Effect of Harvesting Time on Phytochemical Profile and Antioxidant Activity of Essential Oil from Citrus medica Leaves

Abstract

Leaves (500 g) of Citrus medica L. harvested at interval of three hours from 7:00 am to 7:00 pm on a day during dry season were separately hydrodistilled for three hours. Oil yields from the leaves ranged from 0.22 - 0.34%. GC and GC-MS analyses revealed the predominance of monoterpenoids (50.5-70.3%) in the oils. The percentage composition of sesquiterpenoids was in the range of 29.7-29.5 %. The principal constituents of the oils were; β-ocimene (4.1–5.6 %), D-limonene (13.5 – 19.8 %), γ-terpinene (10.8 – 17.9 %), linalool (3.8 – 4.0 %), citronellal (2.7 – 7.5 %), terpinen4-ol (1.2 – 8.7 %), citronellol (10.1 – 13.7 %), linalylanthranilate (2.5 – 9.3 %), δ-elemene (3.0 – 6.4 %), α-bergamotene (4.1 – 6.6 %), humulene (1.2 – 2.8 %), β-caryophyllene (7.9 – 16.5 %), β-bisabolene (3.6 – 5.2 %). The oils were of Dlimonene and γ-terpinene chemotypes. Antioxidant activity assay on the oils revealed that they were biochemically active against DPPH radicals. The activity was concentration dependent with the oil from 7 am harvest having the highest activity and lowest EC50. Hence, the plant may be used as an alternative to synthetic antioxidants.