Uses Of Vernonia Oil Biology

Essay add: 27-11-2017, 16:40   /   Views: 249

The much demanded Vernonia oil is derived from the species Vernonia galamensis, which is an oil seed crop originating in different parts of Africa, such as Ethiopia and Eritrea among many other tropic destinations. It is unusual that it has the ability to thrive in these types of areas due to their under-nourished, cheap soils. Using these kinds of soils may be the cause that the plant resembles a weed-like image and therefore, in some ways it can be said that its desirable qualities are unexpected.

Vernonia Oil (figure 1) [19]

Vernonia galamensis are seeds that contain oil-rich fatty acids and produce the formula of Vernonia oil. A vernonia seed contains 40-42% of oil which has increasing demand all over the globe due to its success in applications within industry and medicine. The popularity of Vernonia oil is on the rise simply due to the characteristics in its formula structure. It is shown in figure 1 that it is a triglyceride where within its structure there is presence of a glycerol that is combined with three hydrocarbon, fatty-acid chains that all possess an epoxide. This alone has high importance as it is the main reason for how the oil behaves. Bonding within the structure occurs through the hydroxyl group of the glycerol which joins to the carboxyl groups of the fatty-acid to result in an ester. The triglyceride can vary in several ways as the glycerol is able to attach to 16, 18 and 20 carbon chains. Vernonia oil is a valuable compound due to it being one of only two naturally occurring epoxidised oils in the world. The presence of the naturally occurring epoxide in vernonia oil adds to the uniqueness and industrial usefulness of the enantiomerically pure oil.

Since vernonia oil has been discovered there has been the discovery of its benefits which is partly the cause of its popularity. It is a renewable resource that has potential in the development of feedstock in chemical industry, not to mention good cost and availability. These are just some of the ways that vernonia oil has become well known over the years, especially in selected parts of the world like the United States.

Uses in industry

Epoxy fatty acids have become very popular raw materials, so much so that the vernonia oil has had a vast effect on industry and medicine due to the many ways it can be applied. Its uses have been evolved into plasticizers, additives in poly-vinyl chloride resins, paint additives, polymers, coatings and plastic additives, just to name a few. Although this is the case, there has not been much evidence of highly commercialised brands with vernonia oil content, but this has not stopped it evolving yet even further as thermo sets, which have been produced with the fatty acids that occur in the structure of vernonia oil. This has been done through the cross-linking of the epoxide functional group within the oil, which produces a flexibility bringing about toughness in its characteristic. It can be said that the potential commercialism of this material is derived from the vernolic acid which contributes to a large portion of the oil-seed, making up between 73 and 80%. The combination of vernonia oil and vernolic acid are ideal for industry as their behaviour is largely different to most epoxidised oils. Its low viscosity, compared to synthesised epoxidised oils, allows it to be a good solvent in paint manufacture. The epoxy group is very reactive which allows it to become chemically bound in dried paint. This in itself is an advantage as it prevents it from evaporating into the air.

In the past few years, there has been an immense amount of interest in vernonia oil. In industry it has been discovered that its epoxy group has great potential to benefit the manufacture of carbon fibre. This is yet another breakthrough for vernonia oil, where it is being combined into making carbon fibres and has created great potential for the production of environmentally friendly wind turbines. Wind turbines are renewable energy that creates electricity with the use of natural wind. They are becoming more and more popular across the globe in the need to reduce global warming which has proven to be a large problem as of late. An industrial wind turbine consists of very large blades that can be as big as 116 ft and operate in a normal fan-like manner. The blades are an important feature of wind turbines and are shaped in a significant way which allows the wind to drive its rotational movement. In summary, wind turbines are devices that are being encouraged more than ever. On the other hand, it can be said that the use of wind turbines are somewhat of a contradiction as the blades which form them are usually made of glass fibre and oil based resins. This carries a disadvantage and promotes low rigidity and low tensile strength, which openly affects durability. In addition to this, the elevated temperatures and conditions used to construct glass fibres put large amounts of pressure on the environment; consequently here is where the environmentally friendly vernonia oil comes into play. The natural composite has caught the attention of many engineers and it has become evident that they want to produce a sustainable technology. The combination of vernonia oil and carbon fibres is yet another aspect of how the oil has been able to adapt and exceed expectations in its ability in industry. Although the characteristics of glass fibre and carbon fibre are almost identical, it has been recognised that carbon fibre is slightly better due to its strength and its light-weight composure in comparison to glass fibre. It has a refined sturdiness, not to mention bond strengths that occur within the composites that formulate it. Vernonia oil has a huge composition made up of varying structures which could prove to be an advantage upon the formation of carbon fibres, so much so that the use of vernonia oil could help improve the strength of carbon fibre. Although it is not fully understood how the oil can produce the strength required, there is potential that may enable even further contribution to other aspects such as "aircraft and automotive fields" [7].

Vernonia oil now joins a family of natural fibre composites that have been discovered over the years. Common examples are hemp, jute, wool and cotton; yet it differs from them as its original composition is that of oil and not textile fibre. The extraction of vernonia oil does not entail a great deal of complexity which sets it as a cooperative material and therefore is encouraging engineers who are currently working with chemists to find methods and routes to produce tonnes of vernonia oil. Over the years chemists have developed a method which involves grinding the plant of origination enough so that it can be heated under reflux with the solvent, hexane. The experimental does not require a vast amount of time and does not put pressure on the environment along the way; however does not produce a yield that is of a great deal. Therefore presents a small hurdle that has to be overcome before further testing, planning and development can proceed.

Vernolic acid (figure 2)WIKI REF.Uses in medicine

Fats and oils have always been used in medicinal applications and now it has become an important feature of drug delivery. Vernonia oil itself has had a huge impact on contribution in drug delivery. "Vernonia oil (or its fatty acids) can be used to synthesise bolaamphiphile which can help to develop nano-sized monolayer vesicles that can potentially target drug delivery to the brain."[1] This has been specifically designed to replace the use of liposomes, which are artificial vesicles made of lipid bilayer, however they do have problems with targeting specific tissue. This is making large improvements in drug delivery and is a major development of the oil itself and of its components.

Over the years there hasn't been much exposure of how vernonia oil is beneficial on a therapeutic level, but now there is an increase of interest in its value of curing particular skin problems. There is a broad range of how the vernonia plant, including its barks, leaves and roots are based to prevent or 'cure' things like nausea, cough, fever and gastric problems such as stomach aches and cramps. However, the epoxidised oils that have been recovered from Vernonia galamensis are inedible therefore have been discovered in a new sense of purpose where they are becoming "effective in preventing and treating various different forms of skin diseases, lesions and wounds."[2] This is why vernonia oil's largest acknowledgement has been through the fact that it can only be used as topical aid and not to be ingested.

Images taken of 'Before and after reaction of vernonia oil' [2]

Vernonia oil and its components cannot be directly used on skin diseases like psoriasis and as a result, is one of the reasons why the epoxy group within its structure is highly sought after. The epoxy group has the ability to bind to proteins so that the epoxidised fatty acid esters can be established as being in "pharmaceutically acceptable condition."[2] The fact that it can be combined with a carrier makes it more suitable to other disorders such as eczema, dry scalp and dandruff. The range of conditions that it can prevent or aid is becoming more and more evident as further research is being conducted. Furthermore, the proteins that it is able to bind to, can be through hydroxyl or amino groups that feature on the actual protein. This can also encourage the protein size for use in therapy, for example these can further improving several other aspects such as immunogenicity of the protein.

Vernolic acid and Vernonia anthelmintica

Vernolic acid, also known as cis-12, 13-epoxy-cis-9-octadecanoic acid, has proved to be a very important participant in vernonia oil as it makes up the majority of its composition (73-80%). Recently, vernolic acid has been used in the "synthesis of deuterium-labelled methyl linoleate and its geometric isomers for the use in study of fat metabolism." [12] Newly discovered structures are becoming key and greatly useful, it seems their abilities are becoming endless. No oilseed has been commercialised to have a natural source of epoxides and although vernonia oil receives the praise of having vernolic acid in its configuration, it was actually Vernonia anthelmintica where it was first discovered and contains around 70-74%. The genus which belongs to the Asteraceae family can be recognised with ease as it has several well-known names such as, Willd, Centratherum anthelminticum and Conyza anthelminticum, with trade names like cumin, purple fleabane and ironweed. As the name 'anthelmintic' suggests, this genus is a natural medicine that helps destroy intestinal worms and has previously been involved in relieving cases of stomach worms and "gastrointestinal trichostrongylids in small ruminants"[13].

Investigations have furthered themselves as Vernonia anthelmintica has been discovered to aid the treatment of Diabetes mellitus, which is generally described as a disease where an individual is unable to produce enough insulin and therefore suffers from high blood sugar levels. Tests have been carried out on rodents to see how far 'curing' diabetes can reach by investigating if ethanolic extract in V.anthelmitica's seeds and its fractions can affect blood glucose levels. This investigation proved successful. It is not the first time plants have been successful when being used in traditional medicines so it is no surprise that Vernonia anthelmintica is amongst approximately 800 plants that may possess anti-diabetic prospects. This genus is found in India and Sri Lanka which is quite positively different to the location that thrives in the production of Vernonia galamensis. However, the conditions prove somewhat similar as they are not in any way demanding and the two strains are mainly found in waste areas and weed growing surroundings. Both vernonia genus' have individual uses with intense development and now carry levels of responsibility in industry and research.

Although its participation is highly related to the oils, traces of vernolic acid have also been discovered in other species of plants away from the Vernonia genus. It can also be found in the Spanish originated Euphorbia lagascae. Records have shown it to contain around 60-65% of vernolic acid and is widely known for being "rich in epoxyleic acid."[14]

Composition and reactions of Vernonia oil

Vernolic oil can be broken down into many structures which can aid other investigations. Some examples of structures are methyl vernolate 2, 12-oxododecanoic acid and vernolic acid (figure 2). As mentioned, vernolic acid has its own desired characteristics such as its low viscosity compared to synthetically epoxidised oils and its ability to be poured below freezing point. In some cases, the epoxides within structures have to be oxidised into hydroxyl groups and this can be done with oxidising agents like Perchloric acid (HClO4). There are several other strong oxidising agents that can be used in place of Perchloric acid, as the main purpose of it is to break epoxide without altering the remaining structure. An example of what else this could be used in this kind of synthetic route is Potassium permanganate (KMnO4). Below is an example of how the structure of vernolic acid would change in an oxidation reaction.

Strong reducing agents can also be used to form hydroxyl groups from epoxides but have a slightly different way of approach. Examples of these include Grignard's reagents (RMgX), Sodium borohydride (NaBH4) and Lithium components (RLi). These agents are all suitable as they are strong, anionic nucleophiles and posses the ability to reduce epoxides because they are relatively more reactive than normal ethers. The cause behind an epoxide's reactivity is simply, ring strain, so when a nucleophile attacks the electrophilic carbon of an epoxide, the ring is opened and the strain is released. In other methods, there are requests where certain aldehydes/ketones need to be reduced for the loss of an oxygen atom. In the case of a carboxylic acid, an oxygen is lost for the result of a simple alcohol (-OH) group.

This therefore requires a strong reducing agent, similar to sodium borohydride, like Lithium aluminium hydride (LAlH4). This one reducing agent has the ability to transform particular aldehyde/ketone or in some cases, carboxylic acid functional groups without altering other important characteristics such as double bonds. In the above reaction, it shows just this. 12-oxododecanoic acid has a carboxylic acid that is being reduced without the alteration of the double bond within the structure. Breaking vernonia oil down has to be carried out with care oxidising/reducing agents have to be selected very carefully to result in the desired structures. This is because, within a vernonia seed, it has been discovered that only 40-42% of its content is vernonia oil therefore, the question of what else exists within it, can be investigated endlessly.

Vernonia oil's structure has the glycerol base which has three epoxide fatty acid chains that branch off the structure. The other aspect that is of interest are the potential chains that may be further branching off of those epoxidised hydrocarbons as these materials are potentially making up the remaining percentage of the vernonia seed. They may hold a significant importance and even consist of unknown materials that can be of benefit to us. Some known base materials called oleochemicals are a vast possibility of what the oil contains. A brief definition of an oleochemical is when oils and fats split into and consist of "fatty acid methyl esters, fatty acids, glycerol, and hydrogenation products of the fatty acid methyl esters."[4]

Here are a few examples of just some oleochemicals that may occur in vernonia seeds:

Stearic acid

Stearic acid has the molecular formula of C18H36O2; molecular weight of 284.48 gmol-1 and is commonly known as Octadecanoic acid. The saturated fatty acid has a carboxylic acid that appears within the long chain and is very common in oil type structures. This acid is also applicable in industry, which is similar to vernonia oil. It has a soapy texture which allows it to be suitable for the synthesis of candles, plastics, rubber and plaster castings.

Palmitic acid

The molecular formula of palmitic acid is C16H32O2; molecular weight of 256.52 gmol-1 and does not differ significantly to that of stearic acid's formula.

The common name for palmitic acid is Hexadecanoic acid and as its name suggests, it is a major component of oil that can be found from palm trees. The oil is also comprised in butter, meat and cheese but has a very well known disadvantage of causing the increased risk of cardiovascular disease if taken excessively.

Oleic acid

This particular acid is known as an 'Omega-nine fatty acid' which is a group of unsaturated fatty acids that have a carbon-carbon double bond on the 9th carbon in the chain. The molecular formula or oleic acid is C18H34O2 with the molecular weight 282.46 gmol-1, which again is not significantly different to the previous acids described. Oleic acid makes up the majority of the very well known olive oil, which is now widely used as major ingredient in cooking.

Linoleic acid

This oleochemical is known as 'Cis, cis-9, 12-octadecadienoic acid' and is a poly-unsaturated fatty acid as its structure features two carbon-carbon double bonds. Again, there is a similarity of molecular formula which is C18H32O2 and has the molecular weight 280.45 gmol-1. This acid is one of two fatty acids that humans and animals ingest as a part of good health. Linoleic acid is very abundant in vegetable oils.

The oleochemicals already described are just some of the structures that can appear within vernonia oil and is why so many reagents and reaction pathways are needed to result in a desired structure. Synthesis can become a very complex task to result in specific structures when breaking vernonia oil down so that it can be applied in several ways.

As previously mentioned, vernonia oil's composition is highly varied. It contains of one glycerol structure that remains consistent and may have attached to it, any of the above structures that have been described. It does not stop there however, as recent investigations have carried out 'separation and identification' of different combinations in which the structure of vernolic acid can exist in vernonia oil's composition. The research describes how vernolic, linoleic, oleic, palmitic and stearic acids present in the seed oil, exist individually and also have the ability to combine with one another. Trivernolin, divernolin and monovernolin depict the number of vernolin chains that are attached to the glycerol, Tri- expresses three chains, Di- expresses two chains and Mono- expresses one. It has been explored that the glycerol backbone can have attached two vernolin chains (divernolin), alongside other various acid chains, such as linoleic acid. This produces a triacylglycerol called a divernoloyllinoleate.

The similarities of the acids are exceptional but with hard work and determination, it is almost certain that they "occur mainly as triacylglyercol esters" [12] in vernonia oil. All of the structures that have been described are just a brief overview of what has been investigated with reliable evidence and the possibilities of discovering more may be endless. It is their similar characteristics that make it difficult to carry out methods to separate them. Research of several journals has concluded that using just one method of separation is unsuitable as certain characteristics like carboxylic acids and epoxy groups make identifying the compound more difficult. For that reason several routes are advised to be taken.

The first method is one that can be done without any challenging obstacles, is Thin-layer Chromatography (TLC). It possesses a stationary phase which is usually a thin layer of silica gel which allows the solvent, in this case Vernonia oil, to be eluted on to it. This method is used to identify compounds within the substance with the aid of their polarity. When the stationary phase on the TLC plate is polar, the mixture of structures within vernonia oil will travel at different rates in attempt to find an attraction to it. As a result of this, non-polar, hydrophobic triglycerides, will move higher on the plate as it will have weak interaction with the stationary phase, therefore failing to bind with it rapidly.

Example of a TLC plate (figure 3)

Other methods used in the separation of the much desired vernonia oil include Gas chromatography. This is one the most precise methods to break down a compound and is a lot more accurate in obtaining results in comparison to a TLC plate. When using a GC, vernonia oil would be placed in a column ready to be vaporised, avoiding any decomposition and then travels through a series of processes, separation of components within the crude oil of Vernonia galamensis seeds is enabled. As separation occurs the different components within the compound begin to leave the column at different rates. This is known as the retention time. The retention time can help what structures contribute to vernonia's make up.

The techniques described have been undertaken in experiments and recent investigations to determine the amounts and ratios of fatty acids that may be carried in vernonia oil. An investigation that was done in 1998 has proved that the following data has been obtained through careful methods and real objectives. The results express that in vernonia oil's composition there is evidence of 80% of vernolic acid, 11.2% of linoleic acid, 3.4% of oleic acid, 2.1% of palmitic acid and 0.8% of stearic acid. This also provides evidence that Vernonia galamensis seeds contain more vernolic acid than Vernonia anthelmintica. It has been recorded that it contains 70-74%.

Arachidic Acid (figure 4)

The presence of these acids that were discovered does not eliminate the content of more structures being involved. Within another investigation carried forward in 2004, it was revealed that as well as the previously mentioned acids, there were also traces of a compound called Arachidic acid. Figure 4 shows how similar its structure is to that of oleochemicals, oleic and stearic acid. Arachidic acid is a long hydrocarbon chain that has the same characteristics as those of oleochemicals; there is proof of a carboxylic acid and a methyl group at the end of the chain. The molecular formula of C20H40O2 and molecular weight of 312.53 expresses that it is somewhat bigger than these fatty acids and this may perhaps be the reason why only a very small, unrecorded amount was extracted in the investigation.

Justification of Research

Aims and objectives

In the investigation of vernonia oil, there will be more than one experimental that will result in several different structures. To specify, vernonia oil will be the main component in methods such as saponification, transterification and acidification. These methods will be undertaken in attempt to extract different structures that occur in the oil's composition and will lead to them being analysed. Vernolic acid and methyl vernolate 2, are two compounds earlier described and are just two examples of the kind of structures that are hoping to be successfully extracted. Subsequently, they will be tested for purity via suitable analysing techniques and equipment. This will follow a conclusion as to whether the methods are correct and suitable routes.

Purity of the structures can be tested using the techniques, such as TLC and Gas chromatography which have proved their reliability in past research however it doesn't stop there. There are many more means of testing that are available for use in this investigation, and one example that will be illustrated is Carbon Nuclear Magnetic Resonance (C13NMR).


C13NMR can be classed as an effective way to analyse the structure of a compound and is immensely suitable in this investigation as it can provide accurate results for heavy carbon containing chains that need to be identified. C13NMR seems more appropriate compared to H1NMR as the structure of the product can be identified using the presence of neighbouring carbons, chemical shifts and therefore give explanations of carbon environments that are present. A NMR spectrometer measures the number of spins and a signal is reached when the energy levels have an increased difference between them. Setting up a sample for a C13NMR may require solvents like DMSO but is not complex nor time consuming; however the results and precision are worth the arrangements. The only disadvantage of using this machinery is the cost of running it altogether, so having the opportunity to use it may be difficult.

Infrared spectroscopy

Infrared spectroscopy is yet another technique which is used often to identify organic and inorganic samples. This method requires hardly any preparation, with solid samples KBr disks can be created or the solid can be diluted in nujol or CCl4 ready to be smeared on an IR plate. With a liquid or oil sample, there is practically no preparation necessary at all. For results to be obtained the sample is drowned in an infrared blaze allowing absorption at different frequencies. Absorption takes place at certain frequencies to counteract the different functional groups that the sample may have and this is how a compound may be identified. Although this application is very popular, it is not as reliable as gas chromatography or Carbon NMR and this is due to the fact that only functional groups and characteristics such as hydroxyl groups and double bonds are identified. This does not give any particular structure confirmation. In this investigation, infrared spectroscopy will be used as a technique that will validate that the main characteristics are present.

Liquid chromatography-mass spectroscopy

High performance liquid chromatography- mass spectroscopy (HPLC-MS) is an application that is of high reliability and as the name suggests, a HPLC is attached to a mass spectrometer. The first advantage of using a LC-MS, is that compared to a Carbon NMR machine, it does not cost a vast amount to run and therefore is one of the reasons why it will be used within this investigation. The second advantage that this technique has is that it is able to detect a broader range of compounds and materials compared to a gas chromatography-mass spectrometer. Therefore, it is used more often when an investigation entails identifying a material. The conditions that will be used are of Isocratic 50:50 (Acetonitrile:Water) form, which will participate when the sample is injected. Once the sample has eluted through the column it comes across two phases known as Electronspray Ionisation (ESI) and Atmospheric Pressure Chemical Ionisation (APCI). When results are ready to be obtained, a spectrum of how UV light is absorbed will be produced. Absorption is dependent on conjugation that may occur in the respective compound being analysed.

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