Substances That Possess Benzene Ring Biology Essay

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Polyphenols is a broad term used in the natural products literature to define substances that possess benzene ring bearing one or more hydroxyl group, including functional derivatives. A number of thousand polyphenols that have been depicted as secondary metabolites in plants materials. These polyphenols commonly known as 'phenolic compounds' can be assembled in separate classes, mainly are found in plant material (fruit, leaves and seed), food and vegetables. According to Harborne et al [1] phenolic compounds are grouped into the following categories:

1. Phenols, phenolic acids, phenylacetic acids; 2. Cinnamic acids, coumarins, isocoumarins and chromones; 3. Lignans; 4. Ten groups of flavanoid; 5. Lignin; 6. Tannins; 7. Benzophenones; 8. Xathones; 9. Betacyanins.

In health protecting issue, these compounds play very important role according to morphological and physiological aspect. They have characteristic properties e.g. phenolic compounds are working as anti-microbial, antioxidant, anti-allergenic, anti-thrombotic, anti-inflammatory, anti-artherogenic, radioprotective, cardioprotective, and anticarcinogenic effects. It is reported that a diet rich in fruits, vegetables, and whole grains decreases the risk of certain types of cancer and other diseases

For the determination of phenolic compounds especially phenolic acids and flavonoids, different solvents have been used with and witho ut acidic and basic media i.e. ethanol, methanol, water, acetone, ethyleacetate, chloroform, diethylether and different ratios of multiple solvents.(Marian Naczk, fereidoon Shahidi; extraction and analysis of phenolics in food, 2004, journal of chromatography A, 1054, 95-111)

Chemically fats and oils are triglycerides, composed of glycerol as a backbone which is esterified with the three molecules of fatty acids. The use or properties depends upon the nature of FAs attached to glycerol. FAs may be saturated and unsaturated with short, medium or long chain length. However, fats and oils from different sources differ in their triglyceride composition, and these differences give rise to wide variations in physical and functional properties.

Vegetable oils usually contain medium chain length FAs ranging from C12 to C24 in which C18 is mostly dominant (Charlie, 2005).

H2C

OH

OH

OH

HC

H2C

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C

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H2C

O

HC

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H2C

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C

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O

C

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Glycerol 3 Fatty Acids Triglyceride

Different kinds of fats and oils are widely available for consumption in the form of cooking oils, health products and food ingredients, as well as for the manufacture of cosmetics, soaps, surfactants, lubricants, plasticizers, paints and coating, and in pharmaceutical, agricultural and industrial products (Poisson & Narce, 2003).

A wide variety of products based on edible fats and oils is available to consumers. Shortenings, salad, butter, margarines, table spreads, mayonnaise, salad dressings, and confections are some of the commonly available products that contain fat or oil as a principal ingredient. Many of these products also are sold in commercial quantities to food processors, snack food manufacturers, bakeries, restaurants, and institutions (Dennis et al., 2006).

Illustration of health topic argued in public during the past many decades include the role of saturated fatty acids (SFAs) and trans fatty acids (TFAs) in cardiovascular diseases (CVDs) (Wesdorp, 1996). Excessive consumption of fats and oils is linked to cancers, obesity, and increased levels of cholesterol in blood with resulting CVDs. FAs also play an important role in biological tissues and as constituents of lipids in biological membranes influence their properties such as fluidity, integrity and the activities of membrane-bound enzymes. One of the most significant advances that have been made is in understanding the importance of dietary FAs for human health (Jalali-Heravi et al., 2004).

The deleterious effect of FAs on plasma lipid composition (low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol and triacylglycerols), recognized that each one of these plasma lipids has been demonstrated as an independent risk factor for ischemic heart disease (Jeppesen et al., 1997, Cullen, 2000; Despres et al., 2000; Sprecher et al., 2003; Eberly et al., 2003, Kris-Etherton et al., 2004, Roche & Gibney 2000; Virginie et al., 2007). The Food & Drug Administration (FDA) recommended that less than 30% of calories from fats should be intake, but some studies reported less than 10%. Several scientists conducted studies find high correlation between excessive amounts of such fats and CVDs (Mensink et al., 2003). An enough intake of both PUFAs and SFAs are necessitated for LDL/HDL ratio in blood, because both are contributor for balancing in lipoprotein metabolism (Hayes & Khosla, 2007). Scientist have begun to pay attention to the dietary FAs intake, with this recent concern about specific FAs, the food industry has looked for particular fats and oils containing these compounds, to optimize the "fat profile" of the final products. A new market has arisen, with providers proposing dozens of specific oils (Virginie et al., 2007). These points demonstrated the important study of the fatty acid composition (FAC) of edible fats and oils. Due to the increasing importance of the quality vegetable oils, their authenticity has become an imperative topic from both a marketable and a health perspective (Owen et al., 2000). Taken altogether, these difficulties have not allowed the food industry to use alternative nutritionally interesting oil sources in manufactured goods. The majority of food products containing important amounts of hidden fats have not paid attention with regard to this important nutritional issue. In these cases, economics remains the major criterion for formulation, leading to the use of the traditional, cheap sources fats and oils (Virginie et al., 2007).

Monitoring the authenticity of edible oils is carried out using instrumental techniques that provide data about their qualitative and quantitative composition. Most of the work on edible fats and oils adulteration is based on chromatographic analysis. High performance liquid chromatography (HPLC) and gas chromatography (GC) analyses (Aparicio & Aparicio-Ruiz 2000; Cordella et al., 2002; Bagci et al., 2003; Tatematsu et al., 2005), and gas chromatography coupled with mass spectrometer (GC-MS) of saponifiables for their classification, or for the FAC and discrimination of fats and oils (Semma, 2002; Jee et al., 2002; Khallouki et al., 2003; Dionisi et al., 2002; Berereton, 2002) have been applied to the quantification of FAs. Although HPLC has been used increasingly over the last decade, GC is still the most widely used technique. Some other techniques also have been applied for fats and oils determinations such as supercritical fluid chromatography (SFC), chiral chromatography, silver ion chromatography, stable carbon isotope ratio analysis (SCIRA), nuclear magnetic resonance (NMR) and FT-Raman spectroscopy (Sanches-Silva et al., 2004), However, chromatographic techniques have been balanced with, or substituted by, many other modern techniques, such as GC-MS, fourier transform infrared (FT-IR) spectroscopy and near-infrared (NIR) spectroscopy (Aparicio & Aparicio-Ruiz, 2000; Cordella et al., 2002). Characterization and determination of the various kinds of saturated (SFAs), mono (MUFAs) and polyunsaturated fatty acids (PUFAs) together with their positional and geometrical isomers have been studied using GC and GC-MS methods in different samples (Ackman, 2002; Brondz, 2002; Jalali-Heravi et al., 2004). Hyphenation of the chromatographic techniques with mass spectrometry provides a very selective tool for the study of FAs (Jalali-Heravi et al., 2004) using appropriate derivatives; makes possible to locate such structural features as branch points, rings, position and type of hetero atoms, and double bonds (Gary et al., 2002). Combinations of different analytical methods generally allow detailed analysis and information on different parameters (Hans-Gerd et al., 2003).

In particular, a wide range of fats and oils parameters can now be analyzed by FTIR Spectroscopy (Sherazi et al., 2009). Sherazi et al., have extensively work for the development of instrumental methods for the analysis of edible fats and oils based on FTIR spectroscopy. Infrared (IR) spectroscopy was generally regarded in the past as a qualitative technique, providing functional group information, but has now changed into a quantitative spectroscopic procedure, supported by powerful chemometric tools simple Beer's law, classical least square (CLS), stepwise multiple linear regression (SMLR), partial least square (PLS) and principal component regression (PCR). For the classification of samples the options includes as similar match, distance match, discrimination analysis, search standers and QC compare search. Therefore quantitative work with FTIR instrumentation can now come up to the simplicity of using UV/visible spectroscopy and gas chromatography, while providing much more specific spectral information in relation to the molecular species targeted for analysis. However, for complex samples such as edible oils there are certain natural limitations to FTIR analysis such as matrix effect, overlapping band, hydrogen bonding effects, etc. Chemometric techniques such as partial least regression can overcome some of these problems. Some methods developed by the NCEAC, University of Sindh Group have undergone an analytical evaluation which exploits a range of strategies to obtain ever better sensitivity, accuracy or speed. Ultimately FTIR and GC-MS techniques are now used to standardize and automate edible fats and oils analysis.

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