Synthesis of 11-aminoalkoxy substituted benzophenanthridine derivatives as tyrosyl-DNA phosphodiesterase 1 inhibitors and their anticancer activity

Enhancement of the Antitumor and Antimetastatic Effect of Topotecan and Normalization of Blood Counts in Mice with Lewis Carcinoma by Tdp1 Inhibitors-New Usnic Acid Derivatives

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is an important DNA repair enzyme and one of the causes of tumor resistance to topoisomerase 1 inhibitors such as topotecan. Inhibitors of this Tdp1 in combination with topotecan may improve the effectiveness of therapy. In this work, we synthesized usnic acid derivatives, which are hybrids of its known derivatives: tumor sensitizers to topotecan. New compounds inhibit Tdp1 in the micromolar and submicromolar concentration range; some of them enhance the effect of topotecan on the metabolic activity of cells of various lines according to the MTT test. One of the new compounds (compound 7) not only sensitizes Krebs-2 and Lewis carcinomas of mice to the action of topotecan, but also normalizes the state of the peripheral blood of mice, which is disturbed in the presence of a tumor. Thus, the synthesized substances may be the prototype of a new class of additional therapy for cancer.

Insights on Antitumor Activity and Mechanism of Natural Benzophenanthridine Alkaloids

Benzophenanthridine alkaloids are a class of isoquinoline compounds, which are widely found in the plants of papaveraceae, corydalis, and rutaceae. Biological activities and clinical studies have shown that benzophenanthridine alkaloids have inhibitory effects on many cancers. Considering that the anticancer activities and mechanisms of many natural benzophenanthridine alkaloids have been discovered in succession, the purpose of this paper is to review the anticancer effects of benzophenanthridine alkaloids and explore the application potential of these natural products in the development of antitumor drugs. A literature survey was carried out using Scopus, Pubmed, Reaxys, and Google Scholar databases. This review summarizes and analyzes the current status of research on the antitumor activity and antitumor mechanism of natural products of benzophenanthridine from different sources. The research progress of the antitumor activity of natural products of benzophenanthridine from 1983 to 2023 was reviewed. The antitumor activities of 90 natural products of benzophenanthridine and their related analogues were summarized, and the results directly or indirectly showed that natural products of benzophenanthridine had the effects of antidrug-resistant tumor cell lines, antitumor stem cells, and inducing ferroptosis. In conclusion, benzophenanthridine alkaloids have inhibitory effects on a variety of cancers and have the potential to counteract tumor resistance, and they have great application potential in the development of antitumor drugs.

Synthesis and Biological Activities of 11- and 12-Substituted Benzophenanthridinone Derivatives as DNA Topoisomerase IB and Tyrosyl-DNA Phosphodiesterase 1 Inhibitors

Herein, a series of 11- or 12-substituted benzophenanthridinone derivatives was designed and synthesized for the discovery of dual topoisomerase IB (TOP1) and tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors. Enzyme-based assays indicated that two compounds 12 and 38 showed high TOP1 inhibitory potency (+++), and four compounds 35, 37, 39 and 43 showed good TDP1 inhibition with IC50 values ranging from 10 to 18 μM. 38 could induce cellular TOP1cc formation, resulting in the highest cytotoxicity against HCT-116 cells (0.25 μM). The most potent TDP1 inhibitor 43 (10 μM) could induce cellular TDP1cc formation and enhance topotecan-induced DNA damage and showed strong synergistic cytotoxicity with topotecan in both MCF-7 and MCF-7/TDP1 cells.

Adamantane-Monoterpenoid Conjugates Linked via Heterocyclic Linkers Enhance the Cytotoxic Effect of Topotecan

Inhibiting tyrosyl-DNA phosphodiesterase 1 (TDP1) is a promising strategy for increasing the effectiveness of existing antitumor therapy since it can remove the DNA lesions caused by anticancer drugs, which form covalent complexes with topoisomerase 1 (TOP1). Here, new adamantane-monoterpene conjugates with a 1,2,4-triazole or 1,3,4-thiadiazole linker core were synthesized, where (+)-and (-)-campholenic and (+)-camphor derivatives were used as monoterpene fragments. The campholenic derivatives 14a-14b and 15a-b showed activity against TDP1 at a low micromolar range with IC₅₀ ~5-6 μM, whereas camphor-containing compounds 16 and 17 were ineffective. Surprisingly, all the compounds synthesized demonstrated a clear synergy with topotecan, a TOP1 poison, regardless of their ability to inhibit TDP1. These findings imply that different pathways of enhancing topotecan toxicity other than the inhibition of TDP1 can be realized.