[Contents of furanocoumarins in grapefruit juice and health foods].

Interactions between grapefruit juice and medications have long been recognized. In recent years, several furanocoumarins (FCs) that inhibit P450 activity in intestinal microsomes have been isolated from grapefruit juice. FCs, i.e., bergamottin (BG), bergapten (BP), bergaptol (BT) and 6',7'-dihydroxybergamottin (DHB), in samples was extracted with acetonitrile, and separated on a Phenyl column using 0.1% phosphoric acid-acetonitrile gradient as a mobile phase, with monitoring at 311 nm. The recoveries of BG, BP, BT and DHB from lemon juice spiked at the level of 5.0 microg/g were 103+/-0.7%, 99.5+/-0.2%, 96.5+/-0.2% and 90.1+/-0.2%, respectively. The quantification limits were 1.0 microg/g in samples. The contents of BG, BP and DHB in grapefruit juice (n=13), citrus fruit of 20 species and health food (n=16) were measured. The contents of BG were 0-16 microg/g, 0-16 microg/g and 0-5.6 microg/g, BT were 0-39 microg/g, 0-13 microg/g and 0-28 microg/g, DHB were 0-10 microg/g, 0-35 microg/g and 0-6.2 microg/g, respectively. BP was not detected. These results suggest that patients prescribed calcium antagonists or antiallergic agents should be cautions about their intake of FCs from grapefruit juice, citrus and health foods.

[Simultaneous determination of neotame, alitame and aspartame in foods by HPLC].

Simultaneous determination of three artificial sweeteners, neotame (NE), alitame (AL) and aspartame (APM) in various foods by high-performance liquid chromatography (HPLC) was developed. Chopped or homogenized samples were packed into cellulose tubing with 0.01 mol/L hydrochloric acid containing 10% sodium chloride, and dialyzed against 0.01 mol/L hydrochloric acid for 24-48 hours. The dialyzate was passed through an Oasis MCX cartridge, and the cartridge was washed with water and methanol. Then the three sweeteners were eluted from the cartridge with a mixture of 0.5 mol/L ammonium chloride-acetonitrile (3 : 2). The sweeteners were separated on a Cosmosil 5C18-AR column using a gradient mode with a mobile phase of 0.01 mol/L phosphate buffer (pH 4.0)-acetonitrile and were detected at 210 nm. The recoveries of NE, AL and APM from 8 kinds of foods spiked with 10 and 100 microg/g were 86-100% and 89-104%, respectively. The detection limits of NE, AL and APM were 1 microg/g in samples. Furthermore, the three sweeteners were successfully identified by using liquid chromatography with tandem mass spectrometry.

[Survey of glycoalkaloids content in the various potatoes].

The content of potato glycoalkaloid (PGA) was investigated in 27 cultivars of raw potatoes and 31 potatoes in commercial foods with peel. The investigation of the 27 cultivars of potatoes showed different contents of glycoalkaloids. "May queen" and "Sherry" showed high contents of PGA (180 mg/kg and 320 mg/kg, respectively) among the raw potatoes of middle size (ca. 100 g). On the other hand, "Inca red" showed the lowest content of 21 mg/kg. Higher contents of PGA were found in smaller potatoes in this study. The content of PGA varied in the range of 48-350 mg/kg in the potatoes in commercial foods with peel.

[Example of examination of allergic substances (egg, milk) in commercial foods].

Allergic substances (eggs, milk) in commercial foods were measured by means of the notified ELISA methods using FASTKIT ELISA kit (N kit) and "Tokuteigenzairyo sokutei kit" (M kit). Some samples were also analyzed with the notified western blot method using "Tokuteigenzairyo western blot kit". In the methods for detection of eggs, proteins of fish egg and chicken muscle were examined using the ELISA and Western blotting methods to check for cross-reaction. Sujiko was false positive with the M kit. Difficulties were also encountered in the notified ELISA and Western blotting methods with raw chicken. In foods labeled as containing eggs, it was difficult to detected in the heart-processed food using both notified methods. In the method for detection of milk, foods containing thickening polysaccharides, showed cross-reaction with the N kit. However, this cross-reaction was eliminated when an improved N kit was used. Foods labeled as containing milk did not present any difficulty.

[Survey of histamine content in seafood on the market].

Food poisoning involving histamine has occurred almost every year for 20 years in Tokyo, and is usually due to ingestion of fish with lean meat, such as sardine, mackerel, horse mackerel and so on. Therefore, we were investigated the levels of histamine and 4 non-volatile amines (tyramine, putrescine, cadaverine, spermidine) in 637 samples on the market. The water activity of samples in which histamine was detected at 5 mg/100 g and over was examined. Histamine, tyramine, putrescine, cadaverine and spermidine were detected in 66, 43, 26, 64 and 5 samples, and the detection ranges were 5-340, 5-51, 5-42, 5-180 and 5-8 mg/100 g, respectively. Most of the samples in which histamine was detected were semi-dried round and split sardine. Water activity of 24 samples of semi-dried round and split sardine in which histamine was detected was in the range of 0.68-0.96.

[Contents and its change during storage of alpha-solanine and alpha-chaconine in potatoes].

Contents of alpha-solanine and alpha-chaconine in native species of potato (May Queen, Danshaku and Waseshiro), and in species (Jagakids Red '90 (Red) and Jagakids Purple '90 (Purple)) on the market, and their change during storage at room temparature were investigated. alpha-Solanine and alpha-chaconine were extracted from potatoes with methanol, cleaned up by using a Sep-Pak Plus C18 cartridge, and then subjected to HPLC. The recoveries of alpha-solanine and alpha-chaconine from potatoes were both more than 96%, and the quantitation limits were both 2 microg/g. alpha-Solanine and alpha-chaconine were detected in periderm in all samples at the levels of 260-320 microg/g in May Queen,190-240 microg/g in Danshaku, 43-63 microg/g in Waseshiro, 140-200 microg/g in Red and 84-130 microg/g in Purple, respectively. alpha-Solanine and alpha-chaconine were detected in the cortex in all samples of May Queen and Danshaku at the levels of 2.7-12 microg/g and 5.8-31 microg/g, respectively. Contents of alpha-solanine and alpha-chaconine in the cortex of May Queen and Danshaku were less than 10% of those in the periderm. When potatoes were stored for 90 days at room temparature in a dark place, no marked change in the contents of alpha-solanine and alpha-chaconine was observed in any of the potato samples.

[Structural analyses of barbaloin-related compounds in aloe drinks].

Four kinds of barbaloin (BA)-related compounds (A, B, C, D) in aloe drinks were isolated by using preparative HPLC. LC/MS analyses of these compounds showed the identical quasimolecular ion peak at m/z 833 [M-H]-. The chemical structures were mainly determined by NMR, including 1H-1H two-dimensional correlation spectroscopy (COSY), nuclear Overhauser and exchange spectroscopy (NOESY), heteronuclear multiple quantum coherence (HMQC), and heteronuclear multiple-bond connectivity (HMBC) experiments. They were identified as BA-related compounds A (10R, 10"S), B (10S, 10"S), C (10S, 10"R), and D (10R, 10"R) coupled through a C-10 to C-7' linkage, and newly found in nature. These results suggested that BA is converted to dimers during storage of aloe drinks.

[Contents of barbaloin-related compounds in aloe drinks and their change during storage].

The contents of barbaloin (BA), isoBA, aloin-dimers A, B, C, D and aloe-emodin (AE) in aloe drinks were investigated. BA and isoBA were detected in 30 of the 31 samples at the levels of 120-570 micrograms/mL and 120-580 micrograms/mL, respectively. Aloin-dimers A, B, C and D were detected in 8 of the 31 samples at the levels of 12-38 micrograms/mL, 13-39 micrograms/mL, 11-36 micrograms/mL and 16-69 micrograms/mL, respectively. AE was detected in all of the 31 samples at the levels of 0.03-1.3 micrograms/mL. When aloe drinks were stored for 4 weeks at 5 degrees C after opening the bottle, decrease of BA and isoBA, and increase of AE and aloin-dimers A, B, C and D were observed in most cases. However, in a few aloe drinks, all of BA, isoBA, aloin-dimers A, B, C, D and AE decreased. In these drinks, the existence of aloin-trimer was elucidated by LC/MS analyses. These data suggested that BA in aloe drinks is converted to the dimer and then to the trimer during storage.