Design and Synthesis of Brazilin-Like Compounds

Abstract

A general and flexible synthetic route, which leads to the synthesis of brazilin-like compounds, was developed. The aza-­brazilin derivatives show strong anticancer activities in MTT assay towards a number of human cancer cell lines including HT29, A549, HL60, and K562.

Key words

synthetic strategy - bioactive derivatives - anticancer - natural-product-like - brazilin

References and Notes

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CCDC804781 (for compound 4a) and CCDC804782 (for compound 4d) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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Representative Brazilin-Like Compounds
Lactone analogue 4e: pale red syrup. ^¹H NMR (300 MHz, CDCl₃): δ = 7.02 (1 H, d, J = 7.5 Hz), 6.70-6.86 (4 H, m), 4.15 (1 H, s), 3.84 (3 H, s), 3.81 (3 H, s), 3.77 (3 H, s), 3.34 (1 H, d, J = 15.3 Hz), 3.04-3.13 (2 H, m), 2.84 (1 H, d, J = 15.6 Hz) ppm. ^¹³C NMR (75 MHz, CDCl₃): δ = 148.41, 148.12, 146.88, 137.37, 133.69, 130.87, 122.96, 121.67, 117.82, 108.72, 77.83, 56.10, 55.48, 52.51, 48.07, 42.13 ppm. MS (EI): m/z (%) = 328 (25) [M⁺ + 1], 327 (100) [M⁺], 309 (23), 308 (86), 294 (32), 278 (9), 250 (4), 239 (4), 220 (4), 208 (4), 191 (4), 176 (58), 151 (65), 133 (13), 107 (12). HRMS: m/z calcd for C₁₉H₂₁NO₄ [M]⁺: 327.1471; found: 327.1479.

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The cytotoxicity assay was carried out on four cell lines (K562, A549, HT-29, and HL60). Cells were cultured at 37 ˚C under a humidified atmosphere of 5% CO₂ in RPMI 1640 medium supplemented with 10% fetal serum and dispersed in replicate 96-well plates. Compounds were then added. After 48 h exposure to the compounds, cells viability were determined by the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-
tetrazolium bromide] (MTT) cytotoxicity assay by measur-ing the absorbance at λ = 570 nm with a microplate spectrophotometer. Each test was performed in triplicate. Cisplatin (DDP) was used as the reference drug.