Oxidatively modified DNA also play vital
aspect in human carcinogenesis. Many nutritional factors are widely considered
to be critical for human health. Among them, free radicals have been of concern
as one of the factors contributing to chronic degenerative disease (O. Patthamakanokporn
et al., 2008). Antioxidants defend fats and lipids in food and act through
reaction with free radicals. The first step in the oxidative deterioration is
the formation of free radical from lipids. Other antioxidants in food which
reduce the capacity of the food to which they were delivered. Oxidation
reaction has deleterious effect on the antioxidant activity where this
oxidation level is influenced by temperature, light, air, physicochemical as
well as the presence of catalyst (Frankel & Meyer, 2000).

Phenolic compounds are one of the natural
antioxidants and the most generous antioxidants in human eating regimen. The
contribution of the fruits’ flavours are one of the role of the phenolic
compounds. As we know, fruits rich in antioxidants, which include vitamin C,
vitamin E, and b-carotene. Phenolic compounds can be determined in both edible
and inedible plants. The genetic and environmental factors affect the phenolic
content produce. The recovery of polyphenols from plant materials was
influenced by the solubility of the phenolic compounds in the solvent used for
the extraction process (Rodríguez-Carpena et al. 2011). This showed that the solvent
polarity will play a key role in increasing phenolic solubility (Naczk and
Shahidi 2006). As to analyse the phenolic content inside the banana peel
extracts, we will use the Folin-Ciocalteu’s colorimetric (FC) method. The ultraviolet–
visible spectrophotometer were chosen as a device to identify the phenolic
contents for qualitative identification.

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One of the antioxidants, gallocatechin was
identified in the banana. By using HPLC, the gallocatechin was separated from
the banana peel extract, which showed strong antioxidant activity.
Gallocatechin was more abundant in peel (158 mg/100 g dry wt.) than in pulp
(29.6 mg/100 g dry wt.). The antioxidant activity of the banana peel extract,
against lipid autoxidation, was higher than the banana pulp extract. The better
antioxidant effects have the higher gallocetachin content. Antioxidants are
rich in fruits and vegetables, nuts, grains, some meats and fish. Combination
of vitamin C with other antioxidants, such as vitamin E, b-carotene, and
selenium, provides a synergistic antihypertensive effect. Experimental
evidences prove that antioxidants can shield human body from free radicals and
reactive oxygen species (ROS) effects. Antioxidants is substance that can avoid
or slow the oxidative damage process toward our body. Besides, antioxidant also
protect the cells from the damage that may cause by free radicals. Free radicals
are unstable molecules or highly reactive chemical that often contains oxygen
and being produced during oxidation. The defensive effect of natural
antioxidant in fruit and vegetable are related to its major group, which are
vitamin, phenolic and carotenoid. Ascorbic acid and phenolic and are known as
the hydrophilic antioxidant while carotenoid was known as lipophilic
antioxidant (Halliwell., 1996). Free radicals can damage important cellular
molecules such as DNA or lipids or other parts of the cell and may lead to
cancer. Banana peel also demonstrated the presence of various phenolic
compounds such as gallocatechin and anthocyanins like peonidin and malvidin.
Phenolic compounds were the secondary metabolites, which being associated with
flavour and colour characteristics of the fruits and vegetables and gaining
considerable attention because of their potent antioxidant and health promoting
properties (Kaur & Kapoor, 2001).

The extraction method employed, types of
solvent polarity used, storage time, presence of interfering substances, sample
particle sizes, conditions and also the chemical nature are some factors may be
influenced the extraction of phenolic compounds in plants. The oxidation
process will produce unpleasant flavours and odors, so the natural antioxidants
from the plant or animal sources will delayed it as they are retard oxidative
rancidity of oil, fats and fat soluble elements. Antioxidants are present
naturally in most raw food sources. The degradation of this antioxidant will
triggered from the processing of the fruits. Nowadays, the most commonly used
antioxidant were synthetic antioxidant including butylated hydroxyanisole
(BHA), butylated hydroxytoluene (BHT), propyl
gallate (PG) and tertiary butylhydroxyanisole (TBHQ).Ascorbic acid or Vitamin C is also another
abundant of antioxidant in nature. This organic acid which is water-soluble
compound that have antioxidants properties. FDA have been generally recognized
it as secure substances. As a potent antioxidant, ascorbic acid has the
capacity to eliminate several different reactive oxygen species, keeps the
membrane-bound antioxidant a-tocopherol in the reduced state, acts as a
cofactor maintaining the activity of a number of enzymes (by keeping metal ions
in the reduced state), appears to be the substrate for oxalate and tartrate
biosynthesis and has a role in stress resistance (Y. Hernández et al., 2006). The
determination of vitamin C have been practised by using several analytical
methods such as titrimetry, spectrometry and amperometry. Most of these methods
may give overtimes due to the oxidizable species present other than AA. High
performance liquid chromatography (HPLC) is the tool used to identify the
composition of ascorbic acid. This ascorbic acid will act as anticancer agent.
It manipulates to protect the DNA from inside of the cells, the hereditary
material in cells from the damage caused by free radicals. It can also reduce
the development of nitrosamines from nitrates. Nitrates chemicals that are
commonly used for foods processing. Once formed, nitrosamine can become
carcinogenic which can cause cancer. The loss of ascorbic acid was also found
to be the highest in the medicinal plant dried at 50oC for 9 hours
(75.60%) compared to freeze drying (21.13%) (Mahanom et al. 1999). This
statement proved that the processing method influenced the amount of ascorbic
acid present in the fruits.