User:Kathy lin/sandbox

Composition
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Flavonoids
Flavonoids are a major component in the diets of many. The compounds are found in tea, apples, tomatoes, onions, and other fruits and vegetables. Flavonoids are known for their broad spectrum of biological activities such as antitumor, and antibacterial.

Antioxidative activity
Some of the biological activity of flavonoids are due to the antioxidative properties. The catechol group in the B ring and 3 hydroxyl group in the structure of flavonoids is responsible for the antioxidative properties. The hydroxyl and catechol groups in the flavonoids are key to the scavenging of reactive oxygen species, reactive nitrogen species, and chelation of metal ions. The catechol group and 3 hydroxyl group are able to donate hydrogen and electron to the reactive species and free radicals, thus stabilizing the free radicals and preventing tissue damage. The flavonoids are helpful in preventing the oxidation of proteins and lipids. Lipid oxidation deletes lipid rafts on the cell’s membrane, which lowers cellular signaling transduction.

Anti-tumor activity
Free radicals cause aging and carcinogenesis. The propolis in moderate climate regions is also anti-tumor as a result of the antioxidative properties of the flavonoids. An example is free radicals caused by sun damage. Hydrogen peroxide (H2O2) damage the genes through peroxidation of DNA and induction of cellular aging. When genes are damaged, there is cell mutation, and formation of the cancer. Propolis was found to inhibit (H2O2-) induced damage to DNA. A study concluded that the flavonoids provided propolis with anti-tumor properties by inhibiting DNA and RNA synthesis of cancerous cells. Specifically, the flavonoids prevented the incorporation of thymidine and uridine into the DNA and RNA molecules.

Anti-inflammatory activity
The anti-inflammatory properties of flavonoids from propolis are also due to anti-oxidative properties. The flavonoids are able to prevent oxidative damage to tissues  caused by the generation of free radicals by macrophages during the inflammatory process. Flavonoids were also found to inhibit the secretions of pro-inflammatory cytokines by the lymphocytes and macrophages.

Antibacterial activity
The flavonoids in the propolis from moderate climate regions have antibacterial activities due to disruption of the bacterial and microbial membranes. The flavonoids require a balance of hydrophilicity and lipophilicity for membrane affinity. The presence of hydroxyl groups in the flavonoid structure are important in membrane disruptive activities and number of hydroxyl groups dictate lipophillicity of the structure. By infiltrating the bacterial membrane, the flavonoids alter membrane fluidity in hydrophilic and lipophilic regions, thereby reducing fluidity of both inner and outer layers of gram negative bacteria. The membrane fluidity was also decreased in gram positive bacteria. Increased rigidity of membranes reduces the motility of bacteria and prevents migration of the bacteria to other regions of the body. Reactive oxygen species are produced bylipopolysaccharides on bacterial membranes. The scavenging activities of flavonoids reduces the reactive oxygen species caused by the bacteria from damaging tissues. The catechol groups of flavonoids are able to cause leakage of small molecules due to bacterial membrane damage. The inner bacterial membrane potential must be maintained for the production of ATP by the ATPase. If there is leakage of protons, then the electrochemical gradient cannot be maintained and ATP synthesis in bacteria is reduced. The B ring of the flavonoids are able to form hydrogen bonds with nucleic acid bases, thus disrupting the process of DNA and RNA synthesis. It was found that DNA synthesis was most inhibited in Proteus vulgaris, while RNA synthesis was most affected in Staphylococcus aureus, both gram positive bacteria. Protein and lipid synthesis activity in bacteria are affected by the disruption of DNA and RNA synthesis.

Anti-viral activity
Flavonoids were found to be anti-viral. The catechol groups of the flavonoids was found to inhibit HIV reverse transcriptase and HIV 1 proteinase. In the same manner of disruption of DNA and RNA synthesis in bacteria, the flavonoids were found to inhibit the replication of the Herpes simplex virus (HSV).

Caffeic acid phenethyl ester (CAPE)
CAPE is a compound responsible for biological activities such as inhibition of cellular proliferation, inducing apoptosis and cellular arrest. CAPE causes the inhibition of DNA synthesis, leading to anti tumor properties. CAPE is also responsible for the interruption of growth signal transduction, inducing apoptosis, and inhibiting the growth of new blood vessels.

Phenolic acids
Phenolic acids are another constituent in propolis, specifically Polish propolis, that have antioxidative properties in the same structure - functional relationship as the flavonoids. The antioxidative properties of phenolic acids are due to the number of hydroxyl groups in the structure and the hydroxyl group position on a ring. On the aromatic ring, the bond energy between hydrogen and oxygen atoms on the hydroxyl groups is smaller than the bond energy on aliphatic portions of the structure. The hydrogen can easily detach from a hydroxyl group on the aromatic ring to stabilize free radical and other reactive species. After the hydrogen detachment, the phenolic acid becomes a phenoxyl radical, which is stable.

Terpenoids
The terpenoids are found in Brazilian and Mediterranean propolis. The presence of terpenoids are useful for ascertaining original propolis from the fake propolis. The terpenoids are volatile compounds that are responsible for the smell of resin in the propolis, and allows for bees to use propolis as air freshener in the hive The terpenoids also exhibit antioxidant and  antimicrobial activities. The anti-bacterial property of the terpenoids is due to penetration is rupture of the bacterial membrane. The hydrogen bond donor group located at the lipophilic decalinic ring system allows terpenoids to puncture cell membranes. The antioxidative properties are also due to the hydrogen bond donor groups, which can stabilize free radicals.

Current uses
A group studied the effects of propolis when added to the lipstick. Two test groups of lipstick were created, one group containing propolis and the other group without propolis. The lipsticks were subjected to rheometer testing and it was found that both samples of lipstick show shear thinning. It was also found that the lipstick with added propolis is able to retain its structure better after application to the skin.

In Korea, there are commercialized products that contain propolis. The concentration of propolis in liquid foundation is 3% and 2% in Propoleo cream. It was reported that Propoleo cream is favorable for oily skin and facial acne. Eye creams contain 1% propolis, and provided anti-bacterial properties. Over 80% of consumers in Korea that purchased products containing propolis were reportedly satisfied with their purchase.

In a study investigating the effects of propolis containing toothpaste on oral and periodontal health, sixteen subjects who underwent oral implants were involved in the study. The subject were divided into two groups: one group was instructed to use propolis containing toothpaste, while one group received toothpaste without the active ingredient. It was found that the subjects that used propolis containing toothpaste had a reduction in microbiota spectrum in the mouth.

Studies and Research
Propolis was tested on livestock, such as cattle, fish, poultry, and pigs. Propolis was found to increase growth performance of the livestock. In new fields of propolis application, it is useful replacement for antibiotics in feedings of lifestock. Studies have tested the diffusivity of propolis compounds in polylactic acid (PLA) films for application in active food packaging and anti-microbial packaging films.

A study investigated the effects of propolis embedded into titanium dioxide (TiO2) nanotubes for dental implants. Test rats underwent mandibular implant surgery and were divided into 3 groups. One group received commercially pure TiO2 implants, another group received TiO2 implants with nanotube formations, and last group received TiO2 implants with propolis embedded nanotubes. It was found that the rats with propolis loaded onto the nanotubules in the implants had greater osseointegration compared to the groups without propolis loaded implants.