Takao Tanahashi

Effects of extracts and neferine from the embryo of Nelumbo nucifera seeds on the central nervous system

The effects of embryos of the seeds of Nelumbo nucifera on the central nervous system were studied in mice. MeOH extracts of embryos of Nelumbo nucifera seeds significantly inhibited locomotor activity in mice. The MeOH extract was successively partitioned between H(2)O and n-hexane, between H(2)O and CHCl(3), and between H(2)O and n-BuOH. CHCl(3) extracts strongly inhibited locomotor activity in mice, although other extracts had no effect on locomotor activity. The main alkaloid of CHCl(3) extracts, neferine, dose-dependently inhibited locomotor activity in mice. Neferine induced hypothermia in mice and apparently potentiated thiopental-induced sleeping time. An anxiolytic, diazepam, decreased locomotor activity, rectal temperature and enhanced sleep elicited by thiopental, similar to neferine. In addition, neferine and diazepam showed anti-anxiety effects in the elevated plus maze test. Neferine did not affect muscle coordination by the rota-rod test. Neferine did not affect strychnine- nor picrotoxin-induced seizure. In contrast, diazepam had apparent muscle relaxant and anti-convulsant effects. These results suggest that neferine has several central effects and that neferine may participate in the efficacy of the sedative effects of embryos of the seeds of Nelumbo nucifera. The mechanisms of the sedative effects of neferine are not similar to those of diazepam.

6H-dibenzo[b,d]pyran-6-one derivatives from the cultured lichen mycobionts of Graphis spp. and their biosynthetic origin.

The spore-derived mycobionts of the lichen Graphis prunicola, G. cognata and G. scripta were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Graphislactones A-D were isolated from the cultures of G. prunicola, while alternariol and graphislactones A and C were isolated from those of G. cognata. From the cultured mycobionts of G. scripta, a new 6H-dibenzo[b,d]pyran-6-one derivative, graphislactone E with graphislactones A and C was obtained. On the other hand, cultivation of the mycobionts of G. prunicola on a malt-yeast extract medium supplemented with 2.5% sucrose and 0.25% sodium acetate produced two new metabolites, graphislactones E and F. Their structures were determined by spectroscopic methods. The biogenetic origin of the carbon skeleton in both compounds was verified by administering sodium [1-13C]-acetate and sodium [1,2-13C(2)]-acetate.

Enzymatic condensation of dopamine and secologanin by cell-free extracts of Alangium lamarckii

Abstract Two novel enzyme activities involved in the condensation of dopamine and secologanin were discovered in the cell-free extracts prepared from the leaves of Alangium lamarckii . The extracts condensed dopamine and secologanin rapidly at pH 7.5 to form both (1 R )-deacetylipecoside ( 1 ) and (1 S )-deacetylisoipecoside ( 2 ) which were converted spontaneously to demethylalangiside ( 3 ) and demethylisoalangiside ( 4 ), respectively. Indentification of the enzymatic reaction products was performed by using TLC, HPLC-photodiode array detector and LC-MS. A simple enzyme assay by a spectrophotometric method was developed for enzyme activity detection during enzyme purification. The discovery of these two enzyme activities in A. lamarckii suggested that the naturally occurring ( S )- and ( R )-forms of various tetrahydroisoquinoline-monoterpene alkaloids and nitrogenous glucosides found in this plant are determined by the first enzymatic step of dopamine and secologanin condensation which yields either the (1 R ) or the (1 S )-condensation product.

Xanthones from the cultured lichen mycobionts of Pyrenula japonica and Pyrenula pseudobufonia

Cultures of the spore-derived mycobionts of the Asian lichen Pyrenula japonica and the North American species P. pseudobufonia gave two xanthones, 1,5,8-trihydroxy-3-methylxanthone and 1,8-dihydroxy-5-methoxy-3-methylxanthone along with the known 1,7-dihydroxy-3-methylxanthone. Their structures were determined by spectroscopic methods. This is the first instance of the isolation of xanthones with a methyl group at C-3 from lichen mycobionts.

Antidepressant-like effects of neferine in the forced swimming test involve the serotonin1A (5-HT1A) receptor in mice.

The effects of neferine, an alkaloid of Nelumbo nucifera Gaertner embryos, on immobility in the forced swimming test, which is used to evaluate antidepressants, were investigated in mice. The administration of neferine from 25 to 100 mg/kg i.p. elicited anti-immobility effects in mice. The molecular dose effects of neferine in the forced swimming test were almost equal to those of the typical antidepressants maprotiline and imipramine. The involvement of the 5-HT receptor subtypes was also studied using 5-HT receptor antagonists. Anti-immobility effects of neferine are antagonized by the serotonin1A (5-HT1A) receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY 100635). However, the 5-HT1B receptor antagonist, 3-[3-(dimethylamino)propyl]-4-hydroxy-N-[4-(4-pyridinyl)phenyl] benzamide dihydrochloride (GR 55562), the 5-HT2 receptor antagonist, 6-methyl-1-(methylethyl)-ergoline-8beta-carboxylic acid 2-hydroxy-1-methylpropyl ester (LY 53857), the 5-HT3 receptor antagonist, ondansetron and the 5-HT4 receptor antagonist, 4-amino-5-chloro-2-methoxy-benzoic acid 2-(diethylamino)ethyl ester (SDZ 205,557) did not affect the anti-immobility effects of neferine. The anti-immobility effect of the selective 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetaralin (8-OH-DPAT) was also antagonized by WAY 100635. Furthermore, co-administration of subactive doses of neferine (10 mg/kg) and 8-OH-DPAT (0.1 mg/kg) produced synergistic antidepressant-like effects. These results suggest that neferine shows antidepressant-like effects in mice similar to typical antidepressants and that these effects are mediated by the 5-HT1A receptor. Therefore, the central effects of neferine are likely to be linked to serotonergic neurotransmission.

Dibenzofurans from the cultured lichen mycobionts of Lecanora cinereocarnea.

From the cultures of the spore-derived mycobionts of the lichen Lecanora cinereocarnea, five dibenzofurans, 3,7-dihydroxy-1,9-dimethyldibenzofuran, 2-chloro-3,7-dihydroxy-1,9-dimethyldibenzofuran, 2,8-dichloro-3,7-dihydroxy-1,9-dimethyldibenzofuran, 3-hydroxy-7-methoxy-1,9-dimethyldibenzofuran, and 2-chloro-7-hydroxy-3-methoxy-1,9-dimethyldibenzofuran, were isolated. Their structures were determined by spectroscopic methods.

Intermediacy of 6-hydroxyloganin in the ring cleavage course of loganin to secologanin

Abstract A possible biosynthetic pathway from loganin to secologanin through ring cleavage of 6-hydroxyloganin was ruled out in feeding experiments in which Eustoma russellianum , Swertia japonica , Lonicera morrowii and Adina pilulifera were each presented with three C-6 and C-7 stereoisomers of 6-hydroxy [7- 2 H] loganin as well as [6,6,7,8- 2 H 4 ] - and [6,6,7,8 carbomethoxy- 2 H 7 ]-loganin. In an associated experiment, the reduction of the aldehyde group of secologanin leading to sweroside was shown to proceed by hydride ion attack from the si face.

Phenolic compounds from the cultured mycobionts of Graphis proserpens.

Spore-derived mycobionts of the lichen Graphis proserpens were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Isocoumarin derivatives 1-3 and 7-oxo-5,7-dihydrooxepino[4,3,2-de]isochromene derivatives, proserins A-C (4-6), were isolated along with three known isocoumarin derivatives and three benzoic acid derivatives. Their structures were determined by spectroscopic methods.

Phenolic and iridoid glycosides from Strychnos axillaris

Five phenolic glycosides 1-5 and an iridoid glucoside 6 were isolated, together with 22 known compounds, from the dried barks and woods of Strychnosaxillaris. Their structures were determined by application of spectroscopic (NMR, MS) and chemical methodologies.

Four secoiridoid glucosides from Fraxinus insularis

Abstract Investigation of the leaves of Fraxinus insularis has led to the isolation of four new secoiridoid glucosides, insularoside-3′- O - β - d -glucoside, insularoside-3′, 6‴-di- O - β - d -glucoside, insuloside and desrhamnosyloleoacteoside, together with ligstroside. The structures of the new compounds were determined on the basis of spectroscopic methods.