Ursolic acid, anti-inflammatory activity

The concept that inflammation and carcinogenesis are related phenomena has been the subject of many studies that have attempted to link these two processes in a mechanistic fashion [94-99]. In connection with this, as is evident in some triterpenoids such as oleanolic acid (142), glycyrrhetic acid (147), and ursolic acid (210) in Table 2, those possessing anti-inflammatory activity in various experimental models exhibited antitumor-promoting activity as well. This suggests that most of the other anti-inflammatory triterpenoids and sterols listed in Table 2 might have antitumor-promoting properties which have not been evaluated, yet. 

In the last few years, interest in triterpenes as anti-inflammatory agents and their mechanisms of action has also increased greatly. Oleanolic acid and ursolic acid have been recognised to have anti-inflammatory activity in carrageenan-induced paw edema in rats or mice, adjuvant-induced arthritis in rats, etc. Oleanolic acid, in addition, was able to suppress the delayed hypersensitivity reaction in mice induced by dinitrochlorobenzene (DNCB). These effects are attributable to different mechanisms of action ranging from the inhibition of histamine release to inhibition of complement activity [1,58]. 

In connection with the work on the relationship between chemical structure and anti-inflammatory activity, the effect of ursolic acid, betulin, betulinic acid and erythrodiol on a system of chronic dermal edema and cellular proliferation caused by repeated administration of TPA has recently been examined [89], This experimental model of chronic inflammation has considerable selectivity for corticosteroids and leukotriene synthesis inhibitors. Erythrodiol and ursolic acid were significantly effective and also reduced the neutrophil infiltration detected by MPO activity. The lupane derivatives, betulin and betulinic acid, despite their possible steroid-like mechanism of action [47], were not effective in the chronic model. This result could mean that a six-member E ring of the pentacyclic structure is necessary for the activity against a multiple dose of TPA. The data confirm that a hydroxyl group at the C-28 position is important for the activity, as is also true in the case of erythrodiol, and it may explain the anti-inflammatory effect of this compound in each of the methods. 

Ursolic acid has been proved to display anti-inflammatory effects by inhibiting NF-kB activation. It has also been reported to induce tumor cell apoptosis and to increase muscle mass [177-182]. 

Ursolic and oleanolic acids have been early described to exert antiinflammatory and antihyperlipidemic activities. Betulinic acid has been reported to exhibit antiretroviral, antimalarial, and anti-inflammatory properties. Thumher and coworkers [183] have demonstrated its cytotoxic activity against a variety of tumor cells originating from the neural crest. It has also... 

Like many other antioxidants, rosemary and its polyphenols possess not only antioxidative activities, but also antitumorigenic activities. Huang et al. (5) investigated the inhibitory effects of rosemary extract, carnosol and ursolic acid on tumor formation in mouse skin. They found that topical application of rosemary inhibits B(a)P- and DMBA-induced initiation of tumor and TPA-induced tumor promotion in DMBA-initiated mice. Carnosol and ursolic acid were found to be strong inhibitors of TPA-induced inflammation, ornithine decarboxylase activity and tumor promotion in mouse skin (5). It was suggested that carnosol acted like other nonsteroidal phenolic anti-inflammatory agents, such as curcumin, which inhibited the metabolism of arachidonic acid. 

---