Synthesis of 2-methoxybenzamide derivatives and evaluation of their hedgehog signaling pathway inhibition

Aberrant hedgehog (Hh) signaling is implicated in the development of a variety of cancers. Smoothened (Smo) protein is a bottleneck in the Hh signal transduction. The regulation of the Hh signaling pathway to target the Smo receptor is a practical approach for development of anticancer agents. We report herein the design and synthesis of a series of 2-methoxybenzamide derivatives as Hh signaling pathway inhibitors. The pharmacological data demonstrated that compound 21 possessed potent Hh pathway inhibition with a nanomolar IC₅₀ value, and it prevented Shh-induced Smo from entering the primary cilium. Furthermore, mutant Smo was effectively suppressed via compound 21. The in vitro antiproliferative activity of compound 21 against a drug-resistant cell line gave encouraging results.

Benzamide analog (21) was identified as a potent hedgehog signaling pathway inhibitor that targeted the Smo receptor and blocked Daoy cell proliferation.

A focused library synthesis and cytotoxicity of quinones derived from the natural product bolinaquinone

Bolinaquinone is a natural product that is a structurally complex, cytotoxic sesquiterpene quinone. A scaffold simplification and focused library approach using a microwave-assisted Suzuki coupling gave 32 bolinaquinone analogues with good-to-excellent cytotoxicity profiles. Mono-arylbenzoquinones, Library A, were preferentially toxic towards BE2-C (neuroblastoma) cells with growth inhibition (GI₅₀) values of 4-12 µM; only the 3,4-dimethoxyphenyl 23 and 3-biphenyl 28 variants were broad-spectrum active-HT29 (colon carcinoma), U87 and SJ-G2 (glioblastoma), MCF-7 (breast carcinoma), A2780 (ovarian carcinoma), H460 (lung carcinoma), A431 (skin carcinoma), Du145 (prostate carcinoma), BE2-C (neuroblastoma), MIA (pancreatic carcinoma) and SMA (spontaneous murine astrocytoma). Library B with a second aryl moiety exhibited broad-spectrum cytotoxicity with MCF-7 cells' GI₅₀ values of 5.6 ± 0.7 and 5.1 ± 0.5 µM for 2,5-dimethoxy-3-(naphthalene-1-yl)-6-(naphthalene-3-yl) 33 and 2,5-dimethoxy-3-(biaryl-2-yl)-6-(naphthalene-3-yl) 36, respectively. Similar potencies were also noted with 2,5-dimethoxy-3,6-diphenyl 30 against A2780 (GI₅₀ = 5.9 ± 0.0 µM) and with 2,5-dimethoxy-3-(biaryl-3-yl)-6-(naphthalene-3-yl) 37 against HT29 (GI₅₀ = 5.4 ± 0.4 µM), while the 3,4-dimethoxy mono-aryl analogue 23 exhibited good levels of activity against A2780 (GI₅₀ = 3.8 ± 0.75 µM), the neuroblastoma cell line BE2-C (GI₅₀ = 3 ± 0.35 µM) and SMA (GI₅₀ = 3.9 ± 0.54 µM). Introduction of the amino-substituted Library C gave 2-(naphthalen-1-yl)-5-(naphthalen-3-yl)-3,6-bis(propylamino) 43, with excellent activity against HT29 (0.08 ± 0.0 µM), MCF-7 (0.17 ± 0.1 µM), A2780 (0.14 ± 0.1 µM), A431 (0.11 ± 0.0 µM), Du145 (0.16 ± 0.1 µM), BE2-C (0.08 ± 0.0 µM) and MIA (0.1 ± 0.0 µM).