Living cells are known to generate free radicals reactive oxygen species (ROS) through physiological and biochemical processes in the body system [1–3]. Free radicals such as OH-, O2
.-, .NO-, RO2
- and LOO- are products of normal metabolic processes in the human body. It is true that the body can handle free radicals, but if these radical productions become excessive, it could cause cell wall and DNA damage, leading to chronic diseases like cancers and cardiovascular disease [1–3].
Dietary antioxidant from food intake, such as vitamin E, selenium and polyphenols like green tea has been reported to decrease the adverse effects of free radicals . They act as scavengers by donating one of their own electrons in order to replace the stolen electron from free radicals .
Several standard established antioxidant drugs such as butylhydroxytoluene (BHT) and rutin have been reported to be toxic to living cells [5–7]. Rutin drugs also known as quercetin rutinoside is a glycoside of the bioflavonoids used in many countries, including South Africa as medications for the treatment of inflammatory disorders, allergies and viruses . However, specific carcinogenic toxicity has been observed . These include swelling of the throat, tongue, lips or face, chest pain, skin rash etc. BHT drugs, are known to be the most prevalent and approved antioxidant scavengers worldwide, have equally been reported to be toxic to the lungs, even at a lower concentration [5–7].
In recent years, there has been an increasing interest in finding natural antioxidants from medicinal plants . Plants are endowed with free radical scavenging molecules, such as vitamins, terpenoids, phenolic acids, tannins, flavonoids, alkaloids, and other metabolites, which are rich in antioxidant and free radical scavenging properties . In addition, the ingestion of natural antioxidants has shown to enhance the immune defence, reduce risks of cancer, cardiovascular disease, diabetes, and other diseases associated with ageing [12, 13].
Carpobrotus edulis (L.) Bolus (Mesembryanthemaceae), also known as igcukuma in Xhosa communities, is an edible easily grown groundcover plant that is widespread in the Eastern Cape of South Africa. It flourishes on sandy soil with thick greenish succulent leaves reaching about 10.8 cm in length. This plant is used by the traditional healers in the above mentioned province to treat tuberculosis, diabetes mellitus, sores, high blood pressure, intestinal worms and constipation. It is possible that this plant may contain some bioactive secondary metabolites that work against opportunistic infections .
The antioxidant action of polyphenol compounds depends on their free radical scavenging capacity and its ability to reduce iron . The total polyphenol amounts determined from plant and their corresponding antioxidant activity may vary widely, depending on the extraction solvents applied. For example, aqueous and acetone showed the highest efficiency for extraction of phenols among the various solvents used . Olubunmi and Anthony , reported that acetone on its own has the capability of extracting both the polar and non-polar compounds from plant samples. Similarly, Brenes et al.  reported that the use of acetone extraction solvent resulted in a complete extraction of phenols from olive oils, when compared with other solvent extracts. Methanol extracts however showed the highest antioxidant activities in seabuckthorn seeds when compared with chloroform and ethyl acetate solvent . Recently, we compared the polyphenol content from various solvents (aqueous, ethanol, acetone and hexane) extract of C. edulis leaf. Aqueous and ethanol were found to be the best solvents for antioxidant activity .
Limited information exists on antioxidant activity of Carpobrotus edulis (L) Bolus. Hanen et al.  examined the phytochemical properties of methanolic extracts using different plant parts including the leaf of C. edulis but no findings are recorded for the antioxidant activity of the aqueous, ethanol, acetone and hexane extracts considering that successful isolation of bio-compounds from plant material is largely dependent on the type of solvent used in the extraction procedure . Therefore, the aim of this study were (1) to determine the quantitative phytochemical present in various extraction solvents of varying polarities, (2), to determine their antioxidant activities in comparison to the established standard drugs in order to justify its therapeutic usage.