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Beta-cryptoxanthin [β-CRX, (3R)-β, β-caroten-3-ol] is a provitamin A and a potent antioxidant that is abundant in Satsuma mandarin orange (Citrus unshiu MARC.), which is the most popular fruit in Japan. The anti-stress effect of β-CRX on humans was evaluated in fifth-year university students during both routine daily life at the university and at pharmacy practice. The study design was a double-blind group comparison and participants (n=20; female 12, male 8) were randomly assigned to β-CRX-rich orange juice or placebo (β-CRX was removed from orange juice) groups. β-CRX or placebo juice (125 mL, once a day, after breakfast) were consumed from 10 d prior to the pharmacy practice and continued for 10 d into the practice period. To assess participants' anxiety, the state-trait anxiety inventory test was carried out before the pharmacy practice. Salivary α-amylase activity (sAA) was measured as a marker of sympathetic nervous system activity. In the placebo-group, sAA in the evening (post-practice sAA) tended to be higher than sAA in the morning (pre-practice sAA) during both routine daily life at the university and during pharmacy practice. In the β-CRX-group, the increase of post-practice sAA was suppressed in females. These results suggested that β-CRX has an anti-stress effect, at least, in females.

Increased oxidative stress is known to accelerate age-related pathologies. Beta-cryptoxanthin (β-CRX, (3R)-β,β-caroten-3-ol) is a potent antioxidant that is highly rich in Satsuma mandarin orange (mandarin), which is the most popular fruit in Japan. We investigated the antioxidative and anti-aging effects of β-CRX and mandarin using senescence-accelerated mice (SAMP10), which were characterized by a short lifespan, high generation of superoxide anions in the brain and poor learning ability with aging. β-CRX (0.5-5.0 µg/ml) or mandarin juice (3.8-38.0%) was added to drinking water of SAMP10 one to 12 months of age. β-CRX was dose-dependently incorporated into the cerebral cortex and the contents were similar to the concentration of β-CRX in the human frontal lobe. These mice also had higher learning ability. The level of DNA oxidative damage was significantly lower in the cerebral cortex of mice that ingested β-CRX and mandarin than control mice. In addition, the mice that ingested β-CRX (>1.5 µg/ml) and mandarin (>11.3%) exhibited a higher survival when 12 month-old, the presenile age of SAMP10, than control mice. These results suggest that β-CRX is incorporated into the brain and has an important antioxidative role and anti-aging effect.

Successful avoidance of the immune surveillance system is critical for the development of a blood-borne metastasis. Previous findings suggest that experimental tumor metastasis was enhanced in senescence-accelerated mice prone 10 (SAMP10) due to a reduction in immune surveillance potential with age. In the present study, water containing green tea (GT)-catechins was freely given to SAMP10 mice, and the chemopreventive effect of GT-catechin intake on tumor metastasis was examined. Natural killer cell activity, which is an indicator of immune surveillance potential and is reduced in control mice with age, was maintained by GT-catechin intake. The early accumulation of lung-metastatic K1735M2 melanoma cells in lungs after intravenous injection of the cells and subsequent experimental lung metastasis was investigated in mice given GT-catechins. The accumulation at 6 and 24 h after injection of K1735M2 cells was significantly suppressed, and the number of lung-metastatic colonies was significantly reduced, in comparison with those in control mice. The results suggest that GT-catechin intake prevented the experimental tumor metastasis in aged SAMP10 mice via its inhibition of a reduction in immune surveillance potential with age.

Relaxin-3 is a recently discovered member of the insulin superfamily and is a ligand for three orphan G-protein-coupled receptors: GPCR135, GPCR142 and LGR7 (leucine-rich repeat-containing G-protein-coupled receptor 7). GPCR135 mRNA is expressed in the pancreas, however, it is not known, whether the peptide affects pancreatic islet function. Reverse transcriptase (RT)-PCR and radioreceptor assay have shown that the relaxin-3 receptor (GPCR135) is expressed in pancreatic islets and rat insulinoma, but LGR7 is not expressed. Moreover, relaxin-3 has been revealed to inhibit the secretion of insulin from pancreatic islets. However, we can not detect relaxin-3 in small intestine and pancreas. These results suggest a novel role of relaxin-3 in the regulation of insulin release.

Mammalian small heat shock protein (s-hsp) has been suggested to participate not only in stress tolerance but also in the growth regulation and differentiation of cells. To confirm the role of s-hsp in cell growth, we investigated the relationship between the expression of hsp26 and yeast cell growth. Cells lacking constitutive hsp70, ssa1ssa2, have been known to have a poor growth rate and to over-express hsp26 and some other hsps. We obtained several cell clones of ssa1ssa2 whose doubling times were different from one another. The amount of hsp26 was closely linked to the doubling time of ssa1ssa2 cells. This result suggests that the expression of hsp26 modulates the growth rate of yeast cells lacking constitutive hsp70, similarly to mammalian cells.

The effect of deuterium oxide (D2O) was examined on the cell growth of photoautotrophically growing Chlorella ellipsoidea. The growth rate was inversely proportional to the concentration of D2O in the medium up to 60 mol%. The growth in D2O medium at concentrations higher than 60 mol% was highly inhibited. However, the cells pre-cultured in 60 mol% D2O medium became able to grow even in practically 100 mol% D2O medium. Deuterium (D) was incorporated into cells proportionally to the concentration of D2O in the medium. The D/H ratio in the cells was lower than that of the cultivation medium. Chlorella cells cultured in practically 100 mol% D2O medium contained ca. 70 mol% D. Of the D incorporated into cells, about 20% was easily exchangeable with H, and the remaining 80% was unexchangeable.

The isotope effect of deuterium (D) on cellular thermo-response, one of the major cell functions, was pursued by using deuterated Chlorella ellipsoidea which was grown in D2O medium and deuterated proportionally to the concentration of D2O in the medium. The deuterated Chlorella (D-Chlorella) cells heat-treated at 43°C in H2O medium were more heat-sensitive than control Chlorella (H-Chlorella) cultured in H2O medium. The D-Chlorella cells grown in higher mol% D2O were more heat-sensitive than those grown in lower mol% D2O. On the other hand, both the D- and H-Chlorella cells heat-treated at 43°C in D2O medium were more heat-resistant than in H2O medium. The degree of heat resistance was linearly proportional to the concentration of D2O in the medium. These results suggest that D in the medium and cells had two opposite effects on Chlorella; deuteration of poorly exchageable regions of biomolecules in the cells made Chlorella heat-sensitive, and both D2O in the medium and D in easily exchangeable regions caused Chlorella to be heat-resistant.