Paraschiv Mirela, Daescu Monica, Bartha Cristina, Chiricuta Bogdan, Baibarac Mihaela
National Institute of Materials Physics, 077125 Bucharest, Romania.
Faculty of Physics, University Bucharest, 077125 Bucharest, Romania.
Pharmaceutics. 2023 Nov 10;15(11):2613. doi: 10.3390/pharmaceutics15112613.
The aim of this work is to highlight the influence of UV light on the hydrolysis reaction of nifedipine (NIF) in the presence of alkaline solutions. In this context, the photodegradation of NIF in the absence of alkaline solutions caused (a) a change in the ratio between the absorbances of three bands in the UV-VIS spectra localized at 224-240 nm, 272-276 nm and 310-340 nm, assigned to the electronic transitions of -COOCH groups, -NO groups and a heterocycle with six atoms; (b) a red-shift of the photoluminescence (PL) band from 458 nm to 477 nm, simultaneous with an increase in its intensity; (c) a decrease in the ratio of the Raman line intensities, which peaked at 1224 cm and 1649 cm, associated with the vibrational modes of -C-C-O in the ester group and C=C stretching; and (d) a decrease in the ratio between the absorbances of the IR bands, which peaked at 1493 cm and 1223 cm, associated with the vibrational modes of the -NO group and C-N stretching. These changes were explained considering the NIF photodegradation reaction, which leads to the generation of the compound 4-(2-nitrosophenyl)-2.6-dimethyl-3.5-dimethoxy carbonyl pyridine. The interaction of NIF with NaOH in the absence of UV light was demonstrated to induce changes in the vibrational mode of the -C-C-O bond in the ester group. The photodegradation of NIF after its reaction with NaOH induces significant changes highlighted in its (a) UV-VIS spectra, by the shift of the absorption band at 238 nm; (b) PL spectra, by the supraunitary value of the ratio between the emission band intensities at 394-396 nm and 450 nm; (c) Raman spectra, by the change in the ratio between the intensities of the lines that peaked at 1224 cm and 1649 cm from 0.61 to 0.49; and (d) FTIR spectra, by the lowered absorbance of the IR band at 1493 cm assigned to the vibrational mode of the -NO group as a result of the generation of the nitroso compound. These changes were explained considering the hydrolysis reaction products of NIF, as the nitroso compound is converted to a lactam-type compound. The photodegradation reaction rate constants of NIF and NIF after interaction with NaOH were also reported. The decrease in thermal stability of NIF samples after interaction with NaOH, as well as of NIF after exposure to UV light compared to NIF prior to exposure to UV light, was demonstrated by thermogravimetry, and the key fragments were confirmed by mass spectrometry.
这项工作的目的是突出紫外光在碱性溶液存在下对硝苯地平（NIF）水解反应的影响。在此背景下，在没有碱性溶液时NIF的光降解导致：（a）紫外-可见光谱中位于224 - 240 nm、272 - 276 nm和310 - 340 nm处的三个谱带吸光度之比发生变化，这些谱带分别对应于-COOCH基团、-NO基团以及一个六元杂环的电子跃迁；（b）光致发光（PL）谱带从458 nm红移至477 nm，同时其强度增加；（c）拉曼线强度之比降低，其峰值分别位于1224 cm和1649 cm，与酯基中-C-C-O的振动模式和C=C伸缩振动相关；（d）红外谱带吸光度之比降低，其峰值分别位于1493 cm和1223 cm，与-NO基团的振动模式和C-N伸缩振动相关。考虑到NIF光降解反应会生成化合物4-(2-亚硝基苯基)-2,6-二甲基-3,5-二甲氧基羰基吡啶，对这些变化进行了解释。在没有紫外光的情况下，NIF与NaOH的相互作用被证明会引起酯基中-C-C-O键振动模式的变化。NIF与NaOH反应后的光降解在其（a）紫外-可见光谱中表现为238 nm处吸收带的位移；（b）PL光谱中表现为394 - 396 nm和450 nm处发射带强度之比的超单位值；（c）拉曼光谱中表现为峰值位于1224 cm和1649 cm的谱线强度之比从0.61变为0.49；（d）傅里叶变换红外光谱（FTIR）中表现为由于亚硝基化合物的生成，归属于-NO基团振动模式的1493 cm处红外谱带吸光度降低。考虑到NIF的水解反应产物，因为亚硝基化合物会转化为内酰胺型化合物，对这些变化进行了解释。还报道了NIF以及NIF与NaOH相互作用后的光降解反应速率常数。热重分析表明，与未暴露于紫外光的NIF相比，NIF与NaOH相互作用后以及暴露于紫外光后的热稳定性降低，并且通过质谱法确认了关键碎片。
