Saartjie Roux

Antidiabetic screening and scoring of 11 plants traditionally used in South Africa

AIM To investigate the traditional antidiabetic uses of indigenous or naturalised South African plants using an optimised screening and scoring method. MATERIALS AND METHODS Eleven plant species were screened against Chang liver, 3T3-L1 adipose and C2C12 muscle cells measuring glucose utilisation in all three cell lines and toxicity in the hepatocytes and adipocytes only. A scoring system was devised to aid interpretation of results. RESULTS Catharanthus roseus results correlated with previously reported in vivo results, with best stimulation of glucose utilisation in hepatocytes. Momordica foetida and Momordica balsamina extracts were active in myocytes but only the latter stimulated glucose utilisation in hepatocytes. Brachylaena discolor gave the best overall results, with all plant parts giving high activity scores and negligible toxicity. In vitro toxicity results for Catharanthus roseus, Vinca major, Momordica balsamina and some Sclerocarya birrea extracts raise concern for chronic use. CONCLUSION This screening system increases the likelihood of identifying drug candidates using in vitro antidiabetic screening of crude plant extracts, whilst the scoring system aids data interpretation. ETHNOPHARMACOLOGICAL RELEVANCE The multitude of metabolic steps affected by Type II diabetes offer many drug targets but they complicate in vitro screening to validate traditional uses or find new drug leads from plants.

Hypoglycaemic activity of four plant extracts traditionally used in South Africa for diabetes

AIM To validate plant species for hypoglycaemic activity. MATERIALS AND METHODS Four plants were investigated for hypoglycaemic activity by evaluating inhibiting effects on carbohydrate-hydrolising enzymes: alpha-glucosidase and alpha-amylase. Acetone plant extracts were screened against C2C12 myocytes, 3T3-L1 preadipocytes and Chang liver cells by measuring glucose uptake. Cytotoxicity was done in preadipocytes and hepatocytes. RESULTS Extract of Euclea undulata rootbark exhibited highest activity, displaying a glucose uptake of 162.2% by Chang liver cells at 50 microg/ml. An inhibition concentration of 50% for Euclea undulata was found to be 49.95 microg/ml for alpha-glucosidase and 2.8 microg/ml for alpha-amylase. No cytotoxicity was recorded for Euclea undulata, while Schkuhria pinnata and Elaeodendron transvaalense exhibited cytotoxicity at 12.5 microg/ml. Alpha-glucosidase and alpha-amylase assays showed inhibitory activity on enzymes for three plant extracts. CONCLUSION Euclea undulata, Schkuhria pinnata and Elaeodendron transvaalense showed in vitro hypoglycaemic activity. Schkuhria pinnata and Elaeodendron transvaalense indicated cytotoxicity on 3T3-L1 preadipocytes and Chang liver cells. Euclea undulata, Pteronia divaricata and Elaeodendron transvaalense inhibited alpha-glucosidase and alpha-amylase enzymes. ETHNOPHARMACOLOGICAL RELEVANCE Screening of plant extracts scientifically validated traditional use of Euclea undulata for treatment of diabetes. Cytotoxicity results revealed that acetone extracts of Schkuhria pinnata and Elaeodendron transvaalense are toxic and raise concern for chronic use.

Randomized clinical trial: Effect of Lactobacillus plantarum 299 v on symptoms of irritable bowel syndrome

OBJECTIVES Irritable bowel syndrome (IBS) is a common diagnosis in gastroenterology. Its etiology is unknown and therapeutic options limited. Trials suggest probiotics may be beneficial. The aim of this study was to assess the symptomatic efficacy of Lactobacillus plantarum 299 v (L. plantarum 299 v) for the relief of abdominal pain in patients with IBS fulfilling Rome II criteria. METHODS This study was conducted in a referral hospital. Trial participants were randomized to receive either two capsules of L. plantarum 299 v at a dosage of 5 × 10(9) cfu per capsule or placebo daily for 8 wk. Severity of abdominal pain was assessed using a visual analog scale at each visit and a quality-of-life IBS (QoL-IBS) questionnaire was also completed. RESULTS There was no significant difference in abdominal pain relief between the study and placebo groups (P = 0.800). There was also no difference in QoL- IBS scores between the groups (P = 0.687). Both groups had a significant improvement in abdominal pain scores over the study period, from an average of 251.55 to 197.90 (P < 0.0001) indicating a large placebo effect. CONCLUSION An 8-wk treatment with L. plantarum 299 v did not provide symptomatic relief, particularly of abdominal pain and bloating, in patients fulfilling the Rome II criteria.

Sutherlandia frutescens limits the development of insulin resistance by decreasing plasma free fatty acid levels.

Intake of high caloric food induces raised plasma free fatty acids, culminating in insulin resistance (IR) and Diabetes mellitus type 2 (DMT2). The present study has shown for the first time that Sutherlandia frutescens reduces plasma free fatty acid levels in rats fed a high fat diet, thereby preventing the development of insulin resistance. A commercially available S. frutescens extract was administered to rats to examine its effects on the progression of high fat diet induced IR. In comparison to rats fed high fat diet only (positive control for IR), levels of plasma free fatty acids (FFA) were significantly reduced after one week (p < 0.025). Twelve weeks of treatment with S. frutescens reduced the level of plasma free fatty acids below that of rats fed a normal diet (negative control) (p < 0.025). QUICKI and HOMA‐IR index confirmed that S. frutescens treated rats did not develop IR when fed a high fat diet for twelve weeks. In addition to preventing IR and reducing plasma FFA, chronic medication over twelve weeks decreased total cholesterol levels and the LDL/HDL ratio. We propose that S. frutescens is an effective medicinal remedy to prevent elevated plasma free fatty acids and IR, and therefore DMT2. Copyright

Sutherlandia frutescens prevents changes in diabetes-related gene expression in a fructose-induced insulin resistant cell model.

ETHNOPHARMACOLOGICAL RELEVANCE The African medicinal plant Sutherlandia frutescens (L.) R.Br. (Fabaceae) is traditionally used to treat diabetes and has been shown to have anti-diabetic properties in animal models. The present study investigated the capacity of an aqueous extract of Sutherlandia frutescens to prevent insulin resistance (a precursor of type 2 diabetes) in a human liver cell culture and to identify genes regulated by Sutherlandia frutescens treatment. MATERIALS AND METHODS A combination of insulin and fructose was used to generate an in vitro model of insulin resistance in human liver cells to compare untreated control, insulin resistant and Sutherlandia frutescens treated insulin resistant cultures. Insulin resistance and its prevention by Sutherlandia frutescens were measured by glucose uptake, gluconeogenesis and lipid accumulation in the cell cultures. Changes in gene expression were quantified using the RT(2)Profiler(TM) PCR Array of 84 diabetes-related genes. RESULTS The insulin resistant Chang liver cells took up significantly less 2-[(3)H]-deoxyglucose (p<0.05) than controls, released more glucose into the culture medium (p<0.05) and accumulated more intracellular lipid (p<0.05). Simultaneous treatment with Sutherlandia frutescens prevented development of these insulin resistance parameters (p<0.05). A total of 27 potential gene targets of Sutherlandia frutescens were significantly up or down regulated in the Sutherlandia frutescens treated insulin resistant cells. The gene VAMP3, which plays a role in vesicle transport, was down-regulated by insulin resistance, and up-regulated by Sutherlandia frutescens. Twenty six other genes encoding vesicle transporters, receptors, signalling molecules, transcription factors, and metabolic enzymes were significantly regulated by Sutherlandia frutescens. CONCLUSION These results confirm that Sutherlandia frutescens can prevent insulin resistance in hepatocytes. The identified changes in gene expression indicate several potential mechanisms of anti-diabetic action for Sutherlandia frutescens, reflecting the multiple bioactive compounds previously identified in aqueous extracts of Sutherlandia frutescens.

Effect of Sutherlandia frutescens on the Lipid Metabolism in an Insulin Resistant Rat Model and 3T3‐L1 Adipocytes

High fat diet induced insulin resistance correlates with dyslipidaemia and ectopic fat deposits in skeletal muscle and liver. The effects of Sutherlandia frutescens, an antidiabetic medicinal plant, on lipid metabolism were evaluated in an insulin resistant (IR) rat model and in 3 T3‐preadipocytes. Wistar rats received normal diet (ND) or high fat diet (HFD). After the onset of IR in the HFD group, the rats were subdivided into two subgroups, which either continued with HFD or were treated with 50 mg S. frutescens/kg BW/day and HFD (HFD + SF). After 4 weeks, the HFD + SF rats had a significantly lower body weight than the HFD rats (p < 0.05). Blood plasma analysis showed a decrease in insulin, free fatty acids and triglycerides. Related changes in lipid parameters were observed in the liver, skeletal muscle and adipose tissue. To investigate the effects of S. frutescens on adipose tissue, 3 T3‐L1 cells were used as a model. Treatment with S. frutescens led to a decrease in triglyceride accumulation, whilst glucose consumption and lactate production were increased (p < 0.05). These results indicate that S. frutescens directly affects mitochondrial activity and lipid biosynthesis in adipose tissue and provide a mechanism by which S. frutescens can restore insulin sensitivity by modulating fatty acid biosynthesis. Copyright

Effect of leaf extracts of Vernonia amygdalina on glucose utilization in chang-liver, C2C12 muscle and 3T3-L1 cells

Diabetes mellitus is a chronic disease which affects millions of people worldwide. The prevalence of this disease is increasing annually and the number of diabetics is projected to rise above 300 million before 2025. The growing number of diabetics, coupled with the harsh side effects of some synthetic drugs has led to the increasing search for more natural products of plant origin. Vernonia amygdalina Del. (Asteraceae) is one of the plants commonly used for the treatment of diabetes in Africa. This study evaluated the effect of leaf extracts of this plant on glucose utilization in 3T3-L1, C2C12 muscle, and Chang-liver cells. Treatment of the cells with the acetone, methanol, water, and n-hexane/isopropanol extracts of V. amygdalina leaves significantly increased glucose utilization in the C2C12 muscle and Chang-liver cells but showed no effect on the 3T3-L1 cells. The water and n-hexane/isopropanol extracts were the most active in the C2C12 cells with a response of 78.3 and 95.6% above the control, respectively, while in the Chang-liver cells, water and acetone extracts had a response of 65.8 and 59.6% above the control, respectively. The results, especially of the water extract, strongly corroborate the ethnomedical uses of V. amygdalina as an antidiabetic plant.

Shifts in metabolic parameters surrounding glucose homoeostasis resulting from tricyclic antidepressant therapy: implications of insulin resistance?

This study displayed the physiological effects the tricyclic antidepressants amitriptyline or trimipramine have on glucose homoeostasis in male Wistar rats. An insulin secreting cell line (INS‐1) was also used to determine effects tricyclic antidepressants have on insulin secretion and insulin displacement. Thirty rats each received a 1 mg kg−1 dose of amitriptyline or trimipramine for a period of 14 weeks; another 14 rats served as the control group. Blood glucose, serum insulin and muscle and liver glycogen levels were determined. Kidney, liver and muscle insulin degradation was measured and compared with insulin degrading enzyme concentrations in the latter two tissues. INS‐1 cells were used to determine the effect 1μM amitriptyline has on insulin secretion. Displacement studies for [3H]glibenclamide by amitriptyline or trimipramine were undertaken on INS‐1 cells. A significant increase in blood glucose (P < 0.01) was found for both test groups after 6 and 14 weeks of receiving the medication, which may be related to a significant decrease in liver and muscle glycogen levels (P < 0.001). Serum insulin levels remained unchanged, although a significant increase in insulin degradation was observed in the muscle, liver and kidney, which may be related to a significant increase in insulin degrading enzyme (P < 0.001) that was found. A significant increase in insulin secretion was observed for the INS‐1 cells treated with amitriptyline, although no significant displacement for the [3H]glibenclamide was evident for amitriptyline or trimipramine. The significant alterations in glucose homoeostasis observed, as well as the significant changes associated with insulin secretion and degradation associated with amitriptyline or trimipramine treatment, imply that prolonged use of these medicines may lead to insulin resistance and full blown diabetes.

Food avoidance in irritable bowel syndrome leads to a nutrition-deficient diet

Abstract Objective: The objective was to assess the dietary intake of subjects with irritable bowel syndrome (IBS) and to compare it to that of international recommendations. The hypothesising assumption of this study was that a situation in which subjects insist that diet or trigger foods play a part in symptom generation may lead to an unbalanced dietary intake. Design: This was a descriptive observational study, with an analytical component. Setting: A private, secondary care-level clinic in South Africa. Subjects: The study population comprised 122 participants. Each subject completed an estimated, three-day dietary record. The data were analysed using a computerised food analysis programme. The fructose intake was analysed semi-quantitatively. IBS subjects’ protein and carbohydrate intake were significantly higher than the recommended dietary allowance for protein and carbohydrate (p-values < 0.000 and < 0.000, respectively). Outcome measures: The identification of dietary risk factors that affect IBS. Results: The IBS subjects’ daily total dietary fibre (15.13 g ± 13.11) was significantly lower (p-value < 0.000) than the dietary reference intake (DRI) target intake of 24.76 g/day, and the intake of micronutrients,(calcium, iron and folate) was significantly less than the DRI. There was no significant difference in macronutrient intake between the diarrhoea-predominant IBS (D-IBS), constipation-predominant IBS (C-IBS) and the control groups. The total number of fructose serves per day was not statistically significant between the three groups (C-IBS 2.68 ± 1.68, D-IBS 2.15 ± 1.86, and controls 3.17 ± 2.39, p-value = 0.157). Conclusion: The IBS subjects in this study consumed diets that were deficient in key micronutrients and total fibre when judged against the recommended DRIs. Dietary adjustments may have been tailored by subjects to minimise symptom development and this led to nutritionally deficient diets.

β-Catenin Regulation in Sporadic Colorectal Carcinogenesis: Not as Simple as APC

Background The wnt/APC/β-catenin pathway is a critical initiator in colorectal carcinogenesis in both hereditary and sporadic colorectal cancer (CRC). The progression of this process remains incompletely understood, although inflammation is pivotal. Drivers of inflammation are elevated in malignant tissue and have been shown to regulate β-catenin expression. Interleukin-17A (IL-17A) is protumorigenic at elevated levels via COX-2 stimulation. Elevated peroxisome proliferator-activated receptor γ (PPARγ) expression has reduced risk of carcinogenesis and good overall prognosis in established CRC. Activation of PPARγ has inhibitory effect on β-catenin. Methods Using qPCR and IHC, we compared β-catenin, PPARγ, COX-2, and IL-17A in the colonic mucosa of patients with sporadic CRC, inflammatory bowel disease (IBD), and irritable bowel syndrome (IBS), against a normal control population. Results β-catenin mRNA and protein expression progressively increased from the Normal group, through IBS and IBD reaching statistical significance in CRC. COX-2 mRNA levels increased similarly with statistical significance in IBD and CRC. However, COX-2 protein expression was inverted with significant expression in the Normal and IBS groups and reduced levels in IBD and CRC. PPARγ mRNA expression was unchanged in IBD and CRC but was significantly elevated in the IBS. IL-17A mRNA was significantly reduced in IBS and CRC but unchanged in IBD. There were no differences in all parameters tested in the Normal and IBS groups. Conclusion β-catenin is confirmed as a major driver of colorectal carcinogenesis but is controlled by many more players other than APC. Elevated levels of PPARγ may have an anticarcinogenic effect. The role of COX-2 expression, especially its posttranscriptional regulation in colorectal cancer, needs further elucidation.