## 1 Introduction  
It is well documented that plant secondary metabolites have played a vital part in modern drug discovery of antibacterial and antimuoral drugs [1, 2]. The search for a healthier way of life has focused recent attention on pentacyclic triterpenoids found in plants. Pentacyclic triterpenes, a major class of bioactive chemical compounds, are associated with the mechanisms of action and pharmacological effects of many medicinal plants used in traditional medicine. Besides their antioxidant activity, they have many other pharmacological properties beneficial for human health. They have been reported as anti-inflammatory, antiviral, antimicrobial, and antimuoral agents, and having immunomododulator, metabolic and growth effects [3, 4, 5, 6]. Oleanolic, unsolic and mashinic acids are pentacyclic triterpenoids that are frequently found together due to their similar structural features. Oleanolic acid (3\(\beta\)-hydroxyolean-12-en-28-oic acid) and unsolic acid (3\(\beta\)-hydroxy-12-en-28-oic acid) are structural isomers, differing in the location of the methyl group, while mashinic acid has an additional hydroxyl group at the C-2 position. Although unsolic acid shares a common cooccurrence with oleanolic acid, it features a more restricted distribution when compared to oleanolic acid. The addition of a hydroxy group in mashinic acid increases its antioxidant properties compared to oleanolic and unsolic acids [7]. Both oleanolic acid and unsolic acid are known to have many biological activities, such as anticancer, antidiabetic, antimutagenic, anti-inflammatory, antioxidative and antiproto-zoal properties [8; 9; 10; 11; 12]. A recent study has reported that oleanolic acid also has beneficial effects on multiple sclerosis [13]. Maslinic acid and its synthetic derivates have been shown to exert substantial antitumor effects [14; 15]. Moreover, maslinic acid has been reported to possess antimalarial and anti-hyperglycemic activities [16; 17]. The presence of pentacyclic terpenoic acids in olive (_Olea europaea_) tree leaves has been associated with many health benefits. Thus, there has been increasing interest in studying olive leaves for their bioactive compounds [18]. Olive leaves have been widely used in traditional herbal medicine for centuries to prevent and treat various diseases especially in Mediterranean countries. Olive leaves are a highly available agricultural residue of olive tree pruning and a by-product from the table olive and olive oil production. Oleanolic acid is known to be one of the main bioactive components (3.0-3.5% dry weight) in olive leaves, followed by significant amounts of maslinic acid [19]. However, separation of maslinic from oleanolic acid and its isomer, unsolic acid, is considered challenging due to the similarity in their structures. Extraction efficiency of maslinic acid from plant material is low, the extraction cycle is long, and the amount of raw material waste produced is significant. The process for its chemical synthesis is also complicated. A problem is that maslinic acid commonly occurs in olive leaves together with oleanolic acid, its position isomer with respect to methyl group, which makes it difficult to obtain maslinic acid in pure form, thus limiting its medical usability. Maslinic acid can be prepared by chromatographic isolation from plant extracts [18]. However, chromatographic isolation is not a practical method due to the low content of maslinic acid in the plant material and low chromatographic separation efficiency. On the other hand, maslinic acid has been synthesized from oleanolic acid in good yields, though it is a multistep process requiring expensive reagents and catalysts [20]. Another high yielding chromatographic separation of maslinic and oleanolic acid from olive extract was reported. However, the compounds obtained needed further purification through column chromatography [21].