Effects of bilobalide, a sesquiterpene in Ginkgo biloba leaves, on population spikes in rat hippocampal slices.

The effects of bilobalide, a sesquiterpene isolated from the leaves of Ginkgo biloba L., were investigated in a rat hippocampal slice preparation. Bilobalide (10-500 microM) significantly increased the amplitude of population spikes evoked by electrical stimulation of Schaffer collateral/commissural fibers in a concentration-dependent manner. Paired-pulse inhibition at interpulse intervals of 10-50 ms was significantly reduced in the presence of bilobalide (50 microM). The inhibitory action of muscimol (1 microM) was attenuated by bilobalide (100 microM). These results suggest that bilobalide induces an enhancement of excitability of CA1 pyramidal neurons, which involves, at least in part, a reduction in GABAergic inhibition in rat hippocampus.

Columbin isolated from calumbae radix affects the sleeping time of anesthetized mice.

In a screening series of bioactive components in edible and medicinal plants, we found that Calumbae Radix (Colombo root, 1% powdered feed, for 5 d) and its component, columbin (20-40 mg/kg/d, for 5 d, orally), shortened the sleeping time induced by a urethane and alpha-chloralose mixture and prolonged the sleeping time induced by hexobarbital in mice.

[Studies on the constituents of edible and medicinal plants. IV. Determination of 4-O-methylpyridoxine in serum of the patient with gin-nan food poisoning].

The serum 4-O-methylpyridoxine (MPN) levels in a 21 months-old patient with gin-nan food poisoning were determined by HPLC. The blood of the patient was taken at 8.5 and 15.5 h after taking about 50 ginkgo albumens. After deproteinization of the serum, the supernatant was pretreated with Sep-pak C18 cartridge and was applied to HPLC. HPLC was performed with a Hibar LiChrosorb RP-18 (4.0 mm i.d. x 250 mm, 7 microns) using a fluorescence detector (wave length of excitation and fluorescence; 290 and 400 nm, respectively). The serum MPN level was determined by the absolute calibration method. The determination limit of MPN in the serum was 0.05 micrograms/ml. The serum MPN concentration was 0.09 micrograms/ml at 8.5 h after taking ginkgo seeds, and was less than the determination limit of MPN (0.05 micrograms/ml) at 15.5 h. MPN, isolated from the seed of Ginkgo biloba L., is responsible for "gin-nan food poisoning," and its cardinal symptoms are mainly tonic and/or clonic convulsions and loss of consciousness. Infants are particularly vulnerable. This method may be available for proving the gin-nan food poisoning, chemically.

Isolation of bilobalide and ginkgolide A from Ginkgo biloba L. shorten the sleeping time induced in mice by anesthetics.

The leaves of Ginkgo biloba L. and aqueous extract from them shortened the sleeping time induced in mice by anesthetics (hexobarbital, alpha-chloralose and urethane, i.p.). Two characteristic terpenoids in G. biloba, bilobalide and ginkgolide A, significantly shortened the sleeping time induced by anesthetics. A toxic substance, 4-O-methylpyridoxine (MPN), responsible for "gin-nan food poisoning" isolated from the seed of G. biloba, was not detected from the extract of the leaves of G. biloba. Therefore, the Ginkgo biloba extract has no toxicities for MPN.

Studies on the constituents of edible and medicinal plants. III. Effects of seven limonoids on the sleeping time induced in mice by anesthetics.

Effects of seven limonoids, obakunone (1), 7 alpha-obakunol (2), 7 beta-obakunol (3), limonin (4), 7 alpha-limonol (5), 7 beta-limonol (6) and nomilin (7), on the sleeping time induced in mice by anesthetics were assayed. All the limonoids, except for 2, shortened the sleeping time induced by alpha-chloralose and urethane. 7 gave the highest reduction rate of sleeping time, and the order of the reduction rate of sleeping time was as follows; 7 > 1 and 3 > 4, 5 and 6. As the chemical structures of these compounds are similar to each other, the relationship between the structure and the effects of limonoids on sleeping time was discussed.

Safety examination of some edible plants, Part 2.

The carcinogenicity of cacalia, dandelion, ostrich-fern, and aralia, which are wild plants used as human food or folk medicine, and of burdock, bambooshoots, and lotus, which are cultivated as vegetables in Japan, was examined in an inbred strain ACI rats. Fresh plant materials were dried, milled, and mixed with the rat basal diet in the ratio of 4--33% of the total. These diets thus prepared were administered to rats for periods ranging upward from 120 days. However, carcinogenic activity was not observed in any of the plants so far tried.