Effect of Initial Temperature Treatment on Phytochemicals and Antioxidant Activity of Azadirachta indica A. Juss.

The present study was undertaken to evaluate the effect of initial temperature treatment on phytochemical and antioxidant potential of commercially important plant Azadirachta indica A. Juss. The leaves were differentially treated after harvest at temperatures 4, -20, and 110 °C and at room temperature, separately. It was found that a quick drying process at 110 °C followed by air-drying helped in maximum retention of bioactive compounds and antioxidant activity, which was significantly higher than other processing methods. Correlation analysis revealed that total phenolic content (TPC) and total flavonoid content (TFC) can be a measure to assess the antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays. Nitric oxide scavenging assay (NOSA) was insignificantly related to DPPH and FRAP. Also, FRAP and DPPH can be a predictive assay for each other, but not with NOSA. Thus, a quick drying process at 110 °C using an oven can be a cost-effective venture, especially in developing countries, for retaining the nutritive value and antioxidant activity of A. indica.