Validated Postbiotic Screening Confirms Presence of Physiologically-Active Metabolites, Such as Short-Chain Fatty Acids, Amino Acids and Vitamins in Hylak® Forte


Hylak® forte is a postbiotic that inhibits the growth of pathogenic bacteria by reducing intestinal pH. It is assumed the potential presence of short-chain fatty acids (SCFAs) in Hylak® forte may contribute to this effect. In this current study, we analysed the composition of Hylak® forte, using a validated gas chromatography assay test method, to ascertain whether SCFAs are present in this postbiotic treatment. Hylak® forte was screened for C1 to C10 SCFAs by a gas chromatographic assay. In this assay, SCFAs were analysed as for their volatile ethyl ester derivatives in a 3.0 mL Hylak® forte sample. An additional screening procedure was conducted for the presence of vitamins and simple sugars. The gas chromatographic method for determining SCFAs was validated according to the requirements of ICH guideline Q2 (R1). Formic and acetic acids were identified in Hylak® forte at 27.92 ppm (90% confidence interval (CI), 26.90–28.94) and 306.17 ppm (90% CI, 277.11–335.22), respectively. Additional compounds were quantified in the solution, including vitamin B1 (0.029 mg/100 g), monosaccharides and disaccharides (2.767 g/100 g), as well as glutamic acid and glutamine (0.047 g/100 g). This study has identified formic acid in a range of 39.33 (90% CI, 36.50–42.17)–48.33 (90% CI, 45.91–50.76) ppm and acetic acid dropping down to 312.33 (90% CI, 295.32–329.35) from initial 415.67 ppm (90% CI, 385.93–445.41) in commercial Hylak® forte samples under forced degradation conditions. In addition, a range of other compounds in Hylak® forte was identified, including riboflavin and glutamine. Further studies are necessary to establish whether these compounds translate into tangible therapeutic effects.

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This study was sponsored by Ratiopharm GmbH, which is an affiliate of Teva Pharmaceutical Industries Ltd. Medical writing support was provided by Matthew Gunther, PhD, of Zoetic Science, an Ashfield company, part of UDG Healthcare plc, and was funded by Ratiopharm GmbH (Ulm, Germany).

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Correspondence to Gabriele Hampp.

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Patil, S., Sawant, S., Hauff, K. et al. Validated Postbiotic Screening Confirms Presence of Physiologically-Active Metabolites, Such as Short-Chain Fatty Acids, Amino Acids and Vitamins in Hylak® Forte. Probiotics & Antimicro. Prot. 11, 1124–1131 (2019).

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  • Hylak forte
  • SCFA
  • Postbiotics
  • Metabiotics
  • Vitamins
  • Gastrointestinal tract