FVIIa-sTF and Thrombin Inhibitory Activities of Compounds Isolated from Microcystis aeruginosa K-139

Abstract

The rise of bleeding and bleeding complications caused by oral anticoagulant use are serious problems nowadays. Strategies that block the initiation step in blood coagulation involving activated factor VII-tissue factor (fVIIa-TF) have been considered. This study explores toxic Microcystis aeruginosa K-139, from Lake Kasumigaura, Ibaraki, Japan, as a promising cyanobacterium for isolation of fVIIa-sTF inhibitors. M. aeruginosa K-139 underwent reversed-phase solid-phase extraction (ODS-SPE) from 20% MeOH to MeOH elution with 40%-MeOH increments, which afforded aeruginosin K-139 in the 60% MeOH fraction; micropeptin K-139 and microviridin B in the MeOH fraction. Aeruginosin K-139 displayed an fVIIa-sTF inhibitory activity of ~166 µM, within a 95% confidence interval. Micropeptin K-139 inhibited fVIIa-sTF with EC50 10.62 µM, which was more efficient than thrombin inhibition of EC50 26.94 µM. The thrombin/fVIIa-sTF ratio of 2.54 in micropeptin K-139 is higher than those in 4-amidinophenylmethane sulfonyl fluoride (APMSF) and leupeptin, when used as positive controls. This study proves that M. aeruginosa K-139 is a new source of fVIIa-sTF inhibitors. It also opens a new avenue for micropeptin K-139 and related depsipeptides as fVIIa-sTF inhibitors.

Current Knowledge on Microviridin from Cyanobacteria

“…This value was inferior than that encountered for Micropeptin K139, a serine protease also detected in cyanobacteria. In contrast, microviridins D-F do not affect thrombin activity, most likely due to the absence of an indole motif, which is encountered in microviridin B, suggesting its role as a recognition motif for thrombin [86].…”

Inhibitors of Serine Proteases from a Microcystis sp. Bloom Material Collected from Timurim Reservoir, Israel

“…This finding adds a new derivative, 4,5-didehydroaraginal (Ddha), to the known building blocks of trypsin-type serine protease inhibiting aeruginosins; others are agmatine, araginol, araginal, 3-aminoethyl-1- N -amidino-Δ 3 -pyrroline [ 3 ] and 1-amidino-2-aminopyrrolidine (Aap) [ 12 ]. A recent study showed that aeruginosin K-139, an araginal containing aeruginosin, blocks the formation of the activated factor VII-soluble Tissue Factor complex (fVIIa-sTF, EC 50 ~166 µM) and inhibits thrombin catalytic activity (EC 50 of 0.66 µM) [ 29 ]. It will be interesting to compare the fVIIa-sTF activity of aeruginosin TR642 with that of aeruginosin K-139 in view of the opposite absolute configuration of the Ile/Leu and Choi sub-units and Ddha versus araginal, respectively.…”