Pentacyclic triterpenes boswellic acid

R.S. Pardhy, S.C. Bhattacharyya, P Boswellic acid, acetyl P boswellic acid, acetyl 11 keto P boswellic acid and 11 keto P boswellic acid, four pentacyclic triterpene acids from the resin of Boswellia serrata Roxb, Indian Journal of Chemistry, 16B, 176 178 (1978). 

Preparations from the gum resin of Boswellia serrata have been used as traditional remedies in Ayurvedic medicine in India for inflammatory diseases (1). The gum contains substances that have anti-inflammatory properties they are pentacyclic triterpenes related to boswellic acid, which inhibit leukotriene biosjmthesis in neutrophilic granulocytes by inhibiting 5-lipoxygenase. Certain boswellic acids also inhibit elastase in leukocytes, inhibit proliferation, induce apoptosis, and inhibit topoisome-rases in cancer cell lines. 

The gum resin of Boswellia serrata (Burseraceae) has been used for the treatment of inflammatory diseases in the traditional Ayurvedic medicine in India. The EtOH extract of the resin significantly decreased LTB4 production in rat peritoneal neutrophils in vitro [95]. The active principles of the gum resin exudate of B. serrata are pentacyclic triterpene acids identified as boswellic acids, whose chemical skeleton belongs to the... 

The boswellic acid derivative, AKBA, decreases the activity of HLE in vitro in a concentration-dependent manner, with an IC50 value of 15 iM. This result has been compared with those obtained with ursolic acid, amyrin and 18p-glycyrrhetinic acid, the last of which showed no inhibitory activity on HLE at concentrations up to 20 pM [105]. Data analyses indicate different mechanisms for the inhibitory actions of the pentacyclic triterpenes AKBA and ursolic acid inhibition is noncompetitive in the case of AKBA but competitive with ursolic acid. These results are in line with the hypothesis that pentacyclic triterpenes interact with the extended substrate-binding domain in HLE that can bind a variety of hydrophobic ligands [104]. Depending on the substrate length, HLE inhibition can be competitive (ursolic acid) or non-competitive (AKBA). 

In summary, HLE inhibition has been established for different compounds, but a dual HLE/5-LOX inhibitory property is characteristic of the pentacyclic triterpenes from the boswellic acid series. Although alternative mechanisms of action may contribute to the anti-inflammatory action of pentacyclic triterpenes, these compounds can serve as parent compounds for a new class of HLE inhibitors. 

---