Trivaric Acid, a Potent Depside Human Leukocyte Elastase Inhibitor

Abstract

Human leukocyte elastase (HLE) is a serine protease implicated in several inflammatory diseases, and represents a major target for anti-inflammatory drug development. In the present study, nordivaricatic acid (1), divarinyl divarate (2), and trivaric acid (3), three depsides isolated from the culture of a soil derived fungal strain were identified as inhibitors of HLE. Two didepsides 1 and 2 showed low inhibitory activity. In contrast, trivaric acid, a para-tridepside, exhibited highly potent inhibitory activity with an IC 50 value of 1.8 µM and a K i of 0.6 µM. Kinetic investigations with trivaric acid showed that this inhibition is reversible, competitive pattern. Further studies on the selectivity of three depsides toward serine proteases showed that they did not inhibit chymotrypsin, trypsin and thrombin even at 150 µM.Key words human leukocyte elastase; depside; trivaric acid; fungus Human leukocyte elastase (HLE, EC 3.4.21.37), also known as human neutrophil elastase (HNE) and human granulocyte elastase, is a member of the chymotrypsin superfamily of serine proteases, and highly expressed in the azurophilic granules of polymorphonuclear leukocytes (PMNLs). HLE can very efficiently degrade tissue matrix proteins such as elastin, collagen, fibronectin, laminin and proteoglycan by activating procollagenase, prostromelysin, and progelatinase, and is potentially one of the most destructive enzymes in the body. 1)Under physiological conditions, HLE is released from PMNLs because of inflammatory stimuli and mediators, and is inactivated by a number of endogenous proteinase inhibitors such as α 2 -antiplasmin, α 1 -antichymotrypsin, antithrombin, and tissue inhibitor of metalloproteinases.2,3) The imbalance between HLE and its endogenous inhibitors leads to abnormal tissue destruction which is associated with a number of inflammatory diseases including pulmonary emphysema, 4) adult respiratory distress syndrome (ARDS), 5) chronic bronchitis, 6) chronic obstructive pulmonary disease (COPD), 7,8) rheumatoid arthritis (RA), 9) and acute lung injury (ALI). 10) In addition, HLE plays an important role in invasion and metastasis of human breast and lung cancer.11) Hence, HLE has been an important therapeutic target.Research and development of potent small molecular HLE inhibitors has been conducted for over three decades worldwide, and a number of synthetic and natural inhibitors have been discovered and evaluated biologically both in vitro and in vivo.12,13) The most advanced synthetic inhibitor is ONO-5046 (sivelestat) which has been launched in Japan (2002) as an injectable formulation for the treatment of acute lung injury associated with systemic inflammatory response syndrome, ARDS and ALI.14,15) MR-889 (midesteine), an irreversible HNE inhibitor, is also in pre-registration for the treatment of COPD in Italy. 16) In our searching for novel HLE inhbitors from natural or synthetic compounds, three depsides from the culture of a soil derived fungal strain were identified as inhibitors of HLE. Fungal Strain and Ferme...

Axenic culture and biosynthesis of secondary compounds in lichen symbiotic fungi, the Parmeliaceae

“…We propose that our methodology may be a eco-friendlier option of obtaining this active biomolecule, although the process must be improved to implement the efficacy. P. saxatilis axenic culture produced nordivaricatic acid, which could be an inhibitor of human leukocyte elastase (HLE) implicated in several inflammatory diseases (Zheng et al 2012); lobaric acid which exert various biological activities, including antitumor, antiproliferative, anti-inflammatory, and antioxidant activities (Hong et al 2018) and physodic acid, which has anticancer activity (e.g. Studzińska-Sroka et al 2016).…”

Fungal Depsides—Naturally Inspiring Molecules: Biosynthesis, Structural Characterization, and Biological Activities

“…The depsides, 25 (IC 50 45.1 µM) and 26 (IC 50 92.6 µM), weakly inhibited HLE in the spectro-photometric immunoassay, while the tridepside, 83 (IC 50 1.8 µM), exhibited high HLE inhibitory activity compared to ulinastatin (IC 50 1.1 µg/mL), which was 25-50-fold greater than that of depsides [25].…”

“…HLE is one of the most destructive enzymes that can degrade tissue matrix proteins, such as collagen, elastin, fibronectin, proteoglycan, and laminin, by activating progelatinase, procollagenase, and prostromelysin [25]. It is released from PMNLs (polymorphonuclear leukocytes) as a result of inflammatory mediators and stimuli.…”

“…Depsides are common lichen metabolites [20][21][22]. However, they have also been reported in some higher plants and fungi [19,[23][24][25][26][27]. Contrary to the lichen depsides, fungal depsides are not widely distributed and are isolated only from a restricted number of fungi (Table 1).…”

Depsidones inhibit aromatase activity and tumor cell proliferation in a co-culture of human primary breast adipose fibroblasts and T47D breast tumor cells

“…Indeed, several studies have already reported biological activities of these naturally occurring depsidones like anti-proliferative actions [2] , [3] , [4] , antimalarial and cytotoxic properties [5] , antibacterial activity against the multidrug-resistant Staphylococcus aureus [6] , radical scavenging, antioxidant activities and antifungal activities [7] , [8] , [9] . On the other hand, because of their structural similarity, leukotriene depsidones may induce allergic reactions in humans [10] . Also, apoptosis or inflammatory processes that involve free oxigen radicals by depsidones have been reported to cause cytoxicity in rat hepatocytes [11] and rat thymocytes [12] .…”