Herb Source: Leaf of Glossy Privet
Synonyms: Ligustrum lucidum Ait
Structural formula:
Molecular Formula and Molecular Weight C30H48O3;456.68
Appearance white powder
Description Ursolic acid, a carboxylic acid present in a wide variety of plants in the form of a free acid or an aglycone of triterpene saponins.It is also known as urson, prunol, micromerol, and malol, is a pentacyclic triterpenoid compound which naturally occurs in a large number of vegetarian foods, medicinal herbs, and plants1,2. For a long time, it was considered to be pharmacologically inactive3. Thus, ursolic acid and its alkali salts (e.g. potassium or sodium ursolates) were exclusively used as emulsifying agents in pharmaceutical, cosmetic, and food preparations3,4. However, upon closer examination, ursolic acid was found to be medicinally active both topically and internally1. Its anti-inflammatory, antitumor (skin cancer), and antimicrobial properties make it useful in cosmetic applications1.
Ursolic acid [(3b)-3-Hydroxyurs-12-en-28-oic acid] rarely occurs without its isomer oleanolic acid [(3b)-3-Hydroxyolean-12-en-28-oic acid]. They may occur in their free acid form, as shown in Figure 1, or as aglycones for triterpenoid saponins which are comprised of a triterpenoid aglycone linked to one or more sugar moieties. Ursolic and oleanolic acids are similar in pharmacological activity1. Several ursolic acid derivatives, both natural and synthetic, have been reported. Novel ursolic acid derivatives, including ursane-type triterpenoid saponins, naturally occur as secondary metabolites through complex metabolic processes in different parts of the plant5,8-12 Synthetic derivatives obtained from ursolic acid have been reported and evaluated for their pharmacological action3,13-16.
Medicinal plants containing ursolic acid have been used in folk medicine before it was known which constituents were responsible for their therapeutic effectiveness. Contemporary scientific research which led to the isolation and identification of ursolic acid revealed and confirmed that several pharmacological effects, such as antitumor, hepatoprotective, anti-inflammatory (oral and topical), antiulcer, antimicrobial, anti-hyperlipidemic, and antiviral, can be attributed to ursolic acid1. However, its anti-inflammatory (topical), antitumor (skin cancer), and antimicrobial properties are pertinent to the cosmetic industry.
Ursolic acid (UA) and oleanolic acid (OA), isolated from Glechoma hederacea, inhibited Epstein-Barr virus activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in mouse skin. The inhibitory effects were evaluated for 20 weeks. Continuous application of UA and OA (41 nmol of each) before TPA-treatment (4.1 nmol) delayed the formation of papillomas in mouse skin and reduced the rate (%) of papilloma bearing mice. Both UA and OA exhibited remarkable inhibitory activity against tumor promotion, which is comparable to the known tumor inhibitor, retinoic acid (RA). Compared to either RA or OA, ursolic acid inhibited tumors more effectively after a single application before initial TPA-treatment as shown in Figure 2. This suggests that the role of tumor inhibition by UA differs from that of either RA or OA. It is suggested that pretreatment of skin with UA may inhibit the first dramatic cellular event in tumor promotion caused by TPA17.
Topical application of ursolic acid derived from rosemary extract inhibited TPA-induced tumor initiation and promotion, inflammation, and ornithine decarboxylase activity in mouse skin. Ursolic acid exhibited strong anti-inflammatory activity. It is even more active than carnosol, another constituent of rosemary extract. As shown in Figure 3, twice weekly application of 1 or 2 祄ol of ursolic acid along with 5 nmol of TPA for 20 weeks inhibited the formation of skin tumors per mouse by 45 or 61%, respectively. Lower doses (0.1 or 0.3 祄ol) of ursolic acid had a similar inhibitory effect as the higher do