Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Raser, Lydia; Kolaczkowski, Stephen V.; Cotton, Therese M.

doi:10.1111/j.1751-1097.1992.tb02142.x

Cited by 23 publications

(13 citation statements)

References 27 publications

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“…6a). Thus, in contrast to the interpretation of Raser et a1, 18 we suppose that this in-plane vibration is rather connected to the rings I, 111, VI and VIII than those rings containing the carbonyl groups. The intensities of hypericin and emodin bands in this region show a remarkable dependence on the excitation wavelength.…”

Section: -1400 Cm-' Regionmentioning

confidence: 64%

Surface‐enhanced resonance raman spectroscopy of hypericin and emodin on silver colloids: SERRS and NIR FTSERS study

et al. 1995

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SYNOPSISSERS, SERRS and NIR FTSERS of emodin and hypericin are reported for the first time on aqueous silver colloid. Intense SERRS spectra can be obtained when using excitation lines at 514 nm for emodin and 598 nm for hypericin. FTIR and NIR FTRaman spectra from these molecules and their model compounds, anthrone and bianthrone, were recorded to assist in the assignment of the SERS bands. From the analysis of the SERS spectra a different orientation for each molecule can be deduced. 0 1995 John Wiley & Sons, Inc.

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Section: -1400 Cm-' Regionmentioning

confidence: 64%

Surface‐enhanced resonance raman spectroscopy of hypericin and emodin on silver colloids: SERRS and NIR FTSERS study

et al. 1995

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“…It is separated from the main band by 1305 cm Ϫ1 in dioxane, 1336 cm Ϫ1 in dimethylsulfoxide (DMSO), 1318 cm Ϫ1 in methanol. The above-mentioned two vibrational progression bands were indeed observed in the resonance Raman spectra of HyH (15,(25)(26)(27). A minor band near 510 nm appears to be the second overtone of the previous band.…”

Section: Electronic Transition Spectramentioning

confidence: 79%

Solvatochromic Effects in the Electronic Absorption and Nuclear Magnetic Resonance Spectra of Hypericin in Organic Solvents and in Lipid Bilayers¶

Weitman¹,

Roslaniec²,

Frimer³

et al. 2001

Photochem Photobiol

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The natural product hypericin was tested in recent years as a biological photosensitizer with a potential for viral and cellular photodamage. We thus studied extensively its spectroscopy and membrane partitioning. Absorption, fluorescence excitation and emission spectra of the sodium salt (HyNa) were measured in 36 protic and aprotic, polar and apolar, solvents. Electronic transition bands as well as vibrational progressions were identified. Aggregation in some nonpolar solvents and protonation in organic acids were demonstrated. Modeling solvatochromism was done by Lippert equation, by the ET(30) parameter and by the Taft multiparameter approach. In all cases, separation into protic and aprotic solvents gave much better fits to the models. 13C chemical shift data could also be correlated with solvent polarity. They correlated best with Lippert's delta f polarity measure, but tended to fall into two distinct solvent groups--each along different lines--corresponding to protic and aprotic media, respectively. This interesting phenomenon suggests that in the case of the charged and slightly water soluble HyNa, two mechanisms of solvation are involved, each resulting in its own line equation. In aprotic media, dipole-dipole interaction is the predominant solvation mechanism. In protic solvents, the most effective means of solvation is likely to be hydrogen bonding. When intercalated into the liposomal phospholipid bilayer, HyNa is oriented at an angle to the interface, thus experiencing a gradient of solvent polarities: a highly polar environment (similar to methanol) for C-2/5, suggesting that they lie not far from the interface; a moderately polar environment (similar to that of n-propanol) for C-6a/14a, which are somewhat deeper within the bilayer; and a more lipophilic environment (akin to n-hexanol) for C-10/11. The fluorescence excitation peak in liposomes also correlates with an aprotic medium of relatively high polarity, as might be excepted from a molecule in a shallow position in the bilayer.

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“…Resonance Raman and surfaceenhanced resonance Raman spectroscopy were used for detailed characterization of hypericin, with the long term objective of correlating its biological activity with molecular structure. 234 Ginseng is also a well known traditional herbal medicine throughout the world, and NIR reflection spectroscopy and FT-Raman spectroscopy were evaluated as rapid and nondestructive methods for classification of powdered ginseng radix according to different cultivation areas in Korea and China. 235 Samples were clearly classified and identified using PLS discriminant analysis of the NIR spectral features after second derivatization.…”

Section: Other Componentsmentioning

confidence: 99%

Vibrational Spectroscopy of Food and Food Products

Li‐Chan¹,

Ismail²,

Sedman³

et al. 2001

Handbook of Vibrational Spectroscopy

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Vibrational spectroscopy may be applied to the qualitative and quantitative analysis of complex food systems. Mid infrared (MIR) spectroscopy and Raman spectroscopy are valuable tools for identification and structural characterization of food components and for elucidating structure–function relation of food biopolymers such as proteins. Fourier transform infrared(FT‐IR) spectrometers and chemometrics have broadened the scope of MIR spectroscopy for quality control analysis, but such applications remain generally limited to homogeneous fluid products such as beverages, juices, fats, and oils. In contrast, near infrared (NIR) and FT‐NIR spectroscopy in conjunction with multivariate calibration techniques is becoming increasingly popular in the food industry for rapid and routine analysis of proximate composition of various foods as well as for authentication and detection of adulteration. Increasing application of Raman spectroscopy in food analysis is expected with recent developments in NIR‐FT Raman spectrometers, fibre optic sampling, and confocal Raman microscopy.

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Resonance Raman and Surface‐enhanced Resonance Raman Spectroscopy of Hypericin

Cited by 23 publications

References 27 publications

Surface‐enhanced resonance raman spectroscopy of hypericin and emodin on silver colloids: SERRS and NIR FTSERS study

Surface‐enhanced resonance raman spectroscopy of hypericin and emodin on silver colloids: SERRS and NIR FTSERS study

Solvatochromic Effects in the Electronic Absorption and Nuclear Magnetic Resonance Spectra of Hypericin in Organic Solvents and in Lipid Bilayers¶

Vibrational Spectroscopy of Food and Food Products

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