Bioprospecting for hypoglycemic activities and safety of selected traditionally used plants in the management of diabetes mellitus
Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar levels that result from defects in insulin secretion, or action, or both. The disorder completely throws the metabolism of dietary carbohydrates, lipids and proteins into disarray. This condition in its fully developed form is characterized by high blood sugar level (hyperglycemia), glycosuria, increased protein breakdown, ketosis and acidosis. Diabetes is a chronic medical condition which can be controlled but lasts a lifetime. Conventional management of diabetes mellitus is expensive and therefore unaffordable and sometimes unavailable to many patients especially in developing and underdeveloped nations. Such antidiabetic drugs have been found to have side effects with long term use and hence facilitating the continued usage of herbal prescriptions as an alternative way to compliment orthodox pharmacotherapy. However, there is limited scientific evidence regarding safety and efficacy to back up the continued therapeutic application of herbal remedies. The aim of this study was to determine through bioassay-guided screening, efficacy and toxic components present in five selected medicinal plants. The following herbs were studied; Lippia javanica, Ocimum lamiifolium, Croton macrostachyus, Azadiratchta indica, and Persea americana. The in-vivo antidiabetic activity and safety of these extracts were screened in white male alloxan-induced diabetic albino mice. The aqueous plant extracts were administered orally and intraperitoneally. The safety of these plant extracts were studied by administering 450mg/kg, 670mg/kg and 1000mg/kg body weight orally and intraperitoneally daily for 28 days in mice. The mineral elements of the aqueous plant extracts were analyzed using atomic absorption spectrometry (AAS) and Total Reflection X-ray Fluorescence system (TRXF) while various phytochemicals present were qualitatively assessed using standard procedures. Results revealed antidiabetic activity of the extracts at varying doses of 25, 48.4, 93.5, 180.9 and 350 mg/kg body weight. The extracts decreased the body weight gain and altered the organ to body weight percentage of the brain, kidney, liver, heart, testes and lungs for both intraperitoneal and oral routes. In both routes, administration of the same doses (450mg/kg, 670mg/kg and 1000mg/kg body weight) caused a change in levels of RBC, WBC, Hb, PCV, PLT, MPV, MCV, MCH, MCHC, neutrophils, lymphocytes, eosinophils, basophils, monocytes and biochemical parameters: AST, ALT, GGT, CK, α-AMYL, LDH, T-BIL, D-BIL, I-BIL, TG, TC, LDL-C, HDL-C, BUN, UA, Urea and Creatinine. The extracts contained tannins, flavonoids, saponins, sterols, anthraquinones and alkaloids. Elemental analysis confirmed the presence of Sodium, Chlorine, Potassium, Calcium, Titanium, Vanadium, Mercury, Chromium, Manganese, Iron, Copper, Zinc, Arsenic, Cadmium, Magnesium, Nickel and Lead at levels above or below the recommended daily allowance. In conclusion the results showed that the plant extracts were effective in reducing blood sugar levels the plants showed no toxicity and revealed the presence of vital phytochemicals and elements which posses’ antidiabetic activities. The study therefore, confirmed the traditional use of these herbs and established their safety and efficacy data that can guide their proper use in the management of diabetes mellitus. Consideration should be made to carry out the same studies using higher animals. Besides, one can subject the plants to organic solvent extraction and compare activities of both aqueous and organic fractions.