Хімія та хімічні технології/ 6. Органічна хімія

T. V. Panasenko, V. P. Buryak, A. S. Gotsulya

Zaporozhe State Medical University, Ukraine

Basic optical characteristics of the electronic absorption spectrum (OOHESP) of drugs. OOHESP Determination of coumarinе derivatives drugs

Resume. Drugs which containing in its structure a coumarine residue, divided into three groups: 4-oxycoumarine, 4-methyl-7-oxycoumarine and furocoumarine derivatives. For the electronic absorption spectra research and the calculation of their OOHESP us were removed spectral curves of dicoumarine, neodicoumarine, phepromarone, sincoumare, carbochromene, psoralene, izopsoralene, bergaptene, xanthotoxine and izopympinelline, in 95% ethanol.

Studying of the nature of drug’s electronic spectra, coumarine derivatives, and calculated OOHEP values allowed to determine nature of the electrons transition that cause the observed absorption bands appearance and the reactionary ability of chromophores of the analyzed compounds.

Key words: drugs, coumarines, UV-spectra OOHESP, chromophores.

Drugs which containing in its structure a coumarine residue, divided into three groups: 4-oxycoumarine, 4-methyl-7-oxycoumarine and furocoumarine derivatives.

The 4-oxycoumarine derivatives include the following drugs: dicoumarine, neodicoumarine, phenromarone, sincumare.

To 4-methyl-7-oxycoumarine derivatives relates a drug carbochromen. To the group of furocoumarines that are used as medicines relate psoralene, izopsoralene, bergaptene, xanthotoxine, izopimpinelline.

The aim of this research is to study the ultraviolet absorption spectra of ten drugs, containing in its molecule a coumarine nucleus, including five drugs belonging to furocoumarines and possesses with the photosensitizing properties [1].

Materials and research methods. Drugs that contain in its composition a coumarin residue (dicoumarine, neodicoumarine, phepromarone, sincumare, carbochromene, psoralene, izopsoralene, bergaptene, xanthotoxine and izopimpinelline), are fully satisfy the requirements that were applied to chemically pure substances. We obtained their standard samples from the State enterprise "Scientific-Expert Pharmacopoeial Centre of Ukraine." As the solvent was used 95% ethyl alcohol. Ultraviolet spectra of test compounds were recorded by means of the spectrophotometer SPECORD 200-2224214 (Germany). Results and their discussion. For UV-spectra research of the test compounds, determination of the nature of the observed absorption bands, we removed the spectral curves of three model compounds in 95% ethanol - coumarine (I), 4-oxycoumarine and 4-methylcoumarine. For the observed absorption bands connection research and establishment of the dependence of the electronic spectra from the structure of coumarine derivatives, we calculated OOHESP in accordance with O. V. Sverdlova method.

UV-spectra of the unsubstituted coumarine, as a model compound, characterized by two absorption bands - one with high intensity, with ε _max 25420 at 274 nm, and the second - the average intensity with ε max 2420 at 310 nm [9]. Oxy – group introduction in position 4 of the coumarin molecule leads to the cleavage of λ_max at 274 nm on 2 peaks at 269 and 280 nm and the second maximum hypsochromic shift on 6 nm. In addition, on 4-oxycoumarine’s spectral curve is observed a flexure at ~ 315 nm [6,7,10]. Studied as a model compound 4-methylcoumarine testifies that introduction of a methyl group in position 4 of the coumarine moleculе almost does not affect to the spectral characteristics of a drug in ethanol solution (λ _max location differs on 1-3 nm), i.e. its UV-spectrum shows a maximum at 271 and 311 nm in ethanol solution [7].

At the transition from the unsubstituted coumarine to its derivatives, we observe a limit narrowing, in that is situated ε max value. The smallest ε max is observed for psoralene (third absorption band, ε _max 4300), and the largest for izopsoralene (first absorption band with ε max 24600). Thus, high values of ε _max exclude n →π*-electron transfer as the reason, which causes the appearance of the absorption bands for the studied group of drugs.

The value of the interval intensity of the studied compounds absorption bands situated in ranges from 0,18 · 108 (third absorption band of psoralene) to 1,39 · 108 (the first absorption band of dicoumarine), i.e., they indicate on the medium or high probability of electrons transitions gives rise to the absorption bands appearance. For 4-oxycoumarine derivatives, except dicoumarine is usually observed an intense phenomena of the A quantities reduce during the transition from the short-wave (with a probable transition of electrons) to long-wave (with less electron transition probability) absorption bands.

Calculated Mіk quantities, i.e matrix element transition are high and fluctuate within the limits of 2,10 · 10^-18 (third absorption band of psoralene) to 5,51 · 10^-18 (first absorption band of dicoumarine). These values indicate on a high reactionary ability of chromophores, causing an appearance of the absorption bands.

Conclusions

1. Had studied the electronic absorption spectra of ten drugs, containing in its composition coumarine and furocoumarine nucleus. The calculated OOHESP numerical values that allow to determine the intensity of the absorption bands and to calculate the reactionary ability of the chromophores of studied drugs.

2. The quantity of molar absorption coefficient of the UV-spectra of drugs, coumarine and furocoumarine derivatives (ε _max) indicate that the appearance of the absorption bands cannot be caused by n →π*-electrons transfer.

3. Calculated values of the integral intensity of the studied compounds absorption bands indicate on medium or high probability of electrons transitions, causing the electronic spectra appearance.

4. The values of the oscillator strength of f electronic transitions, also their logarithms lg f correspond to the placed electrons transitions.

5. The calculated Mіk quantities (matrix transition element) are high, and they indicate that high reactionary ability of the chromophores cause the observed absorption bands emergence.

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