History of Discovery
Cinnamic acid was first isolated from cinnamon bark in 1835 by the German chemist Hugo Weise. He noticed an oily yellow substance crystallizing from a cinnamon extract and determined it was an acidic compound. Further analysis revealed its chemical structure and it was named cinnamic acid after its source. Since then, numerous studies have explored its chemistry and biological properties.
Chemical Structure and Properties
It is an organic compound that belongs to the family of it. Its molecular formula is C9H8O2 and molecular weight is 148.16 g/mol. It consists of a carboxylic acid group bonded to a styrene group which gives it properties intermediate between acids and alkenes. It exists as white to yellowish crystalline solid at room temperature and has a melting point of 133-135°C. It is soluble in organic solvents like ethanol, ether and chloroform but shows very low solubility in water. Upon heating, it exhibits a distinct pleasant aroma reminiscent of cinnamon or honey.
Natural Occurrence and Biosynthesis
It is commonly found in plants either as the Cinnamic Acid or as derivatives like esters, amides or hydroxamic acids. Some plant sources containing significant amounts of it include cinnamon, coffee, blueberries, citrus fruits, bananas, strawberries, blackberries and tomatoes. In plants, it is biosynthesized from the amino acid phenylalanine via the shikimate pathway and the action of the enzyme phenylalanine ammonia lyase. This converts phenylalanine to cinnamic acid which then participates in the biosynthesis of numerous plant secondary metabolites like lignins, flavonoids, coumarins and stilbenes that have important functions in growth, pigmentation and defense.
Uses and Applications
Given its ubiquity in plant kingdom and distinct sensory properties, it finds various applications. It is widely used as a flavoring agent in foods, beverages and candies to provide flavors reminiscent of cinnamon, honey or almonds. Itis approved by FDA for use in food with a set limit of 1g/kg. In perfumes and fragrances industry, it is employed as a raw material or fixative to impart honey-like or balsamic notes to products. It also has applications as a precursor in the synthesis of various commercial compounds like vinyl acrylate esters, chalcones, styrene and certain pharmaceutical drugs.
It has shown several pharmacological properties in experimental and clinical studies as well. Its antimicrobial effects against bacteria, yeasts and molds have been documented. Some evidence indicates it may possess antidiabetic, anti-inflammatory and antioxidant activities too due to presence of unsaturated C=C bond and phenolic OH group. A number of derivatives and polymers of cinnamic acid with enhanced bioactivities are being explored for their potential in drug development.
Biosynthesis of Plant secondary Metabolites
When ingested by plants through the roots, cinnamic acid serves as an important intermediate in the biosynthesis of an enormous number and variety of plant metabolites with diverse biological functions. These include lignins, flavonoids, coumarins, stilbenes and various phenylpropanoids. Lignins constitute the woody, rigid component of plant cell walls responsible for their structure and strength.
They are formed via oxidative coupling of coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol which are synthesized from it with the action of various enzymes. Flavonoids represent a large class of plant pigments that impart color to flowers, fruits and leaves. They are also potent antioxidants and play crucial roles in pollinator attraction and defenses against pathogens.
Key flavonoids derived from it include quercetin, kaempferol, anthocyanins and proanthocyanidins. Coumarins like dicoumarol act as phytoalexins conferring disease resistance properties. Stilbenes like resveratrol found in grapes exhibit health benefits and are being explored for their chemopreventive potential against cancer. Thus, it occupies a central place in the complex pathways leading to a diverse array of specialized metabolites in plants.
Industrial Production
While being naturally abundant in some plant sources, commercial amounts of cinnamic acid are mostly manufactured synthetically for industrial needs via the Perkin reaction or benzaldehyde condensation. In this process, benzaldehyde, sodium acetate and acetic anhydride are reacted together at 140-150°C. Other common precursors used are benzyl cyanide, styrene and its derivatives which upon acid or base hydrolysis yield it.
Some companies also produce it from plant oil sources like cinnamon or citronella oils through acidification followed by solvent extraction and purification. Global demand for this versatile chemical is on the rise due to its various applications in food, fragrance, flavor and pharmaceutical industries. Its annual production volume exceeds 300-400 tons with China and India being the leading producers currently.
Concluding Remarks
Cinnamic acid occupies a pivotal niche in plant biochemistry and serves as a key intermediate linking primary and secondary metabolism. Numerous plant metabolites starting from lignins, flavonoids to coumarins, stilbenes and hydroxamic acids branch out from this core structure giving it immense significance. Its pleasant sensory attributes, diverse pharmacological profile as well as wide industrial utilities in flavor, fragrance and precursor chemical synthesis have established it as a commercially important natural product. Further exploration of its biosynthesis and derivatives holds promise for novel applications. Significant progress has been made in the understanding of cinnamic acid chemistry since its isolation over a century ago. Still, more studies could shed light on its intricate roles and regulation in plants.
Get More Insights On, Cinnamic Acid
About Author:
Ravina Pandya, Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. (https://www.linkedin.com/in/ravina-pandya-1a3984191)
Comments
0 comment