The fruit of mume, Japanese apricot (Prunus mume Sieb. et Zucc.), was evaluated for its phenolics content, high performance liquid chromatography (HPLC) profile and antioxidative activities. The phenolics content of mume fruit was relatively high, the flesh of fully matured fruit containing up to 1% of phenolics on a dry weight basis. Reflecting such a high content of phenolics, the ORAC (oxygen radical absorbance capacity) value for mume fruit flesh showed high values, ranging from 150 to 320 µmol/g Trolox equivalent, depending upon the stage of maturation. 5-O-Caffeoylqunic acid (chlorogenic acid), 3-O-caffeoylquinic acid and tetra-O-acylated sucrose-related compounds were isolated from the flesh of mume fruit, although many unknown peaks were also apparent in the HPLC chromatogram. An alkali hydrolysate comprised four main phenolic acids, caffeic acid, cis/trans-p-coumaric acid and ferulic acid. No flavonoids were observed in the analysis. These results suggest that the majority of phenolics in mume fruit were hydroxycinnamic acid derivatives.

In a study on improving utilization of waste from processing of Satsuma mandarin (Citrus unshiu Marcov.) the limonoid glucosides of fruit, juice, and by-products were measured using HPLC and TLC. All materials had the 17-P-D-glucopyranoside derivatives of limonoids reported in other commercial citrus fruit. Citrus molasses was a good source for industrial scale extraction of limonoid glucosides. An extraction system using polystyrene divinylbenzene resins, was developed which could be expanded to industrial scale.

Mume fruit, the Japanese apricot (Prunus mume SIEB. et ZUCC.), is popular in Japan and is mostly consumed in the pickled form called umeboshi. This fruit is known to have anti-microbial properties, but the principal constituents responsible for the antimicrobial properties have not yet been elucidated. We investigated the antimicrobial activities of the phenolic compounds in P. mume against enterobacteria. In this study, growth inhibitory activities were measured as an index of the antibacterial activities. The phenolic compounds were prepared from a byproduct of umeboshi called umesu or umezu (often translated as "mume vinegar"). Umesu or umezu phenolics (UP) contain approximately 20% phenolic compounds with p-coumaric acid as a standard and do not contain citric acid. We observed the inhibitory effects of UP against the growth of some enterobacteria, at a relatively high concentration (1250-5000 µg/mL). Alkali hydrolysates of UP (AHUP) exhibited similar antibacterial activities, but at much lower concentrations of 37.5-300 µg/mL. Since AHUP comprises hydroxycinnamic acids such as caffeic acid, p-coumaric acid, and ferulic acid, the antibacterial activities of each of these acids were examined. Our study shows that the phenolic compounds in P. mume other than citric acid contribute to its antimicrobial activity against enterobacteria in the digestive tract.

No abstract

Aurapten (7-geranyloxycoumarin) has been reported to be an effective inhibitor of chemical carcinogenesis in some rodent models. In the present study, a method for preparing an aurapten-enriched agricultural product has been established. Out of 17 Rutaceae varieties, the aurapten content in hassaku (Citrus hassaku Hort ex Y. Tanaka) fruit peel was marked, as well as that in natsumikan (C. natsudaidai) and grapefruit (C. paradisi). The aurapten content in hassaku peel was most abundant in April. Hassaku fruit peel oil, which was dissolved by heating precipitates including aurapten which had formed after freezing the peel oil at -20 degrees C, was used. After adsorbing aurapten from peel oil onto synthetic adsorbent SP70, the adsorbent was washed with 40% (v/v) ethanol in water to remove essential oils and pigments remaining on the adsorbent. Aurapten was then eluted with 80% (v/v) ethanol. In a laboratory-scale test, the recovery rates of aurapten and total carotenoids from the eluates were 74.3 and 4.6%, respectively. In a pilot-scale test, the recovery rate of aurapten in the aurapten-enriched preparation from dissolved hassaku oil was 91.0%, and its concentration was 64.1% (w/w). When stored for 180 days under sunlight, aurapten in powder form remained at 88.0-89.0% of the initial level, but only 31.3-43.8% in ethanol. The stability of aurapten in the aurapten-enriched preparation was higher than that of purified aurapten. These results suggest that aurapten is readily recovered from hassaku peel oil using SP70, and thus may be used as a food additive.