Introduction
In the last few decades, there has been a tremendous increase in the prevalence of type 2 diabetes internationally, and has been estimated that the number of diabetic patients will be more than 205 million in the next 20 years (Diabetes Atlas and 6th Edition 2014). Oral hypoglycemic agents and insulin, generally used to treat Diabetes Mellitus (DM), have number of serious side effects (Kyriacou and Ahmed 2010). Hence, interest has increased in finding naturally occurring anti-diabetic therapeutics to replace synthetic drugs (Velioglu et al. 1998). As there have been increasing emphasis on the promotion of a healthy diet for the management of type 2 diabetes, there is a great necessity to investigate the combination of drugs derived from natural resource extracts (Kaur et al. 2013).
Numerous studies have established an inverse correlation between the intake of fruits and vegetables and the onset of diseases such as diabetes, cardiovascular disease, cancer, and aging-related disorders as they are rich source of dietary antioxidants, including polyphenolics, vitamins E and C, and carotenoids (Huang et al. 2005). Polyphenolic compounds, in particular, have been shown to terminate free radical chain reactions in biological systems, and hence can act as nutraceuticals for a range of oxidative stress implicated diseases, like diabetes and cancer (Espín et al. 2007).
Amongst plant foods with health benefits, crops from the family Brassicaceae (also known as Cruciferae) have been the focus of numerous epidemiological and clinical studies (Podsędek 2007) as they are good source of variety of nutrients and health promoting phytochemicals (Liu 2004; Soengas et al. 2011). Brassica vegetables, like knol khol, cabbage, broccoli, cauliflower, kale and