bioactive compounds in vitro in C. gigantea acts as
an antibacterial against many bacteria such as B.
cereus, B. subtilis, E. coli, K. pneumonia, S. aureus,
S typhii, Micrococcus luteus in all alkaloid extracts,
cardiac glycosides, tannins, saponins, flavonoids,
steroids, terpenoids sugar and resins (Seniya et al.,
2011). C. gigantea latex extract shown very good
fungicidal effects thus indicating that latex can be a
useful source for the development of new antifungal
agents against pathogenic fungi (Saratha &
Subramanian, 2010). Thus, the researcher were
interested in conducting an antibacterial activity test
from the methanol extract of Calotropis gigantea
flowers originating from Aceh against gram-positive
bacteria Staphylocccus aureus and gram-negative
bacteria Escherichia coli.
2 METHODS
2.1 Collection of C. gigantea Flowers
Calotropis gigantea flowers was collected from
Kayee Jatoe Cubo village dengan ketinggian 150 m
diatas permukaan laut, Kecamatan Bandar Baru,
Kabupaten Pidie Jaya during October 2017. The
plant was identified in the Herbarium Laboratory,
Department of Biology, Faculty of Mathematics and
Natural Sciences, Syiah Kuala University (Reg. No
of the certificate: No. 943/UN11.1.28.1/DT/2017).
The collected plant parts (flowers) were separated
from undesirable materials. The flowers were dried
in open air under shade for one week.
2.2 Tools and Materials
The tools used for this study were autoclave,
incubator, refrigerator, analytic scale, blender,
vacuum rotary evaporator (Heidolph), vortex,
spectrophotometer, ruler, petri dishes, test plates,
glass ware, micropipets, swab, scissor, label paper
and gloves.
The materials used in this study were methanol,
Calotropis gigantea flowers, gram positive bacteria
(Staphylocccus aureus) and gram negative bacteria
(Escherichia coli) obtained from the Aceh
Provincial Health Laboratory, blank discs, ampicillin
and chloramphenicol discs, 96% alcohol, aluminum
foil, Wagner, Mayer, and Dragendorf reagent,
magnesium powder, chloroform, sulfuric acid,
Lieberman-Burchard reagent, sterile aquadest,
Nutrient Agar (NA), Muller Hinton Agar (MHA)
media, sterile stick cotton.
2.3 Extraction Procedure
Calotropis gigantea flowers which have been dried
as much as 2 kg are smoothed into a blender until
they become powder then macerated with methanol
for 3x24 hours. The maserate obtained was
concentrated with a vacuum rotary evaporator at a
temperature of 50-60
0
C until a concentrated extract
was obtained. Calotropis gigantea flowers extract
100% pure diluted in various concentrations,
namely: 10, 25, 50, 75 and 100%.
2.4 Phytochemical Analysis
The fresh flowers and concentrated methanol
extracts have been conducted a phytochemical test
as Harborne phytochemical method to see whether
they contain secondary metabolites (Table 1)
(Harborne, 2006).
2.5 Antibacterial Activity Test
Antibacterial activity test was carried out by Kirby-
Bauer disc diffusion method. This test uses Muller
Hinton Agar (MHA) media with a depth of 4 mm
(25 ml of MHA media for 100 mm petri dishes and
60 ml for 150 mm petri dishes) (Hood et al., 2010).
The bacterial suspension that will be used for
antibacterial power tests is measured in density
using a spectrophotometer (λ = 625 nm and
absorbance 0.08 - 0.13) to obtain the bacterial
density standard at 1-2 x 10
8
CFU/ml as stated by
European Committee on Antimicrobial
Susceptibility Testing (Kahlmeter, 2006).
Then the
bacteria were inoculated into the MHA media by
dipping sterile stick cotton into the inoculum and
then rubbing it on the entire surface of the MHA
media three times by rotating the cup at an angle of
60
0
C after each application so that the flat media
surface was filled with bacterial suspension. Control
discs, antibiotic discs (ampicillin or
chloramphenicol) and discs containing various
concentrations of samples were placed on the
inoculation media using sterile tweezers and pressed
slowly and incubated at 37
0
C for 24 hours. After
incubation, the diameter of the inhibitory zone in the
form of clear zone is measured using a ruler in
millimeters (mm) and compared with the inhibition
power classification (Morales et al., 2003).