Kiyoshi Kameda

Diglucuronoflavones from purple leaves of Perilla ocimoides

Three flavones from purple leaves of Perilla ocimoides var. crispa were characterized as the 7-O-diglucuronides of apigenin, luteolin, and scutellarein. The latter is a new natural compound.

Structures of alatanin A, B and C isolated from edible purple yam Dioscorea alata

Abstract Three new anthocyanins, alatanins A,B and C, were isolated from the tuber of purple yam Dioscorea alata , and their structures were determined by means of NMR spectroscopy including NOE and HOHAHA of their pertrifluoroacetylates.

Prevention of UV-light induced E,Z-isomerization of caffeoyl residues in the diacylated anthocyanin, gentiodelphin, by intramolecular stacking

Abstract Prevention of UV-B light induced E , Z -isomerization of caffeoyl residues in a diacylated anthocyanin, gentiodelphin, by molecular stacking was studied. We first isolated an isomer of gentiodelphin containing a Z -caffeoyl residue from an acidic methanol solution, irradiated with UV-B light. The isomerized pigment had only one Z -configurated caffeoyl residue, attached to the glucose of the 5-position. Under the irradiation conditions the other caffeoyl residue linking to the glucose on B-ring stacked to the anthocyanidin nucleus and did not isomerize. In acidic and neutral aqueous solutions the content of the Z -isomer was very low when the isomerization reaction was at equilibrium, intramolecular stacking of the caffeoyl residues being stronger than in acidic methanol. Therefore, intramolecular stacking may prevent light-isomerization of the α,β double bond of caffeoyl residues. Under physiological conditions the pigment was more tolerant of UV-irradiation, which may play an important role in quenching solar radiation energy in flower petals.

Study of Waste Fly Powder (Tobiko) Availability Resulting from Konnyaku (Amor-phophalluskonjac) Powder Production Process

1997～1999年度産の飛粉と精製飛粉について組織構造, 臭気物質, 色調, 成分含有量を測定し, 精製操作の超音波処理効果と飛粉の食品素材としての改良を検討した.1) 飛粉素材S (無処理) の色調・臭気物質・無機成分値に, 有意差が認められ, 生産年度による影響があることを認めた.2) SEMによる組織学的観察では, 最適な精製条件の25%エタノールにて照射時間10分間と5分間 (合計15分間) の2段階処理した飛粉 (素材A) は成分粒子が分散形態であったが, 非照射処理の飛粉 (素材B) 粒子は凝集が観察され, 照射が差異を生じさせ精製をもたらした.3) 照射した素材Aは同条件下の非照射の素材Bに比し, TMA, DMA値が有意に低値を示し臭気成分が減少し, 色の褐色度は低下した.4) 3年間共通して精製による損失は, 脂質が最も大きく, 次に灰分, たんぱく質の順であった. 成分的には年次間の傾向は炭水化物, 食物繊維, たんぱく質, K, Ca, Pなどの無機質が比較的多く存在するが, 素材A, B間に有意差は認められず, 精製による損失はわずかであった.5) 素材Aの遊離アミノ酸ではアミノ酸の種類により異なるものの77%以上残存し, アスパラギン酸, セリン, アラニン, グルタミン酸, アルギニン, バリン, フェニルアラニン, イソロイシンなど呈味発現に関するアミノ酸を含有していた. しかし, シスチンとメチオニンは検出されなかった.