Antioxidants and antioxidant activity common eight banana varieties in Kerala

The objective of this research were to study antioxidants and antioxidant compounds from selected eight varieties of banana and the antioxidant activity were analysed using two methods such as total antioxidant activity and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity using different solvents such as petroleum ether, methanol and water. In the present study revealed that variety Red banana showed highest β carotene and (8.53 μg/100g). Ascorbic acid content of banana varieties ranged between 1.52 5.35 mg/100g. Highest ascorbic acid content was noticed in Red banana (5.35 mg). Highest dopamine content was exhibited in variety Robusta (13.3 mg/100g) and lowest was found in variety Rasakadali (3.2mg/100g). The total antioxidant activity revealed that variety Robusta had the highest DPPH activity with an IC50 value of 43.6 μg/ ml in petroleum ether solvent. With regard to total antioxidant activity, variety Padatti exhibited highest activity with an IC50 value of 41.2 μg/ ml in petroleum ether while variety Rasakadali (48.4) and Poovan (48.4) showed maximum activity in methanol followed by variety Red banana with an IC50 value of 44.4 μg/ ml in methanol. Keywords— Antioxidants, Antioxidant activity, β carotene, Ascorbic acid, Dopamine, Total Antioxidant Activity, DPPH Radical Scavenging Activity.


INTRODUCTION
are of the opinion that diets rich in fruits and vegetables are associated with lower incidence of disease risks, including cardiovascular and cancer. They also argue that processing or cooking can enhance the health promoting effects of fruits and vegetables. Now a day's consumption of fruits has been increased due to its nutritional and therapeutic effects on the human health due to the presence of phytochemicals and antioxidants. Studies evidence revealed that a healthy eating habit with increased consumption of fruits plays an important role in the prevention of chronic diseases, such as heart diseases, cancer, stroke, diabetes, Alzheimer's diseases and cataract (Willett, 2002;Wright et al., 2008 ). Free radicals are involved in both the process of aging and the development of cancer. To deal with the free radicals, the body equipped with an effective defense system which includes various enzymes and high and low molecular weight antioxidants. The best sources of antioxidants are fruits and vegetables. The consumption of fruits and vegetables has been inversely associated with morbidity and mortality from degenerative diseases (Terry et al., 2001). Aurore et al. (2009) reported that banana, an herbaceous climacteric fruit, represents one of the most significant fruit crop in world export trade after coffee, cereals, sugar and cocoa and is one of the most important fruit crops grown throughout Kerala (Shanmughavelu et al., 1992). Bananas are one of the most popular food in the world contain various antioxidant compounds such as gallocatechin and dopamine which protects the body against the ill effects of free radicals. Since banana fruits are widely available, they have been used as food without apparent toxic effect. Hence, the present study is an evaluation of antioxidants and antioxidant activity present in eight selected banana varieties available in Kerala. Eight ripe banana varieties used for table purpose were selected for the study. The varieties selected were Palayankodan (AAB), Rasakadali (AB), Robusta (AAA), Poovan (AAB), Nendran (AAB), Kadali (AA), Red banana (AAA), Padatti (AAB). The banana varieties were procured at the time when the characteristic fruit colour developed for each type. They were collected from Instructional Farm, Vellayani and local markets of Trivandrum. To assess the antioxidants and antioxidant activity of banana varieties such asβ carotene,ascorbic acid, dopamine, total antioxidant activity, DPPH radical scavenging activity wereanalysed. β carotene Method suggested by Sadasivam and Manickam (2008) was used for the estimation of β carotene. Ascorbic acid Ascorbic acid was estimated titrimetrically using 2, 6 dichloro indophenol dye (Ranganna, 2001). Dopamine Dopamine was estimated spectrophotometrically using the method suggested by (Li et al., 2009) using dopamine hydrochloride as standard.

Total Antioxidant Activity
The total antioxidant activity was determined through phosphomolybdate method (Buratti et al., 2001). The banana extract was dissolved in phosphomolybdate reagent and incubated in water bath for 90 min. It was allowed to cool and absorbance was measured at 765 nm against the blank.

DPPH Radical ScavengingActivity
Determination of 1,1-diphenyl-2-picrylhydtazyl was carried out using the method described by Ribeiro et al. (2008). The percentage inhibition of DPPH radical was calculated by comparing the result of the test with control (methanol and 1ml DPPH) using the formula (Schlesier et al., 2002).

Percentage inhibition = (Absorbance of control -Absorbance of test) + 100
In the present study, antioxidant activity of banana varieties was studied by the total antioxidant activity and DPPH assay in different solvents such as petroleum ether, methanol and water.

STATISTICAL ANALYSIS
All the analyses were done in triplicates. In order to obtain suitable interpretation the generated data was subjected to statistical analysis like One-way Analysis of Variance (ANOVA) at 0.05% significant level and graphical interpretation of analyzed data was also adopted. Ascorbic acid, a water soluble vitamin protects the body from ill effects of free radicals (Elekofehinti and Kade, 2012). Fresh fruits, vegetables and synthetic tablets supplement the ascorbic acid requirement of the body (Frei and Traber, 2004). However, stress, smoking, infections and burns deplete the ascorbic acid reserves in the body.

III. RESULTS AND DISCUSSION
The ascorbic acid content of the banana varieties was observed to range between 1.52 -5.35 mg/100g. The highest ascorbic acid was observed in variety Red banana (5.35 mg) and the lowest for variety Robusta (1.52 mg) (    ISSN: 2349-6495(P) | 2456-1908(O) www.ijaers.com Page | 121 The concentration of sample that could scavenge 50% free radical (IC50) was used to determine antioxidant capacity of sample compared to standard. The varieties having lowest IC50 had the highest antioxidant capacity. According to Blois (1992), "sample that had IC50<50 ppm, was consider as very strong antioxidant, 50-100 ppm strong antioxidant, 101-150 ppm medium antioxidant, while weak antioxidant with IC50>150 ppm". activity in the range of 6.60 µmol g -1 compared to other varieties of banana pulp, whereas ethanolic extract of poovan banana showed least activity in the range of 3.80 µmol g -1 .
The variations in the antioxidant potential reported by various authors can be attributed to differences in cultivars, extraction procedures, geographical location and prevailing conditions such as soil, temperature, sunlight, horticulture practices and so on (Kim et al., 2001). In the present study, free radical scavenging capacity of banana varieties were studied by the DPPH assay in different solvents such as petroleum ether, methanol and water. Table 3 illustrates the results of DPPH activity of the banana varieties. The IC50 value was calculated from the graph (it was noted as the concentration of sample needed to scavenge the free radicals at 50 per cent inhibition).

IV. CONCLUSION
The present study highlighted that selected banana varieties serves as a natural store of various health beneficial antioxidant compounds. Antioxidant activity and antioxidant capacity of different selected banana varieties determined by different methods its indicated that banana is rich in various health beneficial various bioactive compounds such as ascorbic acid, beta carotene, dopamine, having potent antioxidant activities and free radical scavenging activity. Banana is cheaper in prize and easily available so that everyone can include their daily diet. This antioxidant compounds and antioxidant activity synergistically act to reduce the risk of degenerative