Molecular identification, volatile metabolites profiling, and bioactivities of an indigenous endophytic fungus (Diaporthe sp.)
Graphical abstract
Introduction
Breast cancer is one of the deadly diseases for the woman and it globally leads to significant mortality and morbidity every year. The carcinogenesis and occurrence of breast cancer are undetermined because of various factors are involved in the process [1]. According to the world health organization and American cancer society data, out of the eight-women one would be diagnosed as invasive breast cancer [2]. The breast cancer therapy has been targeted through the expression of progesterone receptor (PR), estrogen receptor (ER), and epidermal growth factor receptor (EGFR). It is reported that the ER and PR are involved in the progression of cancer through upregulating the expression of c-Myc and cyclin D1 while the EGPR plays a vital role in the triple-negative breast cancer [3,4] and this can be treated through the application of anti-estrogen therapy and several chemotherapeutics. The anticancer drugs such as Trastuzumab, Tamoxifen, Capecitabine, Paclitaxel, Gemcitabine, Docetaxel, and Cyclophosphamide are commonly used to treat the breast cancer but these drugs exhibit adverse effects to the normal cells [5]. To overcome the toxicity of the available drugs, researchers focus to discover the alternative novel molecules from the natural resources with targeted cancer cell therapy without harming to normal cells.
Endophytic fungi belong to the phyla of fungi, and they inhabit the inner tissues or beneath the epidermal cell layer of plants including shrubs, marine algae, lichens, palm, and grasses, seagrasses, medicinal plants, and trees [[6], [7], [8]]. In recent years, endophytic fungi have received much research attention for their potential use in various fields. They are a rich source of bioactive secondary metabolites, enzymes, peptides, and biocontrol agents with health care and industrial applications [9,10]. Also, they are used in the production of biofuels, and agricultural crop products [11]. Increased usage of antibiotics has developed the drug-resistant pathogens that pose challenges in treatments, therefore, the discovery of novel compounds from the natural resources including microbes is essential to battle against multidrug-resistant (MDR) microbial pathogens. In this regard, the endophytic fungi are one of the natural sources to isolate the novel antibacterial biomolecules against MDR pathogens [[12], [13], [14], [15], [16]]. Moreover, the endophytic fungi are promising in the production of bioactive compounds with antioxidant and anticancer properties [9,[17], [18], [19]].
The novel molecules are screened using the molecular docking approach and the anti-breast cancer molecules are screened by targeting the ERα, PR, EGFR, and mTOR [1], tumor suppressor p53 protein, anti-apoptotic kinase Akt, Raf-1 MAP kinase, receptor tyrosine kinases, and angiogenesis transcription factor HIF-1 alpha in the erbB family, which are regulated by the chaperone protein [20,21]. Therefore, we hypotheseis that targeting of HSP90 can prevent breast cancer progression. Among various chaperone proteins, HSP90 (90 kDa) co-regulates and stabilizes the various proteins involved in the cellular homeostasis [22,23]. Therefore, the present work aimed at isolating and identify the new endophytic fungi using the ITS gene sequencing and at studying their low molecular weight of secondary metabolites, alkaloids, and volatile compounds. In addition, their bioactivities were tested for antioxidant, antibacterial properties, and cytotoxicity to normal and breast cancer cell line. Also, this work screened the potential anticancer molecules from the endophytic fungus using the molecular docking study.
Section snippets
Sample selection and Isolation of endophytic fungi
The healthy plants (Pinus densiflora,Abies holophylla, and Ligustrum obtusifolium) were collected from the campus of Kangwon National University, the Republic of Korea. The plant leaf was surface sterilized by washing with running tap water for 1 min whereby removing visible debris and then rinsed with deionized water, followed by cleaning them using 70 % ethanol for 30 s and 1 % sodium hypochlorite for 1 min [24]. Then the leaf samples were rewashed with 70 % ethanol for 30 s, rinsed with
Isolation of endophytic fungi
Three plant species were selected for isolating endophytic fungi and assessed the relation between colonization frequencies (CF %) and phytoconstituents by measuring the total phenol and total flavonoids contents in the selected plant leaves (Table 1). The growth rates of fungal endophytes were evidenced by CF (%) and it was found higher in L. obtusifolium (85.21 ± 1.84 %) and less in A. holophylla (5.06 ± 0.24 %). As shown in the Table 1, the total phenol, flavonoids content, and CF were
Conclusion
In summary, a total of five fungal endophytic strains were isolated and identified based on the ITS gene sequences. Among the strains, Diaporthe sp. (SPEF004) was bioactive and its extracts (FEAE) exhibited significant antibacterial, antidiabetic related enzyme inhibitory and cytotoxicity activities. In GCMS based metabolites profiling, 20 compounds were identified from FEAE of Diaporthe sp. (SPEF004). Of them, pyrrolidine-5-one, 2-[3-hydroxypropyl]- seemed to regulate the breast cancer cell
Declaration of Competing Interest
There is no conflict of interest in this study
Acknowledgment
The Korea Research Fellowship Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (2017H1D3A1A01052610), Republic of Korea.
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