**1.17. Steroids**

flavoring agents in many pharmaceutical formulations. Amygdalin has been used in the treatment of cancer [hydrogen cyanide (HCN) liberated in stomach kills malignant cells] and also as a cough suppressant in various preparations. Intake of cyanogenetic glycosides in excess

Plants long used as arrow poisons (e.g., *Strophanthus*) or as heart drugs, for example, *digitalis*, contain cardiac cardiotonic glycosides [38]. Cardiac glycosides help in the treatment of congestive heart (cardiac) failure; that is, they help a weakened heart to be strengthened and function

Cyanogenetic glycosides are a group of materials derived majorly from plants which on hydrolysis liberate hydrocyanic acid (HCN). They therefore call for attention and an object of concern because of their ability in causing damage by poisoning that are natural toxicants. Cassava, an example of a food plant (*Manihot esculenta*), produces cyanogenetic glycosides which require prolonged hydrolysis and boiling in preparation of the starchy tuberous roots

Flavonoids belong to a group of important polyphenols which are widely distributed among plants. They have more than one benzene ring in its structure and are used as antioxidants or free radical scavengers [27]. Flavans are parent compounds from which they are derived. Out of over 4,000 flavonoids that exist, some are found as pigments in higher plants. About 70% of plants contain common flavonoids such as quercetin, kaempferol, and quercitrin. Among other groups of flavonoids in existence are flavones, flavans, anthocyanidins, dihydroflavons, flavonols, chalcones, and catechin [27]. Flavonoids function to reduce the risk of coronary heart diseases [41] and possess anticoagulant, anti-inflammatory, and aphrodisiac

Phenols contribute to the prevention of various degenerative diseases that act as an antioxidant [41]. Phenols, phenolics, or polyphenolics are chemical constituents that are commonly present as natural color pigments giving fruits of plants their colors. The action of phenylalanine ammonia lyses (PAL) on phenylalanine leads to the synthesis of phenolics in plants. Among the various functions of phenols is in plant defense against pathogens and predators of herbivores and therefore used in the control of human infections caused by pathogens [43]. The most common of phenolic compounds widespread in plants is caffeic acid which is followed by chlorogenic acid, the causal agent of excessively sensitive inflammation of the skin (dermatitis) among humans [27]. Phenolics are natural antioxidants functioning as nutraceuticals and available in red wine, apples, and green tea. They serve as anticancer and

to release and evaporate off the HCN before consumption [40].

anti-inflammatory agents as well as prevent heart diseases.

quantities can be dangerous [22].

18 Phytochemicals - Source of Antioxidants and Role in Disease Prevention

**1.13. Cardiac glycosides**

more efficiently [39].

**1.15. Flavonoids**

properties [42].

**1.16. Phenols**

**1.14. Cyanogenetic glycosides**

Plant steroids also known as cardiac or steroid glycosides are one of the most naturally occurring plant phytoconstituents that are applied therapeutically as cardiac drugs or arrow poisons [21]. The cardiac glycosides are majorly steroids having a natural ability to exert specific and powerful action on the cardiac muscle mainly when injected into animal or man. Steroids (anabolic steroids) have the ability to promote nitrogen retention in osteoporosis (a disease following menopause in women causing bones to be porous and subjected to fracture) and in animals with wasting illness [36, 23]. Steroids have the ability to exhibit activities such as antifungal, antiviral, antileukemic, hypnotic, antipyretic, and muscle-relaxant activities and are found in large quantities in many plants [44].
