Total synthesis provides a new way to produce chemotherapeutic agents. The goals of this proposed research are to synthesize anticancer agent strongylophorine-26 and to elucidate its SAR profiles. This grant will develop new methodology to the total syntheses of strongylophorines which are helpful with treating cancer metastasis. Strongylophorine-26 is a promising Rho-dependent inhibitor of tumor cell invasion. It was observed that STP-26 reduces actin stress fibers and induces nonpolarized lamellipodial extensions. However, the limited availability of STP-26 from its natural source has prevented further mechanistic studies, such as whether STP-26 shows antimetastatic or antiangiogenic activity in vivo. Accordingly, an immediate goal of the research proposed in this application is the development of a synthetic route to STP-26, as a reliable source of the drug for more rigorous biological studies. This project will at the same time make available analogs that are required for structure-activity studies, and which are not easily accessible through modification of the natural product. The biological data from the proposed studies of our synthetic materials will in the short term lead to elucidation of the mechanism of action of STP-26 and ultimately to a clearer understanding of Rho mediated anti-metastatic pathways and to new anticancer therapeutics. We propose to develop two independent syntheses of STP-26. Both routes benefit from the use of known tricyclic precursors, and a highly convergent plan in which advanced tetracyclic and quinone precursors are coupled at a late stage. This modular approach is attractive for analog synthesis, because it allows two regions of the target that are important for activity to be systematically varied. The two routes vary mainly with respect to the strategy for introduction of lactone. The first route has the advantage of well-established organic reactions, the key step being a Barton radical cyclization reaction. The second route centers on a new protocol for transition metal catalyzed remote C-H activation. This methodology permits the use of the commercially available material geranyllinalool and the introduction of the lactone ring in a more efficient way. Therefore, a scale-up synthesis will be practical. Furthermore, this novel C-H activation strategy will find broad application to other bioactive terpenoids and steroids. The elucidation of structure-activity relationship (SAR) profiles of analogs of STP-26 will be done through collaboration with Dr. Ting-Chao Chou at Sloan-Kettering Cancer Center and Professor Xin-Yun Huang at Weill Medical College of Cornell University. Our synthetic strategies make it convenient to obtain modified functional groups with the strongylophorine framework, thereby generating structural mimics with potentially greater pharmacological activity and therapeutic potential. Furthermore, our chemical synthesis would facilitate the introduction of substituents into different positions on the quinone ring, which cannot be easily achieved by modification of the natural product. The methoxy group on the quinone ring is known to be important for good activity. Whether this is because of its electronic and/or steric effect will be tested by introducing a series of electron-donating or electron withdrawing groups (alkyl, OEt, NR2, halide, CN etc.) to replace the methoxy group. Moreover, the lactone ring is necessary for activity probably because of its susceptibility to nucleophilic attack. This will be tested by modifying the lactone ring to lactam, lactol, or its seco hydroxyl acid.

Public Health Relevance

Our proposed research focuses on the development of new methods to the synthesis of biologically active natural products and mimics which are useful for treating tumor metastasis. Specifically, the goals of this proposed research are to synthesize anticancer agent strongylophorine -26 and to study the structural requirements for its anti-metastatic activity.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Pilot Research Project (SC2)
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Special Emphasis Panel (ZGM1-MBRS-3 (SC))
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Lees, Robert G
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Hunter College
Schools of Arts and Sciences
New York
United States
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