Acetylation and Hydrolysis of Vanillin and Evaluation of the Antioxidant Activity of the Obtained Acetyl and Hydrolyzed Derivatives
ABSTRACT
Vanillin, chemically known as 4-hydroxy-3-methoxybenzaldehyde is an aromatic compound present in Vanilla beans. It is used as an antioxidant in the management of oxidative stress. The rising incidence of the deleterious effects of oxidative free radicals which have been implicated in disease conditions such as diabetes, cancers, lungs dysfunctions, hay fever amongst many other inflammation conditions necessitated the present study. The aim was to acetylate and hydrolyse vanillin and evaluate the antioxidant activity of the vanillin and the obtained acetyl and hydrolysed derivatives. The identity and purity of the vanillin was ascertained before synthesis by dissolution profile in water and other solvents.
The melting point was also determined to be 80 C -82 C. The vanillin derivatives were synthesized by acetylation reaction and hydrolysis respectively using appropriate reagents. The optical rotation, refractive indices and absorption peaks were determined. The refractive index of vanillin, acetyl product and hydrolysed product were 1.4366 at 28 C, 1.4280 at 23.3 C, 1.4008 at 22.8 C respectively while the optical rotation was 0 for the three samples. Therefore, vanillin, acetyl and hydrolysed products were optically inactive hence neither can rotate the plane of polarized light to either right (dextrorotatory) or left (levorotatory). Acetyl and hydrolysed products gave a remarkable antioxidant activity of IC50 0.68μg/mL and 0.84 μg/mL respectively compared with vanillin at 0.81 µg/mL. These results were compared with the standard antioxidant agent Vitamin C which showed an IC50 of 0.44 μg/mL. The acetyl product demonstrated moderate activity compared with the hydrolysed product and vanillin which showed marginal activities. Hence, acetylation enhances the antioxidant activity of vanillin.
CHAPTER ONE
INTRODUCTION AND REVIEW OF RELATED LITERATURE
1.1 General Introduction
Vanillin is a pleasant smelling aromatic compound occurring naturally in Vanilla beans. It is a phenolic aldehyde and is also found in roasted coffee, Chinese red pine and leptotes bicolour. In the search for novel pharmacologically active compounds, derivatives of vanillin are promising compounds with high potentials for development into drugs. Many derivatives of vanillin are better antioxidants with several health benefits due to their strong free radical scavenging properties. It is also well-known that vanillin has antimicrobial activity. Various studies have revealed the importance of antioxidants in the general wellbeing of the body.
Acetylation and Hydrolysis of Vanillin and Evaluation of the Antioxidant Activity of the Obtained Acetyl and Hydrolyzed Derivatives
Oxidative stress, the imbalance between reactive oxygen and nitrogen species production and the antioxidant defence plays a vital role in different pathophysiological conditions, example cardiovascular diseases, cancers and neurodegenerative disorders. In the above diseases, reactive oxygen species (ROS) such as superoxide onion, hydrogen peroxide and hydroxyl radical attack proteins, lipids as well as DNA and cause genetic instability, angiogenesis, chemo-resistance, proliferation and invasion. Recently, several vanillin-based dendrimers with enhanced antioxidant properties have been synthesized. These dendrimers have been found to have protective effects on fatty acid, DNA and lipoprotein, thereby preventing a number of diseases and enhancing survival.
Acetylation and Hydrolysis of Vanillin and Evaluation of the Antioxidant Activity of the Obtained Acetyl and Hydrolyzed Derivatives
1.2 Statement of Research Problems
Dietary and endogenous antioxidants are essential for the elimination of free radicals in the body. Thus, preventing diseases associated with oxidative stress. A number of antioxidant currently available exhibit some level of toxicity and are quite expensive. Consequently, there is a high demand for novel pharmacologically active antioxidants with higher potency, low toxicity and less cost. Hence, the need for evaluating the antioxidant activity of the acetyl and hydrolysed derivatives of vanillin.
1.3 Justification of the Study
Free radicals in the body alter molecules, generating a condition known as oxidative stress. Oxidative stress has been linked to various human diseases such as atherosclerosis, cancers, stroke as well as Parkinson’s and Alzheimer’s diseases. This results when the free radicals in the body outnumber the antioxidants essential for proper physiological function. The supplementation of antioxidants from external sources can assist in controlling oxidative stress. This justifies the search for effective and non-toxic compounds with antioxidant activity from vanillin.
1.4 Aim of the Study
To evaluate the antioxidant activity of the acetylated and hydrolysed derivatives of vanillin.
1.5 Objectives of the Study
- To carry out some monographic determinations of vanillin such as, melting point, optical rotation and refractive index.
- To synthesize the acetyl and hydrolysed derivatives of vanillin.
- To evaluate the antioxidant activity of the vanillin and those of the acetyl and hydrolysed derivatives and hence compared them.
1.6 Physical Attributes and Constants of vanillin
- Appearance – Crystalline
- Colour – White
- Taste – Pleasant (Vanilla)
- Odour – Pleasant
- Boiling Point – 285 C
- Melting Point – 81 C
- Acidity (PKa) – 781
- Basicity (PKb) – 216
- Molar Mass – 15 g/mol
- Density – 056 g/cm3
- Vapour Pressure – 2 x 10-3 mmHg
Acetylation and Hydrolysis of Vanillin and Evaluation of the Antioxidant Activity of the Obtained Acetyl and Hydrolyzed Derivatives