Molecular Modelling of Vitamin B12 and Its Analogues

Penny Govender, Francis Opoku, Olaide Wahab, Ephraim Kiarii

• Publisher: Jenny Stanford Publishing
• Year: 2021
• Print ISBN: 9789814877589
• eBook ISBN: 9781000452327
• Edition: 1
• Topic: Medicina
• Subtopic: Bioquímica en medicina

For many years, the chemistry of vitamin B12 and its derivatives has been investigated for their inherent eco-friendly and nontoxic nature. This vitamin, also known as cobalamin, is an organic complex that contains a cobalt ion in its structure. Its derivatives are vital bio-inorganic cofactors and possess complex and rich photolytic properties, facilitated by their excited states. This book compiles and details cutting-edge research in the application of vitamin B12 as an environmentally benign catalyst for several organic reactions. It discusses the recent advances and current understanding of the photolytic properties of vitamin B12 derivatives from the perspective of the density functional theory (DFT). The book is of interest for anyone involved in nanotechnology, macromolecular science, cancer, and drug-delivery research.

Chapter 1 Introduction

1.1 Background

The long-term effects of poor nutrition which continues over generations are of much worry globally [1], Vitamin B₁₂ is only prepared by microorganisms in nature and, hence, is obtained by human beings via their diet [2]. Vitamin B₁₂ (cobalamin), the only naturally biomolecule with a carbon-metal bond, is among the most vital molecules in medicine and food [3]. Vitamin B₁₂ a complex water-soluble organic compounds within a tetrapyrrole ring containing Co as a central atom, which is vital to several animals and microorganisms, including humans [3]. Active forms of vitamin B₁₂ are commercially available: adenosylcobalamin, cyanocobalamin and methylcobalamin. Vitamin B₁₂ aids in the formation of red blood cells and the normal functioning of the nervous system and the brain. Vitamin B₁₂ plays a vital role in neurologic function, growth of the myelin sheath and normal DNA synthesis [3, 4]. Vitamin B₁₂ is also an essential micronutrient significant for cardiovascular, cognitive and hemopoietic functions [5]. Animal foods, such as dairy products, fish, liver and meat (e.g. yoghurt, cheese and milk), are the main dietary sources of vitamin B₁₂. It is also present in cobalaminsynthesising oysters and bacteria. Nonetheless, vitamin B₁₂ is not present in plants [6]. Several studies disapprove with these findings [7], but new reports have revealed that plant cells have the capability to produce comparable vitamin B₁₂ compounds which participate with vitamin B₁₂ for the same cellular receptors [8].

Molecular Modelling of Vitamin B₁₂ and Its Analogues
Penny Poomani Govender, Francis Opoku, Olaide Olalekan Wahab, and Ephraim Muriithi Kiarii
Copyright © 2022 Jenny Stanford Publishing Pte. Ltd.
ISBN 978-981-4877-58-9(Hardcover),978-1-003-21339-0(eBook)
www.jennystanford.com

1.2 Causes of Vitamin B₁₂ Deficiency

Vitamin B_l2 deficiency is a usual diagnosis, particularly in older persons [9]. Frequently the deficiency is because of mutations in the genes encoding vital proteins in the diet (vegetarian), cobalamin metabolism and reduced production of stomach acids, which are required for vitamin B₁₂ absorption [10]. Traditionally, vitamin B₁₂ deficiency is caused by a low concentration of vitamin B₁₂ in the plasma or serum of the patient [11]. These findings are disapproved by several studies which claim that an important proportion of persons with a high or normal concentration ofvitamin B₁₂ normally have a deficiency [12]. The risk for vitamin B₁₂ deficiency is higher with increasing age and varies with gender. Vitamin B₁₂ deficiency is particularly common in older persons because of the intrinsic factor and a lack of malabsorption [13]. Vitamin B₁₂ in fortified bread and milk is about 55%-60% absorbed by persons over 60 years [14]. Malabsorption from food, insufficient intake and other medical conditions are causes of vitamin B₁₂ deficiency [15]. Nonetheless, human body storage of vitamin B₁₂ is high, and it is broadly present in food. An earlier report reveals that low folate, high serum homocysteine and low vitamin B₁₂ concentration can be related to dementia, cognitive decline and poor cognitive function [16]. Normal serum vitamin B₁₂ concentrations range from 200to900pg/ ml, where serum levels of <200 pg/ml suggest deficiency and concentrations of <100 pg/ml typically induce neurologic damage or megaloblastic anaemia [17]. Vitamin B₁₂ deficiency induces neurologic damage, megaloblastic anaemia and gastrointestinal lesions [13]. Neurologic symptoms include neuropsychiatric disorders [18, 19], mood changes without anaemia, weakness, memory loss, ataxia and paresthesias [20], Vitamin B₁₂ deficiency may also result in nerve degeneration, cardiovascular disease, pernicious anaemia because of the failure of red blood cell formation, weight loss, constipation, nausea, weakness, irreversible neurological damage and fatigue because of the failure to repair the myelin sheath protecting the nerve cells [4,21,22]. Pernicious anaemia is a disease characterised by the impaired production of red blood cells. Neurologic sequelae as a result of vitamin B₁₂ deficiency comprise demyelination of the corticospinal tract and dorsal columns, peripheral neuropathy and paresthesias. The long-term effects of vitamin B₁₂ deficiency include adverse effects on vascular health, cognition and pregnancy [23]. Several reports have shown that low vitamin B₁₂ in pregnant women is related with high blood pressure in offspring [24], low levels of high-density lipoprotein cholesterol [25] and foetal growth restriction [26]. Vitamin B₁₂ supplements have been effective in reducing the risk of cardiovascular diseases [27] and improving the pregnancy outcome [28]. Thus, vitamin B₁₂-fortified foods can act as an effective approach to enhance the vitamin B₁₂ levels in pregnant women, the elderly and children [29].

1.3 Uses and Effectiveness

Vitamin B₁₂ can be applied to the skin either by blending with avocado oil or alone for eczema and psoriasis. Moreover, vitamin B₁₂ nasal gel is used against pernicious anaemia and inhibiting other vitamin B₁₂ deficiency. Also, vitamin B₁₂ is taken by mouth for the immune system, mental function, Alzheimer’s disease and memory loss and to slow ageing and increase concentration, energy and mood. Vitamin B₁₂ is likewise used for clogged arteries, low male infertility, risk of reclogging arteries after surgery, high triglyceride levels, heart disease, skin infections, allergies, asthma, diarrhoea, mental disorders, inflammatory bowel disease, nerve damage in the feet or hands, depression, swollen tendons, schizophrenia, weak bones (osteoporosis), sleep disorders, diabetes, diabetic nerve damage and high homocysteine concentrations which can be related to heart disease.

1.4 Side Effects and Safety

Vitamin B₁₂ is most possibly safe for most persons (e.g. pregnant and breastfeeding women) when applied to the skin, taken via the nose or by mouth, injected intravenously into the vein or administered as a shot. About 2.6 meg per day of vitamin B₁₂ is the permitted amount for pregnant women, while breastfeeding women should take no more than 2.8 meg per day. Mild itching has been stated i...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• 1. Introduction
• 2. Structure, Constitution and Properties of Vitamin B12
• 3. Nomenclature
• 4. B12 Organometallic Reactivity
• 5. Coenzyme B12-Dependent Enzymes
• 6. Recent Trends
• 7. Catalysis
• 8. Vitamin B12-Catalysed Reactions
• 9. Vitamin B12 Derivatives
• 10. Theoretical Approach
• Index