Abstract
Endophytic fungi are potential sources of novel bioactive metabolites from a natural product drug discovery perspective. This study reports the bioactivity-directed fractionation of the secondary metabolites of the ethyl acetate extract of a fermentation culture of endophytic fungi from Terminalia catappa which were then evaluated for their cytotoxicity against human cervical cancer (HeLa) cells and human foreskin fibroblast (HFF) cells. Furthermore, apoptosis was determined using the Annexin V/propidium iodide (PI) flow cytometry assay. Endophyte extracts N2, N7, N8, N97, N169, and N233 were obtained from Trichoderma sp, Phoma sp, Phomopsis phyllanticola, Fusarium oxyporum, Collectotrichum sp, and Cryptococcus flavescens, respectively. The N97 extract was most active with a 50% inhibitory concentration (IC50) of 33.35 µg/ml. A 50% cytotoxic concentration (CC50) of 268.4 µg/ml was obtained with HFF cells and the selectivity index (SI) was 8.01. The percentages of cell populations were increased at late apoptosis (Annexin+/PI+), with the percentages of 27.4 ± 0.3 and 19.2 ± 0.01 obtained, respectively, for 50 µg/ml and 80 µg/ml of the N97 extract and 2.1 ± 0.1 obtained for the control in late apoptosis (Annexin V+/PI+) . Moreover, a higher reduction in the percentage of viable cells was observed in the HeLa control cells (93.6 ± 0.3), but the percentages of viable HeLa cells were 37 ± 0.05 and 45 ± 0.1, respectively, for the 50 µg/ml and 80 µg/ml treatments with the N97 extract. Also, the percentages of 34.7 ± 0.1 and 33.9 ± 0.4 were, respectively, obtained for 50 µg/ml and 80 µg/ml compared to the control with 4.6 ± 0.2, in early apoptosis (Annexin V+/PI-). These findings highlight the anticancer potential of the N97 extract of endophytic fungi from Terminalia catappa, which is mediated through apoptosis and presumably also attenuation of chemoresistance.
Highlights
Despite the immense advances in medical sciences in recent years, over 32.6 million people are living with cancer worldwide
We report the inhibition of human cervical cancer (HeLa) cell proliferation, a hallmark of the cancer phenotype, by inducing apoptosis mediated by endophytic fungal extracts of Terminalia catappa. e cytotoxic effects of the N97 extract were evaluated on nontumour human foreskin fibroblast (HFF) cells to determine the possible differences in response to the extracts between cancer and normal cells
The plant material was rinsed gently in running water to remove dust and debris. e bark, flowers, twigs, leaves, stem bark, root, and root bark samples were cut into small pieces of ∼5 mm length after proper washing. e leaves were divided into leaf blade and leaf vein. e leaf blade, leaf vein, twigs, and stem pieces were washed in tubes containing a solution of 20% commercial bleach (1% active chloride) for 10 min
Summary
Despite the immense advances in medical sciences in recent years, over 32.6 million people are living with cancer worldwide. Recent statistics show that 65% (5.3 million) of all cancer-related deaths were reported from less developed countries [1]. Among these cancers, uterine cervical cancer is the fourth most common cancer diagnosed in women and the second leading cause of cancer-related morbidity in women worldwide [2]. According to recent reports [2], human papillomavirus (HPV) infections contribute to the high incidence of cervical cancer cases in low- to middle-income countries [2]. Anticancer drug toxicity and side effects such as nephrotoxicity, nausea, hair loss, skin irritation, anaemia, infertility, and resistance pose major challenges for successful cancer clinical outcomes [4, 5]. One way of overcoming such challenges is the identification of underexplored and/or unexplored biological sources to produce novel, efficacious anticancer compounds
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