COMPARATIVE PHYTOCHEMICAL AND ANTIOXIDANT ANALYSIS OF AQUEOUS/METHANOL LEAF EXTRACTS OF THREE SPECIES OF LAVENDER /
JOY ENEMONA ONUH ; SUPERVISOR, ASST. PROF. DR. EMMANUEL MSHELIA HALILU
- 109 sheets; 30 cm +1 CD ROM
Thesis (MSc) - Cyprus International University. Institute of Graduate Studies and Research Pharmacognosy
Lavender belongs to the lamiaceae family and consists of 47 known species. These species are characterized by their distinct aroma and have been utilized for their therapeutic properties. The study was aimed to comparatively investigate the botanical, physicochemical, phytochemical and antioxidant properties of Lavandula dentata, Lavandula stoechas and Lavandula angustifolia. The various plant extracts were obtained by maceration in 80% methanol and water, and further screened for the presence of some secondary metabolites using standard procedures. The total phenolic and total flavonoid contents were estimated using Folin-Ciocalteu reagent and AlCl3 assays respectively. The essential oil was extracted using the Clevenger apparatus and the constituent terpenoids were analyzed using GC-MS. The antioxidant activity of the extracts and the essential oils was assayed using DPPH free radical. Macroscopically, the three plant species were characteristically different on the basis of leaves amongst others. Microscopically, trichomes and stoma of various forms were observed from the upper and lower epidermis. The moisture content, total and acid insoluble ash values, hexane, alcohol and water soluble extractive value of the three species were found to be within the acceptable limit. The % yield of the crude methanol extracts for Lavandula dentata, Lavandula stoechas and Lavandula angustifolia are 26%, 31.6% and 27.8%, the % yield of the water extracts were: 17.6%, 22.3%, 15.1% and the % yield of the essential oils were: 5.17%, 2.16%, and 5.06% respectively as in the above order. The phytochemical analysis revealed saponins, phenolic groups, tannins, flavonoids, alkaloids, cardiac glycosides, steroids and triterpenoids. The total phenolic contents ranged between 0.1010-0.2483 mg GAE/g for all the test samples. The total flavonoids ranged between 0.0810-0.1929 mg QE/g. The GC-MS analysis of the essential oils revealed β-pinene, 1,8-cineole, fenchone, camphor, α-terpineol and sabinene. The antioxidant activity was expressed in terms of IC50 and on this, the Lavandula dentata water extract had the highest activity with IC50 of 4.065 mg/mL and the activity was found to be better than ascorbic acid with IC50 66.35 mg/mL. The overall results showed that Lavender species contains phytochemicals with antioxidants activities which justifies their usage in traditional medicine for the prevention and treatment of diseases whose causes are associated with free radicals.