Fig 1.
The scheme of synthesis, the structure of precursors, and the proposed major structure of enzymatically polymerised polyphenols used in this study.
CA, caffeic acid; FA, trans-ferulic acid; CoA, trans-coumaric acid; pCA, polymerised caffeic acid; pFA, polymerised trans-ferulic acid; pCoA, polymerised trans-coumaric acid; HRP, horseradish peroxidase; MWCO, molecular weight cut-off; R, H or OH.
Fig 2.
Enzymatically polymerised polyphenols promote antigen-specific mucosal antibody responses.
Female BALB/cCrSlc mice were immunised three times intranasally (days 0, 7, and 14) with vehicle (PBS), OVA (2.5 μg/mouse) alone, OVA (2.5 μg/mouse) plus pCA (100 μg/mouse), OVA (2.5 μg/mouse) plus pFA (100 μg/mouse), or OVA (2.5 μg/mouse) plus pCoA (100 μg/mouse). OVA-specific IgA endpoint titres in nasal wash, BALF, and vaginal wash as well as OVA-specific IgG endpoint titres in BALF at day 21 were detected by ELISA. The data were obtained from three biologically independent experiments. PBS, n = 9; OVA, n = 9; OVA plus pCA, n = 9; OVA plus pFA, n = 9; OVA plus pCoA, n = 9. The box-plot shows the median value with the 25th–75th percentiles and the error bars indicate the 5th–95th percentiles. Significance was calculated using the Kruskal-Wallis with Dunn’s post-hoc test: *p < 0.05.
Fig 3.
Enzymatically polymerised polyphenols promote antigen-specific systemic antibody responses.
Female BALB/cCrSlc mice were immunised three times intranasally (days 0, 7, and 14) with vehicle (PBS), OVA (2.5 μg/mouse) alone, OVA (2.5 μg/mouse) plus pCA (100 μg/mouse), OVA (2.5 μg/mouse) plus pFA (100 μg/mouse), or OVA (2.5 μg/mouse) plus pCoA (100 μg/mouse). OVA-specific total IgG, IgG1, IgG2a, and IgG2b endpoint titres in sera at day 21 were detected by ELISA. The data were obtained from three biologically independent experiments. PBS, n = 9; OVA, n = 9; OVA plus pCA, n = 9; OVA plus pFA, n = 9; OVA plus pCoA, n = 9. The box-plot shows the median value with the 25th–75th percentiles and the error bars indicate the 5th–95th percentiles. Significance was calculated using the Kruskal-Wallis with Dunn’s post-hoc test: *p < 0.05.
Fig 4.
Comparison of the mucosal adjuvant effects of the enzymatically polymerised polyphenols with CT.
Female BALB/cCrSlc mice were immunised three times intranasally (days 0, 7, and 14) with OVA (2.5 μg/mouse) plus either pCA (100 μg/mouse), pFA (100 μg/mouse), or pCoA (100 μg/mouse), or OVA (2.5 μg/mouse) plus CT (1 μg/mouse). ELISA detected OVA-specific IgA endpoint titres in nasal wash and BALF; IgG endpoint titres in BALF and vaginal wash; and total IgG, IgG1, and IgG2a endpoint titres in sera on day 21. The data were obtained from three biologically independent experiments. OVA plus enzymatically polymerised polyphenols (EPPs); the median value of the sum of OVA plus pCA, OVA plus pFA, and OVA plus pCoA, n = 27; OVA plus CT, n = 9. The box-plot shows the median value with the 25th–75th percentiles and the error bars indicate the 5th–95th percentiles. Significance was calculated using the Mann-Whitney U test: *p < 0.05.