In Vitro Antioxidant Effect and Inhibition of .ALPHA.-Amylase of Two Varieties of Amaranthus caudatus Seeds

Abstract

Amaranth is a herbaceous annual growing to 15-100 cm tall. It was once nearly as important a food as maize and beans in Central and South America. The Amaranthus plants (Amaranthaceae) are spread throughout the world, growing under a wide range of climatic conditions and they are able to produce grains and leafy edible vegetables.1) Nutritionally, amaranth grain has a 2 to 3 times higher biological value than common cereal grains, while containing substantially higher levels of protein with 2-3 times higher lysine content.2) Due to its nutritional attributes, amaranth grain is presently being exploited by food manufacturers, both in the United States and abroad, in a variety of thermally processed foods, especially confectionery, cereal and bakery 3) products, and has shown potential for use in infant formulas. 4)Current industrial and public interest in the use of amaranth grain has not only been linked to its recognized nutritional properties, but also to its potential beneficial use as a therapeutic adjunct in diets for hypercholesterolemic susceptible individuals.5) Recent studies have demonstrated a variety of important and unique nutraceutical type applications for grain amaranth, 6) including its use as an adjunct to lower blood glucose response in non-insulin-dependent diabetics and in other applications to lower blood serum cholesterol levels. 7,8) Diabetes is a major risk factor for premature atherosclerosis, and oxidative stress plays an important role. In fact, diabetic monocytes produce increased superoxide anion (O 2 Ϫ ). 9)Over the centuries, herbal drugs have served as a major source of medicines for the prevention and treatment of diseases including diabetes mellitus. It is estimated that more than 200 species of plants exhibit hypoglycaemic properties, including many common plants, such as pumpkin, wheat, celery, wax gourd, lotus root and bitter melon but the basis of this activity is frequently not investigated. 10)Synthetic hypoglycaemic agents can produce serious side effects and are not suitable for use during pregnancy. 11)Therefore, the search for more effective and safer hypoglycaemic compounds has continued to be an important area of active research, and after the recommendations made by WHO on diabetes mellitus, 12) research on hypoglycaemic compounds from medicinal plants has become an important aspect of this project.In the present study two varieties of Amaranthus caudatus (Oscar blanco and Victor red) were investigated with the aim of characterizing the plants for their biological activities, antioxidant and antidiabetic, and oil, squalene and phenolic contents. MATERIALS AND METHODS ChemicalsThe following chemicals were obtained from Sigma-Aldrich S.p.a. (Milano, Italy): squalene, thiobarbituric acid (TBA), phosphate buffered saline (PBS), bovine brain extract, FeCl 3 , ascorbic acid, butylated hydroxytoluene (BHT), propyl gallate, potato starch, sodium phosphate buffer, sodium chloride, a-amylase, sodium potassium tartrate and 3,5-dinitrosalicylic acid. Methanol, ethanol, ethyl a...

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