STUDIES OF ESSENTIAL OILS OF PLANT FAMILY UMBELLIFERAE

Abstract

Essential oils are complex mixtures of biological active substances which have numerous applications in the field of food industry, medicine, agriculture and pesticides as they are safe to use as compared to synthetic chemicals having no harmful effect on human health and environment. In the present investigation, essential oils of some indigineous species of plant family Umbelliferae were selected for evaluation of their chemical composition and biological activities. Essential oils were extracted from the seeds of Trachyspermum ammi (L) Sprague, Carum roxburghianum, Daucus carota, Cuminum cyminum Linn., Bunium periscum Bioss, Anethum graveolens L. and Pimpinella acuminata (Edgew) C.B.Clarke. All the volatile oils were obtained by hydrodistillation and characterized by GC-MS. Yield and physico-chemical parameters of the essential oils were also determined using standard methods. Anti-bacterial activity of the essential oils was assayed against gram-positive and gram-negative bacteria by using agar disc-diffusion method and determination of minimum bactericidal concentration (MBC) was carried out by broth macro-dilution method. Inhibition zone diameters ranged from 6.0 to 33.6mm and MBC values ranged from 0.25% to above 4% for the various essential oils. The oils of T.ammi, B.periscum and C.cyminum exhibited significant bactericidal activity against Staphylococcus aureus, Escherichia coli, Serratia marcescens, Klebsiella pneumoniae and Enterococus faecalis while the essential oils of C.roxburghianum and D.carota were active against gram-positive bacteria only. Antioxidant activity of the essential oils was examined using various assays and their efficiency was found to be in the order: T.ammi > C.cyminum > B.periscum > D.carota > C.roxburghianum ixAbstract The antioxidant activities of the selected essential oil components were also examined. Thymol, p-cumenol and gamma-terpinene proved to be the excellent free-radical scavengers followed by S-(+)-carvone, R-(-)-carvone and 4-methoxy cumene whereas cuminal, cuminyl alcohol and p-cymene showed weak activity. Cuminal, R-(-)-carvone, gamma-terpinene and cuminyl alcohol exhibited superior metal chelating activity while p-cumenol and 4-methoxycumene showed weak activity. The essential oils were also tested for their insecticidal activity against Periplaneta Americana. 5% solutions of the essential oils of B.periscum, C.cyminum and T.ammi showed contact toxicity and 100% mortality occurred in the first three hours. The essential oils of C.roxburghianum and D.carota exhibited weak insecticidal activity. In fumigant toxicity assay, 100% mortality occurred after six hours in case of the essential oils of B.periscum and C.cyminum. The essential oils were also tested for insecticidal activity against Musca domestica L (House Fly) and Tribolium castanum. The essential oils from T.ammi, B.periscum and C.cyminum had shown highiest toxicity against both insects while other has mild to moderate insecticidal activity.