Effect of ethylene glycol and glycerol fructosides on the activity and product specificity of bacterial and plant fructosyltransferases

Dryoptkirbioside, A New Fructofuranoside Glycerol, and Other Constituents from Dryopteris kirbi Hook et Grav Rhizomes

A new fructofuranoside glycerol, dryoptkirbioside (1), along with thirteen known compounds (2-14), was isolated from the MeOH extract of Dryopteris kirbi rhizomes by silica gel column chromatography, Sephadex LH-20 column chromatography, and semipreparative HPLC. The structure of the new compound was determined by analyses of its spectroscopic data including nuclear magnetic resonance (NMR), and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and chemical conversions. The hexane-soluble portion and the EAFA fraction showed strong activities against lung (A549), breast (MCF-7), and cervical (HeLa) human cancer cell lines (IC50 values ranging from 4.0 to 8.8 μg/mL). Aspidinol P (5) and aspidinol B (6) exhibited moderate to low cytotoxicity on the three cell lines (IC50 values ranging from 20.4 to 58.7 μM). The MeOH extract and hexane-soluble portion had excellent activities against Staphylococcus aureus and Bacillus subtilis (MICs 11.7 and 23.4 μg/mL), whereas the AcOEt- and BuOH-soluble portions were significantly active on S. aureus (MICs 46.9 and 93.8 μg/mL). The main fractions EAFB , EAFC and nBFB displayed excellent activity against S. aureus (MICs 11.7 and 23.4 μg/mL). Aspidinol B (6) had significant activity, while aspidinol P (5) was moderately active against S. aureus and B. subtilis (MICs 42.0 and 89.5 μM).

Enzymatic synthesis of novel fructosylated compounds by Ffase from Schwanniomyces occidentalis in green solvents

The β-fructofuranosidase from the yeast Schwanniomyces occidentalis (Ffase) produces potential prebiotic fructooligosaccharides (FOS) by self-transfructosylation of sucrose, being one of the highest known producers of 6-kestose. The use of Green Solvents (GS) in biocatalysis has emerged as a sustainable alternative to conventional organic media for improving product yields and generating new molecules. In this work, the Ffase hydrolytic and transfructosylating activity was analysed using different GS, including biosolvents and ionic liquids. Among them, 11 were compatible for the net synthesis of FOS. Besides, two glycerol derivatives improved the yield of total FOS. Interestingly, polyols ethylene glycol and glycerol were found to be efficient alternative fructosyl-acceptors, both substantially decreasing the sucrose fructosylation. The main transfer product of the reaction with glycerol was a 62 g L^-1 isomeric mixture of 1-O and 2-O-β-d-fructofuranosylglycerol, representing 95% of all chemicals generated by transfructosylation. Unexpectedly, the non-terminal 2-O fructo-conjugate was the major molecule catalysed during the process, while the 1-O isomer was the minor one. This fact made Ffase the first known enzyme from yeast showing this catalytic ability. Thus, novel fructosylated compounds with potential applications in food, cosmetics, and pharmaceutical fields have been obtained in this work, increasing the biotechnological interest of Ffase with innocuous GS.

New fructofuranoside in fruit of Pyrus amygdaliformis Vill

The new compound 2-O-β-D-fructofuranosylglycerol was isolated from the hexane residue. Also 2-O-methyl-α-fructofuranoside was isolated for the first time from the fruits of Pyrus amygdaliformis Vill. The chemical structure of isolated carbohydrates was identified using NMR, mass spectroscopic technique and literature data. The minimal inhibitory concentrations (MIC) of P. amygdaliformis Vill. hexane, dichloromethane and butanol extracts of fruits were used for testing microorganisms. Hexane extract showed antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis and Salmonella typhimurium with MIC ranging between 25 and 0.39 mg/mL. The most sensitive strain was found to be K. pneumoniae with MIC value at 0.39 mg/mL in hexane extract.[Figure: see text].