Natural and diet-derived antioxidants

Dietary antioxidants may contribute to the decrease of cardiovascular disease by reduction of free radical formation as well as oxidative stress, say Sheeja E and Edwin E

An antioxidant is a chemical that prevents the oxidation of other chemicals. They protect key cell components by neutralising the damaging effects of free radicals, which are natural by products of cell metabolism.

Live forms living in the earth atmosphere must be equipped with systems to deal with the action of oxygen in living matter. Plants are especially susceptible to damage by active oxygen (exposed to radiation UV light) this is why plants developed numerous antioxidant defence systems that results in certain number of very potent antioxidants.

Besides, plants many of microbial and animal products as well as fermented products, seaweeds, protein hydrolisates were found to be powerful antioxidants. Daily foods contain a wide variety of free radical scavenging molecules, thus vegetables, fruit, tea, wine are product rich in natural antioxidant compounds. Among numerous antioxidants following plant secondary products are of particular interest.

• Plant phenolics: phenylproponoids, coumarines, flavanoids
• Polyphenolic: tannins, proanthocyanidins
• Nitrogen containing compounds; alkaloids, nonprotein aminoacids, isothiocynates, indoles
• Phytosterols
• Carotenoids
• Chlorophyll derivatives
• Plant phenolic, particularly flavanoids, tannins and phenyl propanoids are considered as the most important antioxidants from plant origin.

Many so-called secondary products can act as potent bio-antimutagens. Therefore, there is currently a strong interest in the study of natural compounds with free radical scavenger capacity and their role in human health and nutrition.

Dietary antioxidants may contribute to the decrease of cardiovascular disease by reduction of free radical formation as well as oxidative stress in general, by protection of LDL oxidation and platelet aggregation and by inhibiting synthesis of proinflammatory cytokines. Epidemiological studies have shown that a higher intake of these compounds is associated with lower risk of mortality from cancer and coronary heart disease.

The use of spices has been valued from prehistorically times not solely because of their flavour, but also because of their food preserving power.

A number of studies have been done on their antioxidant activity as well as their antiseptic activity. Several compounds from spicy and aromatic plants are confirmed to possess strong antioxidant activity.

Thus, phenolic diterpenoids: carnosol, rosmanol, carnosoic acid from sage (Salvia officianalis L) and rosemary (Rosmarinus officianalis L), dimmers of thymol and flavonoids from thyme (Thymus vulgaris L) and flavonoids from oregano (Origanum vulgare L) and pepper (Piper nigrum L) were reported as strong antioxidative compounds. Volatile oils of many aromatic plants, besides their well-known antimicrobial activity possess also significant antioxidant properties.

Monoterpene ketones (menthone, thujone, carvone) and hydrocarbons are confirmed as strong free radical scavengers. Therefore, many aromatic and spicy plants as well as their essential oils, could serve not only as a flavouring agent but also as a safe food antioxidant and supplement in preventing deterioration of foodstuff products.

Consumption of food products with natural essential oil or aromatic plant extracts are able to prevent the risk of many free radicals mediated diseases.

Since herbs are known to exert antioxidant activity and are considered to be less or no toxic effects, they would be the best alternative method, when the normal level of antioxidant defence mechanism fails.

The writers are with B R Nahata College of Pharmacy, Mandsaur, Madhya Pradesh