Endophytic Fungus Isolated From Achyrocline satureioides Exhibits Selective Antiglioma Activity—The Role of Sch-642305

Abstract

Glioblastoma is the most devastating primary brain tumor. Current treatment is palliative, making necessary the development of new therapeutic strategies to offer alternatives to patients. Therefore, endophytes represent an interesting source of natural metabolites with anticancer potential. These microorganisms reside in tissues of living plants and act to improve their growth. Evidence revealed that several medicinal plants are colonized by endophytic fungi producer of antitumor metabolites. Achyrocline satureioides is a Brazilian medicinal plant characterized by its properties against gastrointestinal disturbances, anticancer and antioxidant effects. However, there are no reports describing the endophytic composition of A. satureioides. The present study proposes the isolation of endophytic fungus from A. satureioides, extract preparation, phytochemical characterization and evaluation of its antiglioma potential. Our data showed that crude extracts of endophyte decreased glioma viability with IC50 values of 1.60–1.63 μg/mL to eDCM (dichloromethane extract) and 37.30–55.12 μg/mL to eEtAc (ethyl acetate extract), respectively. Crude extracts induced cell death by apoptosis with modulation of redox status. In order to bioprospect anticancer metabolites, endophytic fungus extracts were subjected to guided fractionation and purification yielded five fractions of each extract. Six of ten fractions showed selective antiproliferative activity against glioma cells, with IC50 values ranged from 0.95 to 131.3 μg/mL. F3DCM (from eDCM) and F3EtAc (from eEtAc) fractions promoted C6 glioma toxicity with IC50 of 1.0 and 27.05 μg/mL, respectively. F3EtAc fraction induced late apoptosis and arrest in G2/M stage, while F3DCM promoted apoptosis with arrest in Sub-G1 phase. Moreover, F3DCM increased antioxidant defense and decreased ROS production. Additionally, F3DCM showed no cytotoxic activity against astrocytes, revealing selective effect. Based on promising potential of F3DCM, we identified the production of Sch-642305, a lactone, which showed antiproliferative properties with IC50 values of 1.1 and 7.6 μg/mL to C6 and U138MG gliomas, respectively. Sch-642305 promoted arrest on cell cycle in G2/M inducing apoptosis. Furthermore, this lactone decreased glioma cell migration and modulated redox status, increasing superoxide dismutase and catalase activities and enhancing sulfhydryl content, consequently suppressing reactive species of oxygen generation. Taken together, these results indicate that metabolites produced by endophytic fungus isolated from A. satureioides have therapeutic potential as antiglioma agent.

Structure–Activity Relationship Analysis on Antioxidant and Anticancer Actions of Theaflavins on Human Colon Cancer Cells

“…ROS consists of highly reactive ions and free radicals, including hydrogen peroxide (H 2 O 2 ), superoxide (O 2 – • ), hydroxyl radical ( • OH), and singlet oxygen ( 1 O 2 ). It was well-known that ROS levels have been demonstrated as a key factor in various cell signal ways. − The imbalance of the intracellular ROS level can cause a series of damage to cells, such as the induction of cell cycle arrest in the G2/M or G0/G1 phase. , To investigate whether the cell cycle arrest triggered by TFs was mediated by ROS, the intracellular ROS levels were determined by measuring the fluorescence intensity of DHE as well as DCF. As shown in Figure A, after exposure to TFs for 10 min, the fluorescence intensity of DHE in SW480 cells decreased sharply and fluctuated slowly within 125 min, showing a dose-dependent manner (Figure S3 of the Supporting Information).…”

Ethyl Acetate Extract of Colletotrichum gloeosporioides Promotes Cytotoxicity and Apoptosis in Human Breast Cancer Cells

“…Therefore, wound healing assay was performed under low serum (2% fetal bovine serum) condition to validate that the filling of gap is the result of collective migration of MDA-MB-231 and MCF-7 cells, not the proliferation of cells. Accumulating body of evidence suggest that the bioactive compounds of various fungal endophytes possess potential cytotoxic ability, suppression of proliferation, and cell migration of cancer cells including MDA-MB-231 and MCF-7. − The current study showed that bioactive compounds produced from the endophyte C. gloeosporioides significantly inhibited the filling of wound created in MDA-MB-231 and MCF-7 cells.…”

“…Accumulating body of evidence suggest that the bioactive compounds of various fungal endophytes possess potential cytotoxic ability, suppression of proliferation, and cell migration of cancer cells including MDA-MB-231 and MCF-7. 50 − 52 The current study showed that bioactive compounds produced from the endophyte C. gloeosporioides significantly inhibited the filling of wound created in MDA-MB-231 and MCF-7 cells. Therefore, the wound healing ability induced by the EA extract of C. gloeosporioides indicates that the bioactive compound produced by the endophyte C. gloeosporioides may appear to be an effective lead molecule in the treatment of breast cancer.…”

“…46,47 The result of relative mRNA expression showed that level of CD44 was significantly decreased by 0.195 ± 0.092-fold (t-value 8.750; p-value 0.013) and 0.439 ± 0.042fold (t-value 13.212; p-value 0.006) in MDA-MB-231 (Figure S1A) and MCF-7 (Figure S1B) cells, respectively. Our results clearly indicated that 24 h of exposure with IC 30 , IC 50 The outer membrane of cancer cells undergoes a variety of physical alterations during apoptosis, which include a gradual increase in cell membrane porosity that allows the entry of gloeosporioides was elucidated by analyzing the percentage of early apoptotic, late apoptotic, and necrotic cell population, which was further compared with Tamoxifen. Dot-plot graphs demonstrated that the distribution of MDA-MB-231 (Figure 6A) and MCF-7 (Figure 6C) cells in four cellular events such as live (lower left quadrant), early phase of apoptosis (lower right quadrant), late phase of apoptosis (upper right quadrant), and necrotic (upper left quadrant).…”

“…The results of the cytotoxic assay were expressed as the cell viability percentage against the vehicle control group, which was calculated using the formula [(Abs (570nm) of the treated sample/Abs (570nm) of vehicle control)] × 100. The representative result was from three independent experiments, and the IC 30 , IC 50 and IC 70 values of the EA extract of C. gloeosporioides for each cell were calculated using GraphPad Prism (version 8.0.2) by using the straight line curve method, followed by the interpolation of X-axis value. The concentrations of the EA extract of C. gloeosporioides needed to kill 30, 50, and 70% of the cancer cells are represented by the IC 30 , IC 50 , and IC 70 values, respectively.…”