Manifestation of structure and intermolecular interactions of biologically active brassinosteroids in infrared spectra

Borisevich, N. A.; Skornyakov, I. V.; Хрипач, В. А.; Tolstorozhev, G. B.; Жабинский, В. Н.

doi:10.1007/s10812-007-0108-6

Cited by 7 publications

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“…In this instance the ratio of the corresponding frequencies is the reverse. This is due to the formation of weak associates between the carbonyl O atom and the H atom of the polar solvent [5]. The presence in this region of only one band is consistent with a lack of H-bonding between the C=O and OH groups in such solutions.…”

Section: Resultssupporting

confidence: 56%

Section: As a Result Intramolecular H-bonds Of Different Energy Are mentioning

confidence: 99%

“…However, a reliable correlation between the BS structural features and their biological properties has not been established. Therefore, investigations including the use of IR spectroscopy are interesting both practically and scientifically.IR spectra of natural (22R,23R)-BS have been studied in the range of stretching vibrations [5]. Broad regions of the IR spectra of several highly active (22R,23R)-and the corresponding less active (22S,23S)-isomers of BS have been compared [6].…”

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confidence: 99%

“…IR spectra of natural (22R,23R)-BS have been studied in the range of stretching vibrations [5]. Broad regions of the IR spectra of several highly active (22R,23R)-and the corresponding less active (22S,23S)-isomers of BS have been compared [ Herein we investigate IR spectra of BS from the stigmastane series, namely (22R,23R)-28-homocastasterone (R-HC, 1) and (22R,23R)-28-homosecasterol (R-HS, 2) and their isomers (22S,23S)-28-homocastasterone (S-HC, 3) and (22S,23S)-28-homosecasterol (S-HS, 4):…”

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IR spectra of stigmastane series brassinosteroids differing in configuration and number of diol groups

et al. 2009

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28-homosecasterol have been analyzed. The 28-homocastasterone molecule contains diol groups in ring A and in the side chain whereas that of 28-homosecasterol has one diol group in the side chain. The lack of two OH groups in ring A of homosecasterol compared to homocastasterone results in the appearance of stretching vibrational bands of H-C= (ν max = 3025 cm -1 ) and -C=C (ν max = 1656 cm -1 ) groups of ring A. Substantial changes are observed in the area of OH stretching vibrations. Homocastasterones pressed in KBr possess twice as many OH groups as homosecasterols such that absorption band total intensities in IR spectra of both isomers caused by H-bonds of the diol groups in the side chain amount to 65% whereas the share of the 2α,3α group is only 35% of the total intensity. Hence the contribution from the side-chain OH groups of the studied brassinosteroids to the integral optical density of the bands exceeds that from the ring-A OH groups. In dilute CHCl 3 solutions of the brassinosteroids, the conformations of the brassinosteroid side chains are not the same. As a result, intramolecular H-bonds of different energy are created. The optical density D max in band maxima of free OH groups for homocastasterones is three times higher than that for the corresponding band maxima of homosecasterol. This implies that D max for bands of free OH groups of the homocastasterone ring-A diol group is greater, in contrast with the relatively greater D max for bands of homosecasterol side-chain OH groups bound by an intermolecular H-bond. The homocastasterone diol groups also form intramolecular Hbonds more actively. The lack of the diol group in ring A of the homosecasterols does not affect the frequencies of the C=O stretching vibrations. This leads to the conclusion that the C=O group forms intermolecular H-bonds only with the side-chain OH groups of brassinosteroids pressed in KBr.Keywords: IR spectra, 28-homocastasterone, 28-homosecasterol, R-and S-isomers, H-bond. Introduction. Natural and synthetic brassinosteroid (BS) phytohormones [1] possess several properties that enable them to be used in biology, medicine, and veterinary medicine as new pharmacological agents. According to the literature [2][3][4], the biological activity of BS in plants is due to the presence in their ring B of a 6-keto-or 7-oxa-6-keto structural fragment; in ring A, of a 2α,3α-diol group; and trans-fusion of rings A/B. The structure of the side chain also plays an important role, especially the presence and configuration of OH groups on C22 and C23 and the nature of the substituents on C24. (22R,23R)-BS are biologically most active in the majority of tests. The corresponding (22S,23S)-isomers are not observed in nature and are prepared synthetically [1]. Slight changes in the BS structure lead to significantly different activities. However, a reliable correlation between the BS structural features and their biological properties has not been established. Therefore, investigations including the use of IR spectroscopy are interesting both pr...

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Section: Resultssupporting

confidence: 56%

Section: As a Result Intramolecular H-bonds Of Different Energy Are mentioning

confidence: 99%

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confidence: 99%

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IR spectra of stigmastane series brassinosteroids differing in configuration and number of diol groups

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“…IR spectroscopy was used mainly to confirm the course of chemical reactions during the synthesis of brassinosteroids. Investigations by IR spectroscopy of 24-epi-and 24-homobrassinolides and 24-epi-and 24-homocastasterones were recently published [4]. Electronic spectra of brassinosteroids have not been published.…”

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Solution electronic spectra of brassinosteroid and a synthesized conjugate of a steroid and a fluorescent label

et al. 2008

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Electronic absorption spectra of 24-epicastasterone and 24-epibrassinolide solutions have been recorded and analyzed. The long-wavelength band in solution spectra of the former steroid with maxima in the region 292-286 nm is assigned to the electronic nπ * -transition of a carbonyl chromophore. The latter steroid contains an O-C=O group, for which the extinction coefficient in this spectral region is approximately one order of magnitude less. These differences can be used to identify the studied steroids. A method to synthesize the conjugate of 24-epicastasterone with a fluorescent label, dansylhydrazine, which shows intense fluorescence and absorption, is described. Absorption spectra of the label and conjugate in diethylether, tetrahydrofuran, ethanol, and acetonitrile solutions are practically independent of the solvent properties. The exceptions are solutions of the conjugate in hexane and water. All investigated solutions of label and conjugate show intense fluorescence. As the dielectric constant of the solvent increases, the fluorescence spectra shift to long-wavelength. The fluorescence energetic and time characteristics of both the label and conjugate are similar, which enables the conjugate to be used in developing a method for immunofluorescent analysis of the brassinosteroid 24-epicastasterone.Introduction. The first plant phytohormone brassinolide was isolated from pollen of Brassica napus in 1979 [1]. Structures of more than 60 natural compounds of the brassinosteroid class have been established to date [2]. Numerous of their analogs have been synthesized and exhibit various types of plant growth and development regulation [3]. However, spectroscopic methods of investigating and analyzing this important class of compounds are underutilized. IR spectroscopy was used mainly to confirm the course of chemical reactions during the synthesis of brassinosteroids. Investigations by IR spectroscopy of 24-epi-and 24-homobrassinolides and 24-epi-and 24-homocastasterones were recently published [4]. Electronic spectra of brassinosteroids have not been published.Herein solution electronic spectra of 24-epicastasterone, 24-epibrassinolide, the fluorescent label dansylhydrazine, and a synthesized conjugate of 24-epicastasterone with dansylhydrazine are recorded and analyzed.Experimental. The method for synthesizing the conjugate 3 is exceptionally simple. The target compound 3 was obtained in one step by storing 24-epicastasterone (1) and dansylhydrazine (2) in a mixture of dimethylformamide (DMF) and acetic acid (AcOH) at room temperature:

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Analysis of Brassinosteroids in Plants

Kanwar

Bajguz

Zhou

et al. 2017

J Plant Growth Regul

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Manifestation of structure and intermolecular interactions of biologically active brassinosteroids in infrared spectra

Cited by 7 publications

References 5 publications

IR spectra of stigmastane series brassinosteroids differing in configuration and number of diol groups

IR spectra of stigmastane series brassinosteroids differing in configuration and number of diol groups

Solution electronic spectra of brassinosteroid and a synthesized conjugate of a steroid and a fluorescent label

Analysis of Brassinosteroids in Plants

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