Effect of in vitro simulated digestion on the anti-Helicobacter Pylori activity of different Propolis extracts

Figures & data

Figure 1. HPLC-DAD chromatograms of (A) GPE, (B) DPE, and (C) PPE, registered at 280 nm. Pinocembrin RT = 18.89; chrysin RT = 19.43, galangin RT = 21.05, kaempferol RT = 21.57.

Table 1. Chemical characterisation of the extracts. Values (mg/g dry propolis) are expressed as mean ± standard deviation.

Sample	galangin	pinocembrin
GPE	12.65 ± 0.63	1.64 ± 0.15
DPE	83.46 ± 0.59	27.42 ± 0.29
PPE	13.84 ± 0.23	3.11 ± 0.21

Table 2. Relative gastric stability of reference standards. Values (%) are expressed as mean ± standard deviation.

Sample	Gastric stability
galangin	73.97 ± 8.26
pinocembrin	12.31 ± 1.15

Figure 2. Relative gastric stability of GPE, DPE, and PPE flavonoids. ***p < 0.001 vs reference standard; °°°p < 0.001 DPE vs GPE and PPE; ##p < 0.01 PPE vs GPE; two-way ANOVA followed by Tukey’s post-hoc.

Table 3. Anti-HP activity of DPE and its constituents against the VacA + CagA + 10K clinical isolate and the VacA + CagA- G21 strain. Amoxicillin, clarithromycin, and metronidazole were used as reference drugs. MIC and MBC are expressed as mg/L.

	10K		G21
Sample	MIC	MBC	MIC	MBC
DPE	848.4	848.4	424.2	424.2
galangin	37.5	37.5	18.8	18.8
pinocembrin	18.8	18.8	37.5	37.5
amoxicillin	0.3	0.3	0.1	0.1
clarithromycin	0.03	0.1	0.01	0.01
metronidazole	4.2	8.4	1.1	2.2

Table 4. Urease inhibition by DPE, galangin, and pinocembrin at the respective MBC and IC₅₀.

Sample	Concentration (mg/L)	Urease inhibition (%)^a	IC50 (mg/L)^b	Docking binding energy (kcal/mol)
DPE	848.4	27.8 ± 1.3	1297.2 ± 114.3
galangin	37.5	68.5 ± 7.1	19.4 ± 1.9	−5.6
pinocembrin	18.8	57.9 ± 4.6	15.7 ± 1.2	−5.6

^aHelicobacter pylori 10K clinical isolate urease; ^bJack bean urease.

Figure 3. (A) Binding mode of acetohydroxamic acid (cyan) in the active site of HP urease (PDBID: 1e9y), and best docking pose of (B) pinocembrin and (C) galangin. Interacting residues are shown as gray lines. Hydrogen bonds are represented by yellow dashed lines. Bottom: schematic representation of acetohydroxamic acid, pinocembrin, and galangin, respectively.