Use of Two Different Approaches to Determine The Ionization and Protonation Constants of Aciclovir by Spectrophotometric Method

Year 2024, , 101 - 113, 15.03.2024

Yaşar Doğan Daldal

https://doi.org/10.31466/kfbd.1359190

Abstract

In this study, the determination of the ionization and protonation constant (pKa) of aciclovir, a guanine derivative with potent antiviral activity against herpes simplex and varicella zoster viruses, was performed using the UV-Vis spectrophotometric method. In the study, due to the poor water solubility of aciclovir, it was studied in binary acetonitrile-water mixtures at different concentrations. The program STAR and the log [AHA -Ai)/(Ai- AA)]-pH relationship were used to evaluate the data obtained by the spectrophotometric method for the ionization and protonation constants, and it was found that the pKa values determined by these calculation methods were very close for different acetonitrile-water concentrations. To determine the pKa values of the compound in water, the relationship between the pKa values determined in binary acetonitrile-water mixtures and the macroscopic properties of the binary acetonitrile-water mixtures studied was used. As a result of the calculation, it was found that the pKa values of acyclovir in water determined in this study are compatible with the values in the literature.

Keywords

Aciclovir, Ionization and protonation constant, pKa, Herpes Simplex, UV-Vis Spectrophotometry

Asiklovirin Spektrofotometrik Yöntemle İyonlaşma ve Protonasyon Sabiti Tayininde İki Farklı Yaklaşımın Kullanılması

Abstract

Bu çalışmada herpes simpleks ve varicella zoster virüslerine karşı güçlü antiviral etkiye sahip bir guanin türevi olan asiklovirin iyonlaşma ve protonasyon sabiti tayini (pKa), UV-Vis spektrofotometrik yöntem kullanarak gerçekleştirilmiştir. Çalışmada asiklovirin suda zayıf çözünürlüğünden dolayı, farklı derişimlerdeki asetonitril-su ikili karışımlarında çalışılmıştır. İyonlaşma ve protonasyon sabiti için spektrofotometrik yöntemden belirlenen verilerin değerlendirilmesinde STAR programı ve log [AHA-Ai)/(Ai-AA)]-pH ilişkisi kullanılmış ve bu hesaplama yöntemleriyle farklı asetonitril-su derişimleri için hesaplanan pKa değerlerinin birbirine çok yakın olduğu belirlenmiştir. Bileşiğin sudaki pKa değerlerinin tayini için asetonitril-su ikili karışımlarında belirlenmiş pKa değerleri ve çalışılan asetonitril-su ikili karışımlarının makroskopik özellikleri arasındaki ilişkiden yararlanılmıştır. Hesaplama sonucunda, asiklovirin bu çalışmada belirlenen sudaki pKa değerleri ile literatürdeki değerlerin uyumlu olduğu belirlenmiştir.

Keywords

Asiklovir, İyonlaşma ve protonasyon sabiti, pKa, Herpes Simpleks, UV-Vis Spektrofotometri

Thanks

Yazar, bu çalışmada kullanılan STAR programının tedariği için Barselona Üniversitesinden Dr. Jose L. Beltrán’a teşekkür eder.

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