Apoptosis-inducing effect of diketopiperazine disulfides produced by Aspergillus sp. KMD 901 isolated from marine sediment on HCT116 colon cancer cell lines

Abstract

Aims: Research is to identify the bioactive secondary metabolites produced by Aspergillus sp. KMD 901 isolated from marine sediment and to assess their apoptosis‐inducing effects. Methods and Results: Aspergillus sp. KMD 901 was isolated from marine sediment obtained from the East Sea of Korea. An ethyl acetate extract of KMD 901 exhibited potent cytotoxic activity towards five cancer cell lines (HCT116, AGS, A549, MCF‐7 and HepG2). Sequencing of the internal transcribed spacer (ITS) region in this strain allowed us to identify KMD 901 as a strain of Aspergillus versicolor. The cytotoxic compounds from Aspergillus sp. KMD 901 were purified by reversed‐phase high‐performance liquid chromatography and identified as diketopiperazine disulfides through spectroscopic analyses including extensive 2D NMR and mass spectrometry. The diketopiperazine disulfides were found to induce apoptosis in HCT116 cells based on cell morphology, DNA fragmentation observed by agarose gel electrophoresis, Annexin‐V/PI staining using a flow cytometer and cleavage of poly (ADP‐ribose) polymerase (PARP), caspase‐3, caspase‐8, caspase‐9 and Bcl‐2 family proteins (Bcl‐2, Bcl‐xL and Bax) using Western blotting analysis. Further study using an in vivo xenograft model showed inhibitory effects of acetylapoaranotin (2) on tumour proliferation. Conclusion: A new diketopiperazine disulfide, deoxyapoaranotin (3), along with previously described acetylaranotin (1) and acetylapoaranotin (2) was separated from Aspergillus sp. KMD 901 and found to have direct cytotoxic and apoptosis‐inducing effects towards HCT116 colon cancer cell lines. Significance and Impact of the Study: These results suggest that the diketopiperazine disulfides produced from Aspergillus sp., KMD 901, could be candidates for the development of apoptosis‐inducing antitumour agents. Also, this study indicates that marine natural products as potential source of pharmaceuticals.

Pretrichodermamide C and N-methylpretrichodermamide B, two new cytotoxic epidithiodiketopiperazines from hyper saline lake derived Penicillium sp.

“…These metabolites possess a broad spectrum of biological activities, including antibacterial, antiviral and antifungal activities (Witiak and Wei, 1990;Gardiner et al, 2005;Borthwick, 2012). Several naturally occurring ETPs, such as gliotoxin (antitumor activity) (Cole and Cox, 1981), chaetocin (antimyeloma activity) (Isham et al, 2007), and acetylaranotin (pro-apoptotic activity) (Neuss et al, 1968;Choi et al, 2011) have attracted considerable attention in recent years due to their pronounced cytotoxic activities against various human cancer cell lines (Dubey et al, 2013;Boyer et al, 2013;Reece et al, 2014). The essential structural element of ETPs responsible for the observed biological properties is attributed to the sulfur moiety in the oxidized disulfide form and/or the reduced dithiol form (Chai and Waring, 2000).…”

Biosynthetic Pathway for the Epipolythiodioxopiperazine Acetylaranotin in Aspergillus terreus Revealed by Genome-Based Deletion Analysis

“…5–7 The compound was later identified in Aspergillus terreus , the producer of lovastatin. 8 Subsequent bioactivity studies have shown that acetylaranotin ( 1 ) and its derivatives display an array of interesting biological activities including the inhibition of viral RNA polymerase, 6 the induction of apoptosis in cancer cell lines 9 and antifungal activity 10 .…”

Enantioselective Synthesis of (−)-Acetylapoaranotin

“…KMD 901 and determined that it induces apoptosis in HCT116 colon cancer cells. 13 Here, we report the first total synthesis of 3 , which was enabled by an eight-step, enantioselective synthesis of a key amino acid building block, 7 .…”