Antioxidant potential and Cancer-specific cytotoxic effect of selected marine microalgal extratcs
Microalgae derived metabolites have shown potential biological activities, especially antioxidant and cytotoxicity. Marine microalgae are often considered as a mother lode of antioxidant and antitumor compounds due to their inhabitants in the harsh marine environment. Despite having valuable and...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2023
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/112947/1/112947.pdf |
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| Summary: | Microalgae derived metabolites have shown potential biological activities,
especially antioxidant and cytotoxicity. Marine microalgae are often considered
as a mother lode of antioxidant and antitumor compounds due to their
inhabitants in the harsh marine environment. Despite having valuable and novel
metabolites, the marine microalgae species are still not thoroughly investigated
for their pharmaceutical and nutraceutical importance. Since cancer treatment
with synthetic drugs shows adverse effects, it is urgent to search for alternative
therapy from this promising marine source. Therefore, this study was focused
to investigate the crude extracts of six marine microalgae species, Chlorella sp.,
Tetraselmis sp., Nannochloropsis sp., Isochrysis sp., Chaetoceros sp., and
Thalassiosira sp., isolated from Malaysian coastal region in terms of their
antioxidant activity and cytotoxicity against human breast cancer cells, MCF-7.
These six marine microalgae are considered safe for human and animal usage
as well as frequently used as fish feed and dietary supplements. Moreover,
microalgae need shorter time, less nutrient and no arable land to grow. These
microalgal species were collected and identified based on morphological and
molecular characteristics. A total of forty-eight crude extracts from six marine
microalgae species were prepared using eight different polarity solvents. From
the antioxidant assays, methanol and ethyl acetate extract of Tetraselmis sp.
exhibited significantly higher (p<0.05) antioxidant activities, revealed through
DPPH (54.41 ± 1.18 mg Trolox Equivalent Antioxidant Capacity or TEAC/g
extract) and ABTS (41.57±0.83 mg TEAC/g extract) radical scavenging
activities, respectively than the rest. Ethyl acetate extract of Tetraselmis sp. also
showed high ferric reducing power (113.46±4.83 mg TEAC/g extract). On the
other hand, ethanol extract of Isochrysis sp. reduced the viability of human
breast cancer, MCF-7 cells to 7.24 ± 0.47% after 72 hours of incubation, at a
concentration of 100 μg/ml. The IC50 (half maximal inhibitory concentration)
value was 13.37 ± 0.59 μg/ml after 24 hours in MCF-7 cells and >100 μg/ml in
non-cancerous human lung fibroblast cells, MRC-5. Ethanol extract of Isochrysis
sp. was further investigated for apoptosis induction in MCF-7 cells. With the
increasing concentration of the extract, a reduction in MCF-7 cell population was
observed. The Annexin V-FITC and propidium iodide staining analysis confirmed
that the mode of cell death is mainly apoptosis. Cell cycle analysis revealed the
accumulation of cells in the sub-G0 phase which suggests induction of apoptosis
and G2/M cycle arrest. RT-qPCR analysis revealed an up-regulation of the
proapoptotic Bax gene and tumor suppressor p53 gene. Metabolite profiling by
Liquid Chromatography/Mass Spectrometry showed the presence of possible
metabolites from fatty acid, sphingolipid, carotenoid, and phenolic classes. In
conclusion, marine microalgae from indigenous sources have shown antioxidant
and cancer-selective cytotoxicity. The data suggest that crude ethanolic extract
from marine Isochrysis sp. has induced apoptosis and cell cycle arrest in human
breast cancer cells, MCF-7, while methanol and ethyl acetate extracts from
marine Tetraselmis sp. have good radical scavenging and ferric reduction
capability. Therefore, indigenous marine Isochrysis sp. and Tetraselmis sp. may
have potential therapeutic value for treating human breast cancer and
nutraceutical use, respectively, which needs further investigation along with
extensive in vivo study. |
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