Anticancer activity of marine endophytic fungal extracts from Malaysian seaweeds against hepG2 cells / Harmayumi Wahid

Marine endophytes fungi are known to be the important resource of bioactive
metabolites in drug development for the pharmaceutical industry. This bioactive has
the potential to treat diseases such as cancer, as an alternative to synthetic drug use in
chemotherapy. This study aims to determine the potent cytotoxicity of five marine
endophytic fungal extracts coded as (CN, MV, ED, CS, and UF) isolated from
seaweed; Gracilaria coronopifolia, Gracilaria arcuata Zanardini, Acanthophora
picifera (M.Vahl) Borgesen, Caulerpa sertularioides, and Chaemotorpha minima
respectively, against human hepatocellular carcinoma cells (HepG2) and normal
human liver cells (Chang), and evaluate their potential to induce apoptosis and
antioxidant activity. All five marine endophytic fungi were grown in different salinity
(1% and 3%) of artificial sea salt (ASS) potatoes dextrose agar (PDA). Initial
cytotoxicity screening showed that 2 out of 10 marine endophytic fungal extracts (CN
1% and MV 1%) showed potential cytotoxic effect against HepG2 at 24, 48, and 72
hours incubation time with IC50 values detected for CN 1% (35.2 – 53.3 μg/ml) and
MV 1% (41.8 – 50.0 μg/ml), which are <60 μg/ml. Both extracts were determined as
non-toxic effect to Chang (IC50 value > 60 μg/ml). Further with cytotoxic quick
screening after fractionation, CN 1% and MV 1% itself displayed higher cytotoxicity
effect against HepG2 (35.5 % and 37.4 % respectively) compared to 10 selective
fractions at concentration 20 μg/ml (concentration based on National Cancer Institute
guidelines). Moreover, the morphological studies indicated that CN 1% and MV 1%
induced apoptosis with apoptosis features such as membrane loss, condensation of cell
nuclei, nuclear fragmentation, and apoptotic body formation. Furthermore, the
Annexin-V assay was done to further confirm apoptosis. Data revealed, by treating
with IC50 doses exhibited significant increases in early apoptosis (CN 1%= 18.7 %,
MV 1%= 20.7%) and late apoptosis (CN 1%= 38.4%, MV 1%= 54.4%) entering from
the viable cell, with less than 1% necrosis. Interestingly, both extracts exhibited a
dose-dependent trend in early apoptosis (CN 1%= 70.9%, MV 1%= 33%) after
HepG2 cells were treated with IC70 doses. Similarly, both extracts displayed ABTS
radical scavenging activity with IC50 values (CN1% = 43.6 μg/ml, MV 1% = 53.5
μg/ml). Thus, the conclusion is CN 1% and MV 1% possess cell death mechanism
through apoptosis induction against HepG2 at non-toxic in Chang cells, with
antioxidant properties. This potential extract should be further explored in the future
for marine endophytic fungus discovery for pharmaceutical application.