Full Paper Synthesis, Telomerase Evaluation and Anti-Proliferative Studies on Various Series of Diaminoanthraquinone-Linked Aminoacyl Residue Derivatives Fong-Chun Huang 1 , Kuo-Feng Huang 2 , Ruey-Hui Chen 3 , Jia-Er Wu 4 , Tsung-Chih Chen 5 , Chun-Liang Chen 5 , Chia-Chung Lee 5 , Jin-Yang Chen 5 , Jing-Jer Lin 1 , and Hsu-Shan Huang 4,5 1 Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan 2 Chi-Mei Medical Center, Tainan, Taiwan 3 College of Nursery, Hungkuang University, Taichung, Taiwan 4 School of Pharmacy, Taipei, Taiwan 5 Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan Four series of compounds containing an anthraquinone-linked moiety and symmetrical or asymmetrical aminoacyl residues in side chains at positions 1,4-, 1,5-, 2,6-, and 2,7- were synthesized and evaluated for their inhibitory effects toward telomerase and hTERT expression. Of these, only compound B11 showed selective inhibition of telomerase activity. Although it is not as competent as several of the anthraquinones we identified previously, nevertheless, the result is consistent with that the general structure moiety at the 1,5-position of diaminoanthraquinone- linked compound is important for the telomerase inhibitory activity. Interestingly, compounds A6, A8, C8, and D8 exhibited selective repressing activities toward hTERT expression and showed less effect toward proliferation of the treated cancer cells. Although it is not apparent which structure moiety is responsible for the telomerase repression effects of these compounds, they could be further developed as potential anti-tumor agents. Keywords: Anthraquinone-linkage / Dose-dependent pattern / SEAP expression / Telomerase / TRAP assay Received: April 5, 2011; Revised: May 3, 2011; Accepted: May 3, 2011 DOI 10.1002/ardp.201100122 Introduction G-Quadruplex structures are formed by associating four gua- nine bases through a stable hydrogen bond arrangement. They are formed in DNA or RNA rich in guanine-residues [1]. The vertebrate telomeric DNA sequences are short tandem repeats of TTAGGG sequences. They are capable of forming G-quadruplex structures. Telomerase is an enzyme which synthesizes the G-rich strand of telomere DNA. The presence of telomerase activity is highly correlated with cancer for- mation and is considered as a means that allows cancer cells to escape senescence [2]. It is elevated in more than 85% of cancer cells, thus providing a compelling rationale to target the telomerase for broad-spectrum cancer therapy [3]. Designing small-molecule drugs with telomerase acitivty is emerging as an attractive strategy for cancer chemotherapy, leading to selective inhibition of tumor cell growth [4]. Since G-quadruplex structure formed by telomere DNA sequences is not a substrate for telomerase [5, 6], compounds that bind and stabilize G-quadruplex structures have been considered as potential inhibitors for telomerase [7]. Indeed, a number of small molecules that bind to and stabilize the folded quadruplex were shown to inhibit telomerase activity [8]. The anthracycline antibiotics and related compounds (Scheme 1) have been used widely as anticancer drugs for many decades, but their cardiotoxicity limits their clinical use [9]. The detailed mechanism of how these compounds, all of which contain an anthraquinone pharmacophore, remained elusive although they might render their effects The author contributed equally: Prof. Dr. Jing-Jer Lin, e-mail: jjlin@ym.edu.tw Correspondence: Prof. Dr. Hsu-Shan Huang, School of Pharmacy, National Defense Medical Center, Taipei, Taiwan or No. 161, MinChuan E. Rd., Neihu, Taipei 11490, Taiwan, R.O.C. E-mail: huanghs@ndmctsgh.edu.tw Fax: þ886-2-87923169 Arch. Pharm. Chem. Life Sci. 2012, 345, 101–111 101 ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim