Phytochemistry and Mode of Action of Some Tropical Spices in the Management of Type-2 Diabetes and Hypertension
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African Journal of Pharmacy and Pharmacology Vol. 7(7), pp. 332-346, 22 February, 2013 Available online at http://www.academicjournals.org/AJPP DOI: 10.5897/AJPP12.014 ISSN 1996-0816 ©2013 Academic Journals Review Phytochemistry and mode of action of some tropical spices in the management of type-2 diabetes and hypertension Stephen Adeniyi Adefegha and Ganiyu Oboh* Department of Biochemistry, School of Sciences, Federal University of Technology, Akure, P. M. B. 704, Akure, Ondo State, 340001, Nigeria. Accepted 11 February, 2013 Spices are important food supplements and/or food products, which have been used as flavouring agents and preservatives for thousands of years in tropical Africa, Asia and other parts of the world. They are well known for their medicinal properties, and their use in traditional systems of medicine has been on record for a long time. Although, epidemiological and clinical studies have indicated that spices are important source of natural antioxidant having the digestive stimulant action, bioavailability enhancement nature, carminative attribute, antimicrobial activity, hypolipidemic property, antidiabetic influence, antioxidant capacity, anti-inflammatory ability, anticarcinogenic potential and neuroprotective effect. The present review reports the phytochemical constituents and mode of action of some tropical spices as antidiabetic and antihypertensive agents. The conclusion of this review may help in undertaking research for the development of functional foods and nutraceuticals. Key words: Spices, type-2 diabetes, hypertension, enzymes, antioxidant, phenolics, phytochemicals. INTRODUCTION Spices are food supplements or food products, which potential sources of natural antioxidant such as phenolic have been used not only as flavoring and coloring diterpenes, volatile oils, flavonoids, terpenoids, carote- agents, but also as food preservatives and herbs in folk noids, phytoestrogens, and phenolic acids (Cai et al., medicines for thousands of years in Africa, Asia and 2004; Suhaj, 2006; Kennedy et al., 2011). other parts of the world (Srinivasan, 2005a). They are Spice phytochemicals such as curcumin (turmeric), consumed as whole spices or ground into powder and capsaicin (red chillies), eugenol (cloves), linalool mixed with diets containing cereals, legumes, nuts, fruits, (coriander), piperine (black pepper), zingerone (zinger) vegetables, milk and milk products. They are also used in and cuminaldehyde (cumin) have been reported to inhibit soup preparation in various homes and serve as lipid peroxidation (Shobana and Naidu, 2000; Oboh and ingredients in the preparation of several traditional Rocha, 2007). In recent times, spice antioxidants have delicacies. Spices are utilized as herbs, mainly in the raised considerable interest among food scientists, form of isolates from their extracts. Spices are considered manufactures, and consumers because of their natural to be good contributors to the total nutrient intake of antioxidants (Lu et al., 2011). Consumers are protein, carbohydrates, fats, vitamins and minerals, increasingly aware of the risk posed by synthetic thereby enhancing the nutritional quality of diets antioxidants due to their high volatility and instability at (Pradeep et al., 1993). Apart from the nutrients supplied elevated temperatures. Therefore, focus has been shifted by spices, they possess many phytochemicals which are to the use of natural antioxidants in food preservation (Odukoya et al., 2005; Oboh and Rocha, 2007; Adefegha and Oboh, 2011a). Food oxidation is considered a major cause of food *Corresponding author. E-mail: [email protected]. Tel: deterioration and spoilage, causing rancidity in food +234-7031388644. Fax: +234-34-242-403. (Sherwin, 1990). The resultant effect is noticed in the Adefegha and Oboh 333 decreased nutritional quality, color, flavor, texture and Adefegha and Oboh, 2012a). safety of foods. Many spices have also been recognized Hypertension or persistent high blood pressure is a to possess digestive stimulant action, carminative effect, common cardiovascular disease which has become a antimicrobial activity, antioxidant capacity, antiinflamma- worldwide problem of epidemic proportions, affecting 15 tory property, antimutagenic ability and anticarcinogenic to 20% of all adults with ailments such as arteriosclerosis, potential (Srinivasan, 2005a). Spices contribute greatly to stroke, myocardial infarction and end-stage renal disease the daily antioxidant intake in most diets, especially in (Je et al., 2009). It is regarded as one of the long-term dietary cultures where spices are used as whole meal complications of T2DM. These two diseases (hyperten- (Carlsen et al., 2010). Many spices have been shown to sion and T2DM) are interrelated metabolic disorders with confer health benefits and have been proven to persistent hypertension being the risk factors for strokes, counteract oxidative stress in vitro and in vivo (Oboh et heart attacks, heart failure and is a leading cause of al., 2005, 2010a, 2012a; Shan et al., 2005; Wojdylo et al., chronic renal failure (Sowers and Epstein, 1995; Bakris et 2007; Adefegha and Oboh, 2012a). They are common al., 2000). One of the therapeutic strategies towards the sources of phenolic compounds which have been management of hypertension is the inhibition of reported to show superior antioxidant capacity to fruits, angiotensin-I converting enzymes (ACE); an enzyme cereals, and nuts (Pellegrini et al., 2006; Carlsen et al., which play a pivotal role in rennin-angiotensin system by 2010). The main active components in spices are converting angiotensin-I to angiotensin-II (potent phenolic acids, flavonoids and volatile or essential oils vasoconstrictor). However, phenolic-rich spices have (Shan et al., 2005; Wojdyło et al., 2007; Viuda-Martos et reported to act as good ACE inhibitors (Ranilla et al., al., 2011; Lu et al., 2011). 2010). Therefore, the present review highlights the In Nigeria, over 100 indigenous spices are used as phytochemical constituents and mechanism of action of important components of the “African/Nigerian dishes”, some tropical spices as antidiabetic and antihypertensive bringing original favors and desirable sensory properties agents. The pictures of some spices are as shown in to food. Essentially, “Pepper soup” is famous for its Figure 1 sensory, aromatic, attractive, pungency and spicy flavor resulting from the use of bastered melegueta, clove, alligator pepper, ginger, black pepper, garlic, Ethiopian Phytochemical composition pepper, chili peppers and other spices. Common spices, such as sweet basil, clove, black pepper, turmeric, chili Spices in the diet are not considered vital from the pepper, and ginger are usually part of daily African nutritional point of view, though they are widely household meals and also used as traditional African consumed throughout the world. They are not normally medicine. Numerous studies have reported that spices included in diet surveys, nor are they suggested or are important source of natural antioxidant, possessing recommended in what are known as balanced diets, digestive stimulant action, bioavailability enhancement probably because it was thought that the intake of these nature, carminative attribute, antimicrobial activity, hypoli- spices was so small that their contribution of nutrients pidemic property, antidiabetic influence, anti-inflammatory may not be significant (Pradeep et al., 1993). As part of ability, anticarcinogenic potential and neuroprotective normal diet, plant foods are thus not only a source of effect (Srinivasan et al., 2004; Shan et al., 2005; nutrients and energy provider, but may confer additional Srinivasan, 2005a; Adefegha and Oboh, 2011b). role of providing health benefits beyond their basic Diabetes mellitus (DM) is one of the leading causes of nutritional functions (Shahidi and Naczk, 2004). Attention global morbidity and mortality, and a major risk for is being focused on identifying dietary phytochemicals cardiovascular diseases (Alderman et al., 1999). which are plant secondary metabolites (array of bioactive Diabetes mellitus is a metabolic disease characterized by constituents) that are capable of eliciting health hyperglycaemia resulting from defects in insulin secre- enhancing effects and disease preventing abilities (Visioli tion, insulin action, or both (World Health Organization and Galli, 1998). (WHO), 1999). The control of postprandial hyperglycemia Phytochemicals describe the chemicals present in is an important strategy in the management of diabetes different parts of plant organs (leaves, stems, roots, mellitus, especially type 2 diabetis mellitus (T2DM), and flowers, fruits and seeds). Consumption of food rich in reducing chronic complications associated with the several phytochemicals such as saponins, alkaloids, disease (Kim et al., 2000; Ali et al., 2006; Ortiz-Andrade terpenes, phenylpropanoids, isoprenoids, steroids, et al., 2007). Hence, the inhibition of enzymes ( α- coumarins, flavonoids, phenolic acids, lignans, contain Glucosidase and α-amylase) involved in the digestion of chemicals such as flavonoids, terpenoids, lignans, carbohydrates can significantly decrease the postprandial sulfides, polyphenolics, carotenoids, coumarins, saponins increase of blood glucose after a mixed carbohydrate and plant sterols with biological activities that may diet, by delaying the process of carbohydrate hydrolysis provide therapeutic effects (Dorman et al., 2003, 2004; and absorption and phenolic phytochemicals from spices