is one of the richest sources of polyphenols and vitamin C. Previously, the researchers had demonstrated the inhibitory effect of Sarunashi juice (sar-j) on mutagenesis, inflammation, and mouse skin tumorigenesis. They had identified the components of A. arguta responsible for the anti-mutagenic effects as water-soluble and heat-sensitive phenolic compounds. Subsequently, the researchers proposed the polyphenolic compound isoQ as a constituting component with anticarcinogenic potential.
Dr. Arimoto‑Kobayashi explains, “In this study, we sought to investigate the chemo‑preventive effects of A. arguta juice and its constituting component isoQ on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice, and identify the possible mechanisms underlying the anti-tumorigenic effects of
To this end, the team induced tumor growth in mice using NNK, a known cancer-causing compound present in tobacco products. Using a series of experiments and controls, the team studied the effects of sar-j and isoQ on lung tumorigenesis in mice.
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The results were encouraging: The number of tumor nodules per mouse lung in the group that received NNK injections and oral doses of A. arguta juice was significantly lower than that in the group injected with NNK only. Moreover, the oral administration of isoQ also reduced the number of nodules in the mouse lungs.
Next, the team broke ground by discovering the likely mechanism of action. NNK and 1-methyl-3-nitro-1-nitrosoguanidine or “MNNG” are known mutagensagents that trigger DNA mutations. The team therefore designed a series of experiments to study the effect of sar-j and isoQ on NNK- and MNNG-mediated mutagenesis using Salmonella typhimurium TA1535a bacterial strain commonly used for detecting DNA mutations. As expected, the mutagenicity of NNK and MNNG detected using S. typhimurium TA1535 decreased in the presence of sar-j. However, when similar tests were conducted using S. typhimurium YG7108, a strain lacking key enzymes responsible for DNA repair, sar-j was unable to decrease the mutagenic effects of NNK and MNNG. Based on this critical observation, the researchers concluded that sar-j seems to mediate its antimutagenic effect by accelerating DNA repair.
Finally, using cell-based experiments, the team also showed that sar-j suppressed the action of “Akt,” a key protein involved in cancer signaling. It is a known fact that Akt and an associated protein called “PI3k,” get over-activated in several human cancers.
Source: Eurekalert
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