide (H2O2), 2,2′-azinobis[3-ethylbenzothiazoline6-sulfonic acid] diammonium salt (ABTS), as well as reducing power was concentration dependent. The extract exhibited lower and average scavenging activities against 1,1diphenyl2picrylhydrazyl (DPPH) and nitric oxide (NO) radicals with IC50 value of 0.739 and 0.49 mg/ml respectively. The administration of the plant extract at 250, 500 and 1000 mg/kg significantly increased the activities of the antioxidant enzymes in the hepatotoxic rats induced with carbon tetrachloride. On the other hand, the stem bark extract had lower effect on lipid peroxidation level except at the dose of 250 mg/kg. The effect of oral administration of S. henningsii extract was evaluated in normal Wistar rats for 28 days. The observed result indicated non- toxic effect of sub-acute administration of plant extract to the animals except at certain doses. This is because, there was no apparent damage to some haematological and biochemical parameters used in assessing organ specific toxicity. However, the alterations observed on platelet, white blood cells and its differentials imply parameter and dose selective toxicity when repeatedly consumed on daily basis at the doses investigated. This study also investigated the antidiabetic activities of the extract at the doses of 125, 250 and 500 mg/kg body weight in diabetic rats induced with streptozotocin -nicotinamide for 15 days. The extract appreciably (P <0.05) reduced the blood glucose level, feed and water intake while the best result was obtained at 250 mg/kg. Similarly, the level of triacylglycerol at the three doses investigated was significantly decreased. In addition, the glucose tolerance was reduced to near normal level after 90 min at certain doses. The clinical significance of the extract on some biochemical and haematological parameters lessen both hepatic and renal damages. Anaemic condition in diabetic animals was also improved after plant extract administration. However, no significant effect was observed in white blood cells and some of its differentials. The extract demonstrated strong glucose utilization in 3T3-L1 cells with a response of 278.63 percent of the control at 12.5μg/ml while that of Chang liver cells was 103.54 percent. The cytotoxicity result revealed non toxic effects of the extract to both cell lines. Treatment of 3T3 L1 cells with the extract did not reduce lipid accumulation. The extract inhibited the activity of α- glucosidase and α- amylase in a concentration dependent manner with IC50 values of 38 μg/ml and 60.9 μg/ml respectively. The percentage protein antiglycation of S. henningsii was 18.4, 38.2 and 61.2 perceent for 0.25, 0.5 and 1 mg/ml respectively while aminoguanidine a known inhibitor of protein glycation was 87.2 percent at 1 mg/ml. The FRAP assay values of the extract was 357.05 μmol Fe (II)/g. The findings from this study support the folkloric usage of this plant for the management of diabetes mellitus in the region.
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- Date Issued: 2011
Chemical transformations and phytochemical studies of bioactive components from extracts of Rosmarinus officinalis L
- Authors: Okoh, Omobola Oluranti
- Date: 2010
- Subjects: Essences and essential oils , Rosmarinus , Lamiaceae , Solution (Chemistry) , Extractive distillation , Medicinal plants , Bioactive compounds
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11331 , http://hdl.handle.net/10353/354 , Essences and essential oils , Rosmarinus , Lamiaceae , Solution (Chemistry) , Extractive distillation , Medicinal plants , Bioactive compounds
- Description: Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80 percent of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 percent and 67 percent, the HD derived oil showed inhibitions of between 52.2 percent and 65.30 percent at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nosocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
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- Date Issued: 2010
Extractives from six species of Lamiaceae
- Authors: Davies-Coleman, Michael Trevor
- Date: 1988
- Subjects: Lamiaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4532 , http://hdl.handle.net/10962/d1016235
- Description: In continuation of the phytochemical studies of plants belonging to the Lamiaceae (formerly Labiatae) the acetone extractives of six Southern African species from this family have been examined. The genus Syncolostemon has not been investigated before and a new 6- substituted-5 ,6-dihydro-a-pyrone , synrotolide was isolated from S. rotundifolius. The structure of synrotolide was fully elucidated as 6fixii [3'R, 61S-(diacetyloxy)-4 1R, 5 1 8-(dihydroxy)-1~-hepteny~ -5,6-dihydro-2H-pyran- 2-one. Oleanolic acid is the major component of both~ rotundifolius and S. densifloris. The flavonol quercetin was isolated from S. densifloris as its 3, 3', 4' , 7 tetramethyl ether. A further 6-substituted-5,6-dihydro-a-pyrone, boronolide, was obtained from Tetradenia barberae. The structure of boronolide was known but the absolute stereochemistry was unassigned. Chemical degradation established the total structure of this compound as 6R- [1 'R, 2'R, 3's -(trisacetyloxy)heptyl] -5,6-dihydro-2H-pyran-2-one. The chemistry of naturally occuring 6-substituted-5,6-dihydro-apyrones has not as such been previously reviewed and a comprehensive review covering the literature up to June 1987 is presented here. Three known labdane diterpenoids nepetaefuran, hispanalone and dubiin were iso lated from Leonotis nepetaefolia, Ballota africana and L. ocymifolia var. ocymifolia (formerly~ dubia). Both~ nepetaefolia and L. dubia have been examined before. An X-ray analysis of saponified dubiin and a circular dichroism study of 6-deacetyldehydrodubiin and related compounds corroborated the structure of dubiin as 48, 5R, 6R, 8R, 9R, 10R-[6-acetoxy-15,16-epoxy-9-hydroxylabda-13 (16), 14-dien-19, 20- olactoneJ. The chemotaxonomic relationships of the genera Ballota and Leonotis are discussed.
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- Date Issued: 1988