The Modified Mosher’s Method and the Sulfoximine Method

Kusumi, Takenori; Ooi, Takashi; Ohkubo, Yumi; Yabuuchi, Tetsuya

doi:10.1246/bcsj.79.965

Cited by 83 publications

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“…3,4) The modified Mosher's method is widely used for the determination of the absolute stereochemistry of chiral secondary alcohols. 5) In this study, the absolute configurations of these compounds (PS-1 and EG-1) were reinvestigated using this reliable method.First, a closely related compound, macarangioside A (2), 6) was hydrolyzed with mild alkaline hydrolysis (Chart 1) to afford degalloyl-2 (2a), of which the NMR spectra ( suggested that EG-1 must be the C-9 epimer of PS-1. According to the literature, 3,4) the absolute structures of both PS-1 and EG-1 were determined in a similar manner, e.g., by comparison of the spectral data for aglycones with those reported for blumenol B without an adequate chiroptical method.…”

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“…The absolute structures of the aglycones were determined to be the same as (6S,9R)-6,9-dihydroxymegastigman-4-en-3-one by comparisons of the spectral data of aglycones (PS-1a and EG-1a) obtained by enzymatic hydrolysis of glucosides (PS-1 and EG-1) with those reported for blumenol B. 3,4) Thus compounds PS-1 and EG-1 were concluded to be the same compound until now, although the NMR spectra were measured in different solvents, e.g., methanol-d 4 and pyridine-d 5 , respectively. 3,4) The modified Mosher's method is widely used for the determination of the absolute stereochemistry of chiral secondary alcohols.…”

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Reinvestigation of the Absolute Stereochemistry of Megastigmane Glucoside, Icariside B5

et al. 2010

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NoteBlumenol B was isolated from the leaves of Podocarpus blumei in 1972.1) The absolute stereochemistry of blumenol B was then determined as (6S,9R) by chemical conversion of related compounds.2) In 1988, two groups independently reported the isolation of b-D-glucopyranoside of blumenol B, named differently as dihydrovomifoliol-O-b-D-glucopyranoside (PS-1) from Pinus sylvestris and icariside B 5 (EG-1) from Epimedium grandiflorum var. thunbergianum, respectively.3,4) (The former is designated as PS-1 and the latter EG-1 in this study for readers' convenience.) The absolute structures of the aglycones were determined to be the same as (6S,9R)-6,9-dihydroxymegastigman-4-en-3-one by comparisons of the spectral data of aglycones (PS-1a and EG-1a) obtained by enzymatic hydrolysis of glucosides (PS-1 and EG-1) with those reported for blumenol B.3,4) Thus compounds PS-1 and EG-1 were concluded to be the same compound until now, although the NMR spectra were measured in different solvents, e.g., methanol-d 4 and pyridine-d 5 , respectively. 3,4) The modified Mosher's method is widely used for the determination of the absolute stereochemistry of chiral secondary alcohols. 5) In this study, the absolute configurations of these compounds (PS-1 and EG-1) were reinvestigated using this reliable method.First, a closely related compound, macarangioside A (2), 6) was hydrolyzed with mild alkaline hydrolysis (Chart 1) to afford degalloyl-2 (2a), of which the NMR spectra ( suggested that EG-1 must be the C-9 epimer of PS-1. According to the literature, 3,4) the absolute structures of both PS-1 and EG-1 were determined in a similar manner, e.g., by comparison of the spectral data for aglycones with those reported for blumenol B without an adequate chiroptical method. Therefore we next performed detailed analysis to determine the absolute structures by chemical conversion and the modified Mosher's method for PS-1 and EG-1.Enzymatic hydrolysis of 2a (ϭPS-1) afforded an aglycone (2b). The (R)-and (S)-a-methoxy-a-trifluoromethylphenylacetic acid (MTPA) esters were prepared using the conventional procedure (2c and 2d from 2b, see Experimental) (Chart 1). The distribution pattern of Dd S-R values for 2c and 2d clearly demonstrated that 2b possessed the 9R configuration (Fig. 1a). In addition, the configuration of glucose was determined to be the D-series in HPLC analysis following acid hydrolysis of 2 and derivatization of the liberated glucose. The application of the b-D-glucosylation-induced shifttrend rule also supported the above result (Table 1).7) The absolute stereochemistry of C-6 was also confirmed based on the circular dichroism (CD) spectra. The CD spectral data for 2a and 2b were essentially identical to those of blumenol B, of which the absolute stereochemistry was determined by chemical and spectroscopic analyses.2) Therefore the structure of 2a (ϭPS-1, dihydrovomifoliol-O-b-D-glucopyranoside) was confirmed unambiguously to be (6S,9R)-6,9-dihydroxymegastigman-4-en-3-one 9-O-b-D-glucopyranoside, e.g., 9-O-b-D-glucopyranosi...

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Reinvestigation of the Absolute Stereochemistry of Megastigmane Glucoside, Icariside B5

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“…The absolute configuration of 6 was determined using a modified Mosher's method for the aglycon (6b). The (R)-and (S)-methoxytrifluoromethylphenyl acetate (MTPA) esters of 6b were prepared using conventional procedures, and the distribution patterns of the Δδ S-R values for 6b demonstrated that 6 has a 3R-configuration 14) (Fig. 5).…”

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Culcitiolides E–J, Six New Eremophilane-Type Sesquiterpene Derivatives from <i>Senecio culcitioides</i>

Mitsui

Hayashi

Kawai

et al. 2013

CHEMICAL & PHARMACEUTICAL BULLETIN

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Culcitiolides E-J (1-6), six new eremophilane-type sesquiterpenes, were isolated from the stem of Senecio culcitioides Sch. Bip. (Asteraceae). The structures were determined by detailed NMR spectral analysis. The inhibitory activities of these compounds against nuclear factor κB (NF-κB)-dependent gene expression were assessed. Culcitiolides E, H, and I potently inhibited NF-κB-induced gene expression at 20 µm.Key words Senecio culcitioides; eremophilane; culcitiolide; nuclear factor κB Senecio culcitioides Sch. Bip. is distributed throughout the Peruvian Andes in South America at an altitude of 4500-5000 m. S. culcitioides belongs to the family Asteraceae and has been used as a traditional folk medicine to treat cough, bronchitis and asthma.1-3) Nuclear factor κB (NF-κB) is a transcription factor and functions as a key regulatory element in inflammatory and immune responses and in cancer. During our search for new classes of inhibitors of NF-κB derived from natural products, we previously isolated culcitiolides A-D, eremophilane-type sesquiterpenoids from the stem of the previously uninvestigated plant S. culcitioides, and we showed that culcitiolides C and D are potent NF-κB inhibitors. 4) Our continuous effort to identify NF-κB inhibitors in S. culcitioides led to the isolation of six new eremophilane-type sesquiterpenoids exhibiting potent NF-κB inhibitory activity. Herein, we describe the isolation and structural elucidation of culcitiolides E-J and the evaluation of their inhibitory activities against NF-κB-dependent gene expression.

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“…2c). 8) Therefore, myrseguinoside A (1) was elucidated to be (ϩ)-trans-sobrerol 6-O-b-D-glucopyranoside.…”

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Myrseguinosides A-E, Five New Glycosides from the Fruits of Myrsine seguinii

2011

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In our continuing studies on the chemical constituents of Myrsine seguinii H. LÉVEILLÉ (syn. Rapanea neriifolia) (Myrsinaceae) collected in Okinawa, five new glycosides along with eight known compounds were isolated from the dried fruits of this plant. In our previous research, flavonol glycosides, seguinosides A-K and myrsinionosides A-E, were isolated from the leaves of the title plant.1-4) Hirota et al. also reported the isolation of benzoic acid derivatives, myrsinoic acids A-F, as anti-inflammatory compounds from the fresh leaves and twigs of this plant.5,6) However, no phytochemical investigation on the fruits of M. seguinii have been performed so far. This paper deals with structural elucidation of the five new compounds, named myrseguinosides A-E (1-5) from the fruits of this plant. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and human cancer cell growth inhibitory activities of these compounds are also discussed. Results and DiscussionAir-dried fruits (670 g) of M. seguinii were extracted with MeOH three times by maceration. The combined methanolic extracts were evaporated under reduced pressure to yield a viscous gummy material. The MeOH extract was then subjected to various kinds of column chromatography to yield 13 compounds (1-13) (Fig. 1).Compound 1 was obtained as a colorless amorphous powder and its elemental composition was determined to be Asaminami-ku, Hiroshima 731-0153, Japan. Received June 28, 2011; accepted July 25, 2011; published online August 1, 2011 Chemical investigation of the 1-BuOH soluble fraction of the dried fruits of Myrsine seguinii (Myrsinaceae) led to the isolation of five new glycosides, named myrseguinosides A-E (1-5), together with eight known compounds (6-13). The absolute structures of the new glycosides were elucidated by spectroscopic and chemical analyses to be a monoterpene glucoside (1), two flavonol glycosides (2, 3), and two oleanane-type triterpene saponins (4, 5). Myrseguinosides B (2), D (4), and E (5) exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicalscavenging activity and growth inhibitory activity toward human cancer cells, respectively.

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The Modified Mosher’s Method and the Sulfoximine Method

Cited by 83 publications

References 40 publications

Reinvestigation of the Absolute Stereochemistry of Megastigmane Glucoside, Icariside B5

Reinvestigation of the Absolute Stereochemistry of Megastigmane Glucoside, Icariside B5

Culcitiolides E–J, Six New Eremophilane-Type Sesquiterpene Derivatives from <i>Senecio culcitioides</i>

Myrseguinosides A-E, Five New Glycosides from the Fruits of Myrsine seguinii

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