University of Macau / Institute of Chinese Medical Sciences

University of Macau / Institute of Chinese Medical Sciences

University of Macau / Institute of Chinese Medical Sciences

In the polyol pathway, Aldose reductase (AR) is an important enzyme in reduction of aldehydes and aldosugars to their suitable alcohols. AR, using NADPH as a coenzyme, has a molecular weight of 37 000 dalton. AR in its activated form, known to increase the sorbitol accumulation in lens, is responsible for the cataract formation in diabetis diseases. Therefore, the inhibition of aldose reductase is important to prevent the incedence of cataract formation in diabetus mellitus. In the treatment of diabetis dependent cataract, chemically synthetized drugs were sometimes less than beneficial due to the severe side effects they cause. Recently a huge amount of study has been intensified on developing new drugs from natural compounds and even by utilizing plant extracts for their easily metabolizing polyphenolic compounds. In this study, BLAR, source of enzyme, was obtained as crude via differential centrifugation and ammonium sulfate precipitation. The enzyme assay conditions were optimized for the protein, substrate, coenzyme, and salt concentrations, also for the effects of pH and temperature. Ocimum basilicum, Lavandula stoechas, Melissa officinalis, Glycyrrhiza glabra L. and Tilia tomentosa were selected as commonly used alternative medicine plants. Plant extracts were prepared in ethanol and ethyl acetate and their inhibitory effects were tested on crude bovin lens aldose reductase enzyme. Fifty percent inhibitory concentrations (IC50) were found between values of 25.53 &micro / g/mL and 54.15 &micro / g/mL for ethanol extracts and between 41.55 &micro / g/mL and 82.96 &micro / g/mL for the ethyl acetate extracts of selected plants. In addition, the plant extracts were also characterized for their antioxidant activities by of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and test of total phenolic content (TPC) .

Thesis (doctoral)--University of Göttingen, 2002. / Includes bibliographical references (p. [102]-118).

M. Tech. Chemistry / Sutherlandia frutescens is a popular indigenous South African medicinal plant which has been identified to re-establish itself on acid rock mine dumps. Medicinal plants such as S. frutescens are harvested from the wild and widely used for primary health care. The primary objective of the study was to determine the effect of soil contamination on the secondary metabolites profile of the plant.

Thesis (MTech. degree in Pharmaceutical Sciences)--Tshwane University of Technology, 2008. / The aim of the study is to investigate whether the chemical composition and antimicrobial activity of orally administered medicinal plants are affected by in vitro dissolution and gastrointestinal absorption processes. Few in vitro screening assays for biological activities of plant extracts consider the effect of the gastrointestinal system. This is an important factor for the bioavailability of plant extracts intended to be administered via the oral route. In this study, crude water and methanol extracts of selected plants (green tea, 'buchu', thyme, sage and wild camphor) were prepared and exposed to simulated gastric fluid and simulated intestinal fluid during dissolution studies. The crude extracts and resulting simulated gastric fluid and simulated intestinal fluid products were screened for antimicrobial activity.

Siphonochilus aethiopicus (Schweinf.) B.L. Burtt (Zingiberaceae), commonly known as wild ginger, is a highly sought after plant for use in traditional medicine in South Africa. Over-exploitation of this medicinal plant has resulted in regional extinction in the wild. As a result, there is great interest in the medicinal properties of S. aethiopicus, and as a plant for small scale cultivation to increase the supply for use in traditional medicine. Water, ethanol and ethyl acetate extracts were prepared from the leaves, rhizomes and roots of S. aethiopicus. These extracts were tested for in vitro anti-inflammatory activity in the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) assays, and in the microdilution antibacterial assay. The aqueous extracts showed no significant prostaglandin synthesis inhibition in the COX-1 and COX-2 assays. The ethanol and ethyl acetate extracts of the leaves showed the highest levels of activity at a concentration of 250 µg ml¯¹ per test solution, in both the COX-1 and COX-2 assays. The ethanol and ethyl acetate extracts of the rhizomes and roots also had moderate levels of activity in the COX-1 assay. These results provide some evidence for the rational use of S. aethiopicus in traditional medicine for anti-inflammatory purposes. In the microdilution antibacterial assay, no inhibitory activity against the test bacteria was detected with the aqueous extracts. The ethanol and ethyl acetate extracts tested showed greater antibacterial activity at minimal inhibitory concentrations ranging from 0.78 to 3.13 mg ml¯¹ against the gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) than the Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae). No distinct differences were observed between the ethanol and ethyl acetate extracts, or between the different plant parts. A serial extraction of S. aethiopicus rhizome material was conducted and the extracts were tested in the COX-1 assay and the microdilution assay as a preliminary investigation for a bulk extraction. The hexane and ethyl acetate extracts gave slightly higher COX-1 inhibition than the ethanol extract. No distinct differences were observed in the microdilution assay. A bulk ethyl acetate extract of S. aethiopicus rhizome material was prepared, yielding 6.3 g of a thin orange oil. Vacuum liquid chromatography (VLC) was used to fractionate ≈4 g of the extract. The VLC fractions were evaluated using thin layer chromatography (TLC) and a bioautographic assay, using S. aureus as a test organism. The fractions were also tested in the COX-1 assay. The bioautography revealed a number of compounds which exhibited antibacterial activity. Fraction C was purified further using preparative TLC, and 24.9 mg of a pure compound from R,0.54 (toluene:ethyl acetate 93:7) was isolated. The structure of the compound was elucidated from nuclear magnetic resonance (NMR) spectra, and mass spectroscopy of the compound was also recorded. The compound was identified as the sesquiterpenoid furanoeremophil-2-en-1-one, which is structurally identical to the recently reported compound 4aαH-3,5α,8aβ-trimethyl-4,4a,9-tetrahydro-naphtho[2,3-b]-furan-8-one. The compound showed only a very minimal bacteriostatic effect in the microdilution assay. S. aethiopicus plants were harvested before and after seasonal senescence. Ethanol extracts were prepared from fresh or dried material of the leaves, rhizomes and roots, and tested in the COX-1 assay and the microdilution assay TLC fingerprints of the various extracts were also prepared. No noteworthy changes in COX-1 inhibition, due to senescence, were observed with extracts prepared from fresh material, although there did appear to be a slight decrease in activity in the α-roots and an increase in the β-roots after senescence (fresh and dry). A decrease in the antibacterial activity of the leaves and an increase in the antibacterial activity of the α-roots was observed after senescence. These results suggest that the time of harvest may only have a minimal influence on the degree of anti-inflammatory and antibacterial activity. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

Ethnobotanical and dietary questionnaires were used to assess the utilization of plants to treat the signs and symptoms of anemia by women in La Chapelle, Haiti. The usual diet of respondents was found to be low to intermediate in iron bioavailability. The ethnobotanical questionnaire showed that most respondents (82%) used plant-based home remedies to treat anemia Amaranthus dubius, Citrus aurantium, Corchorus olitorius, Moringa oleifera, Phaseolus vulgaris and Portulaca oleracea used in the diet and as remedies for anemia were analyzed. Amaranthus dubius was found to have the higher in availability by in-vitro dialysis, 30%. The intra species variation in iron availability was influenced by storage and cooking times. The interspecies variation in iron availability was explained by the acidity of the plant species' cooked homogenate (r = 0.4168, p = 0.007).

<p>The incidence of cardiovascular diseases, including hypertension, is on the increase worldwide. Medicinal plants played an important role in the treatment of hypertension for centuries. Very few scientific studies have, however, been done to validate the use of these phytotherapies. O africana is on of the many phytotherapies that has been use indigenously for years to treat hypertension. The objectives of this study were to determine the most effective does of O africana aqueous extract which will reduce blood pressure / to determine whether chronic administration of O africana can be used to prevent and treat hypertension / to determine whether O africana exert its effects by modulation of the renin-angiotensin system.</p>