Djoko Agus Purwanto (2024) Hambatan Inisiasi Karsinogenesis oleh (-)•Epigaloka Tekin Gala T Melalui Mekanisme Peningkatan Aktifitas O'•Alkilguanin•DNA Alkil Transferase (Suatu Pendekatan Biologi Molekuler Untuk Mendapatkan Senyawa Penawar Karsinogen). Disertasi thesis, UNIVERSITAS AIRLANGGA.

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Abstract

(-)-Epigallocatechin gallate (EGCG) is a major component of tea catechin, which was reported to inhibit cancer development induced by chemical carcinogen. However, it is still not known how does the mechanism occur. In this study, the role of EGCG on the enhancement of 06-alkylguanineDNA alkyltransferase (AGT) in primarily rat liver cell culture was evaluated using Liquid Scintillation Counter method. The result showed that in the range of 12-48 hour after various concentrations (8.3-66.7 ppm) of single dose EGCG treatments, the AUC (area under curve) of AGT activity was increased by 1.4- to 2.8-fold (p < 0.01) than the constitutive level. To confirm that the expression of AGT increased by EGCG treatment, it could be shown by the decreased of 06-methylguanine-DNA induced by N-methyl-N-nitrosourea (MNU). The evidence showed that the formation of this 06-methylguanineDNA by MNU at the highest concentration (48 J.lM) could be prevented 92,6 % by EGCG 66,7 ppm in the culture media. Furthermore, mutation of K-ras in codon 12 th which had been proven the most frequent mutation caused by chemical carcinogen was also analyzed. using PCR-SSCP method, subsequently continued by DNA sequencing. EGCG concentration of 16.6 ppm could prevent K-ras mutation induced by MNU 32 J.lM. Result of these studies indicate that EGCG has substantial anti-cancer-initiating activity due to enhancing the AGT expression.

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