Evaluation of Antioxidant and Cytotoxic Capacity of Croton bonplandianum. Baill 1711
3.2. Brine Shrimp Lethality Test
In the brine shrimp lethality test methanolic extracts was
toxic with an with a LD50 value of 115.76 (0.0048 - 13.76)
µg/ml. Dichloromethane extract was not toxic (Table 2).
4. Discussion
Plants have been mentioned as one of the most important
targets to search for natural antioxidants from the point
of view of safety [10,11]. The activities of antioxidants
have been attributed to various mechanisms including
prevention of chain initiation, decomposition of perox-
ides, radical scavenging and reducing capacity [12]. Con-
sequently, these activities vary with assay methods and a
single assay may be inadequate. It is for this reason that
antioxidant activities of the extracts in this study were
evaluated Phenols and flavonoids represent two phyto-
chemicals whose relative abundance in plant extracts has
been profusely linked to antioxidant activities. Phenols
and flavonoids in extracts may explain their high anti-
oxidant activities [12]. DPPH radical scavenging assay
provides an easy, rapid, and convenient method to evalu-
ate antioxidants and radical scavengers [13]. It is based
on the ability of 1,1-diphenyl-2-picryl-hydrazyl (DPPH),
a stable free radical, to decolorize in the presence of an-
tioxidants. The DPPH radical contains an odd electron,
which is responsible for the absorbance at 515 nm and
also for the visible deep purple colour. When DPPH ac-
cepts an electron donated by an antioxidant compound,
the DPPH is decolorized, and this effect can be quantita-
tively measured from the changes in absorbance [14].
The extracts tested in this study showed DPPH radical
scavenging activities.
Bioactive compounds are often toxic to shrimp larvae.
Hence, in vivo lethality to shrimp larvae can be used as a
rapid and simple preliminary monitor for bioactive com-
pounds during the isolation of natural products. The eggs
of the brine shrimp Artemia salina (Leach) are readily
available as fish food in pet shops. When placed in artifi-
cial sea water, the eggs hatch within 48 hours, providing
large numbers of larvae. These tiny shrimp larvae have
Table 2. Brine shrimp lethality test of extracts.
Extract
code Dose
µg/ml No. of
shrimp No. of
survivors LD 50
µg/ml STD.
Drug LD 50
µg/ml
1000 30 04
100 30 20
CBM
10 30 23
115.76 Etoposide 7.4625
1000 30 16
100 30 19 CBD
10 30 24
1327.85 Etoposide 7.4625
been extensively used as a tool to monitor the cytotoxic-
ity of samples under study. This is a rapid, inexpensive,
in-house, general bioassay which has been developed for
screening, fractionation and monitoring of physiologi-
cally active natural products[9].The methanolic extract
was toxic with LD50 value of 115.76 (0.0048 - 13.76)
µg/ml against Artemia salina when tested in vitro, indi-
cated a possibility that the extract may contain a toxic
compounds.
5. Conclusion
The results of the present study indicate that the extracts
showed significantly different but appreciably potent
antioxidant and cytotoxic activity that cannot be neglec-
ted. These results support the traditional healers claim,
but it could also mean that methanolic extract is poten-
tially toxic, since brine shrimp lethality activity can also
be used as an indicator for toxicity. There is need to test
this compound on cancer cell lines and other tests in or-
der to establish its safety and the possibility of develop-
ing an anticancer agent. The study therefore not only
reveals these as accessible reservoirs of natural antioxi-
dants and cytotoxic compounds, but very importantly,
provides good scientific justification for the isolation of
pure bioactive compounds.
6. Acknowledgements
The authors are grateful to the Pharmacy Department,
Bahauddin Zakariya University Multan, Pakistan. Inter-
national Center of Chemical And Biological Sciences,
University of Karachi is also acknowledged for antioxi-
dant activity and brine shrimp lethality tests.
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