Masaki Miyake

Biochemistry and biological functions of citrus limonoids

Abstract Limonoids are one of bitter principles in citrus juices. Excessive bitterness lowers the quality and value of citrus juices. Nomilin is considered to be the precursor of all other limonoids accumulated in Citrus and related species. It is biosynthesized from acetate via the terpenoid biosynthetic pathway in the phloem region of stems and then translocated to the leaves, fruit tissues, peels, and seeds where it is further metabolized to other limonoids. The citrus limonoid aglycones are then glucosidated by limonoid UDP‐D‐glucose transferase in maturing fruit tissues and seeds. These limonoid glucosides are accumulated in such high concentrations that they are one of major secondary metabolites in citrus fruit tissues, and they play an important role in fruit quality and possibly in human health. Research on creation of transgenic citrus trees that produce fruits free of the limonoid bitterness problem is in progress. Limonoids have been shown to induce glutathione S‐transferase activity and inhib...

Accelerated Death Kinetics of Aspergillus niger Spores under High-Pressure Carbonation

ABSTRACT The death kinetics of Aspergillus niger spores under high-pressure carbonation were investigated with respect to the concentration of dissolved CO2 (dCO2) and treatment temperature. All of the inactivation followed first-order death kinetics. The D value (decimal reduction time, or the time required for a 1-log-cycle reduction in the microbial population) in the saline carbonated at 10 MPa was 0.16 min at 52°C. The log D values were linearly related to the treatment temperature and the concentration of dCO2, but a significant interaction was observed between them.

Promoting Effect of Kaempferol on the Differentiation and Mineralization of Murine Pre-osteoblastic Cell Line MC3T3-E1

A number of agents have been reported to influence osteoblastic differentiation and to prevent and treat bone loss. We found that kaempferol, a flavonoid identified in extracts of the medicinal plant, Polygonum tinctorium. Lour, had stimulatory effects on the differentiation and mineralization of the murine pre-osteoblastic cell line, MC3T3-E1. After enhancing the alkaline phosphatase activity, significant augmentation of calcification by kaempferol was observed between concentrations of 10 and 20 μM, without any marked effect on cell proliferation. When kaempferol was combined with ipriflavone, which is clinically applied to treat bone loss, calcification was synergistically augmented, suggesting that these two flavonoids may have different mechanisms of action. These results suggest that kaempferol may be a promising agent for the prevention or treatment of bone loss, especially when combined with ipriflavone.

Limonoid glucosides inCitrus aurantium

Abstract 17-β- d -Glucopyranosides of limonin, obacunone, deacetylnomilin, nomilin, deacetylnomilinic acid, nomilinic acid, isolimonic acid, ichangin and 19-hydroxydeacetylnomilinic acid were isolated from sour orange seeds. The aglycone of the latter compound is a possible intermediate in the biosynthesis of limonin.

Ichangensin glucoside in citrus junos, citrus sudachi and citrus sphaerocarpa

Abstract Ichangensin 17-β- d -glucopyranoside, a new limonoid glucoside, was isolated from seeds of Yuzu (Citrus junos). This glucoside was also present in seeds of Sudachi (Citrus sudachi) and Kabosu (Citrus sphaerocarpa). The 17-β- d -glucopyranosides of deacetylnomilin, nomilin, nomilinic acid, obacunone, limonin and deacetylnomilinic acid were also present in seeds of these species of citrus. Like Sudachi and Yuzu, Kabosu also contained ichangensin aglycone. The presence of ichangensin and ichangensin glucoside supports the previous suggestions that these species are related to Ichang Chie (Citrus ichangensis).

Studies on chemical and technological aspects of celery (Apium graveolens Linn) seed.

In order to utilize Satsuma mandarin peel residue effectively, which contains many useful compounds, the method of extraction and recovery of hesperidin from dried Satsuma mandarin peel residue was studied. The results obtained were as follows; (1) The hesperidin content in a extracted solution was the highest, when the residue was extracted for 30 min with stirring at 20~40°C. (2) The optimum pH for crystallization of hesperidin from the extracted solution was around 5.0. And the recovery became much higher by heating the solution adjusted to pH 5.O in the range of 70~90°C. (3) Therecovery yields were remarkably influenced by the quantity of added water to the residue. The best result was obtained by adding 800ml of water to 100g of the sample. In this condition, the recovery and purity of hesperidin was 27.3% and 93.7%, respectively. (4) To recover hesperidin effectively, it is necessary to adjust the hesperidin content in the extracted solution to approximately 500mg/100ml. Also, a higher yield (53.0%) was obtained by recycling the secondary extracted solution after concentration. (Received Nov. 20, 1989)

Limonoid Glucosides in Juices of Satsuma Mandarin (Citrus unshiu Marc.)

(1992). Limonoid Glucosides in Juices of Satsuma Mandarin (Citrus unshiu Marc.) Bioscience, Biotechnology, and Biochemistry: Vol. 56, No. 5, pp. 836-837.

Limonoid glucosides in Tetradium rutaecarpa

Abstract Limonin 17-β- d -glucopyranoside, limonin diosphenol 17-β- d -glucopyranoside and 6β-hydroxy-5-epilimonin 17-β- d -glucopyranoside were isolated from Tetradium rutaecarpa fruit tissues. The limonoid aglycones were identified by 1 H and 13 C NMR spectroscopy. Limonin, rutaevin and limonin diosphenol were also isolated.

Quality of Hesperidin Removed Satsuma Mandarin (Citrus unshiu Marc.) Juice

搾汁直後の温州ミカン果汁中のヘスペリジンを合成吸着剤で吸着除去した果汁の品質について調べ,次の結果を得た。(1) ヘスペリジン含量75mg区のびん詰製品は製造直後からヘスペリジンが急速に不溶化し,50mg区,25mg区を含め可溶性ヘスペリジンが10mg以下でほぼ平衡となった。(2) びん詰製品上澄部のパルプは,不溶化したヘスペリジンと結合して沈降し,0.2%程度でほぼ平衡となった。(3) 25mg区,50mg区の製品は,びん壁にフロックが付着したが,75mg区はフロックが急速に沈降した。除去区はフロックの形成が全く認められなかった。(4) 製品上澄部のパルプの粒度分布は,時間の経過と共に2μ以下に片寄ったが,除去区は1～10μの広い範囲に分散した。(5) 製品上澄部の果汁成分は,20℃, 20日間の貯蔵で対照区に比べ除去区のパルプ含量が約5倍,カロチノイドが約2.5倍,濁度が約4倍も高い値を示し,精油が製造直後の65%も保持された。