The antibacterial activity of 14 essential oils and their major constituents in the gaseous state was evaluated against Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. For most essential oils examined, H. influenzae was most susceptible, followed by S. pneumoniae and S. pyogenes, and then S. aureus. Penicillin-susceptible and -resistant S. pneumoniae were comparable in susceptibility. Escherichia coli, which was used as a control, showed least susceptibility. A minimal inhibitory dose (MID) was introduced as a measure of the vapour activity. Among 14 essential oils, cinnamon bark, lemon-grass and thyme oils showed the lowest MID, followed by essential oils containing terpene alcohols as major constituents. The essential oils containing terpene ketone, ether and, in particular, hydrocarbon had high MIDS. The vapour activity on short exposure was comparable to that following overnight exposure, and rapid evaporation was more effective than slow evaporation of essential oils. The vapour concentration and absorption into agar of essential oils reached a maximum 1 or 2 h after rapid evaporation. These results indicate that the antibacterial action of essential oils was most effective when at high vapour concentration for a short time.

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The antioxidant components of cacao liquor, which is a major ingredient of chocolate, were isolated with column chromatography and high-performance liquid chromatography. Quercetin and its glucoside were identified by spectrometric methods. Clovamide and deoxyclovamide were characterized by (1)H and (13)C NMR and MS spectrometry. Their antioxidative activity was measured by peroxide value of linoleic acid and thiobarbituric acid reactive-substance value of erythrocyte ghost membranes and microsomes. In the bulk oil system, clovamide had the strongest antioxidative activity but was less active in the other experiments. In the case of the two hydrophilic systems, flavans such as quercetin and epicatechin were more potently effective than the glucosides. It is considered that chocolate is stable against oxidative deterioration due to the presence of these polyphenolic compounds.

We compared levels of (ϩ)-catechin, (Ϫ)-epicatechin, and their metabolites in rat plasma and urine after oral administration. Rats were divided into four groups and given (ϩ)-catechin (CA group), (Ϫ)-epicatechin (EC group), a mixture of the two (MIX group) or deionized water. Blood samples were collected before administration and at designated time intervals thereafter. Urine samples were collected 0 -24 h postadministration. (ϩ)-Catechin, (Ϫ)-epicatechin and their metabolites in plasma and urine were analyzed by HPLC-mass spectrometry after treatment with ␤-glucuronidase and/or sulfatase. After administration, absorbed (ϩ)-catechin and (Ϫ)-epicatechin were mainly present in plasma as metabolites, such as nonmethylated or 3Ј-O-methylated conjugates. In the CA and MIX groups, the primary metabolite of (ϩ)-catechin in plasma was glucuronide in the nonmethylated form. In the EC and MIX groups, in contrast, the primary metabolites of (Ϫ)-epicatechin in plasma were glucuronide and sulfoglucuronide in nonmethylated forms, and sulfate in the 3Ј-O-methylated forms. Urinary excretion of the total amount of (Ϫ)-epicatechin metabolites in the EC group was significantly higher than the amount of (ϩ)-catechin metabolites in the CA group. The sum of (ϩ)-catechin metabolites in the urine was significantly lower in the MIX group than in the CA group, and the sum of (Ϫ)-epicatechin metabolites in the MIX group was also significantly lower than in the EC group. These results suggest that the bioavailability of (Ϫ)-epicatechin is higher than that of (ϩ)-catechin in rats, and that, in combination, (ϩ)-catechin and (Ϫ)-epicatechin might be absorbed competitively in the gastrointestinal tract of rats.