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

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 ß-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 ±â€¯0.65 and 2.66 ±â€¯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 ±â€¯0.046 µg/mL) more than clavulanate, sulbactam and tazobactam (classical ß-lactam inhibitors) (IC50 = 68.38 ±â€¯0.17 µg/mL, 52.68 ±â€¯0.64 µg/mL, and 29.94 ±â€¯0.01 µg/mL, respectively). IC50 of the other ME of U.intestinalis, C.tomentosum, and H.scoparia were 16.87 ±â€¯0.10 µg/mL, 16.54 ±â€¯0.048 µg/mL, and 25.72 ±â€¯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 ß-lactamases. Besides that, they contain important components with potential health benefits.

Gram (-) microorganisms DNA polymerase inhibition, antibacterial and chemical properties of fruit and leaf extracts of Sorbus acuparia and Sorbus caucasica var. yaltirikii.

Investigation of novel plant-based agents might provide alternative antibiotics and thus fight antibiotic resistance. Here, we measured the ability of fruit and leaf extracts of Sorbus aucuparia (Sauc) and endemic Sorbus caucasica var. yaltirikii (Scau) to inhibit nonreplicative (Klenow Fragment-KF and Bacillus Large Fragment-BLF) and replicative (DnaE and PolC) bacterial DNA polymerases along with their antimicrobial, DPPH free radical scavenging activity (RSA), and chemical contents by total phenolic content and HPLC-DAD analysis. We found that leaf extracts had nearly 10-fold higher RSA and 5-fold greater TPC than the corresponding fruit extracts. All extracts had large amounts of chlorogenic acid (CGA) and rutin, while fruit extracts had large amounts of quercetin. Hydrolysis of fruit extracts revealed mainly caffeic acid from CGA (caffeoylquinic acid) and quercetin from rutin (quercetin-3-O-rutinoside), as well as CGA and derivatives of CGA and p-coumaric acid. Plant extracts of Sorbus species showed antimicrobial activity against Gram-negative microorganisms. Scau leaf extracts exhibited strong inhibition of KF activity. Sauc and Scau leaf extracts also strongly inhibited two replicative DNA polymerases. Thus, these species can be considered a potential source of novel antimicrobial agents specific for Gram-negative bacteria.