Nuclear amination catalyzed by fungal laccases: Comparison of laccase catalyzed amination with known chemical routes to aminoquinones

Laccases are able to initiate nuclear amination of p-hydroquinones with primary aromatic amines, resulting in the formation of the corresponding monoaminated and diaminated quinones. Two laccase catalyzed reactions are compared with established synthetic routes to aminoquinones, showing that formation of products from laccase catalyzed reaction is comparable with reaction using sodium iodate as oxidant. Advantages and disadvantages of laccase catalyzed amination are discussed. It is concluded that laccase catalysis is less suitable than sodium iodate oxidation for the amination of simple p-hydroquinones with simple amines.     

Natural abenquines and synthetic analogues: Preliminary exploration of their cytotoxic activity

In this study, we explore the cytotoxic activity of four natural abenquines (2a–d) and fourteen synthetic analogues (2e–j and 3a–h) against a panel of six human cancer cell lines using a SRB assay. It was found that most of the compounds revealed higher levels of cytotoxic activities than naturally occurring abenquines. The analogues carrying ethylpyrrolidinyl and ethylpyrimidinyl with either an acetyl group (2 h–i) or a benzoyl group (3f–g), were the most potent against all human cancer cell lines and displayed EC₅₀ between a range of 0.6–3.4 μM. Notably, of the compounds tested, compound 2i proved the most cytotoxic against both ovarian (A2780) and breast (MCF7) cells, showing EC₅₀ = 0.6 and 0.8 μM respectively. Likewise, the analogues 2i, 3f and 3 g showed strong activity against cell HT29 with EC₅₀ = 0.9 μM for these compounds.     

Design,synthesis, and biological activity of Plastoquinone analogs as a new class of anticancer agents

In this paper, based on Plastoquinone (PQ) analogs possessing substituted aniline containing alkoxy group(s), new 2,3-dimethyl-5-amino-1,4-benzoquinones (PQ1-15) were designed and synthesized in either two steps or one-pot reaction. Specifically, the substituted amino moiety containing mono or poly alkoxy group(s) with various positions and groups were mainly explored to understand the structure-activity relationships for the cytotoxic activity against three human cancer cell lines (K562, Jurkat, and MT-2) and human peripheral blood mononuclear cells (PBMC). PQ2 was found to be most effective anticancer compound on K562 and Jurkat cell lines with IC₅₀ values of 6.40 ± 1.73 μM and 7.72 ± 1.49 μM, respectively. Interestingly, the compound was non-cytotoxic to normal PBMC and also MT-2 cancer cells. PQ2 which showed significant selectivity in MTT assay was chosen for apoptotic/necrotic evaluation and results exhibited that it induced apoptosis in K562 cell line after 6 h of treatment. PQ2 showed anti-Abelson kinase 1 (Abl1) activity with different inhibitory profile than Imatinib in the panel of eight kinases. The binding mode of PQ2 into Abl ATP binding pocket was predicted in silico showing the formation of some key interactions. In addition, PQ2 induced Bcr-Abl1 mediated ERK pathway in human chronic myelogenous leukemia (CML) cells. Furthermore, DNA-cleaving capability of PQ2 was clearly enhanced by iron (II) complex system. Afterward, a further in silico ADMET prediction revealed that PQ2 possesses desirable drug-like properties and favorable safety profile. These results indicated that PQ2 has multiple mechanism of action and two of them are anti-Bcr-Abl1 and DNA-cleaving activity. This study suggests that Plastoquinone analogs could be potential candidates for multi-target anticancer therapy.