The Biosynthesis of Flavonoids

The biosynthesis of flavonoids is a very complex process and involves series of reactions. The basic pathways to the core flavonoid skeletons have been established both enzymatically and genetically.7,8 The flavonoid biosynthesis, starts with general phenylpropanoid pathway. The synthesis of phenylpropanoids starts with the removal of the amino group of phenylalanine by phenyl ammonium lyase (PAL) to produce trans-cinnamic acid. The aromatic ring of trans-cinnamic acid is then hydroxylated to produce p-coumaric acid by the enzyme cinnamate 4-hydroxylate (C4H). Coumaric acid can then be ligated to coenzyme A by a ligase [ 4-coumaroyl-CoA ligase (4CL) ].




Coumaroyl-CoA, an intermediate formed by the phenylpropanoid pathway is a substrate for the enzyme chalcone synthase (CHS) and stilbene synthase (STS). Coumaroyl-CoA alongwith malonyl-CoA results in the formation of Chalcones and stilbene as shown below:


Ring closure of chalcone to produce a pyran ring in naringenin occurs spontaneously. This step is catalysed by a chalcone isomerase (CHI).
 
Flavones and flavonols can be made from flavanone (naringenin). Flavanone 3-hydroxylase (F3H) catalyzes the hydroxylation of C-3 position of C-ring. Then the introduction of a double bond between C-2 and C-3, results in the formation of flavonol. The desaturation of C-ring is calatyzed by flavonol synthases (FLS). 


 
Further, the reduction of keto group in the C-ring is reduced by the action of dihydroflavonol reductase (DFR), and then anthocyanidin synthase (ANS) introduces two double bonds in the C-ring forming anthocyanidin. flavonoid 3-O-glucosyltransferase (F3GT) transfers the glucose residue from nucleotide sugar to 3-OH position forming anthocyanin

The Biosynthesis of Flavonoids

The Biosynthesis of Flavonoids

The biosynthesis of flavonoids is a very complex process and involves series of reactions. The basic pathways to the core flavonoid skeletons have been established both enzymatically and genetically.7,8 The flavonoid biosynthesis, starts with general phenylpropanoid pathway. The synthesis of phenylpropanoids starts with the removal of the amino group of phenylalanine by phenyl ammonium lyase (PAL) to produce trans-cinnamic acid. The aromatic ring of trans-cinnamic acid is then hydroxylated to produce p-coumaric acid by the enzyme cinnamate 4-hydroxylate (C4H). Coumaric acid can then be ligated to coenzyme A by a ligase [ 4-coumaroyl-CoA ligase (4CL) ].

Coumaroyl-CoA, an intermediate formed by the phenylpropanoid pathway is a substrate for the enzyme chalcone synthase (CHS) and stilbene synthase (STS). Coumaroyl-CoA alongwith malonyl-CoA results in the formation of Chalcones and stilbene as shown below:

Ring closure of chalcone to produce a pyran ring in naringenin occurs spontaneously. This step is catalysed by a chalcone isomerase (CHI).

Flavones and flavonols can be made from flavanone (naringenin). Flavanone 3-hydroxylase (F3H) catalyzes the hydroxylation of C-3 position of C-ring. Then the introduction of a double bond between C-2 and C-3, results in the formation of flavonol. The desaturation of C-ring is calatyzed by flavonol synthases (FLS).

Further, the reduction of keto group in the C-ring is reduced by the action of dihydroflavonol reductase (DFR), and then anthocyanidin synthase (ANS) introduces two double bonds in the C-ring forming anthocyanidin. flavonoid 3-O-glucosyltransferase (F3GT) transfers the glucose residue from nucleotide sugar to 3-OH position forming anthocyanin.

Caffeine

 

IUPAC NAME 1,3,7-trimetil- 1H-purina- 2,6(3H,7H)-dion

Nama lain[sembunyikan] 1,3,7-trimetilksantina, trimetilksantina, teina, metilteobromina

More popular caffeine or caffeine, xanthine alkaloid compound is crystalline and bitter taste that works as a psychoactive stimulant drug and a mild diuretic. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term "caffeine" to refer to the chemical compound in coffee. Caffeine also called guaranina when found in guarana, mateina when found in mate, and teina when found in tea. All terms are equally refer to the same chemical compound.Caffeine is found naturally in foods such as coffee beans, tea leaves, kola fruit, guarana, and mate. In plants, it acts as a natural pesticide that paralyzes and off certain insects that eat plants. He is generally consumed by humans in extracting it from coffee beans and tea leaves.Caffeine is a central nervous system stimulant drugs in humans and can ward off drowsiness temporarily. Drinks that contain caffeine, such as coffee, tea, and soft drinks, are very popular. Caffeine is a psychoactive substance most consumed in the world. Unlike other psychoactive substances, caffeine legal and unregulated in nearly all jurisdictions the world. In North America, 90% of adults consume caffeine every day

Coffee beans, the main source of caffeineCaffeine found in many plant species, where it acts as a natural pesticide. It was reported that high levels of caffeine found in the newly emerging seedlings. Crippling caffeine and off certain insects that eat plants. High levels of caffeine which is also found in soil around the seedling beans. It is known that he served as a germination inhibitor that inhibits the germination of other nearby coffee seedlings, thus improving the survival rate of seedling coffee itself.Sources of caffeine are commonly used are coffee, tea, and cocoa. In addition, mate and guarana plants  is also sometimes used in the manufacture of energy drinks and teas. Two alternative names caffeine, mateina and guaranina, derived from the name of the two plants. Some fans claim that mateina mate is stereoisomer of caffeine. This is not true, because caffeine is an achiral molecule, so he did not has enantiomer or stereoisomer. Impression and the different effects found in many natural sources of caffeine are caused by caffeine sources also contain a mixture of other xanthine alkaloids, including teofilina which stimulates heartbeat, Theobromine, and other substances such as polyphenols. The main sources of caffeine are coffee beans world. The content of caffeine in coffee varies, depending on the type of coffee bean and the method of manufacture used . In general, one serving of coffee contains about 40 mg (30 mL espresso arabica varieties) caffeine, up to 100 mg of caffeine to one cup (120 mL) of coffee. Generally, dark-roast coffee has a lower caffeine content because the roasting process reduces the caffeine content in the seeds. varieties of arabica coffee generally contains less caffeine content than Robusta coffee varieties.  Coffee also contains teofilina small number, but it does not contain Theobromine.

Tea is another source of caffeine. Although tea contains higher levels of caffeine than coffee, tea is generally served in a dish levels much lower. The content of caffeine also vary on the types of tea leaves differently. Tea contains small amounts of Theobromine and teofilina levels are slightly higher than the coffee. Water color of tea is not a good indicator to determine the caffeine content. For example, the Japanese tea such as green tea gyokuro paler colored contains far more caffeine than tea lapsang souchong darker colored.Caffeine is also contained in some soft drinks such as cola. Soft drinks typically contain about 10 to 50 milligrams of caffeine per serving. Caffeine in the drink can be derived from this type of beverage ingredients themselves ataunya of additives obtained from the dekafeinasi. Guarana, a key ingredient manufacture energy drinks, contains large amounts of caffeine with the amount of Theobromine and teofilina small. Chocolate derived from cocoa beans contains a small amount of caffeine. Stimulating effect produced by the combination of chocolate comes from the effects of Theobromine, teofilina, and caffeine. Chocolate contains a very small amount of caffeine to cause stimulation equivalent to coffee. 28 g serving of milk chocolate bars contain high levels of caffeine equivalent to a cup of coffee didekafeinasi.Lately, many manufacturers started adding caffeine into their bath products (shampoo and soap), claiming that caffeine can be absorbed through the skin. However, the effectiveness of such products has not been proven, because the caffeine will not easily absorbed through the skin.

 Synthesis and characteristics of caffeine
  Caffeine anhydrous (dry).In 1819, the German chemist Friedlieb Ferdinand Runge isolated the relatively pure kafeinan for the first time. According to Runge, he did so on the orders of Johann Wolfgang von Goethe. In 1827, Oudry isolated "teina" of Tea, but was later proved by Mulder and Jobst that teina is a compound similar to caffeine.  The structure of caffeine successfully solved by the end of the 19th century by Hermann Emil Fischer, who is also a person the first to successfully synthesize these compounds in total. All the nitrogen atom caffeine essentially planar (sp2 orbital hybridization), caffeine causes the molecule to be aromatic. Because caffeine easily obtained as byproducts of the process dekafeinasi, caffeine usually biosynthesized chemically. If necessary, caffeine can be synthesized from dimetilurea and malonic acid.

Metabolism and toxicityCaffeine molecule metabolites that have 1-3-7-amino trimetilurat, paraksantina, teofillina and Theobromine with each trajectory metabolism. caffeine adenosine receptor binding in the brain. Adenosine nucleotides is the reduced activity of nerve cells when tethered to the cell. Such as adenosine, caffeine molecule is also tied to the same receptors, but the effects are different. Caffeine will not slow down the activity of nerve cells / brain, whereas blocking adenosine to function. The impact resulted in increased brain activity and hormone epinephrine released. These hormones will increase heart rate, raise blood pressure, increase blood supply to the muscles, reducing blood supply to the skin and internal organs, and secrete glucose from the liver. Furthermore, caffeine also increases the neurotransmitter dopamine in the brain surface.Caffeine can be quickly removed from the brain, unlike alcohol or stimulants of the central nervous system so it does not interfere with other higher mental functions and brain pedestal. Consumption of caffeine in a sustainable manner will cause the body to become tolerant to the presence of caffeine. Therefore, if the internal production of caffeine removed (called "dependency discharge"), the body becomes less sensitive to adenosine and cause a sudden drop in blood pressure which in turn cause headaches and other symptoms. A recent study says caffeine can reduce the risk of Parkinson's disease, but it still requires in-depth study.Too much caffeine can cause poisoning (intoxication) caffeine (ie high on caffeine). Among these symptoms are restlessness, anxiety, insomnia, joy, flushing, frequent urination (diuresis), and problems gastrointestial. These symptoms can occur even if only 250 mg of caffeine taken. If more than 1g of caffeine consumed in a day, symptoms such as muscle cramps (muscle twitching), tangling thoughts and words, kardium arrhythmias (disturbances in heart beat) m and turmoil psychomotor (psychomotor agitation) may occur. Caffeine intoxication can also lead to panic and anxiety illnesses.Although it is still safe for humans, caffeine, teofilina, and Theobromine (in cocoa) more poison for some animals, like cats and dogs because of differences in liver metabolism.