Abstract:
Seaweeds are an important source of bioactive metabolites in drug development
and nutraceuticals. The aim of this study was to investigate the in vitro cytotoxic
activity of de-polysaccharide methanol extract and partition fractions of hexane,
chloroform, ethyl acetate (EtOAc) and aqueous fractions of brown algae
Choonospora minima against human rhabdomyosarcoma (RD) cell line. The
selected fractions and crude methanol extract were subjected for MTT and neutral
red uptake assay to determine the cell viability. Apoptotic morphological features
were observed using crystal violet and fluorescence dye Hoechst staining
methods. The results of both MTT and neutral red assay showed that the decrease
of the percentage of cell viability in dose dependent manner as signified by cell
death. The hexane and chloroform fractions of C.minima showed potential
cytotoxic activity with IC50 of 93.98±1.33 μg/ml and 106.94±1.68 μg/ml against
human rhabdomyosarcoma (RD) cell line compared to the standard
cycloheximide (IC50: 36.17±1.78 μg/ml). In addition, a significant cytotoxic
activity was observed between total crude extract and fractions of C.minima
against RD cell lines (P>0.05). Further, potential cytotoxic activity of hexane
(133.13±4.50 μg/ml) and chloroform (142.09±0.64 μg/ml) fractions of C.minima
was confirmed by neutral red assay compared to the standard cycloheximide
(32.78±0.91μg/ml). Gas chromatography-mass spectrometry analysis of the
hexane fraction revealed the presence of several anti-cancer compounds. In
addition, apoptotic morphological features such as cell membrane blebbing,
formation of membrane bound vesicle, nuclear fragmentation and micro nuclei
formation, cellular shrinkage, cellular aggregation and formation of cell clumps
and chromatin condensation were observed both in hexane and chloroform
fractions of C.minima when stained with crystal violet and florescence dye
Hoechst stain. The results suggest that the hexane fraction of C. minima is a
potential source of natural compounds to combat as anti-cancer therapy. The
research grant (ASP/01/RE/SCI/2017/50) by University of Sri Jayewardenepura
is acknowledged.
