Characterization of Chitinolytic and Antifungal Activities in Marine-Derived Trichoderma bissettii Strains

Trichoderma fungi have been intensively studied for mycoparasitism, and the latter is closely related to their cell-wall degrading enzymes including chitinase. Here, we studied marinederived Trichoderma spp., isolated from distinct sources and locations, for chitinolytic and antifungal activity. Based on morphological and phylogenetic analyses, two strains designated GJ-Sp1 and TOP-Co8 (isolated from a marine sponge and a marine alga, respectively) were identified as Trichoderma bissettii. This species has recently been identified as a closely related species to Trichoderma longibrachiatum. The extracellular crude enzymes of GJ-Sp1 and TOP-Co8 showed activities of chitobiosidase and β-N-acetylglucosaminidase (exochitinase) and chitotriosidase (endochitinase). The optimum chitinolytic activity of the crude enzymes was observed at 50°C, pH 5.0, 0–0.5% NaCl concentrations, and the activities were stable at temperatures ranging from 10 to 40 C for 2 h. Moreover, the crude enzymes showed inhibitory activity against hyphal growth of two filamentous fungi Aspergillus flavus and Aspergillus niger. To the best of our knowledge, this is the first report of the chitinolytic and antifungal activity of T. bissettii.

Comparison of Biological Activities of Korean Halophytes

Halophytes are expected to possess abundant secondary metabolites and various biological activities because of habitat in extreme environments. In this study, we collected 14 halophytes (Asparagus oligoclonos, Calystegia soldanella, Carex pumila, Chenopodium glaucum, Elymus mollis, Glehnia littoralis, Limonium tetragonum, Messerschmidia sibirica, Rosa rugosa, Salsola komarovii, Spergularia marina, Suaeda glauca, Suaeda maritima, and Vitex rotundifolia) native to Korea and compared their total polyphenol contents, antioxidant and anti-inflammatory activities. The total polyphenol contents of R. rugosa (27.28%) and L. tetragonum (13.17%) were significantly higher than those of the other 12 halophytes and L. tetragonum, R. rugosa, and M. sibirica showed significantly greater antioxidant activities than the other 11 halophytes, as determined by DPPH (2,2-diphenyl-1-picrylhydrazyl). A. oligoclonos, E. mollis, and C. pumila showed significantly greater anti-inflammatory activities than the other 11, as determined by NO (Nitric oxide) and PGE₂ (Prostaglandin E₂) levels. In contrast, these three extracts had normal and low total polyphenol contents among the 14 halophytes. Consequently, the total polyphenol content in the 14 studied halophytes appeared to be related to antioxidant, but not anti-inflammatory activity levels.

Antioxidant and Anti-inflammatory Activity of Six Halophytes in Korea

The aim of this study was to measure and compare polyphenol content, antioxidant, and anti-inflammatory activity of six halophytes (Limonium tetragonum, Suaeda glauca, Suaeda japonica, Salicornia europaea, Triglochin maritimum, and Sonchus brachyotus). Depending on the total polyphenol content, the plants were categorized into two groups: (1) a high total polyphenol content group that included L. tetragonum, S. brachyotus, and S. europaea, and, (2) a low total polyphenol content group consisting of S. glauca, T. maritima, and S. japonica. Antioxidant activity was evaluated using DPPH and hydroxyl radical scavenging assays, and by measuring ROS. Anti-inflammatory activity was evaluated by measuring NO and PGE₂. L. tetragonum and S. brachyotus, that have high polyphenol content, also showed strong antioxidant activity. In addition, L. tetragonum, S. brachyotus, and S. europaea showed good anti-inflammatory activity. Consequently, the total polyphenol content was thought to be related to antioxidant and anti-inflammatory activity. Therefore, S. brachyotus and L. tetragonum are good candidates for use in pharmaceuticals and functional foods.

Escitalopram, a selective serotonin reuptake inhibitor, inhibits voltage-dependent K⁻ channels in coronary arterial smooth muscle cells

We investigated the inhibitory effect of escitalopram, a selective serotonin reuptake inhibitor (SSRI), on voltage-dependent K⁺ (Kv) channels in freshly separated from rabbit coronary arterial smooth muscle cells. The application of escitalopram rapidly inhibited vascular Kv channels. Kv currents were progressively inhibited by an increase in the concentrations of escitalopram, suggesting that escitalopram inhibited vascular Kv currents in a concentration-dependent manner. The IC₅₀ value and Hill coefficient for escitalopram-induced inhibition of Kv channels were 9.54±1.33 µM and 0.75±0.10, respectively. Addition of escitalopram did not alter the steady-state activation and inactivation curves, suggesting that the voltage sensors of the channels were not affected. Pretreatment with inhibitors of Kv1.5 and/or Kv2.1 did not affect the inhibitory action of escitalopram on vascular Kv channels. From these results, we concluded that escitalopram decreased the vascular Kv current in a concentration-dependent manner, independent of serotonin reuptake inhibition.