Fig. 3. In vitro and in vivo butyrate release from NtL-ButM and Neg-ButM in the GI tract.
a, Both NtL-ButM and Neg-ButM released butyrate slowly in the simulated gastric fluid over 20 d. b, Both NtL-ButM and Neg-ButM released their complete butyrate load within minutes in simulated intestinal fluid (SIF) containing high levels of the esterase pancreatin. Neither polymer released butyrate in PBS on these timescales. n = 3. c–e, The amount of butyrate released in the ileum (c), caecum (d) or colon (e) contents after a single intragastric administration of NtL-ButM or Neg-ButM at 800 mg kg−1 to SPF C3H/HeJ mice. Butyrate was derivatized with 3-nitrophenylhydrazine and quantified by LC–MS/MS (ileum samples) or LC–UV (caecum and colon samples). The dotted red lines represent butyrate content in untreated mice. n = 9–10 mice per group. Data represent mean ± s.e.m.