by Alan Gaspari Nutrient Journal
Ursolic acid (similar chemical structure to oleanolic acid) is a natural pentacyclic triterpenoid carboxylic acid that is found fruits and many herbs but mostly in coats of apples (waxy substance). Studies are showing many beneficial effects such as antioxidative, antimicrobial, anti-inflammatory, and anticancer activities. Ursolic acid is also claimed to promote muscle strength and mass, reduce muscle catabolism, and support fat loss. It can be found in sport supplements, cosmetics and health products.
Bioavailability and Absorption
Mice who were orally administered with high dose of ursolci acid (80,32mg/kg of Lu-Ying extract containing ursolic acid) exhibited extremely low concentrations of ursolic acid in plasma . Which suggested either high binding activity in organs and low blood distribution or low bioavailability because ursolic acid is metabolised in the wall of the intestine and liver.
Ursolic Acid for Increased Muscle Mass
Ursolic acid has been recognised as a potential therapy for treating muscle atrophy . Not only that, in animal models daily administration of ursolic acid also stimulated muscle hypertrophy . This was achieved by ursolic acid’s inhibition of skeletal muscle mRNA expression which is associated with atrophy and increased skeletal muscle insulin and insulin-like growth factor 1 (IGF1) signaling . Ursolic acid can also stimulate skeletal muscle Akt activity, probably via enhanced skeletal muscle insulin/IGF-I signaling . Skeletal muscle Akt activity stimulates muscle growth and may reduce fat gain .
Infusion of ursolic acid to mice has shown that ursolic acid is able to sustain resistance exercise-induced mTORC1 activity for longer than control group .
Effects of ursolic acid in humans are not known as there are currently no clinical studies available.
Reducing White Fat, Increasing Brown Fat
As mentioned before, ursolic acid was able to increase Akt activity in muscles. Besides increased muscle hypertrophy Akt activity also reduces body fat . This lead scientists to hypothesize  that mice treated with ursolic acid might increase fat burning. Mice treated with 10mg/kg of ursolic acid and fed with high-fat diet over the course of 15 weeks showed significantly decreased body weights, abdominal fat and levels of blood glucose and plasma lipids compared to control group . Another study showed that mice that consumed high-fat diet (55% calories from fat) with 0,14% ursolic acid for 6 weeks gained less weight than mice that only consumed high-fat diet . This also indicates that ursolic acid reduces obesity. Ursolic acid also increased brown fat tissue. Contrary to white fat which stores energy, brown fat expends energy to generate heat and maintain body temperature . Although more prevalent in children than in adults, activation and the amount of brown fat increases during adolescence which is associated with significantly lower gains in weight and adiposity . During puberty brown fat increase more in boys than in girls and is closely related to gains in muscle volume .
Other Potential Uses
Ursolic acid is well-known for its hepatoprotective effects . It is suspected that this beneficial effect is due to its anti-oxidant and anti-inﬂammatory actions, and its effects on drug-metabolizing enzymes. Ursolic acid has also been reported to be weak aromatase inhibitor , tumorigenic inhibitor and weak anti-cancer remedy , antihyperlipidemic and hypoglycemic  and anti-HIV agent .
Ursolic Acid Side Effects
In animal test ursolic acid exhibited low toxicity of LC50 0.95 mg/ml . Slight toxicity was also reported in study testing possible anti-HIV agents . Severe disruption of spermatogenesis was reported in animals as a result of ursolic acid treatment . Therefore, caution is advised when using ursolic acid as curative or protective agent.
Liao, Qiongfeng, et al. “LC-MS determination and pharmacokinetic studies of ursolic acid in rat plasma after administration of the traditional chinese medicinal preparation Lu-Ying extract.” Yakugaku Zasshi 125.6 (2005): 509-515.
Kunkel, Steven D., et al. “mRNA expression signatures of human skeletal muscle atrophy identify a natural compound that increases muscle mass.” Cell metabolism 13.6 (2011): 627-638.
Izumiya, Yasuhiro, et al. “Fast/Glycolytic muscle fiber growth reduces fat mass and improves metabolic parameters in obese mice.” Cell metabolism 7.2 (2008): 159-172.
Kunkel, Steven D., et al. “Ursolic acid increases skeletal muscle and brown fat and decreases diet-induced obesity, glucose intolerance and fatty liver disease.” PloS one 7.6 (2012): e39332.
Ogasawara, Riki, et al. “Ursolic acid stimulates mTORC1 signaling after resistance exercise in rat skeletal muscle.” American Journal of Physiology-Endocrinology and Metabolism 305.6 (2013): E760-E765.
http://www.sciencedaily.com/releases…0729132109.htm Retrieved from ScienceDaily at 4. July 2014
Rao, Vietla S., et al. “Ursolic acid, a pentacyclic triterpene from Sambucus australis, prevents abdominal adiposity in mice fed a high-fat diet.” Journal of medicinal food 14.11 (2011): 1375-1382.
Gilsanz, Vicente, Houchun H. Hu, and Shingo Kajimura. “Relevance of brown adipose tissue in infancy and adolescence.” Pediatric research 73.1 (2012): 3-9.
Liu, Jie. “Oleanolic acid and ursolic acid: research perspectives.” Journal of ethnopharmacology 100.1 (2005): 92-94.
Gnoatto, Simone CB, et al. “Evaluation of ursolic acid isolated from Ilex paraguariensis and derivatives on aromatase inhibition.” European journal of medicinal chemistry 43.9 (2008): 1865-1877.
Hsu, Hsue-Yin, Jenq-Jer Yang, and Chun-Ching Lin. “Effects of oleanolic acid and ursolic acid on inhibiting tumor growth and enhancing the recovery of hematopoietic system postirradiation in mice.” Cancer letters 111.1 (1997): 7-13.
Somova, L. O., et al. “Cardiovascular, antihyperlipidemic and antioxidant effects of oleanolic and ursolic acids in experimental hypertension.” Phytomedicine10.2 (2003): 115-121.
Kashiwada, Yoshiki, et al. “Anti-AIDS Agents 38. Anti-HIV Activity of 3-O-Acyl Ursolic Acid Derivatives 1.” Journal of natural products 63.12 (2000): 1619-1622.
Akbarsha, M. A., et al. “Ursolic acid generates symplasts in rat spermatogenic clones.” Phytotherapy Research 12.1 (1998): 32-36.