A Cycloalkanol from Derivatization Studies on Vanillin: Evaluation of Antioxidant Activity of Obtained Derivatives

Abstract

Background: Vanillin is a white monoclinic crystalline compound whose chemical nomenclature is p-hydroxy-m-methoxy benzaldehyde. It is a phenolic aldehyde with a pleasant flavor and popularly found in vanilla beans and roasted coffee amongst many other sources. It serves as in addition; it possesses antitumor and particularly antioxidant activity which formed the essence of this study. Objectives: The insidious presence of free oxygenated and nitrogen radicals in the human body has become a worrisome concern. These chemical species continue to plague the human cells, tissues and organs resulting in different pathophysiological conditions such as cancers and neurodegenerative disorders like Alzheimer’s disease and Parkinson’s disease amongst many other ailments. The search for novel pharmacological compounds with the aim of curbing the rising incidence of these radicals led the choice of vanillin in this present study. Methodology: Vanillin was separately subjected to a series of derivatization reactions namely, acetylation, O-demethylation, reduction and oxidation. The melting points, refractive indices and optical rotations of the lead compound and derivatives were obtained. The antioxidant activities of the five compounds were determined using the DPPH (2, 2-diphenyl-1-picrylhydrazyl hydrate) test. Comparison of the obtained antioxidant activities was done to determine if any improvements could be seen in the derivatives. Results: The identities of the derivatives have been revealed to be vanillyl acetate (E-1) (acetyl derivative), 3, 4-dihydroxy benzaldehyde or protocatechui aldehyde (E-2) (demethylated derivative), o-methoxy-p-methyl cyclohexan-1-ol (J-1) (reduced derivative) and vanillic acid (J-2) (oxidized derivative) respectively using the IR spectral technique. Vanillin, E-2 and J-2 derivatives gave marginal antioxidant activity of IC50 of 0.81, 0.84 and 0.0.85 µg/mL respectively while J-1 and E-1 demonstrated moderately significant IC50 of 0.59 and 0.63 µg/mL which compare favorably with 0.44 µg/mL elicited by Vitamin C (a standard antioxidant drug). It is pertinent to point out that the obtained reduced derivative is a substituted cycloalkanol (a saturated cyclic compound) instead of a substituted phenolic compound as was expected. Conclusion: The results from this study indicate that reduction and acetylation separately enhance the antioxidant activity of vanillin.