Metabolic profile and biological activities of Lavandula stoechas L

Abstract

Medicinal and aromatic plants play a significant role in drug discovery. Lavandula stoechas L. has been used as folk medicine to treat various diseases. The aim of this work is to investigate the phytochemisty of Lavandula stoechas with biological activities. An aerial part of the plant was extracted with methanol. Another sample of plant was boiled in water then aqueous part was extracted with ethyl acetate. Identification and quantification of phenolic compounds, organic acids and flavonoids in methanol extract were carried out by High Performance Liquid Chromatography/Time of Flight/Mass Spectrometry, HPLC-TOF/MS. Rosmarinic acid was found as a chief compound (80.9%). The essential oil was generated by steam distillation and identified by GC-MS. The main constituents were camphor (48.1%) and fenchone (30.5%). The essential oil exhibited good insecticidal activity on Sitophilus granarius and Sitophilus oryzae pests as 43.3% and 62.9% mortality, respectively. However, the methanol extract has only insecticidal activity against S. granaries (50.0%). The antioxidant activities were investigated using assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging, reducing power (FRAP), and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS•+) radical scavenging on both extracts. In addition, total phenolic contents were determined. Total phenolic content of EtOAc extract was found as 2.18 g GAE (Gallic acid equivalent) phenolic compounds/kg plant. Whereas, total phenolic of methanol was 3.33 g GAE/kg plant. EtOAc extract revealed the considerable DPPH• scavenging, ABTS•+ scavenging and reducing power activities with the values of 28.71 (IC50, µg/ml), 8.72 (IC50, µg/ml) and 6.99 (µmol trolox equivalent/mg extract) respectively.

Keywords: Chemical constituents; Lavandula stoechas.; antioxidant activity; essential oil components; insecticidal activity.