Antidiabetic activity and mechanism of action of extracts of Brachylaena elliptica (Thurb.) DC. and Brachylaena ilicifolia (Lam) Phill & Schweick
- Authors: Sagbo, Idowu Jonas
- Date: 2017
- Subjects: Herbs -- Therapeutic use Pharmacognosy Diabetes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8154 , vital:31624
- Description: International Diabetes Federation (IDF) estimated that there are 415 million people globally that are suffering from diabetes and this figure is likely to double by 2040. In South Africa, the number of people suffering from diabetes is believed to be rising steadily and the current antidiabetic therapies include the use of expensive pharmaceutical drugs which after display numerous adverse side effects. Herbal medicine is an alternative treatment strategy used by many rural populations for the management of diabetes, which is cost-effective and with minimal reported side effects. The aim of this study was to validate the antidiabetic activity and to elucidate the possible mechanisms of action of the aqueous leaf extracts prepared from two plants, Brachylaena elliptica and Brachylaena ilicifolia, used by traditional healers in the Eastern Cape, South Africa for the treatment of diabetes. The current pharmaceutical drugs target site, including carbohydrate digestion, regulation of blood glucose levels through insulin levels or activating glucose uptake in liver and muscle. The plants extracts were therefore evaluated for their potential to mimic or replace these drugs. The inhibibitory effects on alpha amylase, alpha glucosidase, DPP-IV activity and pancreatic lipase were evaluated at various concentrations of the plant extracts. To evaluate the suitability of these extracts for cell based in vitro assay as well as to determine the safety of the plant extracts for human consumption, cytotoxicity towards HepG2 cells was assessed using the MTT assay. The effect of both plant extracts on glucose uptake in HepG2 and L6 cells, lipid accumulation in 3T3-L1 preadipocytes and NO production in RAW macrophages were investigated. Both plant extracts were also tested for INS-1 proliferation using the imageXpress®Micro XLS analysis. The MTT reduction assay was also used to investigate the effect of extracts on INS-1 glucose metabolism and as a reflection of insulin secretion. The inhibitory activity of the crude extracts of both plants on protein glycation, collagenase activity and CYP3A4 interaction were also evaluated The crude extracts of both plants displayed no significant inhibition on alpha amylase, alpha glucosidase, dipeptidyl peptidase-IV, lipase, protein glycation and collagenase compared to relevant standard inhibitors, acarbose, EGCG, Diprotin A, Orlistart and aminoguanidine. The mild inhibition of B. elliptica on alpha glucosidase activity at the highest concentration of the extract tested, was considered as not physiologically relevant. The aqueous extracts of bothplants showed < 40 percent cell death in HepG2 cells even at high concentration and hence support the use of the plants by traditional healers. The extracts of B. ellipticaat 25 µg/ml, displayed a proliferative effect on INS-1 cells when compared to the negative control and B. ilicifolia at 25 μg/ml. The treatment of HepG2 cells with 100 µg/mlB. elliptica and B. ilicifolia extracts revealed a higher glucose uptake of 121 percent and 123 percent respectively when compared to the pharmaceutical drug berberine. However, both plants extracts displayed weak significant glucose uptake in L6 muscle cell line at all the tested concentrations when compared to insulin at 6 μg/ml. The crude extracts of both plants demonstrated no significant effect on 3T3-L1 lipid accumulation and INS-1 glucose metabolism. The extracts of both plants strongly reduced NO production in RAW macrophages at the highest concentration (100 μg/ml) tested in this study, which at least in part, may be explained by the flavanoids and phenols content of these plants. In addition, the crude extracts of both plants displayed weak significant inhibition on the CYP3A4 activity indicating that both plant extracts do not interfere with the cytochrome P450 activation or metabolism of anti-diabetic drugs, that may be taken together with the plant extracts. In conclusion, the results obtained from this study revealed that both plants could possibly exert their hypoglycemic effect via interactions with insulin receptor, thereby enhancing glucose metabolism as well as maintaining and repairing the health state and function of the pancreatic beta cells. The findings in this study, therefore provide evidence that B. elliptica and B. ilicifolia possess antidiabetic properties, and support their folkloric use for the management of diabetes. However, due to the potential toxicity of both plant extracts, they must be prescribed with caution.
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- Date Issued: 2017
Phytochemical analysis and antibacterial properties of aqueous and ethanol extracts of Brachylaena elliptica (Thurb.) dc. and Brachylaena ilicifolia (Lam.) Phill & Schweick
- Authors: Sagbo, Idowu Jonas
- Date: 2015
- Subjects: Medicinal plants , Traditional medicine , Herbs -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11297 , http://hdl.handle.net/10353/d1021289 , Medicinal plants , Traditional medicine , Herbs -- Therapeutic use
- Description: Resistance of human pathogenic bacterial strains results in selective pressure against known antibiotic. However, plant derived compounds that possess antibacterial potential are currently being investigated for treatment of wound infections in diabetic patients as they are inexpensive and non-toxic. Hence, this dissertation was designed to evaluate two medicinal plants (Brachylaena elliptica and Brachylaena ilicifolia) traditionally used in the treatment of various diseases such as diabetes, and its secondary complications in diabetic patients. The in vitro antioxidant activity of both plants were evaluated using DPPH (1, 1-diphenylhydrazl), ferric reducing power, ABTS (2, 2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid), NO (nitric oxide) and H2O2 (hydrogen peroxide) techniques. The antibacterial test and Minimum inhibitory concentration (MIC) was determined by agar dilution method against 5 bacteria strains (Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogene, Proteus vulgaris and Proteus mirabilis) infecting wounds in diabetic patients using amoxicillin and ciprofloxacin as positive control. The phytochemical analyses were assessed using standard published methods. Identification of bioactive components in essential oils of both plants were assessed using GCMS. The aqueous and ethanol extracts of both plants were also evaluated to identify bioactive components using LC-MS. The results of the phytochemical analysis revealed the presence of phenols, tannins, flavanoids, flavanols, proanthocyanidins, saponins and alkaloids in both plants. Both plants indicated strong antioxidant activities which might be due to the presence of bioactive compounds. The aqueous and ethanol leaf extracts of both plants demonstrated appreciable broad spectrum activities against these wound pathogens with MIC ranging between 5 and 0.3 mg/ml. The GC-MS analysis of the essential oils of both plants revealed the presence of monoterpenes, oxygenated sesquiterpenes, phenolics and esters. The LC-MS analysis of the aqueous and ethanol leaf extracts of both plants showed that both plants are rich in alkaloids, terpenes, terpenoids, monoterpernoids, and flavanoids. Conclusively, this study has partially justified the ethnomedicinal use of B. elliptica and B.licifolia leaves for the treatment of various diseases, including diabetes and wound infections caused by bacteria in diabetic patients. These may be attributed to the presence of antioxidant compound such as phenols, flavanoids, saponins, tannins, alkaloids and other phytochemical compounds.
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- Date Issued: 2015