Pine needles (Pinus densiflora Siebold et Zuccarini) have long been used as a traditional health-promoting medicinal food in Korea. To investigate their potential anticancer effects, antioxidant, antimutagenic, and antitumor activities were assessed in vitro and/or in vivo. Pine needle ethanol extract (PNE) significantly inhibited Fe(2+)-induced lipid peroxidation and scavenged 1,1-diphenyl- 2-picrylhydrazyl radical in vitro. PNE markedly inhibited mutagenicity of 2-anthramine, 2-nitrofluorene, or sodium azide in Salmonella typhimurium TA98 or TA100 in Ames tests. PNE exposure effectively inhibited the growth of cancer cells (MCF-7, SNU-638, and HL-60) compared with normal cell (HDF) in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In in vivo antitumor studies, freeze-dried pine needle powder supplemented (5%, wt/wt) diet was fed to mice inoculated with Sarcoma-180 cells or rats treated with mammary carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA, 50 mg/kg body weight). Tumorigenesis was suppressed by pine needle supplementation in the two model systems. Moreover, blood urea nitrogen and aspartate aminotransferase levels were significantly lower in pine needle-supplemented rats in the DMBA-induced mammary tumor model. These results demonstrate that pine needles exhibit strong antioxidant, antimutagenic, and antiproliferative effects on cancer cells and also antitumor effects in vivo and point to their potential usefulness in cancer prevention.

Since it has been reported that Perilla leaves (Perilla frutescens) have antimutagenic, antioxidant, and anti-inflammatory properties, we hypothesized that Perilla leaves may have a potential anticancer activity. Therefore, we examined the possibility that cancer cell growth is reduced by treatment with a Perilla leaf ethanol extract (PLE) using human leukemia HL-60 cells and then investigated the mechanism of the growth inhibition. We found that PLE treatment suppressed cell viability in a dose-dependent manner. Flow cytometric analysis revealed that PLE treatment caused the appearance of a sub-G1 DNA peak and induced cell cycle arrest at the G1 phase. We detected DNA ladders in PLE-treated cells by agarose gel electrophoresis, and the cleavage of pro-caspase-3 and poly(ADP-ribose) polymerase with remarkable activation of caspase-8, -9, and -3. Western blot analysis revealed dose-dependent increases in Bax and cytochrome c in cytosol fractions and decreased Bid and pro-caspase-8 and -3 in PLE-treated cells. In addition, glucose-regulated protein 78, phosphorylated eukaryotic translation initiation factor 2 subunit alpha, phosphorylated c-jun N-terminal kinase, and p21 levels were increased by PLE treatment in a dose-dependent manner, whereas the p27 level was not changed. We concluded that PLE induced apoptosis through the combinations of mitochondrial, death receptor-mediated, and endoplasmic reticulum pathways and suppressed the cell proliferation via p21-mediated G1 phase arrest in HL-60 cells.

It is known that a close relationship exists among oxidative damage, senescence, and aging. Water dropwort (Ostericum sieboldii Miq. Nakai) and Sedum (Sedum sarmentosum Bunge) are popular green vegetables in Korea and are reported to have strong antioxidative activity. We investigated whether dropwort and Sedum have the potential to prevent aging using H(2)O(2)-induced prematurely senescent human diploid fibroblasts (HDFs). Dropwort and Sedum had similarly high contents of polyphenols, but dropwort had a flavonoid content about twofold higher than that of Sedum. Exposure of young HDFs to H(2)O(2) induced G2/M cell cycle arrest, positive senescence-associated (SA) beta-galactosidase (beta-gal) staining, and elevated p53, p21, and p16 protein levels. However, cotreatment with dropwort or Sedum ethanol extract significantly lowered p53, p21, and p16 levels and intracellular reactive oxygen species levels and attenuated the cell cycle arrest compared with H(2)O(2)-alone treatment. Interestingly, the increase in p16 level was prevented more quickly and clearly by dropwort treatment than Sedum treatment. The number of SA beta-gal-positive cells at 7 days after treatment was significantly reduced in dropwort-treated cells compared to H(2)O(2) alone-treated cells, whereas it was slightly reduced in Sedum-treated cells with no significance. In conclusion, dropwort showed a potential anti-senescence activity in H(2)O(2)-treated HDFs, which might be mediated by reducing p16, p21, and p53 levels and oxidative stress.

Ascorbate peroxidase (APX), an antioxidant enzyme, scavenges H202 that is produced by normal metabolism and cellular oxidative stresses. To investigate its role during germination and seedling growth, we isolated a cDNA encoding cytosolic APX (cAPX) in hot pepper (Capsicum annuum L.). The full-length clone, Ca-cAPX1, is 1011 bp long and has an ORF encoding 249 amino acid residues. During seedling development, cAPX activity and expression levels were higher at Days 5 and 6 post-imbibition, respectively, whereas those of catalase (CAT) increased at Days 8 and 10. The increased amount of H202 in that early developmental stage (Day 5) may have been counteracted mainly by APX, and further removed by CAT in cooperation with APX. To determine whether the accumulation of H202 via suppression of cAPX expression might be a factor in stimulating germination, we constructed a transformant of Ca-cAPX1. Compared with the wild type, the germination rate for the antisense-suppressed Arabidopsis increased by 26%, while its H202 content rose by 50%. Therefore, we propose that the pre-germination suppression of cAPX expression stimulates seed germination by promoting the accumulation of H~Oz