Dinuclear Transition Metal Complexes as Auxiliary Chromophores in Chiroptical Studies on Bioactive Compounds

Frelek, Jadwiga; Klimek, Agata; Ruśkowska, Patrycja

doi:10.1002/chin.200401279

Cited by 6 publications

(16 citation statements)

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“…In addition, the coupling pattern of H-7 (δ H 3.58 d, J = 10.8 Hz) indicated its axial orientation (one large coupling due to dihedral angles of approximately 180° and 90° with the H 2 -6 protons), while the NOE correlations of H-7/H 3 -19, H-7/H-10a, and H 3 -19/H-10a suggested the same orientation of H-7, H 3 -19, and H-10a. Furthermore, the absolute configuration of the 7,8-diol was determined by an in situ dimolybdenum CD method [ 31 , 32 ], based on which the sign of the induced CD (ICD) bands at 310, 350, and 400 nm reflected the O-C-C-O torsion angle. After addition of dimolybdenum tetraacteate [Mo 2 (OAc) 4 ] into a DMSO solution of 3 , a metal complex was generated immediately and the ICD spectrum was acquired.…”

Section: Resultsmentioning

confidence: 99%

Cembranoids from a Chinese Collection of the Soft Coral Lobophytum crassum

et al. 2016

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Ten new cembrane-based diterpenes, locrassumins A–G (1–7), (–)-laevigatol B (8), (–)-isosarcophine (9), and (–)-7R,8S-dihydroxydeepoxysarcophytoxide (10), were isolated from a South China Sea collection of the soft coral Lobophytum crassum, together with eight known analogues (11–18). The structures of the new compounds were determined by extensive spectroscopic analysis and by comparison with previously reported data. Locrassumin C (3) possesses an unprecedented tetradecahydrobenzo[3,4]cyclobuta[1,2][8]annulene ring system. Compounds 1, 7, 12, 13, and 17 exhibited moderate inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production with IC50 values of 8–24 μM.

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Section: Resultsmentioning

confidence: 99%

Cembranoids from a Chinese Collection of the Soft Coral Lobophytum crassum

et al. 2016

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“…The ROESY correlation of H 3 -14 with H-7 indicated a cis-configuration of H 3 -14 and H-7 in 3. The absolute configuration in 3 was assigned by the in situ dimolybdenum circular dichroism (CD) method with dimolybdenumtetraacetate [Mo 2 (OAc) 4 ] as an auxiliary chromophore [20,21]. The sign of the Cotton effect observed in the induced spectrum comes from the chirality of the vicinal-diol moiety, as indicated by the sign of the O-C-C-O torsion angle.…”

Section: Resultsmentioning

confidence: 99%

Sesquiterpenoids with PTP1B Inhibitory Activity and Cytotoxicity from the Edible Mushroom Pleurotus citrinopileatus

Tao

et al. 2016

Planta Med

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One new perhydrobenzannulated 5,5-spiroketal sesquiterpene, pleurospiroketal F (1), as well as six new modified bisabolene sesquiterpenes pleurotins A-F (2-7) were isolated from solid-state fermentation of Pleurotus citrinopileatus. The structures of compounds 1-7 were determined by NMR and MS spectroscopic analysis. The absolute configuration of 1 was determined by X-ray diffraction analysis, while the absolute configurations of 3-7 were assigned using the in situ dimolybdenum circular dichroism method and circular dichroism data comparison. Protein tyrosine phosphatase 1B plays a crucial role as a negative regulator of the insulin-dependent signal cascades. Therefore, the protein tyrosine phosphatase 1B inhibitor can be used for treating type 2 diabetes mellitus and obesity. Compounds 2 and 6 showed moderate inhibitory effects on protein tyrosine phosphatase 1B with IC50 s of 32.1 µM and 30.5 µM, respectively. The kinetic study confirmed compound 2 to be a noncompetitive inhibitor. Compounds 1-7 did not show cytotoxic activity against cancer cell lines (IC50 > 50 µM).

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“…Corroboration of the (1S,2R) assignment was provided by the so-called dirhodium method with dirhodium tetraacetate acting as auxiliary chromophore [7][8][9]. In this methodology the in situ formation of chiral complexes results from mixing optically active vic-amino alcohols with the achiral [Rh 2 (OAc) 4 ].…”

Section: Editorialmentioning

confidence: 99%

Complementarity of Electronic and Vibrational Circular Dichroism Spectroscopy in Structure Determination of Vic-Amino Alcohols

Magdalena¹

2015

J Bioanal Biomed

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EditorialThere is no doubt that determination of the absolute configuration of isolated natural products or synthesized compounds remains one of the most important tasks in all fields of chemistry, biochemistry, structural biology and medicinal chemistry. This is unquestionably due to the fact that biological activity is closely related to the stereostructure of bioactive compounds. Therefore, access to methods allowing simple and primarily unequivocal determination of their absolute configuration (AC) and/or conformation is of particular significance. Such a role is at present fulfilled by chiroptical techniques. In the last two decades chiroptical spectroscopy has been one of the most rapidly developing areas of chiral analysis due to the availability of modern, highly specialized and dedicated to particular chiroptical techniques commercial instruments. Recent progress in ab initio simulations of chiroptical properties has also significantly contributed to the increase of the use of chiroptical spectroscopy as a stereochemistry probe [1]. It is generally accepted that combined experimental and theoretical analysis opens much broader application opportunities for chiroptical spectroscopy by giving theoretical basis to experimental results [1][2][3][4]. Moreover, utilization of multiple (at least two) chiroptical techniques increases the confidence level of the stereochemical assignment and is nowadays considered by many authors to be the best practice [1][2][3][4][5].In this Editorial, we will focus on such a combined experimental and theoretical approach of electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) to determine the absolute configuration and conformation. We intend to demonstrate that both these chiroptical techniques are well cooperating and mutually complementary. Moreover, we want to show that the concerted use of the two methods clearly provides more definitive ACs although in many cases stereochemistry can be determined by using only a single chiroptical property. As a model compound for this study (1S,2R)-2-amino-1,2-diphenylethanol (1) with formula shown here below and representing vic-amino alcohols was chosen (Figure 1).Information obtained through ECD concerns chromophore and its nearest surroundings whereas the data from VCD covers the whole molecule. Therefore, in the case of ECD the acquired information is restricted to the chromophore unit and its nearest surroundings. Consequently, the assignment of AC can be easily achieved by semiempirical and empirical rules known as sector and helicity rules supported by quantum mechanics calculations. In contrast to ECD, the advantage of VCD spectroscopy comes mainly from the presence of numerous well-resolved vibrational transitions from the skeleton of the whole chiral molecule. Thus, high information content about vibrations of the electronic ground state is provided. Since the functional groups responsible for vibrations are distributed over the entire skeleton of the molecule, the VCD contains information on the geo...

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Dinuclear Transition Metal Complexes as Auxiliary Chromophores in Chiroptical Studies on Bioactive Compounds

Abstract: For Abstract see ChemInform Abstract in Full Text.

Cited by 6 publications

References 1 publication

Cembranoids from a Chinese Collection of the Soft Coral Lobophytum crassum

Cembranoids from a Chinese Collection of the Soft Coral Lobophytum crassum

Sesquiterpenoids with PTP1B Inhibitory Activity and Cytotoxicity from the Edible Mushroom Pleurotus citrinopileatus

Complementarity of Electronic and Vibrational Circular Dichroism Spectroscopy in Structure Determination of Vic-Amino Alcohols

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