Hypoglycemic Activity of Phoradendron tomentosum in Streptozotocin-diabetic Rats

Mistletoe, Phoradendron tomentosum (D.C.) Engelm (Loranthaceae), is used in Mexico as a folk medicine in the treatment of diabetes mellitus (DM). The objective of this study was to test the hypoglycemic effect of an aqueous extract of this plant on normoglycemic and streptozotocin (STZ)-diabetic male rats. Blood glucose concentrations were measured at the beginning and at the end of the experiment. Diabetic blood glucose concentrations (BG) were seen one month after STZ-diabetic induction. BG in STZ-diabetic rats was significantly reduced by Phoradendron tomentosum aqueous extract after 45 days treatment (293.2 ± 56.6 mg/dl → 112.0 ± 35.6 mg/dl). There was a significant difference at the end of the experiment, between diabetic treated (112.0 ± 35.6 mg/dl) versus diabetic control groups (226.0 ± 29.3 mg/dl). With respect to normoglycemic treated group no significant difference between the pre and post-treatment (80.6 ± 27.6 mg/dl vs. 72.6 ± 15.0 mg/dl respectively) glucose levels was found. The results showed Phoradendron tomentosum aerial part aqueous extract is hypoglycemic in STZ-diabetic rats after 45 days consumption. INTRODUCTION DM is a worldwide public health problem, characterized as a chronic metabolic disorder by complete or relative insufficiency in the secretion and/or action of insulin [1]. DM type 2 results from a combination of tissue resistance (or insensitivity) to insulin action and an inadequate compensation of insulin secretion response. This type of diabetes varies among countries and populations; it is influenced by genetics, obesity, sedentary lifestyle, high intake of carbohydrates, environmental factors, and aging [2]. According to the predictions of the World Health Organization (WHO), it is estimated that by year 2025 there will be almost 40 million diabetic patients in Latin America and 11.7 million diabetics in Mexico [3]. Drugs such as biguanides and sulphonylureas are available to control blood glucose in non-insulin dependent DM (type 2) patients; however, after a certain period with these treatments, their efficacy wanes and dosage adjustment may be required. Moreover, existing agents for the treatment of DM type 2 are not without adverse or unwanted effects [4,5]. Therefore, it is important to carry out additional research in order to find new hypoglycemic drugs with minimum side effects to offer alternatives to prevent or control this disease. For multinational drug companies and research institutes, the plant kingdom has become a target to search and to find new drugs (about 50% of raw material for the pharmaceutical industry) [6]. The interest in using medicinal plants has increased considerably to treat different public health problems. The World Health Organization (WHO), in their 31st Assembly resolution, suggests that it is necessary that a complete inventory and evaluation of the efficacy, safety and standardization of medicinal plants be made [7]. A few years later WHO considered that the people in developing countries are using medicinal plants as a primary mode of healthcare [8] and recently researchers consider it necessary to classify medicinal plants and preserve knowledge of their use(s), owing to the rapid industrialization and the loss of ethnic cultures and customs and healthcare traditions [9]. There is no exact estimate of the number of plants used in the empirical control of DM worldwide. Ethnobotanical reports reveal that more than 1200 plants are used for this purpose and about 350 of these plants have been confirmed to possess hypoglycemic activity [10]. In Mexico, traditional health care providers recommend more than 150 plants for this disease [11]. Of these, about one third have been studied and found to possess hypoglycemic activity [12,13]. Previous studies suggest that some semi-parasitic plants have hypoglycemic effects in streptozotocin (STZ)-induced diabetic rats [14]. Phoradendron tomentosum (D.C.) is a semi-parasitic plant widely distributed throughout the Northern part of Mexico and Southwest of Texas (Fig. 1). Empirical observations of folk medicine shows that consumption of an aqueous extract of this plant helps to control disorders such as diabetes, varicose veins, and dysmenorrhea [15]. The effect of this plant has not been scientifically studied; therefore, the aim of