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Investigation of common chemical components and inhibitory effect on GES-type β-lactamase (GES22) in methanolic extracts of Algerian seaweeds

Houchi, Selma, Mahdadi, Rachid, Khenchouche, Abdelhalim, Song, Junke, Zhang, Wen, Pang, Xiaocong, Zhang, Li, Sandalli, Cemal, Du, Guanhua
Microbial pathogenesis 2019 v.126 pp. 56-62
Codium, Dictyota dichotoma, Halopteris scoparia, Ulva, alpha-linolenic acid, arachidonic acid, beta-lactamase, dose response, inhibitory concentration 50, linoleic acid, macroalgae, oleic acid, phenols, plant extracts, sulbactam
This study aimed to investigate the total phenolic content (TPC), the identification of the common compounds by HPLC-ESI-MS and HPLC-ESI-MS-TOF and the inhibitory effects against class A-type β-lactamase (GES-22 variant, produced recombinantly) in methanolic extracts (MEs) of four Algerian seaweeds [Ulva intestinalis, Codium tomentosum, Dictyota dichotoma and Halopteris scoparia]. The TPC varied among the four species, ranging between 0.93 ± 0.65 and 2.66 ± 1.33 mg GAEs/g DW. C.tomentosum had higher total phenol content than other seaweeds while, all of them inhibited uncompetitively GES-22 activity in a dose-dependent manner. Nitrocefin was used as chromogenic substrate to evaluate the inhibitory effect on GES-22. The methanolic extract of D.dichotoma exhibited significant inhibitory effect on GES-22 (IC50 = 13.01 ± 0.046 μg/mL) more than clavulanate, sulbactam and tazobactam (classical β-lactam inhibitors) (IC50 = 68.38 ± 0.17 μg/mL, 52.68 ± 0.64 μg/mL, and 29.94 ± 0.01 μg/mL, respectively). IC50 of the other ME of U.intestinalis, C.tomentosum, and H.scoparia were 16.87 ± 0.10 μg/mL, 16.54 ± 0.048 μg/mL, and 25.72 ± 0.15 μg/mL, respectively. Except H. scoparia, other three seaweed extracts showed almost two times or more inhibition on GES-22. Furthermore, four common compounds in these MEs were identified, α-linolenic acid (C18:3ω3), linoleic acid (C18:2ω6), oleic acid (C18:1ω9), the eicosanoid precursors ‘‘arachidonic acid’’ (C20:4ω6). Baicalein (C15H10O5) was identified in U.intestinalis and D.dichotoma seaweeds. The fact that all seaweed extracts inhibited the GES-22 better than commercial samples makes these seaweeds candidate for discovering new inhibitors against β-lactamases. Besides that, they contain important components with potential health benefits.