The Lycopodium alkaloids

Phloroglucinol compounds of natural origin

Composition of Plant Cuticular Waxes

More than 25 dammarane-type tetracyclic triterpenoid saponins have been isolated from ginseng, the root and rhizome of Panax ginseng C.A. Meyer (Araliaceae). The genuine sapogenins of those saponins, 20(S)-protopanaxa-diol and -triol, were identified as 20(S) 12beta-hydroxy-and 20(S) 6alpha,12beta-dihydroxy-dammarenediol-II, respectively. There are two types of preparations from ginseng: white ginseng prepared by drying after peelling off and red ginseng prepared by steaming and drying. Some partly deglycosylated saponins such as ginsenoside Rh-1, Rh-2, and Rg-3 are obtained from red ginseng as artifacts produced during steaming. Several workers studied the metabolic transformation by human intestinal bacteria after oral administration of ginsenoside Rb-1 and Rb-2 and found that the stepwise deglyco-sylation yielded compound K and finally 20(S)-protopanaxadiol. Ginsenoside Rg-1 was converted into 20(S)-protopanaxatriol via ginsenoside Rh-1. Yun et al. in Korea conducted the epidemiological case-control studies of ginseng and suggested its cancer preventing activities. Kitagawa et al. demonstrated in vitro that ginsenosides, especially 20(R)-ginsenoside Rg-3, specifically inhibited cancer cell invasion and metastasis. Azuma et al. found that ginsenoside Rb-2 inhibited tumor angiogenesis, and Kikuchi et al. reported that ginsenoside Rh-2 inhibited the human ovarian cancer growth in nude mice. Recently, ginsenoside Rg-3 was produced as an anti-angiogenic anti-cancer drug in China. The aforementioned reports suggest that less glycosylated protopanaxadiol derivatives are effective in cancer prevention. Apart from Ginseng tetracyclic triterpenoid saponins, some oleanane-type pentacyclic triterpenoid compounds showed the anti-carcinogenic activity in the two-stage anti-cancer-promotion experiments in vitro and in vivo.

/pdf/chemistry-and-cancer-preventing-activities-of-ginseng-1q6gapje4u.pdf

Chemistry and cancer preventing activities of ginseng saponins and some related triterpenoid compounds.

Lignin, a phenolic polymer in the secondary wall, is the major cause of lignocellulosic biomass recalcitrance to efficient industrial processing. From an applications perspective, it is desirable that second-generation bioenergy crops have lignin that is readily degraded by chemical pretreatments but still fulfill its biological role in plants. Because plants can tolerate large variations in lignin composition, often without apparent adverse effects, substitution of some fraction of the traditional monolignols by alternative monomers through genetic engineering is a promising strategy to tailor lignin in bioenergy crops. However, successful engineering of lignin incorporating alternative monomers requires knowledge about phenolic metabolism in plants and about the coupling properties of these alternative monomers. Here, we review the current knowledge about lignin biosynthesis and the pathways towards the main phenolic classes. In addition, the minimal requirements are defined for molecules that, upon incorporation into the lignin polymer, make the latter more susceptible to biomass pretreatment. Numerous metabolites made by plants meet these requirements, and several have already been tested as monolignol substitutes in biomimetic systems. Finally, the status of detection and identification of compounds by phenolic profiling is discussed, as phenolic profiling serves in pathway elucidation and for the detection of incorporation of alternative lignin monomers.

/pdf/metabolic-engineering-of-novel-lignin-in-biomass-crops-4emnnx1bxv.pdf

Metabolic engineering of novel lignin in biomass crops

The constituents of Betula ermanii CHAM. in Japan were identified as follws. Fresh leaves : 20(S), 24(R)-epoxydammmaran-3β, 11α, 25-triol (1), 3-O-β-D-glucopyranoside of 1 (2), 2'-acetate of 2 (3), 11, 2'-diacetate of 2 (4), dammar-24-en-3β-, 11α-20(S)-triol (5), 3-O-β-D-2-O-acetylglucopyranoside of 5 (6). Outer bark : betulin (7), betulin 3-caffeate (8), oleanolic acid (9). Inner bark : (+)-lyoniresinol 3α-O-α-L-rhamnopyranoside (10), (-)-lyoniresinol 3α-O-β-D-xylopyranoside (11), 9, 9'di-O-feruloyl-(-)-secoisolariciresinol (12), acerogenin E (13), 3, 4, 5-trimethoxyphenol β-D-apiofuranosyl(1→6)-β-D-glucopyranoside (14), 4-(4-hydroxyphenyl)-2-butanol 2-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (15), (+)-catechine 7-O-β-D-xylopyranoside (16), lupeol (17), monogynol A (18). Root outer bark : lupeol caffeate (19), betulin 3-caffeate (8), oleanolic acid caffeate (20), dammarendiol II 3-caffeate (21). Compounds 2, 3, 4, 6, 19 and 21 are new.

Chemical Evaluation of Betula Species in Japan. I.Constituents of Betula ermanii

The constituents of Betula platyphylla var. japonica were identified as follows : Fresh leaves : 12-O-acetyl-3-O-malonylbetulafolienetriol, 12-O-acetyl-3-O-malonylbetulafolienetriol oxide I (=papyriferic acid), 12-O-acetyl-betulafolienediolone, hydroxyhopanone, caryophyllene oxide, kaempferol 3-O-(4-O-acetyl)-α-L-rhamnopyran-oside, quercetin 3-O-(4-O-acetyl)-α-L-rhamnopyranoside. Outer bark : betulin, lupeol, betulinic acid, betulone, betulin 3-O-caffeate, oleanolic acid, oleanolic acid 3-O-acetate. Inner bark : (-)-catechin, (-)-catechin 7-O-β-D-xylopyranoside, rhododendrin (=betuloside), aceroside VII, aceroside VIII, 1, 7-bis[4-hydroxyphenyl]-3-hepten-5-one, 2-hydroxy-1, 7-bis[4-hydroxyphenyl]-3-hepten-5-one, acerogenin E, (3R)-3, 5'-dihydroxy-4'-methoxy-3', 4"-oxo-1, 7-diphenyl-1-heptene, 7α-hydroxy-β-sitosterol, 7β-hydroxy-β-sitosterol. Root bark : dammarenediol II 3-O-p-coumarate, dammarenediol II 3-O-caffeate, ocotillol II 3-O-caffeate, stigmast-4-ene-3-one. Spikes : caryo-phyllene oxide, (-)-rhododendrol (=betuligenol), 12-O-acetylbetulafolienetriol. The compounds with an asterisk are new.

/pdf/chemical-evaluation-of-betula-species-in-japan-ii-4197b4h9wb.pdf

Chemical Evaluation of Betula Species in Japan. II. Constituents of Betula platyphylla var. japonica

The sapogenin of Ginseng saponins, ginsenosides-Rb1, -Rb2 and -Rc, was once reported to be protopanaxadiol (III). But it was found recently that dammarane type triperpenes with hydroxyl or methoxyl group at C(12) and C(20) give an equilibrated mixture of epimeric compounds at C(20). On mild hydrolysis of the saponins 20-epi-protopanaxadiol has been obtained as the genuine sapogenin for which the name of 20 (S)-protopanaxadiol (V) is proposed. The prosapogenin (XI), which was obtained by the partial hydrolysis of the above mentioned three saponins is found to be 3-O-(2β-D-glucopyranosyl-β-D-glucopyranosyl)-20 (R)-protopanaxadiol. The remaining glycosidic linkage in ginsenosides-Rb1, -Rb2 and -Rc should be located at C(20)-OH.

Chemical Studies on the Oriental Plant Drugs. XXVIII. Saponins and Sapogenins of Ginseng : Stereochemistry of the Sapogenin of Ginsenosides-Rb1, -Rb2 and -Rc

A new triterpene named now betulafolientriol oxide I (IV), mp 237-240°, [α]22D+26° (CHCl3), was isolated from the leaves of Betula platyphylla SUKATCHEV var japonica HARA in addition to betulafolientriol (I), hydroxyhopanone (II), and dammar-24-ene-12β, 20(S)-diol-3-one (III) The isolation of III was the first example of its occurrence in nature The chemical and spectrometric investigation of IV and its derivatives showed that IV is a derivative of I, having a modified side chain of a substituted tetrahydrofuran ring The oxidation of betulafolientriol (I) with perbenzoic acid gave betulafolientriol oxide I (IV) along with its C-24-epimer (XIV) The structure of XIV including its all stereochemistries was clarified by the derivation of XIV from 25-bromo-20 (S), 24 (S)-epoxy-dammarane-3α, 12β-diol (XV) Accordingly, the structure of betulafolientriol oxide I (IV) was established as 20 (S), 24 (R)-epoxy-dammarane-3α, 12β, 25-triol The achievement of chemical conversion of IV into ocotillone II (XII) showed that the stereochemistry at C-24 of ocotillol II (VIII) and its derivatives is expressed in term of (R) configuration (the methyl at C-20/ the hydroxyisopropyl at C-24 : trans)

Triterpenes of Japanese White Birch and the Configuration at C-24 of Ocotillol II and Its Related Compounds

The constituents of Betula maximowicziana REGAL in Japan were identified as follows. Fresh leaves : 12β-acetoxy-20(S), 24(R)-epoxy-3α, 17α, 25-trihydroxydammarane, 20(S), 24(R)-epoxy-3α, 17α, 25-trihydroxydammarane, 3-epi-ocotillol II, 12β-acetoxy-20(S), 24(R)-epoxy-3α, 25-dihydroxydammarane, 12β-acetoxy-20(S), 24(R)-epxy-3α, 17α, 25-trihydroxydammarane 3-O-β-D-glucopyranoside (betulamaximoside A)*, 12β-acetoxy-20(S), 24(R)-epoxy-3α, 17α, 25-trihydroxydammarane 3-O-β-D-(6-O-acetyl)-glucopyranoside (betulamaximoside B)*, 12-O-acetyl-betulafolienetetraol, betulafolieneteraol, 6-methoxykaempferol, 6-methoxy-3-O-methylkaempferol and naringenin. Outer bark : betulin, betulin 3-O-caffeate, lupeol, lupane-3β, 20, 28-triol, lupane-3β, 20, 28-triol 3-O-caffeate, acetyl-oleanolic acid. Inner bark : acerogenin E, 16-hydroxy-17-O-methylacerogenin E*, alnusdiol β-D-glucopyranoside*, lyoniresinol 3α-O-α-L-rhamnopyranoside, 3, 4, 5-trimethoxyphenol β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside, benzyl alcohol β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside, (+)-catechin 7-O-β-D-xylopyranoside and monogynol A. Root bark : dammarenediol II 3-O-caffeate, dammar-24-ene-3β, 20(S), 26-triol 3-O-caffeate*, dammar-24-ene-3β, 20(S), 26-triol 3-O-coumarate*, oleanolic acid 3-O-caffeate. The six compounds with asterisks are new.

Nobutoshi Tanaka

Papers

Chemical Evaluation of Betula Species in Japan. I.Constituents of Betula ermanii

Chemical Evaluation of Betula Species in Japan. II. Constituents of Betula platyphylla var. japonica

Chemical Studies on the Oriental Plant Drugs. XXVIII. Saponins and Sapogenins of Ginseng : Stereochemistry of the Sapogenin of Ginsenosides-Rb1, -Rb2 and -Rc

Triterpenes of Japanese White Birch and the Configuration at C-24 of Ocotillol II and Its Related Compounds

Chemical Evaluation of Betula Species in Japan. III. Constiutents of Betula maximowicziana