Correlation between Anti-oxidant property and Total phenolic and flavonoid content of Azadirachta Indica A Juss Flowers

Plants are the source of potential secondary metabolites which are the reasons for the antioxidant activity. Neem flowers also having higher amounts of antioxidants and phenolic substances [1]. We have investigated the antioxidant activity of shade dried neem flower powder extracts by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, phospomolybdenum assay, and ferric reducing antioxidant power assay (FRAP) methods respectively [2]. The antioxidant activity of different extracts of neem flower powder has been investigated and among them 80% hydroalcoholic extract displayed the highest scavenging activity with the IC50 value of 18 mg/L in phospomolybdenum assay, 29 mg/L in DPPH, 30 mg/L in FRAP assay. Whereas petroleum ether extract shows lowest antioxidant potential amongst the three extracts with the IC50­ value of 76 mg/L in FRAP, 37 mg/L DPPH, 28 mg/L in phospomolybdenum assay (Table 1). On examining the total Phenolic and flavonoid content of different extracts the 80% hydroalcoholic extract possesses the greatest phenolic content about 83.88 mg/L followed by methanol, acetone and petroleum ether about 62.05, 7.52, 3.56 mg/L respectively. The highest flavonoid content of 57.36 mg/L in 80% hydroalcoholic extract followed by methanol, acetone and petroleum ether about 20.56, 11.25, 1.56 mg/L respectively (Table 2) [3]. The order of total phenolic and flavonoid content of different extracts are found to be as; 80% hydroalcoholic > methanol > acetone > pet. ether respectively. The correlation between the antioxidant and total phenolic content, total flavonoid content was calculated using Prism Pad software and observed at 95% confidence interval level (Fig 1a & 1b). From the correlation graph, it is observed that there is a good correlation between antioxidant, total phenolic content (phospomolybdenum assay, R2 – 0.702) and total flavonoid content (DPPH assay, R2 – 0.665) and it is possible to suggest that total phenolic and flavonoid content of the plant extracts are the main reason for the antioxidant activity [4].