Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex
<b>Background/Objectives:</b> Aberrant expression of c-MYC drives aggressive cancers. A guanine-rich promoter sequence (Pu27) folds into a transcriptionally repressive G-quadruplex (G4). Epigallocatechin gallate (EGCG), the main green tea polyphenol, displays anticancer activity, but cle...
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2025-05-01
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| description | <b>Background/Objectives:</b> Aberrant expression of c-MYC drives aggressive cancers. A guanine-rich promoter sequence (Pu27) folds into a transcriptionally repressive G-quadruplex (G4). Epigallocatechin gallate (EGCG), the main green tea polyphenol, displays anticancer activity, but clear, easily replicated evidence for direct binding to the c-MYC G4 is lacking. We therefore obtained the first biophysical confirmation of an EGCG–c-MYC G4 interaction using routine UV–visible spectroscopy. <b>Methods</b>: A pre-annealed Pu27 G4 (5 µM) in potassium-rich buffer was titrated with freshly prepared EGCG (0–20 µM) at 25 °C. Full-range UV–Vis spectra (220–400 nm) were recorded after each addition, and absorbance variations at the DNA (260 nm) and ligand (275 nm) maxima were quantified across three independent replicates. <b>Results</b>: EGCG induced pronounced, concentration-dependent hyperchromicity at 260 nm, reaching ~8–10% above baseline at a 4:1 ligand/DNA ratio and exhibiting saturable binding behaviour. Concurrently, the 275 nm band displayed relative hypochromicity coupled with a subtle bathochromic shift. These reciprocal perturbations—absent in buffer-only controls—constitute definitive evidence of a specific EGCG•G4 complex most consistent with external π-stacking or groove engagement rather than intercalation. <b>Conclusions</b>: This study delivers the first rigorous, quantitative UV–Vis confirmation that a readily consumed dietary polyphenol directly targets the c-MYC promoter G4. By marrying conceptual elegance with methodological accessibility, it provides a compelling molecular rationale for EGCG’s anti-oncogenic repertoire, inaugurates an expedient platform for screening G4-reactive nutraceuticals, and paves the way for structural and cellular investigations en route to next-generation c-MYC-directed therapies. |
| format | Article |
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| spelling | doaj-art-debe7cb0763f49eab658df72be6fdf0c2025-08-20T03:48:01ZengMDPI AGPharmaceuticals1424-82472025-05-0118571910.3390/ph18050719Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-QuadruplexJustin Tang0Department of Biomedical Science, University of Guelph, Guelph, ON N1G 2W1, Canada<b>Background/Objectives:</b> Aberrant expression of c-MYC drives aggressive cancers. A guanine-rich promoter sequence (Pu27) folds into a transcriptionally repressive G-quadruplex (G4). Epigallocatechin gallate (EGCG), the main green tea polyphenol, displays anticancer activity, but clear, easily replicated evidence for direct binding to the c-MYC G4 is lacking. We therefore obtained the first biophysical confirmation of an EGCG–c-MYC G4 interaction using routine UV–visible spectroscopy. <b>Methods</b>: A pre-annealed Pu27 G4 (5 µM) in potassium-rich buffer was titrated with freshly prepared EGCG (0–20 µM) at 25 °C. Full-range UV–Vis spectra (220–400 nm) were recorded after each addition, and absorbance variations at the DNA (260 nm) and ligand (275 nm) maxima were quantified across three independent replicates. <b>Results</b>: EGCG induced pronounced, concentration-dependent hyperchromicity at 260 nm, reaching ~8–10% above baseline at a 4:1 ligand/DNA ratio and exhibiting saturable binding behaviour. Concurrently, the 275 nm band displayed relative hypochromicity coupled with a subtle bathochromic shift. These reciprocal perturbations—absent in buffer-only controls—constitute definitive evidence of a specific EGCG•G4 complex most consistent with external π-stacking or groove engagement rather than intercalation. <b>Conclusions</b>: This study delivers the first rigorous, quantitative UV–Vis confirmation that a readily consumed dietary polyphenol directly targets the c-MYC promoter G4. By marrying conceptual elegance with methodological accessibility, it provides a compelling molecular rationale for EGCG’s anti-oncogenic repertoire, inaugurates an expedient platform for screening G4-reactive nutraceuticals, and paves the way for structural and cellular investigations en route to next-generation c-MYC-directed therapies.https://www.mdpi.com/1424-8247/18/5/719G-quadruplexc-MYCEpigallocatechin gallate (EGCG)polyphenolDNA bindingUV–Vis spectroscopy |
| spellingShingle | Justin Tang Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex Pharmaceuticals G-quadruplex c-MYC Epigallocatechin gallate (EGCG) polyphenol DNA binding UV–Vis spectroscopy |
| title | Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex |
| title_full | Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex |
| title_fullStr | Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex |
| title_full_unstemmed | Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex |
| title_short | Using UV–Vis Titration to Elucidate Novel Epigallocatechin Gallate (EGCG)-Induced Binding of the c-MYC G-Quadruplex |
| title_sort | using uv vis titration to elucidate novel epigallocatechin gallate egcg induced binding of the c myc g quadruplex |
| topic | G-quadruplex c-MYC Epigallocatechin gallate (EGCG) polyphenol DNA binding UV–Vis spectroscopy |
| url | https://www.mdpi.com/1424-8247/18/5/719 |
| work_keys_str_mv | AT justintang usinguvvistitrationtoelucidatenovelepigallocatechingallateegcginducedbindingofthecmycgquadruplex |