Journal of Ethnopharmacology 128 (2010) 384–389 Contents lists available at ScienceDirect Journal of Ethnopharmacology journal homepage: www.elsevier.com/locate/jethpharm Hypoglycemic activity and antioxidant potential of some medicinal plants traditionally used in Turkey for diabetes Mustafa Aslan ∗ , Nilüfer Orhan, Didem Deliorman Orhan, Fatma Ergun Gazi University, Faculty of Pharmacy, Department of Pharmacognosy, 06330 Ankara, Turkey article info Article history: Received 15 August 2009 Received in revised form 13 January 2010 Accepted 14 January 2010 Available online 25 January 2010 Keywords: Antidiabetic Hypoglycemic Antioxidant Allium porrum Cydonia oblonga Helianthus tuberosus abstract Cydonia oblonga Mill. (Rosaceae) leaves, Helianthus tuberosus L. (Asteraceae) tubers, and Allium porrum L. (Liliaceae) bulbs are used as a folk remedy for the treatment of diabetes and they are also consumed as food in Turkey. In the present study, the antidiabetic and antioxidant activities of the ethanol extracts of these plants were studied in normal and streptozotocin-induced diabetic rats for 5 days. All extracts were administrated orally to rats at the doses of 250 and 500 mg/kg. Blood glucose level was measured according to glucose oxidase method. In order to determine antioxidant activity, thiobarbituric acid reactive substance (TBARS) and reduced glutathione (GSH) levels in liver, kidney, and heart tissues were measured by using spectrophotometric methods. Oral administration of Cydonia oblonga (500 mg/kg) and Allium porrum (500 mg/kg) extracts for 5 days in diabetic rats caused a decrease in blood glucose levels by 33.8% and 18.0%, respectively. Moreover, Allium porrum and Cydonia oblonga extracts induced significant alleviation on only heart tissue TBARS levels (44.6 and 45.7%), Helianthus tuberosus and Allium porrum extracts showed an inhibitory effect on kidney tissue TBARS levels (24.5 and 14.8%). None of the extracts restored GSH levels in kidney, liver, and heart tissues of diabetic rats. © 2010 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Diabetes mellitus, one of the most common endocrine metabolic disorders, has a significant impact on the health, quality of life, and life expectancy of patients as well as on the health care system (Bowling and Beal, 1995). With the number of cases expected to increase rapidly in the years to come, diabetes is a growing health challenge worldwide. With the active encouragement of the WHO, an attempt is being made to collect traditional medical information used for the treatment of diabetes for study in modern laboratories in order to scientifically evaluate therapeutic efficacies (Serraclara et al., 1998). In diabetes, hyperglycaemia generates reactive oxygen species (ROS), which in turn cause lipid peroxidation and membrane dam- age and these free radicals play an important role in the production of secondary complications in diabetes mellitus (kidney, eye, blood vessel, and nerve damage) (Hunt et al., 1988). Antioxidants have been shown to prevent the destruction of -cells (Slonim et al., 1983; Murthy et al., 1992) by inhibiting the peroxidation chain reaction and thus they may provide protection against the devel- opment of diabetes (Halliwell and Gutteridge, 1989; Gordon, 1996; Montonen, 2005). ∗ Corresponding author. Tel.: +90 312 2023184; fax: +90 312 2235018. E-mail address: marslan@gazi.edu.tr (M. Aslan). Plants contain natural antioxidants (tannins, flavonoids, vita- mins C and E, etc.) that can preserve -cell function and prevent diabetes induced ROS formation (National Nutrition Council, 1999). In Turkish folk medicine, some traditional and edible plants have been utilized to decrease symptoms of diabetes. Among these, Cydonia oblonga Mill. (Rosaceae), common name quince and known in Anatolia as ‘ayva’, is a perennial tree whose fruits and leaves can be used in many ways. The decoction of Cydonia oblonga leaves is traditionally used in the treatment of cough, cold, bronchitis, abdominal pain, diarrhoea, nervousness, insomnia, disurea, and against hyperglycemia (Tabata et al., 1993; Baytop, 1999; Tuzlacı and Tolon, 2000; Sezik et al., 2001). Allium porrum L. (Liliaceae), common name leek, is a bulbous perennial plant and has been used in the treatment of hyperlipidemy, infertility in women, and externally for the treatment of hemorrhoids in different regions of Anatolia. The fresh bulbs of plant are boiled and drunk (1–2 glasses) before meals against diabetes in rural area of Turkey (Tabata et al., 1993; Baytop, 1999; Sezik et al., 2001; Pieroni et al., 2005). Helianthus tuberosus L. (Asteraceae), common name Jerusalem arti- choke, is cultivated as a vegetable throughout the world and regarded as a diuretic, lactagogue, aphrodisiac, and collagogue. Fresh tubers are eaten to decrease diabetes symptoms in Turkish traditional medicine (Honda et al., 1994; Inanc ¸ et al., 2007). It is also used in the treatment of hemorrhoids (Sezik et al., 2001). In this study, the antidiabetic and antioxidant activities of Cydonia oblonga leaves, Helianthus tuberosus tubers and Allium por- rum bulbs were selected based on ethnopharmacological surveys 0378-8741/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2010.01.040