Chemical constituents of the roots of Scorzonera divaricata and their chemotaxonomic significance

The phytochemical study of the roots of Scorzonera divaricata Turcz led to the isolation of 27 compounds, including eight sterols (1–8), one lignan (9), two cumarins (10, 11), five phenylpropanoids (12–16), six benzene derivatives (17–22), methyl-β-D-fructofuranoside (23), monolinolein (24), and three aliphatic acids (25–27). The structures of isolated compounds were identified using NMR and ESI-MS spectroscopic methods and comparing them with those previously reported. Except for β-daucosterol (8), scopoletin (10) and caffeic acid (16) from S. divaricata, this is the first report of the other 24 compounds from S. divaricata. Among them, eleven compounds (2–6, 11, 17, 19, 20, 23, 25) were reported from genus Scorzonera for first time, suggesting that they could be used to distinguish S. divaricata from the other species of Scorzonera. Furthermore, the chemotaxonomic significance of isolated compounds from S. divaricata has also been discussed.     

Fatty acid derivatives and dammarane triterpenes from the glandular trichome exudates of Ibicella lutea and Proboscidea louisiana

Ibicella lutea and Proboscidea louisiana, both of the Martyniaceae family, are known for rich glandular trichomes on their leaves and stems. Chemical investigations of the glandular trichome exudates on leaves of the two plants furnished three types of secondary metabolites, glycosylated fatty acids, glycerides (2-O-(3,6-diacetyloxyfattyacyl)glycerols and 2-O-(3-acetyloxyfattyacyl)glycerols) and dammarane triterpenes. The glycosylated fatty acids from I. lutea were determined to be 6(S)-(6-O-acetyl-β-d-glucopyranosyloxy)-octadecanoic acid (1A), -eicosanoic acid (1B) and -docosanoic acid (1C), as well as their respective deacetyl congeners (2A, 2B and 2C), whereas P. louisiana furnished 8(S)-(6-O-acetyl-β-d-glucopyranosyloxy)-eicosanoic acid (3A) and -docosanoic acid (3B) and their respective deacetyl congeners (4A and 4B), together with 2B. Both plants contained 12 identical 2-O-[(3R,6S)-3,6-diacetyloxyfattyacyl]glycerols (5A-L), in which the fatty acyl moieties contained between 17 and 21 carbon atoms. The corresponding mono-acetyloxy compounds, 2-O-[(3R)-3-acetyloxyfattyacyl]glycerols (6A–L) were detected in both plants. Among these glycerides, ten compounds (5A, 5C, 5F, 5H, 5K, 6A, 6C, 6F, 6H and 6K) had iso-fattyacyl structures and four (5E, 5J, 6E and 6J) had anteiso-fattyacyl structures. A previously unknown dammarane triterpene, betulatriterpene C 3-acetate (7), was isolated together with three known dammarane triterpenes, 24-epi-polacandrin 1,3-diacetate (8), betulatriterpene C (9) and 24-epi-polacandrin 3-acetate (10) from I. lutea, whereas 12 dammarane triterpenes, named probosciderols A–L (12–23), and the known compound betulafolienetriol (11) were isolated from P. louisiana. The structures of these compounds were elucidated by spectroscopic analysis including 2D-NMR techniques and chemical transformations. The 6-O-acetylglucosyloxy-fatty acids 1A–C (42%) and the dammarane triterpenes 7–10 (31%) were the two most abundant constituents in the glandular trichome exudate of I. lutea, whereas the dammarane triterpenes 11–23 (47%) and the glucosyloxy-fatty acids (4A, 4B and 2B) (38%) were the most abundant constituents in the glandular trichome exudate of P. louisiana.     

Synthesis of 1,6-thioanhydro-D-glucitol

Treatment of 2,4-O-benzylidene-1,6-di-O-tosyl-D-glucitol (1) with potassium thiolbenzoate afforded the 6-S-benzoyl compound 2 and its 5-benzoate 4, the structure of which was proved chemically. When 1 was acetylated and then treated with the thiolate, the acetylated 6-S-benzoyl compound 19 was obtained in good yield in addition to some 1,6-di-S-benzoyl derivative 21. Treatment of 19 with acetic anhydride-acetic acid-sulfuric acid afforded 2,3,4,5-tetra-O-acetyl-6-S-acetyl-1-O-tosyl-D-glucitol (26), which was converted by sodium methoxide into a mixture of 1,5-anhydro-6-thio-D-glucitol (28) and 1,6-thioanhydro-D-glucitol (29). These two compounds were isolated as their acetates (30 and 31) by column chromatography, or by converting 28 into its S-trityl derivative (32).     

The synthesis of new deoxynitroinositols by cyclization of 6-deoxy-3-O-methyl-6-nitro-d-allose and -l-talose

6-Deoxy-3-O-methyl-6-nitro-d-allose (5) and -l-talose (6) were synthesized from 1,2-O-isopropylidene-3O-methyl-α-d-allofuranose (1) by the nitromethane method via their furanoid, 1,2-O-isopropylidene derivatives (2 and 3). The barium hydroxide-catalyzed cyclization of the free nitrohexoses (5 and 6) was investigated. Under conditions favoring kinetic control (pH ～8, 0°), 5 gave mainly 1d-5-deoxy-2-O-methyl-5-nitro-allo-inositol (7), with the 1l-epi-1 (8) and epi-6 (9) stereoisomers as minor products. Compound 6 afforded a high yield of the myo-5-isomer (11); the 1l-allo-5 (13) and 1d-epi-1 (14) isomers were formed in small proportions but not isolated. The thermodynamically controlled, mutual interconversion of the stereoisomeric products was studied, as was the formation of nitronate salts and the regeneration of free nitroinositols. Upon immediate acidification, the nitronate obtained from 11 gave 11 and the neo-2 epimer (12) in a ratio of 2:3. The nitronate produced by 7 underwent rapid β-epimerization. The five isolated deoxynitroinositol monomethyl ethers were further characterized as tetra-acetates (7a, 9a, 11a, and 12a) and isopropylidene derivatives (7b, 8b, and 9b).     

Anthocyanins and flavonols from the flowers of Amherstia nobilis endemic to Myanmar

Three anthocyanins (1–3) and eight flavonols (4–11) were isolated from the flowers of Amherstia nobilis endemic to Myanmar. Anthocyanins were identified as cyanidin 3-O-glucoside (1), 3-O-xyloside (2), and peonidin 3-O-glucoside (3). On the other hand, flavonols were identified as isorhamnetin 3-O-glucoside (4), 7-O-glucoside (5), 3,7-di-O-glucoside (6) and 3-O-rutinoside (7), quercetin 3-O-rutinoside (8) and 3-O-glucoside (9), and kaempferol 3-O-rutinoside (10) and 3-O-glucoside (11). Although an anthocyanin, pelargonidin 3-O-pentoside, has been reported from the flowers of A. nobilis, it was not found in this survey. The presence of flavonols in A. nobilis was reported in this survey for the first time. Flavonoid composition of Amherstia was chemotaxonomically compared with those of phylogenetically related genera Cynometra and Brownea.     

Chemical constituents from the roots of Fallopia multiflora var. Ciliinerve

Phytochemical investigations on the roots of Fallopia multiflora var. Ciliinerve led to the isolation of eighteen compounds, including six chromones [2-methyl-5- carboxymethyl-7-hydroxychromone (1), 2-methyl-5-methylcarboxymethyl-7- hydroxychromone (2), 2,5-dimethyl-7-hydroxychromone (3), 2-methyl-5-hydroxymeth-yl-7-hydroxychromone (4), 2-methyl-5-carboxylicacid-7-hydroxy-chromone (5), and 2,5-dimethyl-7-hydroxychromone-7-O-β-D-glucopyranoside (6)], three lignans [Isolariciresinol (8), 5-[4-(3,4-dimethoxyphenyl)-2,3-dimethylbutyl]-1,3-benzodioxole (9), and isolariciresinol-9-O-β-D-xylopyranoside (10)], four anthraquinones [physcion-8-O-β-D-glucopyranoside (11), emodin-8-O-β-D-glucopyranoside (12), Rhein (13), and Chrysophanol (14)], three isobenzofurans [5,7-dihydroxy-isobenzofuran (15), 5-methoxy-7-hydroxy-isobenzofuran (16), and 5-methoxy-isobenzofuran-7-O-β-D-glucoside (17)], one phenolic acid [2,5-diacethylhy-droquinone (7)], and one pyran [Zanthopyranone (18)]. Among them, compounds 1, 3, 6, 13 and 14 were reported from F. multiflora var. Ciliinerve for the first time, compounds 2, 8, 10 and 15–17 were isolated from the genus Fallopia for the first time, and compounds 4, 9 and 18 were isolated for the first time from Polygonaceae family. Furthermore, the isolation of compounds 5 and 7 were reported for the first time in plants. Their structures were identified by spectroscopic methods and compared with those previously published. The chemotaxonomic significance of these isolated compounds has also been discussed.     

Alkaloids of formosan Fissistigma and Goniothalamus species

Separation of the basic fractions from Formosan Fissistigma glaucescens, F. oldhamii and Goniothalamus amuyon afforded one new quaternary phenanthrene alkaloid, N-methylatherosperminium (15), along with the known alkaloids, (?)-discretamine (1), (?)-tetrahydropalmatine (2), palmatine (3), (?)-asimilobine (4), (?)-norannuradhapurine (5), (?)-crebanine (6), (?)-calycinine (fissoldine, fissistigine A) (7a), (?)-anolobine (8), (?)-xylopine (9), (?)-anonaine (10a), oxocrebanine (11), liriodenine (12), atherosperminine (13), N-noratherosperminine (14) and (+)-O-methylflavinantine (O-methylpallidine) (16).     

Stereoselective hydrogenolysis of dioxolane-type benzylidene derivatives: Synthesis of some benzyl ethers of benzyl β-d-arabinopyranoside

The following derivatives of benzyl β-d-arabinopyranoside are described: exo-3,4-O-benzylidene (2), endo-3,4-O-benzylidene (3), and the 2-benzyl ether derivatives (4 and 5) of 2 and 3. Hydrogenolysis (LiAlH₄-AlCl₃) of the exo-isomers (2 and 4) gave mainly 4-hydroxy-3-O-benzyl derivatives (6 and 11), whereas the endo-isomers (3 and 5) gave mainly 3-hydroxy-4-O-benzyl derivatives (7 and 12). Acid hydrolysis of 4 and 5 yielded the 2-O-benzyl derivative (10).     

Synthesis and cytokinin activity of N-acylaminodeazapurines

Three 7-acylaminoimidazo[4,5-b]pyridines, namely 7-pentanoylaminoimidazo[4,5-b]pyridine (1), 7-benzoylaminoimidazo[4,5-b]pyridine(2), and 7-(2-furoylamino)imidazo[4,5-b]pyridine(3), six 4-acylaminoimidazo[4,5-c]pyridines, namely 4-propionylaminoimidazo[4,5-c]pyridine(4), 4-butyryl-aminoimidazo[4,5-c]pyridine(5), 4-pentanoylaminoimidazo[4,5-c]pyridine(6) 4-hexanoylaminoimidazo[4,5-c]pyridine(7),4-benzoylaminoimidazo[4,5-c]pyridine(8), and 4-(2-furoylamino)imidazo[4,5-c]-pyridine(9), and seven 7-acylaminoimidazo[4,5-c]pyridines, namely 7-propionylaminoimidazo[4,5-c]-pyridine(10), 7-butyrylaminoimidazo[4,5-c]pyridine(11), 7-pentanoylaminoimidazo[4,5-c]pyridine(12), 7-hexanoylaminoimidazo[4,5-c]pyridine(13), 7-benzoylaminoimidazo[4,5-c]pyridine(14), 7-phenylacetylaminoimidazo[4,5-c]pyridine(15), and 7-(2-furoylamino)imidazo[4,5-c]pyridine(16) were synthesized and tested for their cytokinin activity with the tobacco callus bioassay. 2 showed a cytokinin activity at 1 × 10⁻⁸ M and gave a callus yield about 72% of that produced by kinetin at 1 × 10⁻⁶ M. 1, 3 and 8 showed the optimum growth responses in the range of 10⁻⁷−10⁻⁶ M. 4, 5, 7, 9–16 were slightly active. These results support previous reports that a nitrogen atom at the 3-position in the purine ring plays an important role in conferring high cytokinin activity.     

Synthesis of acetylenic sugars and uronic acids via two-carbon chain extension of d-ribose

Treatment of methyl β-d-ribofuranoside with acetone gave methyl 2,3-O-isopropylidene-β-d-ribofuranoside (1, 90%), whereas methyl α-d-ribofuranoside gave a mixture (30%) of 1 and methyl 2,3-O-isopropylidene-α-d-ribofuranoside (1a). On oxidation, 1 gave methyl 2,3-O-isopropylidene-β-d-ribo-pentodialdo-1,4-furanoside (2), whereas no similar product was obtained on oxidation of 1a. Ethynylmagnesium bromide reacted with 2 in dry tetrahydrofuran to give a 1:1 mixture (95%) of methyl 6,7-dideoxy-2,3-O-isopropylidene-β-d-allo- (3) and -α-l-talo-hept-6-ynofuranoside (4). Ozonolysis of 3 and 4 in dichloromethane gave the corresponding d-allo- and l-talo-uronic acids, characterized as their methyl esters (5 and 6) and 5-O-formyl methyl esters (5a and 6a). Ozonolysis in methanol gave a mixture of the free uronic acid and the methyl ester, and only a small proportion of the 5-O-formyl methyl ester. Malonic acid reacted with 2 to give methyl 5,6-dideoxy-2,3-O-isopropylidene-β-d-ribo-trans-hept-5-enofuranosiduronic acid (7).     

Chemical constituents from bulbs of Fritillaria pallidiflora Schrenk

A new steroidal alkaloid, 5α, 14α, 17β-cevanin-6-oxo-3β, 20β, 24β-triol(1), together with ten known compounds (2–11) were isolated from the bulbs of Fritillaria pallidiflora Schrenk. Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. Compounds 8, 9, 10 were obtained from the genus Fritillaria for the first time; Compounds 2, 3, 4 and 11 are isolated from this plant for the first time.     

Flavonoid glycosides from the aerial parts of Curcuma comosa

Four new flavonoid glycosides, curcucomosides A–D (1–4), three known flavonoid glycosides, 5–7, and four known diarylheptanoids, 8–11, were isolated from the ethanol extract of the aerial parts of Curcuma comosa. The structures of the new compounds were established as rhamnazin 3-O-α-l-arabinopyranoside (1), rhamnocitrin 3-O-α-l-arabinopyranoside (2), rhamnazin 3-O-α-l-rhamnopyranosyl-(1→2)-O-α-l-arabinopyranoside (3), and rhamnocitrin 3-O-α-l-rhamnopyranosyl-(1→2)-O-α-l-arabinopyranoside (4) by spectroscopic analysis and chemical reactions whereas those of the known compounds were identified by spectral comparison with those of the reported values.     

Resolution of anomeric 2-amino-2-deoxy-d-glycofuranosides and -glycopyranosides by cation-exchange chromatography

Methyl 4,6-O-benzylidene-2-deoxy-α-D-ribo-hexopyranoside (1) is converted into methyl 3,4-di-O-benzoyl-6-bromo-2,6-dideoxy-α-D-ribo-hexopyranoside (3) via the 3-O-benzoyl derivative (2) of 1 by subsequent treatment with N-bromosuccinimide. Compound 3 is the key intermediate in high-yielding, preparative syntheses of the title dideoxy sugars, which are constituents of many antibiotics. Dehydrohalogenation of 3 affords the 5,6-unsaturated glycoside 7. which undergoes stereospecific reduction by hydrogen with net inversion at C-5 to give methyl 3,4-di-O-benzoyl-2,6-dideoxy-β-L-lyxo-hexopyranoside (8), whereas reductive dehalogenation of 3 provides the corresponding D-ribo derivative 4. The unprotected glycosides 9 (L-lyxo) and 5 (D-ribo) are readily obtained by catalytic transesterification, and mild, acid hydrolysis gives the crystalline title sugars 10 (L-lyxo) and 6 (D-ribo) in 45 and 57% overall yield from 1 without the necessity of chromatographic purification at any of the steps.     

A facile synthesis of nucleoside derivatives of 1,4-oxathiane

Adenosine-5′-carboxaldehyde (1a) was treated with nitromethane under alkaline conditions, to give the two stereoisomeric 5′-C-(nitromethyl) derivatives (2 and 3) of adenosine. Catalytic hydrogenation of 2 gave 9-(6-amino-6-deoxy-β-D-allofuranosyl)adenine (4), which, on treatment with nitrous acid, yielded 9-(β-D-allofuranosyl)hypoxanthine (6). Similar treatment of 3 gave the α-L-talo nucleosides 5 and 7. Reaction of 2′,3′-O-p-anisylidene adenosine-5′-carboxaldehyde (1b) with ethoxycarbonylmethylene-triphenylphosphorane afforded 9-(ethyl 5,6-dideoxy-β-D- ribo-hept-5-enofuranosyluronate)adenine (8), which was hydrolyzed to the corresponding uronic acid (9). Catalytic hydrogenation of 8 gave 9-(ethyl 5,6-dideoxy-β-D-ribo-heptofuranosyluronate)adenine (10). Reduction of 8 with lithium aluminum hydride yielded two new analogs of adenosine: 9-(5,6-dideoxy-β-D-ribo-heptofuranosyl)adenine (12) and 9-(5,6-dideoxy-β-D-ribo-hept-5-enofuranosyl)adenine (13).     

Flavonoids in the leaves of Hillebrandia and Begonia species (Begoniaceae)

The fresh leaves of Hillebrandia sandwicensis and 126 Begonia taxa were chemotaxonomically surveyed for flavonoids. Of their taxa, H. sandwicensis and 119 species, one variety and three hybrids were analyzed for flavonoids for the first time. Ten flavonols and eleven C-glycosylflavones were isolated and characterized as quercetin 3-O-rutinoside (1), kaempferol 3-O-rutinoside (2), isorhamnetin 3-O-rutinoside (3), quercetin 3-O-glucoside (4), quercetin 3-methyl ether 7-O-rhamnosylglucoside (5), quercetin 3,3'-dimethyl ether 7-O-rhamnosylglucoside (6), quercetin glycoside (13), quercetin glycoside (acylated) (14), kaempferol glycoside (17) and quercetin 3-O-rhamnoside (18) as flavonols, and isovitexin (7), vitexin (8), isoorientin (9), orientin (10), luteolin 6-C-pentoside (11), luteolin 8-C-pentoside (12), schaftoside (15), isoschaftoside (16), chrysoeriol 6,8-di-C-pentoside (19), apigenin 6,8-di-C-arabinoside (20) and isovitexin 2''-O-glucoside (21) as C-glycosylflavones. Quercetin 3-O-rutinoside (1) alone was isolated from H. sandwicensis endemic to Hawaii. Major flavonoids of almost Begonia species was also 1. Begonia species were divided into two chemotypes, i.e. flavonol containing type and C-glycosylflavone containing type. Of 14 section of the Begonia, almost species of many section, i.e. sect. Augustia, Coelocentrum, Doratometra, Leprosae, Loasibegonia, Monopteron and Ruizoperonia, were flavonol types. On the other hand, C-glycosyflavone type was comparatively most in sect. Platycentrum.     

Thiophenes,polyacetylenes and terpenes from the aerial parts of Eclipata prostrata

One new bithiophenes, 5-(but-3-yne-1,2-diol)-5′-hydroxy-methyl-2,2′-bithiophene (2), two new polyacetylenic glucosides, 3-O-β-d-glucopyranosyloxy-1-hydroxy-4E,6E-tetradecene-8,10,12-triyne (8), (5E)-trideca-1,5-dien-7,9,11-triyne-3,4-diol-4-O-β-d-glucopyranoside (9), six new terpenoid glycosides, rel-(1S,2S,3S,4R,6R)-1,6-epoxy-menthane-2,3-diol-3-O-β-d-glucopyranoside (10), rel-(1S,2S,3S,4R,6R)-3-O-(6-O-caffeoyl-β-d-glucopyranosyl)-1,6-epoxy menthane-2,3-diol (11), (2E,6E)-2,6,10-trimethyl-2,6,11-dodecatriene-1,10-diol-1-O-β-d-glucopyranoside (12), 3β,16β,29-trihydroxy oleanane-12-ene-3-O-β-d-glucopyranoside (13), 3,28-di-O-β-d-glucopyranosyl-3β,16β-dihydroxy oleanane-12-ene-28-oleanlic acid (14), 3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl oleanlic-18-ene acid-28-O-β-d-glucopyranoside (15), along with fifteen known compounds (1, 3–7, and 16–24), were isolated from the aerial parts of Eclipta prostrata. Their structures were established by analysis of the spectroscopic data. The isolated compounds 1–9 were tested for activities against dipeptidyl peptidase IV (DPP-IV), compound 7 showed significant antihyperglycemic activities by inhibitory effects on DPP-IV in human plasma in vitro, with IC₅₀ value of 0.51 μM. Compounds 10–24 were tested in vitro against NF-κB-luc 293 cell line induced by LPS. Compounds 12, 15, 16, 19, 21, and 23 exhibited moderate anti-inflammatory activities.     

Natural products as sources of new fungicides (V): Design and synthesis of acetophenone derivatives against phytopathogenic fungi in vitro and in vivo

A series of acetophenone derivatives (10a–10i, 11, 12a–12g, 13a–13g, 14a–14d and 15a–15l) were designed, synthesized and evaluated for antifungal activities in vitro and in vivo. The antifungal activities of 53 compounds were tested against several plant pathogens, and their structure–activity relationship was summarized. Compounds 10a–10f displayed better antifungal effects than two reference fungicides. Interestingly, the most potent compound 10d exhibited antifungal properties against Cytospora sp., Botrytis cinerea, Magnaporthe grisea, with IC₅₀ values of 6.0–22.6?µg/mL, especially Cytospora sp. (IC₅₀?=?6.0?µg/mL). In the in vivo antifungal assays, 10d displayed the significant protective efficacy of 55.3% to Botrytis cinerea and 73.1% to Cytospora sp. The findings indicated that 10d may act as a potential pesticide lead compound that merits further investigation.     

Flavonoids and phenolic acids from the aerial parts of Alyssum alyssoides L. (Brassicaceae)

Two phenolic acids (1 and 2) and seven flavonoids (3–9) were isolated from the aerial parts of Alyssum alyssoides (Brassicaceae). All these compounds (1–9) were isolated from this particular species for the first time. Their structures were identified, on the basis of MS and NMR spectra as: p-hydroxy-benzoic acid (1), 3-methoxy-4-hydroxybenzoic acid (vanillic acid) (2), kaempferol 3-O-β-D-glucopyranoside (astragalin) (3), kaempferol 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (nicotiflorin) (4), quercetin 3-O-β-D-glucopyranoside (isoquercetin) (5), quercetin 3-O-β-D-galactopyranoside (hyperoside) (6), isorhamnetin 3-O-β-D-glucopyranoside (7), isorhamnetin 3-O-β-D-galactopyranoside (8) and isorhamnetin 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (narcissin) (9). The chemotaxonomic significance of these compounds was summarized.     

Asymmetric synthesis and effect of absolute stereochemistry of YCZ-2013, a brassinosteroid biosynthesis inhibitor

The four stereoisomers of 2RS,4RS-1-[[2-(2,4-dichlorophenyl)-4-(2-(2-propenyloxy)phenoxymethyl)-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole (YCZ-2013), a novel brassinosteroid biosynthesis inhibitor, were prepared. The diastereomers of 2RS,4R-5 and 2RS,4S-5 were prepared by using the corresponding optically pure R and S toluene-4-sulfonic acid 2,3-dihydroxypropyl ester (R-4,S-4). The enatiomerically and diastereomerically pure acetonide (5) was obtained by a method involving diastereoselective crystallisation of the tosylate salt, followed by re-equilibration with the mother liquor and chromatography. The optical purity of four target compounds (YCZ-2013) was confirmed by chiral high-performance liquid chromatography (HPLC) and NMR. The effects of these stereoisomers on Arabidopsis stem elongation indicated that the cis isomers of 2S,4R-YCZ-2013 and 2R,4S-YCZ-2013 exhibited potent inhibitory activity with IC₅₀ values of approximately 24 ± 3 and 24 ± 2 nM, respectively. The IC₅₀ values of the trans isomers of 2S,4S-YCZ-2013 and 2R,4R-YCZ-2013 are approximately 1510 ± 50 and 3900 ± 332 nM, respectively. Co-application of brassinolide (10 nM), the most potent BR, and GA₃ (1 μM) to Arabidopsis seedlings grown in the dark with 2R,4S-YCZ-2013 and 2S,4R-YCZ-2013 revealed that brassinolide recovered the induced dwarfism of Arabidopsis seedlings, whereas GA₃ showed no effect.     

Chemical modification of the nonreducing,terminal group of maltotriose

O-α-d-Galactopyranosyl-(1→4)-O-α-d-glucopyranosyl-(1→4)-d-glucopyranose (12) was prepared by inversion of configuration at C-4″ of 2,3,2′,3′,6′,2″,3″-hepta-O-acetyl-1,6-anhydro-4″,6″-di-O-methylsulfonyl-β-maltotriose (7), followed by O-deacylation, acetylation, acetolysis, and de-O-acetylation. The intermediate 7 was obtained by treatment of 1,6-anhydro-β-maltotriose (2) with benzal chloride in pyridine, followed by acetylation, removal of the benzylidene group, and methane-sulfonylation. Selective tritylation of 2 and subsequent acetylation afforded 2,3,2′,3′,6′,2″,3″,4″-octa-O-acetyl-1,6-anhydro-6″-O-trityl-β-maltotriose (6), which was O-detritylated and p-toluenesulfonylated to give 2,3,2′,3′,6′,2″,3″,4″-octa-O-acetyl-1,6-anhydro-6″-O-p-tolylsulfonyl-β-maltotriose (13). Nucleophilic displacement of 13 with thioacetate, iodide, bromide, chloride, and azide ions gave 6″-S-acetyl- (14), 6″-iodo- (15), 6″-bromo- (16), 6″-chloro- (19), and 6″-azido- (20) 1,6-anhydro-β-maltotriose octaacetates, respectively. 6″Deoxy- (18) and 6″-acetamido-6″-deoxy (21) derivatives of 1,6-anhydro-β-maltotriose decaacetates were also prepared from 15 and 16, and 20, respectively. Acetolysis of 14, 15, 16, 18, 19, and 21 afforded 1,2,3,6,2′,3′,6′,2″,3″,4″-deca-O-acetyl-6″-S-acetyl (22), -6″-iodo (23), -6″-bromo (24), -6″-deoxy (25), -6″-chloro (26), and -6″-acetamido-6′-deoxy (27) derivatives of α-maltotriose, respectively. O-Deacetylation of 24, 25, and 26 furnished 6″-bromo-(28), 6″-deoxy- (29), and 6″-chloro- (30) maltotrioses, respectively, which on acetylation gave the corresponding β-decaacetates.