Enzymatic Synthesis and Antimicrobial Activity of Oligomer Analogues of Medicinal Biopolymers from Comfrey and Other Species of the Boraginaceae Family

Abstract

This study reports the first enzymatic synthesis leading to several oligomer analogues of poly[3-(3,4-dihydroxyphenyl)glyceric acid]. This biopolymer, extracted from plants of the Boraginaceae family has shown a wide spectrum of pharmacological properties, including antimicrobial activity. Enzymatic ring opening polymerization of 2-methoxycarbonyl-3-(3,4-dibenzyloxyphenyl)oxirane (MDBPO) using lipase from Candida rugosa leads to formation of poly[2-methoxycarbonyl-3-(3,4-dibenzyloxyphenyl)oxirane] (PMDBPO), with a degree of polymerization up to 5. Catalytic debenzylation of PMDBPO using H2 on Pd/C yields poly[2-methoxycarbonyl-3-(3,4-dihydroxyphenyl)oxirane] (PMDHPO) without loss in molecular mass. Antibacterial assessment of natural polyethers from different species of Boraginaceae family Symhytum asperum, S. caucasicum,S. grandiflorum, Anchusa italica, Cynoglossum officinale, and synthetic polymers, poly[2-methoxycarbonyl-3-(3,4-dimethoxyphenyl)oxirane (PMDMPO) and PMDHPO, reveals that only the synthetic analogue produced in this study (PMDHPO) exhibits a promising antimicrobial activity against pathogenic strains S.aureus ATCC 25923 and E.coli ATCC 25922 the minimum inhibitory concentration (MIC) being 100 µg/mL.

Schiff Base-Based Hydrogel Embedded with In Situ Generated Silver Nanoparticles Capped by a Hyaluronic Acid–Diethylenetriamine Derivative for Wound Healing Application

“…A bacterial suspension at a concentration of 10 6 CFU/mL was prepared. 81 Next, 25 μL of each bacterial culture was added to 24-well plates containing 2 mL of TSB at pH values of 5.5 or 7.4 along with unique hydrogels (AgF 1.77 , AgF 1.14 , AgF 0.89 , and AgF 0.30 ). These plates were incubated at 37 °C under stationary conditions.…”

New Bioactive Peptides from the Mediterranean Seagrass Posidonia oceanica (L.) Delile and Their Impact on Antimicrobial Activity and Apoptosis of Human Cancer Cells

“…Bacterial strains or fungal strains were incubated in test tubes containing TSB or Sabouraud (5 mL) and 2% v / v glucose at 37 °C for 24 h. Then, a 2.5 μL microbial suspension was added to each well, containing 200 μL of TSB or Sabouraud broth with 2% w / v glucose. [ 68 , 69 ]. Aliquots of sub-MIC concentrations of natural extracts of P. oceanica or of chemically synthesized peptides were directly added to the wells, and the plates were incubated at 37 °C for 24 h. After biofilm formation, the wells were washed twice with sterile NaCl 0.9% and stained with 200 μL of 0.1% v / v crystal violet solution for 30 min at 37 °C [ 70 ].…”

A Novel Peptide with Antifungal Activity from Red Swamp Crayfish Procambarus clarkii

“…Sub-MIC concentrations were tested for their ability to interfere with the growth as sessile community of S. aureus ATCC 25923, P. aeruginosa ATCC 15442, and C. albicans ATCC 10231, as previously described [ 55 ]. Bacterial strains or the fungal strain were incubated in test tubes with TSB or Sabouraud (5 mL) containing 2% w / v glucose at 37 °C for 24 h. After that, small aliquots (2.5 μL) from the diluted microbial suspensions whose turbidity was equivalent to a 0.5 McFarland standard were added to each well of a polystyrene sterile flat-bottom 96-well plate filled with TSB or BS (200 μL) with 2% w / v glucose [ 56 , 57 ]. Sub-MIC concentration values of amino acidic fraction from hemocytes and hemolymph of P. clarkii or of chemically synthesized peptides were directly added to the wells and the plates were incubated at 37 °C for 24 h. After biofilm growth, samples were washed twice with sterile 0.9% NaCl and stained with 200 μL of 0.1% w / v crystal violet solution for 15 min at 37 °C [ 58 ].…”