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Int. J. of Marine Science 2012, Vol.2, No.6, 43
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44
positive bacteria such as
B. subtilis
and
S. aureus
(Caiferi et al., 1998). The
Latrunculia brevis
and
Prianos
sp. were contained potent antibacterial
Discorhabdin D which was chemically characterized
as pyrrolophenanthroline alkaloid (Ford and Capon,
2000). Extracts made from
Sigmoceptrella
sp.
collected as by catch during traveling operation in the
Great Australian Bay sent has inhibitory against many
bacteria (Ovenden and Capon, 1999). The bioactive
compound Arenosclerins A-C derived from the sponge
Arenosclero
brasiliensis
was very effective against
12 antibiotic resistant bacteria isolated from a hospital
(Torres et al., 2002). Sipkema et al (2005) reviewed
the various bioactive potential present in the marine
sponges.
The potency of sponge derived medicines lies in the
fact that each of these thousands of metabolites and
their derivatives has its own specific dose related
inhibitory effect, efficacy and potential (diminished)
side effect that determine its suitability for medicinal
use. Leone et al (2008) has isolated Exiguaquinol
from the sponge
Neopetrosia exigua
and this was
found to inhibit the bacterial enzymes
Helicobacter
pylori
(Glutamate racemase that inter converts
L-glucose and D-glucose) needed for the construction
of bacterial cell walls. A cytotoxic and antibacterial
bromophenol was isolated from a sponge
Dysidea
sp.
(Zhang et al., 2008). The sponge
Suberea mollis
was
found to contain the moderately antibacterial
Subereaphenol A (Shaala et al., 2008). Halicyclamine
A isolated from the sponge
Haliclona
sp. inhibited the
inosine
-
5
′
-
dehydrogenase (IMPDH) and anti-
Mycobacterium tuberculosis
activity (Blunt et al.,
2010).
In India, Gulf of Mannar region is a rich bed for
valuable marine sponges. As marine sponges open
new avenues to develop novel drugs, a preliminary
screening was made on the available sponges, hitherto
unstudied for their bio-medical potential. In this
direction the sponges available from Gulf of Mannar
coast were collected and from this collection four
species of sponges with good antimicrobial response
were further chosen to select the best species for an
in-depth study.
2 Results and Discussion
In the preliminary screening, 12 species of sponges
were tested for antimicrobial activities. Of the 12 species
of sponge tested, the extracts of four species were
chosen for further study. Both ethyl acetate and
methanol extracts of the sponges were tested. Of the
two solvents used, the extracts of ethyl acetate
exhibited more antimicrobial activity than methanol
(see Supplementary data, Table 1, 2). Hence ethyl
acetate extracts were used further. Based on the
antimicrobial activity, 4 species of sponges (TCN-8
and TCN-10) were selected for further study.
The results of the microbial assays for the crude
extracts of 12 sponges are presented in Table 2 and
Table 3.
As can be seen from the results, several of the extracts
assayed showed a good antibacterial activity
especially against
E. coli
(NCIM 2065),
P. aeruginosa
(NCIM 5031),
B. subtilis
(NCIM 2063) and
S. aureus
(NCIM 2079)
.
When compared to methanol extract,
the ethyl acetate extracts of all the sponges showed a
high antibacterial activity. Both Gram positive and
Gram negative bacteria were sensitive to the crude
extracts. Fungi especially
S. cerevisiae
(NCIM 3054)
and
A. niger
(NCIM 501) are more resistant than
C.
albicans
(NCIM 3102) (Table 4).
Of the ethyl acetate and methanol extracts of twelve
sponges tested, the methonolic extracts of the sponge
S. inconstans
var.
moeandrina
,
and
A. globostellata
were highly sensitive to all the microbes tested
(Figure 1). The three sponges belonged to the species
S. inconstans
were good antimicrobial agents among
this other species. Although these species were
collected from two different locations, they showed a
good antibacterial activity. Hence
S. incontans
var.
moendrina
Dendy was selected for in depth study and
compound isolation (Figure 2). To extract the
antimicrobial bioactive principles from the sponges,
ethyl acetate was found to be good solvent than
methanol. Ethel acetate was found to be good solvent
that methanol. Ethyl acetate extract of
S. inconstans
var.
moendrina
Dendy
inhibited growth of the bacteria
S. abony
effectively (19.66±0.88 mm) when compared
to the inhibitory role of all the other extracts.