Potential of Ginkgo biloba L. leaves in the management of hyperglycemia and hypertension using in vitro models Marcia Da Silva Pinto a , Young-In Kwon b , Emmanouil Apostolidis b , Franco Maria Lajolo a , Maria Inés Genovese a , Kalidas Shetty b, * a Laboratório de Química, Bioquímica e Biologia Molecular de Alimentos, Departamento de Alimentos e Nutrição Experimental, FCF, Universidade de São Paulo, Av. Prof. Lineu Prestes 580, Bloco 14, 05508-900 São Paulo, SP, Brazil b Laboratory of Food Biotechnology, Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA article info Article history: Received 10 April 2008 Received in revised form 7 July 2009 Accepted 7 July 2009 Available online 8 August 2009 Keywords: Ginkgo biloba L. Antioxidant activity Diabetes Hypertension Phenolics abstract Leaves from four different Ginkgo biloba L. trees (1 and 2 – females; 3 and 4 – males), grown at the same conditions, were collected during a period of 5 months (from June to October, 2007). Water and 12% eth- anol extracts were analyzed for total phenolics content, antioxidant activity, phenolic profile, and the potential in vitro inhibitory effects on a-amylase, a-glucosidase, and Angiotensin I-Converting Enzyme (ACE) enzymes related to the management of diabetes and hypertension. The results indicated a signif- icant difference among the trees in all functional benefits evaluated in the leaf extracts and also found important seasonal variation related to the same functional parameters. In general, the aqueous extracts had higher total phenolic content than the ethanolic extracts. Also, no correlation was found between total phenolics and antioxidant activity. In relation to the ACE inhibition, only ethanolic extracts had inhibitory activity. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Ginkgo biloba L. is one of the oldest living plant species (Jacobs and Browner, 2000) and it is often referred to as ‘‘a living fossil” since it can live for as long as 1000 years. It grows throughout Chi- na, Korea, Japan, Europe, and the United States. The Ginkgo leaf contains many bioactive compounds, including flavonol and flavone glycosides, terpenoids and ginkgolides (Jacobs and Browner, 2000). Many studies have reported several physio- logical actions attributed to these compounds, including antioxi- dant and vasoactivating properties, inhibition of platelet activating factor and neuro-transmitter modulation (Pietri et al., 1997; Ferrandini et al., 1993; Kudolo et al., 2002; Diamond et al., 2000; Braquet and Koltai, 1994; Chung et al., 1987; White et al., 1996; Ramassamy et al., 1992). Due to its association with improvement in cognitive function (Brevoort, 1998), it is one of the most consumed phytopharmaceuticals in the USA and Europe (Blumenthal, 2001). Studies have indicated that major chronic diseases, including type 2 diabetes, cardiovascular diseases and some forms of cancer are influenced by dietary and lifestyle factors (Hu, 2005; Kearney et al., 2005; Willet, 2002). According to Lock et al. (2005) the total worldwide mortality attributed to inadequate intake of fruits and vegetables is around 2.6 million deaths per year. Many studies have reported the potential beneficial effects of the ingestion of the standardized commercially available extract of G. biloba L. leaves known as (EGb 761) in the management of type 2 diabetes and hypertension (Braquet and Koltai, 1994; Carlson et al., 2007; Hibatallah et al., 1999; Kubota et al., 2006; Kudolo, 2001; Kudolo et al., 2005, 2002; Tada et al., 2008; Wu et al., 2008; Ye et al., 2007). However there is a lack of information about the effect of seasonal changes in the health-relevant functionality of Ginkgo leaves. The therapeutic approach available for type 2 diabetic patients is by retarding the breakdown and absorption of glucose through the inhibition of pancreatic a-amylase and intestinal a-glucosidase enzymes, respectively. Natural a-amylase and a-glucosidase inhib- itors from fruits and vegetables could offer a good strategy to con- trol the post-prandial hyperglycemia mainly due to the presence of phenolic compounds and provide an effect without the side effects present in the most available drugs such as abdominal distention, flatulence, meteorism and possibly diarrhea (Matsui et al., 2001; Kwon et al., 2006; McDougall et al., 2005; Khan et al., 1990; Kotowaroo et al., 2006; Gao et al., 2007; Bhandari et al., 2008; Ali et al., 2006). One of the long-term complications of diabetes is high blood pressure, or hypertension. Angiotensin I-Converting Enzyme (ACE) is an important enzyme involved in maintaining vascular tension by two different reactions which it catalyzes: conversion 0960-8524/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2009.07.021 * Corresponding author. Tel.: +1 413 545 1022; fax: +1 413 545 1262. E-mail address: kalidas@foodsci.umass.edu (K. Shetty). Bioresource Technology 100 (2009) 6599–6609 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech