• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 108
  • 18
  • 10
  • 7
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 157
  • 157
  • 157
  • 76
  • 74
  • 33
  • 32
  • 31
  • 31
  • 30
  • 28
  • 21
  • 19
  • 18
  • 17
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Acute and chronic toxicity of the flavonoid-containing plant, Artemisia afra in rodents.

Mukinda, James Tshikosa January 2005 (has links)
The aim of this study was to investigate the possible toxicity of the flavonoid-containing plant, Artemisia afra and especially establish the safety of the aqueous extract of this plant after acute and chronic administration to mice and rats respectively.
132

Socio-economic aspects of the sustainable harvesting of buchu (Agathosma Betulina) with particular emphasis on the Elandskloof community

Williams, Samantha January 2005 (has links)
The aim of this thesis was to explore the socio-economic factors that impact on the sustainable harvesting of buchu in the Western Cape of South Africa. Some of the factors that were explored include poverty, natural resource tenure, legislation, and local practices with regard to the harvesting of buchu.
133

The extraction, purification and evaluation of compounds from the leaves of Leonotis Leonorus for anticonvulsant activity.

Muhizi, Thèoneste January 2002 (has links)
The aim of this study is to isolate and evaluate the anticonvulsant components from the leaves of Leonotis leonorus (L) R.aR. and to see if there is any change in activity with the origin of the plant material and I or the season in which plant material is collected. Therefore, in this study, two sites were chosen for collection of plant material and the collection was made in summer and in winter. Chemical, physical and pharmacological methods were used to isolate, identify and to evaluate compounds isolated from the leaves of Leonotis leonorus for anticonvulsant activity.
134

Acute and chronic toxicity of the flavonoid-containing plant, Artemisia afra in rodents.

Mukinda, James Tshikosa January 2005 (has links)
The aim of this study was to investigate the possible toxicity of the flavonoid-containing plant, Artemisia afra and especially establish the safety of the aqueous extract of this plant after acute and chronic administration to mice and rats respectively.
135

Modulation of the redox status, phase 2 drug metabolizing enzymes and fumonisin-induced cancer promotion in rat liver by selected Southern African medicinal plants

Hikuam, Willem Christoph January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Doctor of Technology: Biomedical Technology in the Faculty of Health and Wellness Sciences at the Cape Peninsula University of Technology 2014 / According to the World Health Organization, cancer is the leading cause of death in the developed world, while it is the second leading cause of death in the developing world. In particular, liver cancer is the fifth most commonly diagnosed cancer in men, however, it is the second most frequent cause of death, responsible for an estimated 700,000 deaths annually. General limited access to health services, including treatment and the overall management of cancer in developing countries often contribute to the increased mortality rates when compared to developed countries. For centuries, medicinal plants have been used to prevent, and to a certain extent, treat cancer as a readily available and affordable alternative. In many instances, the curative or preventative claims still remain anecdotal. However, increasing evidence suggest that polyphenolic components of plants possess antioxidant activities, which are credited with curative/beneficial properties of medicinal plants. The curative properties could either be related to the primary compounds present in the plant itself, or the bio-activation products of plant components affecting hepatic drug metabolising and antioxidant enzymes systems related to carcinogen metabolism and maintaining oxidative homeostasis, respectively. Similarly, chronic consumption of medicinal plants could also result in hepatotoxicity, either caused by the primary plant components or bio-activation products. Due to these observations it is paramount to understand the mechanisms involved in the metabolism of plant components to critically assess beneficial versus potential harmful properties associated with chronic consumption. The focus of the current study was aimed at elucidating the bio-activity of four multipurpose indigenous plants to Southern Africa, i.e. Adansonia digitata, Agathosma betulina, Siphonochilus aethiopicus and Myrothamnus flabellifolius. Traditionally, A. digitata has been used as an immunostimulant, anti-inflammatory and analgesic agent, while also as an antipyretic agent in the treatment of diarrhoea and dysentery. Similarly, traditional medicinal uses of A. betulina include treatment cholera, haematuria, calculus, kidney diseases, as well as infections of the bladder, urethra, and prostate among others. S. aethiopicus was traditionally employed to treat infections associated with pains and fevers, whereas M. flabellifolius served as treatment of conditions ranging from respiratory ailments, backache, kidney problems, haemorrhoids, chest pain, and asthma. In the first part of this study, the polyphenolic contents and antioxidant capacities of the four plants were characterised. The emphasis was placed on using different solvents, namely water, ethanol and acetone for the extraction of the plant material and different methodologies to assess the antioxidant contents and -capacities of the various extracts as both these factors can influence the outcome. When considering the antioxidant contents, total polyphenols, flavanols, and flavonols of the different solvent extracts prepared from the four plants were determined, whereas three different assays were used for the antioxidant capacities, i.e. oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC) and ferric-reducing antioxidant power (FRAP) assays. The A. digitata acetone extract had the highest (7.121 mg gallic acid equivalent (GAE)/milligram (mg) soluble solids), whereas the water extract of the same plant had the lowest total phenolic content (0.008 mg GAE/mg soluble solids). In general, the acetone extracts demonstrated the highest total polyphenol, flavanol, and flavonol contents, followed by the ethanol extracts, with the water extracts having the lowest contents. M. flabellifolius was the only distinct deviation from this rule, where the water extract demonstrated the highest total polyphenol content. Considering antioxidant capacities, the acetone extracts provided the highest antioxidant capacities for all plants when assessed using the TEAC (8.56-32.68 milimole (mmole) trolox equivalent (TE)/mg soluble solids) and FRAP (5.69-37.39 mmole ascorbic acid equivalent/mg soluble solids) antioxidant assays, with the exception of M. flabellifolius where the water extract demonstrated the highest activity (22.73 mmole ascorbic acid equivalent/mg soluble solids). Antioxidant capacity determinations with TEAC and FRAP assays followed similar patterns, which were different from capacities determined by the ORAC (0.46-533.54 mmoleTE/mg of soluble solids) assay. Corroborating the antioxidant content findings, the acetone extracts also demonstrated the highest antioxidant capacities (140.41-533.54 mmoleTE/mg of soluble solids), followed by ethanol (94.62-151.29 mmoleTE/mg of soluble solids) and water (0.46-134.02 mmoleTE/mg of soluble solids). Only M. flabellifolius (TEAC and FRAP) and S. aethiopicus (FRAP) deviated from this trend. Correlations between the polyphenolic contents and antioxidant capacities indicated that acetone and ethanol were more effective in extracting polyphenolic compounds than water, while also providing extracts with superior antioxidant activities. Furthermore, ORAC assay was the antioxidant capacity determining assay of choice for the aqueous plant extracts, whereas the TEAC and FRAP assays were more suitable when determining the antioxidant capacities of the acetone and ethanol plant extracts. These results confirm the notion that no single assay can comprehensively determine the antioxidant activities of plant extracts and that a battery of assays should be used, as the various antioxidant capacity determination techniques use different substrates with different targets for measurement. The second part of this study comprised an in vivo experimental animal model to assess the potential toxicity, antioxidant status and modulation of the hepatic phase 2 drug metabolising enzymes following chronic consumption of the various plant extracts in male Fisher rats. Rats consumed aqueous extracts of the various plants (2% and 5% (w/v)) as the sole source of drinking fluid for 90 days, and the serum chemical pathology parameters for monitoring liver and kidney function conducted. These included alkaline phosphatase (ALP), aspartate transaminase (AST), alanine transaminase (ALT), total iron (Fe), and creatinine (CREA). Parameters for blood and hepatic redox status included total polyphenols, ORAC, reduced glutathione (GSH), oxidised glutathione (GSSG), their ratio (GSH:GSSG), conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS). Assessment of the phase 2 hepatic xenobiotic metabolising enzymes included glutathione S-transferase (GST)  and activity in the cytosolic fraction and, UDP-glucuronosyltransferase (UDP-GT) activity in liver microsomes. When considering the liver and kidney function none of the plant extracts induced any significant toxicity, while 2% A. digitata significantly increased serum Fe. When considering the redox status, the whole blood and liver samples yielded similar results, with significant decreases in oxidised glutathione (GSSG) in rats consuming the 2% M. flabellifolius (82.76 mole/L) and 5% A. digitata (90.42 mole/L) with a resultant significant increase in the glutathione redox status (GSH:GSSG ratio of 5.69 and 5.64, respectively) when compared to rats consuming water (4.77). The GSH:GSSG ratio was also significantly increased by consumption of 2% A. betulina (8.45) and 5% S. aethiopicus (5.99). The consumption of all plant extracts, except 5% A. betulina and M. flabellifolius, significantly increased lipid peroxidation in the plasma CDs assay. These results indicated an increased antioxidant capacity in the liver with/without an associated reduced cellular oxidative stress status, which could be interpreted as a reduced susceptibility to oxidative damage. When considering the phase 2 hepatic enzymes, none of the plant extracts caused any significant changes in GST, GST or UDP-GT activities. The third part investigated the chemoprotective properties against cancer promotion in the liver utilising diethylnitrosamine (DEN) as cancer initiator and maize culture material of Fusarium verticillioides, containing the fumonisin B mycotoxins, as promoters in male Fischer rats. The rats consumed 2% (w/v) aqueous extracts of A. digitata, A. betulina, and S. aethiopicus over 28 days after cancer initiation and liver sections subjected to glutathione-S-transferase placental form positive GSTP+ staining and pre-cancerous liver foci categorised according to size. In addition, blood and liver analyses were done as described in the chronic feeding study above. Consumption of the A. digitata and, to a certain extent, S. aethiopicus extracts, altered the oxidative stress status in the liver as indicated by the increased lipid peroxidation, as determined by significantly increased liver CDs and the decreased GSH:GSSG ratio in the blood. This can be related to a subchronic toxicity due to the high total polyphenol intake as mentioned above. These underlying sub chronic toxic effects of A. digitata and S. aethiopicus are likely to be responsible for the observed inhibitory effect on the proliferation of GSTP+ minifoci in the liver. Hepatic phase 2 metabolising enzyme activities were not significantly altered by A. digitata and S. aethiopicus consumption, while GST activity was significantly increased by A. betulina treatment. Based on the findings of the current study, aqueous extracts of A. digitata, A. betulina, and S. aethiopicus may serve as hepatoprotectors with a potential to modulate liver carcinogenesis, specifically cancer promotion. To our knowledge, no other studies have attempted to describe the possible chemoprevention mechanisms of these indigenous medicinal plants. Assessments of phase 1 hepatic enzymes and other antioxidant enzymes are suggested for future studies to further describe biochemical and molecular mechanisms associated with consumption of these extracts. Additionally, identifying main compounds present in the plant extracts could culminate in development of drugs and novel nutraceuticals. It is also recommended that increasing concentrations of the plant extracts and/or the ethanol extracts to be used in future studies to better describe dose-responses of the different plants in liver carcinogenesis.
136

The traditional use of medicinal plants to treat sexually transmitted diseases

Tshikalange, T.E. (Thilivhali Emmanuel) 27 June 2005 (has links)
All six plants studied (Senna petersiana, Terminalia sericea, Cassine transvaalensis, Elephantorrhiza burkei, Rauvolfia caffra and Anredera cordifolia) proved to have considerable antibacterial activity. The water extracts of five of the six plants tested, showed activity against Bacillus pumilis, B. subtilis and Staphylococcus aureus respectively. Water extracts from S. petersiana showed a significant antibacterial activity by inhibiting all Gram-positive and two Gram-negative bacteria. A cytotoxicity assay of three plants (S. petersiana, T. sericea and A. cordifolia) on primary vervet monkey kidney ceelsl showed that A. cordifolia was the least cytotoxic extract with an ID50 value of 1.560 mg/ml. Both S. petersian and T. sericea showed an ID50 value of 0.024 mg/ml. Cytotoxicity as determined in this study does not necessarily mean that the active compound which can be isolated from these plants will also be toxic. Antiviral activity of S. petersiana, T. sericea and A. cordifoli crude extracts were investigated against herpes simplex virus type I at the non-toxic concentrations. Both T. sericea and A. cordifoli extracts showed to be non-active against HSV -I, but S. petersiana showed a 20 % reduction in replication of the virus after the sixth day of the experiment. Because of the sensitivity and instability of compounds in the root extract of S. petersiana, it was very difficult to isolate any pure compound. Bioassay-guided fractionation of the seeds of S. petersiana resulted in the isolation luteolin. Its structure was identified and confirmed through spectroscopic methods including IH, BC, UV, HMBC and HMBQ. An antibacterial assay of luteolin isolated from the seeds of S. petersiana showed activity against Baccilus cereus, B. pumilis, Streptococcus aureus and Staphylococcus areus at the concentration of I mg/ml. In the assay to assess the possible antiviral activity of luteolin against herpes simplex type I virus, 50% of the virus was inactivated at the concentration of 250 μg/ml. The results of this study have shown that it is possibl4e that the extracts studied, can provide humankind with valuable agents of potential use in the treatment of herpes and some bacterial species. / Dissertation (MSc ( Plant Physiology))--University of Pretoria, 2006. / Plant Science / unrestricted
137

Modulatory and antidiabetic effects of vindoline and Catharanthus roseus in type 2 diabetes mellitus induced male Wistar rats and in RIN-5F cell line

Goboza, Mediline January 2019 (has links)
Thesis (DPhil (Biomedical Science))--Cape Peninsula University of Technology, 2019. / Diabetes mellitus (DM) is a group of metabolic disorders characterised by persistent high blood glucose levels together with abnormal metabolism of macromolecules. If the hyperglycemia is not controlled, adverse metabolic changes could occur leading to the progressive development of severe complications. Formation of reactive oxygen/nitrogen species and inflammatory responses are principal mechanisms that have been implicated in the development of hyperglycemia-induced tissue damage. The commercially available drugs utilised in the treatment of diabetes have been linked to detrimental side effects hence the need to discover alternative medicines especially from medicinal plants. Catharanthus roseus is both a medicinal and ornamental plant that is traditionally used to treat various diseases. It has been reported to possess antidiabetic, anticancer, antimicrobial and antioxidant properties. The plant has been shown to possess more than 100 monotepernoid indole alkaloids which were linked to the plants’ antihyperglycemic and antioxidant effects. Therefore, this study was carried out to investigate the effect of vindoline; a bioactive compound derived from C. roseus against type 2 diabetes–induced complications. The study also investigated the effects of Catharanthus roseus extracts in RIN-5F cell line. The study was carried out in two parts: viz in vitro and the in vivo assessments. The in vitro study initially investigated the polyphenolic content and antioxidant activities of vindoline and the 3 extracts (methanolic, aqueous and the dichloromethane) of C.roseus. The assays used to evaluate the antioxidant capacity of the extracts include oxygen radical absorbance capacity (ORAC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibitory assay. Among the evaluated extracts, the methanolic extract demonstrated both high total polyphenolic content and antioxidant capacity. The HLPC analysis of the extracts was performed and showed highest concentrations of vindoline in the dichloromethane extract and the aqueous extract exhibited the least. The antioxidant activities of vindoline were determined and compared to a known antioxidant, ascorbic acid. Vindoline revealed stronger ORAC activity than ascorbic acid however the ferric reducing antioxidant power did not show any significant differences (p < 0.05). Insulin secretion studies were performed in a β-cell insulinoma cell line- RIN-5F exposed to different concentrations of glucose (high, low and in the absence of glucose). The studies were carried out to compare the β-cell stimulatory effect of vindoline to the extracts. After performing cytotoxic experiments, concentrations that resulted in about 80% cell viability were used to determine the insulin secretory effects. In cells that exposed to glucotoxicity (50 mM glucose), vindoline showed the highest β-cell stimulatory effect (p < 0.05) when compared to the untreated controls and to the cells that were treated with the methanolic extract. In cells that were exposed to a low glucose concentration, vindoline additionally showed significant β-cell stimulatory effect at p < 0.05 when compared to the aqueous and the methanolic extracts. Thereafter, the intracellular reactive oxygen species assay (ROSA) was performed in glucotoxicity-induced cells after treatment with vindoline and the respective extracts. The results were compared to the untreated control: vindoline, methanolic and the dichloromethane extracts indicated significant reduction in ROS generation (p < 0.05). Further measurement of the release of TNF-α, a pro-inflammatory cytokine in the cells following treatment, the results were not significant among the groups at p < 0.05. The carbohydrate enzymes inhibitory activity of vindoline and extracts of C.roseus (50, 25, 12.5 and 6.125 mg/ml) were measured. The alpha glucosidase inhibitory activities of the extracts at 50 mg/ml resulted in < 30% enzyme inhibition with no significant differences among the groups at p < 0.05. At lower concentrations, the dichloromethane extract exhibited significantly lower inhibitory activities when compared to the methanolic and the aqueous extract (p < 0.05). The alpha amylase inhibitory activity of the methanolic extract was significantly increased at all concentrations; recording the highest enzyme inhibition of approximately 40% (p < 0.5). However, the dichloromethane extract did not show any enzyme inhibitory activity. The enzyme inhibitory activity of vindoline was compared to acarbose-a known standard drug, for both enzymes; vindoline did not show appreciable enzyme inhibition when compared to acarbose (p < 0.05). In vivo studies were performed in a type 2 diabetes (T2DM) rat model in which T2DM was induced in 6 weeks old male Wistar rats by having them drink 10% fructose solution ad libitum for 14 days followed by a single intraperitoneal injection of streptozotocin (STZ 40 mg/kg) in freshly prepared 0.1 M citrate buffer (pH 4.5). Animals were randomly divided into six groups (n=8) and received daily treatments for 6 weeks with the vehicle, vindoline (20 mg/kg) or glibenclamide (5 mg/kg) via oral gavage. The effects of the treatments on blood glucose, insulin, body weight, organ weight, serum biochemical parameters, oxidative status, inflammatory markers and tissue histology were assessed in diabetic and non-diabetic rats. Administration of vindoline significantly (p < 0.05) reduced the fasting blood glucose in diabetic rats by 15% and significantly increased serum insulin levels when compared to the diabetic controls. Vindoline and glibenclamide significantly (p < 0.05) reduced the levels of circulating hepatic enzymes in T2DM; the results were significant when compared to the diabetic controls. Treatment with vindoline significantly improved the hepatic antioxidant status as indicated by increased ORAC, superoxide dismutase and catalase activities, indicative of the protective effect of vindoline in diabetes-induced hepatic injury. Assessment of the levels of pro-inflammatory cytokines in the hepatic tissue indicated remarkable reduction of TNF-ɑ by (-41%) and IL-6 (-28%) in diabetic rats treated with vindoline when compared to the diabetic controls (p < 0.05). The serum lipid profile showed marked increases in the levels of serum lipids (triglycerides, low density lipoproteins, total cholesterol and very low density lipoproteins) in diabetic controls when compared to all treatment groups (p < 0.05). Therefore, vindoline and glibenclamide showed possible protective effects against diabetes-induced cardiovascular disease. Kidney function assessment revealed increased levels of urea and creatinine in the diabetic control group. Vindoline and glibenclamide significantly reduced the urea and creatinine levels in diabetic rats. Vindoline additionally improved the FRAP in diabetic hearts. The SOD activity and ORAC were increased while lipid peroxidation was reduced in the kidneys of diabetic rats treated with vindoline when compared to the diabetic control (p < 0.05). Histopathological assessment in diabetic rats showed severe damage of the liver, kidney and pancreas. Treatment of diabetic rats with vindoline restored the structure of these organs which was indicated by minimum structural changes. The expression of pro-apoptotic marker caspase 9 in response to glucose stress was significantly higher in the diabetic control group when compared to all the treatment groups. Treatment with vindoline showed remarkable reduction of caspase 9 expression in the diabetic rats. In conclusion, persistent high blood glucose levels resulted in free radical induced tissue damage in the type 2 diabetes rat model. Vindoline demonstrated protective effects against diabetes induced hepatic, cardiac, pancreatic and nephritic injuries. In addition, vindoline improved insulin secretion in both in vitro and in vivo setups hence the findings suggest that vindoline could be an important agent that can be considered in the treatment and management of diabetes and diabetic complications.
138

An investigation into the bioactivity of Sutherlandia frutescens (Cancer bush)

Egbichi , Ifeanyi M. 03 1900 (has links)
Thesis (MSc (Biochemistry))--University of Stellenbosch, 2009. / Sutherlandia frutescens (S. frutescens), sub-species microphylla, is a member of the Fabacea family and is used as a herbal remedy for the treatment of several ailments which include influenza, diabetes, cancer, tuberculosis, chronic fatigue syndrome, rheumatoid arthritis, anxiety, clinical depression, and more recently, those living with human immunodeficiency virus/ acquired immune deficiency syndrome (HIV/AIDS) (1-4). Many of the symptoms of these ailments are associated with a perturbation of the stress response which may be associated with disorders of the endocrine system. Of all the traditional plants in South Africa, S. frutescens is regarded the most profound in that it is a multipurpose traditional remedy. The plant has enjoyed a long history of use and reports indicating its efficacy as a safe treatment for various health conditions have added to the popularity of this medicinal plant. The extracts of S. frutescens have been shown to exhibit anti-proliferative effects on cancer cells, antioxidant activity, and to possess anti-diabetic and anti-inflammatory potential (5, 6), providing scientific evidence for its therapeutic use in the treatment of cancer and diabetes. However, this study focuses on the potential use of this medicinal plant in the treatment of stress and stress related diseases. Chronic stress is characterized by elevated plasma levels of glucocorticoids. These steroid hormones are synthesized in the adrenal cortex in a series of reactions involving the steroidogenic enzymes. The major aim of this thesis was the determination of the influence of S. frutescens extracts on the adrenal cytochrome P450 enzymes. Aqueous, methanol and chloroform S. frutescens extracts were prepared and the interaction with the cytochrome P450 enzymes was investigated. The effect of these extracts towards progesterone (PROG), deoxycortisol and deoxycorticosterone (DOC) binding to the cytochrome P450 enzymes as well as their influence on the metabolism of these steroid substrates was investigated. A similar study (7) showed that compounds from the S. frutescens extracts could interact with these enzymes and possibly affect adrenal steroidogenesis. This study further investigates the bioactive properties of the plant material in terms of the influence of S. frutescens on the cytochrome P450 enzymes and the effect of the manufacturing process on the bioactivity of the plant.
139

Effects of medicinal herbs on contraction rate of cultured cardiomyocyte. Possible mechanisms involved in the chronotropic effects of hawthorn and berberine in neonatal murine cardiomyocyte / Possible mechanisms involved in the chronotropic effects of hawthorn and berberine in neonatal murine cardiomyocyte

Salehi, Satin 29 September 2009 (has links)
Herbs have been used for many centuries in diverse civilizations for the treatment of heart disease. Only a few natural supplements claim to have direct cardiovascular actions including hawthorn (Crataegus spp.) and berberine derived from the Berberidaceae family. Several different studies indicate important cardiovascular effects of hawthorn and berberine. For example, both exert positive inotropic effects and have been used in the treatment of congestive heart failure. Recently, it was shown that hawthorn extract preparations cause negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the effect of hawthorn extract to decrease the contraction rate of cultured cardiomyocytes. We hypothesized that hawthorn extract may be acting through muscarinic receptors to decrease contraction rate of cardiomyocytes. Atrial and ventricular cardiomyocytes were treated with hawthorn extract in the presence of atropine or himbacine. Changes in the contraction rate of cultured cardiomyocytes revealed that both muscarinic antagonists significantly attenuated the negative chronotropic activity of hawthorn extract. Using quinuclidinyl benzilate, L-[benzylic-4,4'-3H] ([³H]-QNB) as a radioligand antagonist, the effect of a partially purified hawthorn extract fraction to inhibit muscarinic receptor binding was quantified. Hawthorn extract fraction 3 dose-dependently inhibited [³H]-QNB binding to mouse heart membranes. These findings suggest that muscarinic receptors may be involved in the negative chronotropic effect of hawthorn extracts in neonatal murine cardiomyocytes. Berberine exhibits variable positive and negative chronotropic effects in different species. Our first aim was to examine the effect of berberine in a cultured neonatal murine cardiomyocyte assay. Our study demonstrates that berberine has significant negative chronotropic actions on cardiomyocytes which is not an effect of beta-adrenergic receptor blockade. Pertussis toxin (PTX), a Gi/o protein inhibitor, blocked the negative chronotropic activity of berberine. Muscarinic, adenosine, opioid, and α₂ receptors are coupled through a G-protein (Gi/o) to adenylyl cyclase in an inhibitory fashion. Activation of these receptors are primarily responsible for PTX-sensitive negative chronotropic effects in heart. We hypothesized that berberine may be acting through one of these receptor type to decrease contraction rate of cardiomyocytes. For this purpose, we studied the effects of the muscarinic-receptor antagonists, atropine, himbacine, or AF- DX 116 on the negative chronotropic activity of berberine. Muscarinic antagonists completely blocked the effect of berberine on contraction rate of cardiomyocytes, whereas the bradycardic effect of berberine was not inhibited by the opioid, adenosine, or α2 receptor antagonists naloxone, CGS 15943, or phentolamine, respectively. Using [³H]QNB as a radioligand, we demonstrated that berberine bound to muscarinic receptors of adult mouse heart membranes with relatively high affinity. Furthermore, berberine dose-dependently inhibited [³H]QNB binding to muscarinic M2 receptors exogenously expressed in HEK 293 cells. Therefore, the findings of the present study suggest that berberine has muscarinic agonist effects in cultured neonatal murine cardiomyocytes, potentially explaining reported physiological effects of berberine. Cardiac hypertrophy represents the most important factor in the development of congestive heart failure. We investigated the inhibitory effect of berberine on hypertrophy of H9c2 cells. In rat heart-derived H9c2 myoblast cells treated with different hypertrophic agonists such as insulin growth factor II (IGF-II), arginine vasopressin (AVP), phenylephrine, and isoproterenol, protein content and size of cells were significantly increased compared to control group. However, the number of H9c2 cells after treatment with hypertrophic agonists did not differ significantly compared to control. The increases in area of cells and protein content induced by the hypertrophic agonists were inhibited by treatment with berberine in a concentration-dependent manner. Our findings have provided the first scientific evidence that berberine may have an inhibitory effect on hypertrophy of heart-derived cells, and provide a rationale for further studies to evaluate berberine's cardiac activity. / Graduation date: 2010
140

Pharmacological evaluation of some central nervous system effects of Cotyledon Orbiculata.

Kabatende, Joseph January 2005 (has links)
The use of traditional medicine through the use of medicinal plants in Africa and especially in South Africa has long been considered an important characteristic of people's daily lives and socio-cultural heritage. Cotyledon Orbiculata is among the medicinal plants that are used by South African traditional practitioners for the treatment of epilepsy and painful conditions such as corns, warts, toothache, earache, boils and various other ailments. However, the claim of therapeutic successes of medicinal plants by traditional medicine practitioners are hardly subjected to scientific scrutiny. This study therefore, investigated the anti-epileptic property of Cotyledon Orbiculata by studying the effects of the methanol extract of the plant against chemically induced seizures by pentylenetetrazole, picrotoxin, bicuculline and N-methyl-DL-aspartic acid in mice. The study also investigated the analgestic effects of Cotyledon Orbiculata by studying the effect of the plant extract on pain induced by acetic acid and hot plate thermal stimulation.

Page generated in 0.0877 seconds