FT-IR Analysis, Phytochemical Content and Antioxidant Activity of Murraya koenigii Leaf Extracts

Murraya koenigii (M. koenigii) which belongs to the family Rutaceae is a medicinal plant that is rich with phytochemicals. Phytochemicals are bioactive compounds that can be used as sources for prevention and treatment of many diseases. This study aims to determine the total phenolic content (TPC), total flavonoid content (TFC), total antioxidant activity (TAA), and characterisation of phytochemicals of the M. koenigii leaves; after applying different drying methods and a variety of solvents for extraction of phytochemicals. Sun-dried, shade-dried, and fresh M. koenigii leaves are employed in the study along with the use of n-hexane, methanol, and distilled water as a solvent for extraction of phytochemicals based on polarity. The maceration method is used for extraction, the Folin-Ciocalteu method for evaluation of total phenolic content, the colorimetric test for total flavonoid content, phosphomolybdate assay for antioxidant activity analysis, and Fourier transform infrared spectroscopy (FT-IR) for determining various functional groups present in these phytochemicals. Phytochemical contents, antioxidant activities and functional groups are compared in different types of leaves as well as different solvents. The results of the study revealed that shade-dried leaves extracted using distilled water and fresh leaves extracted using methanol have high TAA which is 0.371 ± 0.02 µg/mL and 0.375 ± 0.01 µg/mL, respectively. This high antioxidant activity is due to high phenolic and flavonoid content in these samples, 67.03±3.10, 0.75±0.13 (mg GAE/g dry weight) for M. koenigii Shade Dried Water extract (MKShDW) and 112.94±1.03, 0.52±0.08 (mg QE/g Fresh Weight) for M. koenigii Fresh Methanolic extract (MKFrMe), respectively. Thus, these leaves can be used as a good source of natural antioxidants. Various functional groups are observed in the FT-IR analysis of this study such as alkanes, alcohols/phenols, aldehydes, esters, ethers, amines, amides, etc.