Yun-Hee Shon

Antimutagenicity and induction of anticarcinogenic phase II enzymes by basidiomycetes

Extracts from Phellinus linteus, Phellinus igniarius, and Agrocybe cylindracea have been tested for their antimutagenic properties against direct-acting mutagens [4-nitro-o-phenylenediamine (NPD) and sodium azide (NaN(3))] and indirect-acting mutagens [2-aminofluorene (2-AF) and benzo[a]pyrene (B[a]P)], using the Salmonella typhimurium tester strains TA 98 and TA 100. In addition, the chemopreventive potentials of these extracts to induce NAD(P)H:quinone oxidoreductase (QR) and glutathione S-transferase (GST) activities and glutathione (GSH) level extracts from the filtrate of the cultured broth of P. linteus, polysaccharide extracts from the cultured broth (PI I) and mycelia (PI II) and water extract of fruiting bodies (PI II) of P. igniarius, and polysaccharide extracts from the cultured broth (AC I) and mycelia (AC II) of A. cylindracea showed inhibitory effects on the mutagenic activities induced by the direct-acting mutagens, NPD and NaN(3), and the indirect-acting mutagens, 2-AF and B[a]P. QR was induced with PI I, PI II, AC I, and AC II, and GST activity was induced with PL I, PL II, PI I, PI II, PI III and AC I in murine Hepa1c1c7 cell culture. In addition, PL I, PL II, PI I, PI II, PI III and AC II increased glutathione level. These results suggest that P. linteus, P. igniarius, and A. cylindracea have antimutagenic activities and may play a role in the prevention of cancer by inducing QR and GST activities and increasing GSH level.

Evaluation of the antimutagenic potential of chitosan oligosaccharide: Rec, Ames and Umu tests

Two types of chitosan oligosaccharides (COS), COS I (1-kDa < MW < 3-kDa) and COS II (3-kDa < MW < 5-kDa), were tested for antimutagenic activities against chemical mutagens using Umu gene expression, Ames, and Bacillus subtilis Rec mutagenicity tests. At the highest chitosan oligosaccharide dose (1 mg) tested, mutagenic activity of indirect-acting mutagen was inhibited by ∼50% in the Umu gene expression system and in the Ames test. Chitosan oligosaccharide (0.01, 0.1 and 1 mg) also suppressed 4-nitroquinoline-N-oxide (NQO)-induced mutagenicity in the B. subtilis Rec− assay.

Inhibition of cytochrome P450 isozymes and ornithine decarboxylase activities by polysaccharides from soybeans fermented with Phellinus igniarius or Agrocybe cylindracea.

Polysaccharides (5, 10, 25, 50 and 100 μg ml−1) from soybeans and soybeans fermented with Phellinus igniarius or Agrocybe cylindracea inhibited cytochrome P450 1A1, cytochrome P450 1A2 and cytochrome P450 2B1 activities in rat liver microsomes. The polysaccharides (5, 10 and 25 μg ml−1) also suppressed 12-O-tetradecanoylphorbol-13-acetate-induced ornithine decarboxylase activity. The most potent inhibitors of cytochrome P450 isozymes and ornithine decarboxylase activities were the polysaccharides from soybeans fermented with Agrocybe cylindracea.

Cancer chemoprevention: inhibitory effect of soybeans fermented with basidiomycetes on 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate-induced mouse skin carcinogenesis

In a two-stage skin carcinogenesis model, mice initiated with 7,12-dimethylbenz[a]anthracene and promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 12 weeks developed an average of 15.8 skin tumours per mouse with 100% tumour incidence. Topical application of polysaccharides from soybeans fermented with either Phellinus igniarius or Agrocybe cylindracea together with TPA twice weekly for 12 weeks inhibited the number of skin tumours per mouse by 70 or 88%, respectively, and the percentage of mice with tumours was lowered by 70 or 30%, respectively.

Induction of a TC1-mediated experimental autoimmune thyroiditis by deglycosylated porcine thyroglobulin.

RETRACTED

Chemopreventive effect of protein extract ofAsterina pectinifera in HT-29 human colon adenocarcinoma cells

We investigated the effect of protein extract ofAsterina pectinifera on the activity of 4 enzymes that may play a role in adenocarcinoma of the colon: quinone reductase (QR), glutathioneS-transferase (GST), ornithine decarboxylase (ODC), and cyclooxygenase (COX)-2. QR and GST activity increased in HT-29 human colon adenocarcinoma cells increased that had been exposed to 4 concentrations of the protein extract (80, 160, 200 and 240 μg/mL). Additionally, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ODC activity decreased significantly in cells exposed to the extract in concentrations of 160 μg/mL (p<0.05), 200 μg/mL (p<0.005), and 240 μg/mL (p<0.005). TPA-induced COX-2 activity also decreased in cells exposed to extract concentrations of 10, 20, 40, and 60 μg/mL. COX-2 expression was also inhibited in cells exposed to this extract. These results suggest that this protein extract ofA pectinifera has chemopreventive activity in HT-29 human colon adenocarcinoma cells, and therefore, may have the potential to function as a chemopreventive agent in human colorectal cancer.