Caffeic acid
Caffeic acid (CA) is a hydroxycinnamic acid, a naturallyoccurring organic compound. This yellow solid consists of both phenolic andacrylic functional groups. It is found in all plants because it is a keyintermediate in the biosynthe-sis of lignin, one of the principal sources ofbiomass. Caffeic acid has been shown to inhibit carcinogenesis, although otherexperiments show possible carcinogenic effects. It is also known as anantioxidant in vitro and also in vivo. Caffeic acid also showsimmune-modulatory, antiviral and anti-inflammatory activity. Caffeic acidoutperformed the other antioxidants, reducing aflatoxin production by more than95 percent. The studies are the first to show that oxidative stress that wouldotherwise trigger or enhance Aspergillus flavus aflatoxin production can bestymied by caffeic acid. This opens the door to using natural anti-fungicidemethods by supplementing trees with antioxidants. Caffeic acid and itsderivative, Caffeic acid phenethyl ester (CAPE) have shown tumor-shrinkingproperties. When an anti-cancer drug was being sought, caffeic acid and CAPEwere derived from Burning Bush (Euonymus alatus). "The subcutaneous andoral administrations of CA and CAPE significantly reduced liver metastasis.These results confirm the therapeutic potential of the compounds and suggestthat the anti-metastatic and anti-tumor effects of CA and CAPE are mediatedthrough the selective suppression of MMP-9 enzyme activity and transcriptionaldown-regulation by the dual inhibition of NF-κB as well as MMP-9 catalyticactivity." (Chung, 2004: FASEB J. 18 (14): 1670–81) A study using thecaffeic acid phenethyl ester (CAPE) showed a positive effect on reducingcarcinogenic incidence. Caffeic acid phenethyl ester (CAPE) is an activecomponent of propolis from honeybee hives. It is known to have antimitogenic,anticarcinogenic, anti-inflammatory, and immune-modulatory properties and apotential co-adjuvant in diabetes therapy. Another study alsoshowed that CAPE suppresses acute immune and inflammatory responses and holdspromise for therapeutic uses to reduce inflammation. Thisanti-inflammatory and anti-cancer property has also been shown to protect skincells when exposed to ultraviolet (UV) radiation, in particular UVC radiationand UVB radiation. This anti-cancer effect was also seen when mice skin wastreated with bee propolis and exposed to TPA (a chemical) that induced skinpapillomas. CAPE significantly reduced the number of papillomas. Caffeic acidand chlorogenic acid from coffee beans both reduced DNA methyla-tion in vitroin two lines of human cancer cells. DNA methylation contributes to the growthof tumors and regulates the epigenetics of cells that are passed along with DNAto future generations. Caffeic acid has beenshown to be an inhibitor of the lipoxygenase enzyme that forms leukotrienesfrom arachidonic acid. This function has been useful in scientific experimentsto elucidate the roles of the leukotrienes in various inflammatory responses.Like many other secondary metabolites in plants, caffeic acid is usuallyaccumulated at low levels; theextraction and isolation of these compounds from plant sources are usuallydifficult and expensive. Microbial conversion provides an alternative approachto caffeic acid production.
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