Abstract:
Medicinal plants are exploited by human beings as pharmaceuticals, agrochemicals, and
poisons since ancient times. Ocimum gratissimum is one of these medicinal plants which
belongs to the genus Ocimum and is commonly used in Ethiopia as a traditional medicine to
treat infectious diseases of the upper respiratory tract, bowl, skin, and eye. Thus, in this study,
phytochemical investigation and antimicrobial activity of evaluation of O. gratissimum were
done. The shade dried root of the plant was grinded and extracted by maceration technique
using chloroform/methanol 1:1 (v/v) resulted in 7 g (3.5%) of crude extract. The silica gel
column chromatography of crude extract led to the isolation of three compounds. The
structure of the isolated compounds were elucidated using spectroscopic techniques (1D and
2D NMR). Finally, compound-1 was identified as 7-hydroxy-8-((E)-3-hydroxy-7,8-
diisopropyl-2,9,9-trimethyldec-7-en-2-yl)-3-phenyl-4H-chromen-4-one, compound-2 was
identified as 17-((E)-5-ethyl-6-methylhept-3-en-2-yl)-2,3,4,7,8,9,10, 11,12,13,14,15,16,17-
tetradecahydro-10,13-dimethyl-1H-cyclopenta[α]phenanthren-3-ol ( Stigmasterol), and
compound-3 was identified as icosahydro-9-hydroxy-5a, 5b, 8, 8, 11a-pentamethyl-1-(prop-
1-en-2-yl)-1H-cyclopenta[α]chrysene-3a-carboxylic acid ( Betulinic acid) with melting points
of 160-162, 166-170, 276-277 °C, respectively. The hydro-distillation of the seed and
leaves of the plant were resulted three essential oils (EO-1, EO-2, and EO-3). The oils were
characterized by GC-MS and all of them afforded Benzene-1,2,3-trimethoxy-5-(2-propenyl)-
(Elemicin) 36.12, 16, and 36.08%, respectively as major component. The antimicrobial
activities of the crude extract, isolated compounds, and the essential oils were evaluated
against four bacterial strains (B. cereus, E. coli, S. aureus, S. typhi and) and a fungal strains
C. albicans using disc diffusion method. Generally, the crude extract showed low activity
with inhibition zone 11±0, 11±0, 9.5±3.54, 12±2.5, 10.5±2.12 mm, respectively against all
the tested strains when compared with standard drugs Gentamycin (23±1.41, 22.5±3.53,
22.5±2.12, and 23±1.41 mm, respectively) and Clotrimazole (15.5±0.71 mm). The essential
oil EO-3 showed the highest zone of inhibition 8.5±0.71, 9.25±0.35, 8.5±.71, 9.25±0.35, and
8±1.41 mm, respectively against all the tested strains than the two essential oils. Therefore,
the antimicrobial activity displayed by the plant validates the traditional claims.
