Review on Oleanolic Acid: Extraction Techniques, Analytical Methods and Pharmacology

Oleanolic acid is a kind of pentacyclic triterpene that is present in a variety of plants, namely fruits and vegetables. Natural plant foods that contain oleanolic acid include apples, ginger, pears, tomatoes, grapes, strawberries, olives, mango, and olive oil, along with culinary and therapeutic herbs, including rosemary, sage, oregano, ginseng, basil, olive leaf, fennel and garlic. Through several in-vitro preclinical investigations, researchers have discovered that oleanolic acid has a wide spectrum of biological properties, including hepatoprotective, anti-inflammatory, anti-diabetes, antimicrobial, antihypertensive, gastroprotective, and antihyperlipidemic effects, as well as cancer treatment. There are several techniques available for the extraction of oleanolic acid from a wide range of species. Extraction from plant species uses various techniques, including soxhlet extraction, sonication, ultrasonic extraction, percolation, cold maceration, and maceration. The major solvents used in extraction are diethyl ether, petroleum ether, n-hexane, ethanol, methanol, ethyl alcohol, and ethyl acetate. Various analytical methods, including HPTLC, HPLC, GC-MS, UHPLC-ESI-MS/MS, UHPLC-PDA, LCAPCI-IT-MS, LC-MS, HPLC-MS/MS, RP-UFLC-DAD, HPLC-PAD-ESI/MS, and others, were employed to identify as well as quantify oleanolic acid in different plant species and formulations. Hence, this review compiles information on the pharmacological actions, extraction methodologies, and analytical methods for investigating and developing methods to assess oleanolic acid from various plant species, herbal remedies, and ayurvedic formulations.