cathepsin-g and boswellic-acid

Frankincense preparations, used in folk medicine to cure inflammatory diseases, showed anti-inflammatory effectiveness in animal models and clinical trials. Boswellic acids (BAs) constitute major pharmacological principles of frankincense, but their targets and the underlying molecular modes of action are still unclear. Using a BA-affinity Sepharose matrix, a 26-kDa protein was selectively precipitated from human neutrophils and identified as the lysosomal protease cathepsin G (catG) by mass spectrometry (MALDI-TOF) and by immunological analysis. In rigid automated molecular docking experiments BAs tightly bound to the active center of catG, occupying the same part of the binding site as the synthetic catG inhibitor JNJ-10311795 (2-[3-[methyl[1-(2-naphthoyl)piperidin-4-yl]amino]carbonyl)-2-naphthyl]-1-(1-naphthyl)-2-oxoethylphosphonic acid). BAs potently suppressed the proteolytic activity of catG (IC(50) of approximately 600 nM) in a competitive and reversible manner. Related serine proteases were significantly less sensitive against BAs (leukocyte elastase, chymotrypsin, proteinase-3) or not affected (tryptase, chymase). BAs inhibited chemoinvasion but not chemotaxis of challenged neutrophils, and they suppressed Ca(2+) mobilization in human platelets induced by isolated catG or by catG released from activated neutrophils. Finally, oral administration of defined frankincense extracts significantly reduced catG activities in human blood ex vivo vs placebo. In conclusion, we show that catG is a functional and pharmacologically relevant target of BAs, and interference with catG could explain some of the anti-inflammatory properties of frankincense.

Topics: Adult; Amino Acid Sequence; Animals; Anti-Inflammatory Agents, Non-Steroidal; Binding, Competitive; Boswellia; Cathepsin G; Cathepsins; Drug Delivery Systems; Humans; Hydrolysis; Molecular Sequence Data; Plant Extracts; Protein Binding; Serine Endopeptidases; Triterpenes

Age-related diseases, such as osteoarthritis, Alzheimer's disease, diabetes, and cardiovascular disease, are often associated with chronic unresolved inflammation. Neutrophils play central roles in this process by releasing tissue-degenerative proteases, such as cathepsin G, as well as pro-inflammatory leukotrienes produced by the 5-lipoxygenase (5-LO) pathway. Boswellic acids (BAs) are pentacyclic triterpene acids contained in the gum resin of the anti-inflammatory remedy frankincense that target cathepsin G and 5-LO in neutrophils, and might thus represent suitable leads for intervention with age-associated diseases that have a chronic inflammatory component. Here, we investigated whether, in addition to BAs, other triterpene acids from frankincense interfere with 5-LO and cathepsin G. We provide a comprehensive analysis of 17 natural tetra- or pentacyclic triterpene acids for suppression of 5-LO product synthesis in human neutrophils. These triterpene acids were also investigated for their direct interference with 5-LO and cathepsin G in cell-free assays. Furthermore, our studies were expanded to 10 semi-synthetic BA derivatives. Our data reveal that besides BAs, several tetra- and pentacyclic triterpene acids are effective or even superior inhibitors of 5-LO product formation in human neutrophils, and in parallel, inhibit cathepsin G. Their beneficial target profile may qualify triterpene acids as anti-inflammatory natural products and pharmacological leads for intervention with diseases related to aging.

Topics: Arachidonate 5-Lipoxygenase; Cathepsin G; Enzyme Activation; Frankincense; Lipoxygenase Inhibitors; Plant Extracts; Triterpenes