Antioxidants are chemical species with the ability to postpone oxidation or inhibit the propagation stage of free radical reactions in living cells. In the living cell, the destruction of cellular macromolecules such as proteins, carbohydrates, lipids and nucleic acids by free radicals causes degenerative diseases including cancer, cardiovascular disease, cataracts, Alzheimer’s disease, atherosclerosis, hypertension, diabetes mellitus and aging (1). There has been an increased interest in the study of antioxidant compounds because their presence has been shown to be efficacious in inhibiting free radicals hence slowing or quenching the emergence of degenerative diseases. Reports in literature indicate that antioxidants improve human health by boosting the immune system, inhibiting cancer cells, reducing cardiovascular diseases and diabetes (2) effect healing of chronic ulcers (3). They have also been shown to possess anti-allergenic, anti-inflammatory, anti-microbial, anti-thrombotic, cardio-protective and vasodilatory effects (4, 5).
Naturally occurring antioxidants are present in different forms, they include compounds such as phenolics, flavonoids, coumarins, xanthones, lignans, tannins, curcuminoids, tocopherol, lycopene and β-carotene (5). They can be found in the fruits, leaves, seeds, and oils of plants (6).
Edible oilseeds are reported to be good sources of compounds with biological activity (7). Such seeds produce diverse kinds of secondary metabolites with a wide range long-term therapeutic and physiological potential (8). The oilseeds may contain secondary metabolites with the ability to induce carcinogen detoxification, prevent tumor growth and block carcinogens, as well as exhibit antioxidant properties which can improve overall immune response (9, 10). Supplementing the body with exogenous antioxidants or boosting the antioxidants in the body is reportedly beneficial in fighting the undesirable and unwanted effects of oxidative damage induced by Reactive Oxygen Species (ROS). Synthetic antioxidants have been commonly used as food additives to help manage or minimize the risk of certain cancers, cardiovascular diseases, coronary heart diseases and in some cases ageing (11, 12). Epidemiological studies have shown that the inclusion and intake of antioxidant substances in our diets reduces death ascribed to chronic degenerative diseases (12).
Cucumeropsis edulis seeds (Melon seeds) are an example of such oilseeds found in abundance in the savannah zones of Ghana. Cucumeropsis edulis (C. edulis), commonly known as melon and locally called “wrewre” in Ghana. It grows in rich sandy soils in the hot climate zones of Africa. Dried seeds of C. edulis are usually roasted, milled, and used as sauce thickener (13) as well as making soups and stews in some parts of Ghana and neighboring countries including Nigeria and Burkina Faso. The C. edulis seeds have been reported to have excellent nutritional value (14). It is rich in carotene (Provitamin A), essential amino acids, vitamins, and mineral elements (15, 16).
In the current study, antioxidant properties and the anti-inflammatory activities the C. edulis seeds were studied. The bioactive compounds in the seed were extracted with solvents of different polarities. The interest is to study the antioxidant and the anti-inflammatory activities of the extracts obtained from different solvent types. Polyphenols are the most abundant group of phytochemicals, different kinds of polar solvents for example; methanol, ethanol and acetone have been employed in their extraction from the plant source (17).
The aim of this study is to investigate medicinal activities of C. edulis seeds. Knowledge of the nature of the secondary metabolites and their solubility in a particular type of solvent (polar or nonpolar) will significantly inform the method of processing food products from the seeds of C. edulis for enhanced medicinal benefits.