Abstract:
The aim of this study is to extract volatile oil from Ocimum basilicum L. and determine the chemical components of two species of Ocimum basilicum L. (Rehan). It also aimed at preparing cream using gum Arabic and basil oil and tests its effectiveness as a mosquito repellant {at different percentages of the extract}. The essential oil was extracted from dry leaves of these two species using a hydro-distillation modified Clevenger type apparatus.
O. basilicum L. purple gave a 1.5% yield of essential oil while O. basilicum L. green gave a 0.8% yield of essential oil. The chemical composition of the two sweet basil (Ocimum basilicum L.) cultivars were investigated by GC-MS. Thirty nine compounds were identified in the essential oil of O. basilicum L. purple. The main components found in the oil were Linalool (30.10%), methyl eugenol (20.56%), geraniol (11.35%), methyl cinnamate (10.01%), 1,8-cineole (6.55%), E-bergamoten (3.72%), amophrene (2.35%).2-propenoic acid (1.47%), camphor (1.01%), m-Xylene (1.15%), alph-terpineol (1.15%), Z-Ocimene (0.84 %), germacrene (0.78%), borneol (0.76%). The essential oil from O. basilicum L. green was composed of thirty three constituents. Methylcinnamate (35.21%), linalool (16.38%), methyl eugenol (12.87%), methyl chavicol (9.3), 1,8-cineole (4.92%), 2-propenoic acid (3.95%), E-bergamoten (2.88%), eugenol (2.95%), tau-cadinol (1.56%), m-xylene (1.15%) camphor (1.10%), Z-Ocimene (0.85 %), fenchyl alcohol (0.80%) were identified as the major components.
Some of the physicochemical properties of the extracted essential oil such as colour: (pale yellow for both types), odour: (O. basilicum L. green has a strong fragrance), moisture: (20%), refractive index: (1.5, viscosity is 3.2 for both), total acid number (4.4 for O. basilicum L. green and 2.9 for O. basilicum L. purple), iodine number: (38.07 for O. basilicum L. green and 31.73 for O. basilicum L. purple), saponification value: (137.4 for O. basilicum L. green and 109.4 for O. basilicum L. purple) were determined.
The extracted oil was used with Acacia senegal to make an emulsion which was formulated into a mosquito repellent cream.
The repellent cream showed 99% repellency at 10% from oil extracted. The repellency percentage showed 85% repellency at 5% from oil extracted.
