Phytochemical Profile and Antimicrobial Potential of Propolis Samples from Kazakhstan

Abstract

In the current paper, we present the results of Kazakh propolis investigations. Due to limited data about propolis from this country, research was focused mainly on phytochemical analysis and evaluation of propolis antimicrobial activity. uHPLC-DAD (ultra-high-pressure-liquid chromatography coupled with diode array detection, UV/VIS) and uHPLC-MS/MS (ultra-high-pressure-liquid chromatography coupled with tandem mass spectrometry) were used to phytochemical characteristics while antimicrobial activity was evaluated in the serial dilution method (MIC, minimal inhibitory concentration, and MBC/MFC, minimal bactericidal/fungicidal concentration measurements). In the study, Kazakh propolis exhibited a strong presence of markers characteristic of poplar-type propolis-flavonoid aglycones (pinocembrin, galangin, pinobanksin and pinobanskin-3-O-acetate) and hydroxycinnamic acid monoesters (mainly caffeic acid phenethyl ester and different isomers of caffeic acid prenyl ester). The second plant precursor of Kazakh propolis was aspen-poplar with 2-acetyl-1,3-di-p-coumaroyl glycerol as the main marker. Regarding antimicrobial activity, Kazakh propolis revealed stronger activity against reference Gram-positive strains (MIC from 31.3 to above 4000 mg/L) and yeasts (MIC from 62.5 to 1000 mg/L) than against reference Gram-negative strains (MIC ≥ 4000 mg/L). Moreover, Kazakh propolis showed good anti-Helicobacter pylori activity (MIC and MBC were from 31.3 to 62.5 mg/L). All propolis samples were also tested for H. pylori urease inhibitory activity (IC₅₀, half-maximal inhibitory concentration, ranged from 440.73 to 11,177.24 µg/mL). In summary Kazakh propolis are potent antimicrobial agents and may be considered as a medicament in the future.

Keywords: Helicobacter pylori; Kazakhstan; black poplar; dendrogram; flavonoids antibacterial; hydroethanolic extracts; propolis; urease.

Figure 1

Representative uHPLC-DAD chromatograms of Kazakhstan propolis. Figure Legend: 1—Caffeic acid; 2—Vanilline; 3—Caffeoylglycerol; 4—p-Coumaric acid; 5—Benzoic acid; 6—Ferulic acid; 7—Isoferulic acid; 8—Caffeoylmalic acid (Phaseolic acid) isomer; 9—Cinnamic acid; 10—Pinobanksin-5-methyl ether; 11—Quercetin; 12—luteloin; 13—Quercetin-3-methyl-ether; 14—Pinobanksin; 15—Naringenin; 16—Apigenin; 17—Kaempferol; 18—Isorhamnetin; 19—Quercetin-methyl-ether; 20—Luteolin-5-methyl-ether; 21—1,3-di-p-Coumaroylglycerol; 22—Quercetin-dimethyl-ether; 23—2-Acetyl-1,3-di-caffeoylglycerol; 24—Rhamnetin; 25—Caffeic acid 2-methyl-2-butenyl ester; 26—Caffeic acid 3-methyl-2-butenyl ester; 27—Caffeic acid 3-methyl-3-butenyl ester; 28—(R/S) 2-Acetyl-1-caffeoyl-3-p-coumaroylglycerol; 29—Chrysin; 30—Caffeic acid benzyl ester; 31—(R/S) 2-Acetyl-1-caffeoyl-3-feruloylglycerol; 32—Pinocembrin; 33—Sakuranetin; 34—Galangin; 35—Genkwanin; 36—Caffeic acid pentyl or isopentylester ester; 37—Caffeic acid phenethyl ester (CAPE); 38—Pinobanksin 3-O-acetate; 39—Kaempferide (Kaempferol 4′-methyl ether); 40—Methoxychrysin; 41—2-Acetyl-1,3-di-p-coumaroylglycerol; 42—(R/S) 2-Acetyl-3-p-coumaroyl-1-feruloylglycerol; 43—2-Acetyl-1,3-di-feruloylglycerol; 44—p-Coumaric acid benzyl ester; 45—Ferulic acid benzyl ester; 46—Caffeic acid cinnamyl ester; 47—Pinobanksin-3-O-propanoate; 48—p-Coumaric acid phenethyl ester; 49—Tectochrysin; 50—Pinostrobin; 51—p-Coumaric acid cinnamyl ester; 52—Pinobanksin 3-O-butanoate or isobutanoate; 53—Pinobanksin 3-O-pentanoate or isopentenoate isomer I; 54—Pinobanksin 3-O-pentanoate or isopentenoate isomer II; 55—Pinobanksin-3-O-hydroxycinnamate; 56—p-Methoxy cinnamic acid cinnamyl ester.

Figure 2

Dendrogram of Kazakh propolis chemical composition. Figure legend: Dlink—Linkage Distance; D max—Maximal distance.

Figure 3

Urease activity inhibition by tested 70EEP of Kazakh propolis.