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Antidiabetic Properties of Guava leaves Extract
Diabetes is a common metabolic disease associated with an unusual postprandial surge of the glucose in the blood resulting from insulin insufficiency or dysfunction. Moreover, the disorder occurs in three forms which include: gestational, type 1, and 2 diabetes. The most affected individuals are the obese due to their poor eating habits and the older who tend to be less active. An alpha-glucosidase enzyme secreted from intestinal chorionic epithelium hydrolyzes complex carbohydrates to simple sugars which are easily absorbed into the bloodstream. Nevertheless, inhibition of this enzyme tends to decelerates the process of absorption and digestion of carbohydrates. The overall peak concentration of postprandial blood glucose is reduced, and the blood sugar level comes under control. However, the inhibitor does not cause the pancreas to produce more insulin but blocks the pancreatic amylase which hydrolyzes complex oligosaccharides in the small intestine lumen. This gives pancreas more time to secrete insulin to cover the meal. For instances, catechins, flavonoids, tannins, alkaloids, anthocyanidins, betulinic acid, lupeol and phenol compounds are observed to play a major role in the control of type 2 diabetes. The antioxidants act as alpha-glucosidase inhibitors. In some countries, Psidium guajava leaf tea is used for the control and management of health complications due to the presence of alkaloid, quinones, saponins, flavonoids, as well as steroids/triterpenoids. Alkaloids, flavonoids, saponins, tannins, steroids/triterpenoids occur as bioactive antidiabetic principles which act as alpha-glucosidase inhibitors. This review mainly concentrates on the control of diabetes by inhibition of carbohydrate hydrolyzing enzyme by use of black tea fortified with guava leaves extract.
Diabetes is a well-known metabolic disorder characterized by an abnormal postprandial increase of blood glucose level resulting from insulin insufficiency or dysfunction. Diabetes Mellitus is a non-communicable disease that is considered as one of the five leading causes of death in the world. There are three types of diabetes: type 1, type 2, and gestational diabetes. There is no known effective cure for the disease. Only lifelong treatment and management of diabetes is acknowledged. The diabetic patients have to put up with the available drugs and insulin that are currently in use and which are associated with several undesirable side effects. These undesirable side effects and the high cost of anti-diabetic drugs have steered the search for plants with hypoglycemic properties and their use in the management of diabetes. An alpha-glucosidase enzyme secreted from intestinal chorionic epithelium hydrolyzes complex carbohydrates to simple sugars which are easily absorbed into the bloodstream. Inhibition of this enzyme by guava leaves extract slows down the process of digestion and absorption of carbohydrates. The peak concentration of postprandial blood glucose is reduced, and the blood sugar level comes under control. The inhibitor does not cause the pancreas to produce more insulin but blocks the pancreatic amylase which hydrolyzes complex oligosaccharides in the small intestine lumen. This gives pancreas more time to secrete insulin to cover the meal. The mechanism of antidiabetic activities of Psidium guajava leaves is associated with the activity of the intestinal glycosidase that is related to postprandial hyperglycemia. These inhibitors are later on broken down by the bacteria, and absorbed, and eliminated by the kidney hence has no side effects on the body.
Development and acceptability of a shelf stable and affordable black tea drink fortified with Psidium guajava leaves extract for the diabetic group.
- To determine the concentrations of the phenolic compounds in the guava leaves extract.
- To determine the concentrations of the phenolic compounds in the black tea.
- To determine the antimicrobial properties of the extract.
- To determine the shelf stability of the extract in the black tea.
- To formulate an antidiabetic black tea drink fortified with guava leaves extract.
- There is limited research on the antidiabetic, antimicrobial and antioxidant properties of the guava leaves extract and black tea.
- Addition of guava leaves extract in black tea results in the production of high quality, shelf-stable and safe tea drink
Scope and Limitation
This research was undertaken in The University of Nairobi laboratory. It was limited to those that consume large amount of black tea daily and the diabetic.
Determination of Total Phenolic Compounds
The overall phenolics in both black tea and guava leaves extract were analyzed by use of Folin Ciocaiteu reagent. An aliquot of 9 ml of both guava leaves and black tea infusion were mixed separately with 4 ml Folin Ciocaiteu reagent. They were allowed to react for about 5 minutes. 3.2 ml of 75%w/v NaCo3 was added to the mixtures which was then incubated for 30 mins. The mixtures absorbance were measured at 765 nm in which the total phenolic concentration was expressed as mg Gallic acid in 100 ml of the liquid samples.
Formulation of Black Tea Fortified with Guava Leaves Extract
Black tea was fortified with guava leaves extract to give a desirable quality characteristic of the tea which will be acceptable to the consumers.
5.2 Analytical Methods
- AOAC method 33-50.02 Sensory Evaluation by use of Triangle difference test and hedonic scale
- Determination of total phenolic content according to AOAC SMPR 2015.009.
- AOAC 2008 method for the preparation of black tea and guava leaves infusion.
Drying of the guava leaves was carried out to reduce the moisture content as well as remove the wax on the surface of the leaves. Rupturing of the cell walls helped to increase the extraction efficiency of phenolic compounds. The organoleptic characteristics including color, odor and flavor of guava leaves extract didn’t change with drying. Guava leaves were observed to have higher concentration of phenolic compound since the total phenols in tea are reduced during processing. Fermentation and roasting of the tea leaves resulted in the reduction of total phenolic content.During fermentation catechins were oxidized to orthoquinone which underwent dimerization to form bisflavonols. Fortified black tea had a desirable flavor due to the presence of anthocyanins in the guava leaves.The presence of flavonoids and the reduction of the moisture content of the guava leaves increased the shelf stability of the tea. The presence of bioactive compounds in the guava leaves increased the nutritive value of the tea.
It is possible to develop an antidiabetic tea that is fortified with guava leaves extract since the overall acceptance of the product was above like. In addition, the quality of life of the diabetics would improve with the use of the fortified tea to manage diabetes. Guava leaves extract and black tea are endorsed with the alpha-glucosidase inhibitors which enhance reduction of the peak concentration of postprandial blood. These inhibitors include flavonoids, tannins, alkaloids, anthocyanidins, catechins and phenolic compounds. In addition, Guava leaves are locally available making them cost-effective. Majority of people consume black tea hence it’s an appropriated food sample for the research. Guava leaves extract contain desirable properties making it fit the work of an additive. They contain compounds such as flavonoids that serve the purpose of preservatives and proanthocyanidins complexes that act as flavor and color agents. They are endorsed with bioactive compounds that improve the nutritional value of the food product. Due to their antimicrobial properties, they will be effective in extending the shelf life of tea. The existence of the biologically active molecules in the extract will enhance the nutritional value of tea.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
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