調理後の甘さが大きく異なる多様なサツマイモ品種·系統や育種素材を供試して，塊根のβ-アミラーゼ活性およびデンプンの含量，糊化温度と蒸しいものマルトース含有率との関係を調べた．マルトース含有率はβ-アミラーゼ活性の上昇に伴って増加したが，活性が約0.2 m mole maltose/min/mg proteinを越えると含有率の増加は抑制された．マルトース含有率とデンプン含有率との間には相関が認められなかったが，デンプン糊化温度との間には弱い負の相関が認められた．特に，β-アミラーゼ活性が高い塊根では糊化温度が低いほどマルトース含有率が高い傾向が見られた．また，デンプンの糊化温度が比較的高い品種「ベニアズマ」を本州より気温の低い北海道で栽培すると，糊化温度が有意に低下し，β-アミラーゼ活性は同等かあるいはそれ以下にも拘わらず，マルトース含有率が有意に高くなった．サツマイモの加熱調理に伴うマルトース生成には塊根のβ-アミラーゼ活性に加えてデンプンの糊化し易さも重要であると考えられた．
Considerable differences were found in the incidence of age-associated diseases and the mean lifespan between countries of similar social background. Previously, the inhibition of age-associated disease progression was considered to be attributable to anti-oxidants in foods, such as isoflavones and resveratrol. However, the results of recent studies do not support the role of anti-oxidants in the inhibition of age-associated diseases and senescence. We have reported that healthy foods such as beans, mushrooms, seafoods and vegetables, and healthy dietary traditions such as the Mediterranean diet and Japanese foods are rich in polyamines (spermine and spermidine). Polyamines are synthesized in rapidly growing cells; however, this ability decreases with aging. In addition to de novo synthesis, cells can take up polyamines from their surroundings. An important source of whole body polyamines originates in the intestinal lumen, e.g., food-derived polyamines. Polyamines in the intestinal lumen are absorbed quickly, and continuously increased polyamine intake elevates blood polyamine levels in humans and mice. In addition to the many biological activities that help protect cells and tissues from harmful stimuli, we have shown that polyamines suppress pro-inflammatory status, characterized by the suppression of leukocyte function associate antigen 1 (LFA-1) expression and pro-inflammatory cytokine production. Moreover, increased intracellular spermine from extra-cellular sources enhanced the activities of DNA methyltransferases (DNMT) and suppressed polyamine deficiency-induced genome-wide demethylation/methylation in vitro. Long-term increased polyamine intake inhibited age-associated pathological changes and suppressed abnormal genome-wide demethylation/methylation in Jc1 : ICR male mice. In addition, increased polyamine intake was associated with a decreased incidence of colon tumors in BALB/c mice after 1,2-demethylhydrazine administration. Aging is associated with decreased polyamine synthesis, enhanced pro-inflammatory status (e.g., increased LFA-1 expression), decreased DNMT activities, and enhanced genome-wide demethylation/methylation; therefore, dietary polyamine represents a valuable food element to suppress age-associated pathologies and extend the lifespan of humans.
Hot water extracts of green soybean, Glycine max (WEGS) significantly decreased the levels of ovalbumin (OVA)-specific IgE in mice and significantly suppressed toluene diisocyanate-induced nasal mucosa secretion. An open-label human pilot study including 16 subjects with Japanese cedar pollinosis (JCP) was conducted. The symptom scores for JCP were better in the long-term WEGS intake group than in the short-term intake group. WEGS have great potential as an orally active immune modulator for the treatment of various allergic diseases. We conducted a preliminary investigation of the effects of visible light irradiation on plant extracts, and observed a strong suppressive effect on interleukin (IL)-2 expression in Jurkat cells following treatment with visible light-irradiated ethanol extract from green soybeans (LIEGS). This effect was produced only by extracts from green soybeans and not soybeans of other colors. LIEGS suppressed lipopolysaccharide-induced IL-6, IL-12, and TNF-α expression levels in human monocyte THP-1 cells in a concentration-dependent manner. LIEGS suppressed the development of atopic dermatitis-like skin lesions and reduced the dermatitis scores of NC/Nga mice.