The comparison of the antioxidant, antibacterial and antiviral potential of Polish fir honeydew and Manuka honeys

Abstract

The aim of the present study was to compare the antioxidant, antibacterial and antiviral activities of Podkarpackie coniferous honeydew honey and Manuka honey. The quality of tested honey samples (honeydew-12 and Manuka-4) regarding honey standard was evaluated as well as additional indicators (methylglyoxal, total phenolics and HPTLC phenolic profile, antioxidant potential, glucose oxidase activity, and hydrogen peroxide) were compared. Antibacterial potential was analyzed against Gram-positive (S. aureus and B. cereus) and Gram-negative (E. coli and S. enterica) bacteria. Antiviral activity against different RNA (phi6, MS2) and DNA (T7, phiX174) bacteriophages considered as "viral surrogates" was determined. Based on the determined physicochemical parameters the good quality of tested honeys was confirmed, excluding two samples. The content of polyphenolic compounds in honeydew honey ranged from 583.87 to 1102.42 mg of gallic acid/kg and was strongly correlated with the antioxidant properties. Moreover, for samples with the strongest activity these parameters were comparable to Manuka honey. However, the obtained HPTLC polyphenolic profiles were completely different for honeydew than for Manuka honey which exhibited additional bands (Rf = 0.74 and 0.52). Honeydew honeys were characterized by a strong antiviral and antibacterial properties most of all against Gram-positive bacteria. The MICs (minimal inhibitory concentrations) for S. aureus and B. cereus ranged 15-35% and 8-15% for honeydew and Manuka honeys, respectively. The strongest antiviral properties of honeydew honey were demonstrated mainly against RNA bacteriophages (phi6, MS2) which was even higher than for Manuka honey, especially against MS2 virus. The obtained results suggest that Podkarpackie honeydew honey with the controlled glucose oxidase activity may be a natural substance used to combat viral and bacterial diseases.

Keywords: Antibacterial; Antioxidants; Antiviral; Bacteriophages; GOX; Honeydew honey; Hydrogen peroxide; Manuka Honey; Polyphenols.

Fig. 1

Image of the chromatographic plate: before derivatization in UV 366 nm (A), and after derivatization in white light (B) and UV 366 nm (C). Tracks 1–2: questionable honey samples, 3–12: honeydew honey, 13–16: Manuka honey.

Fig. 2

Hydrogen peroxide content in 25% (w/v) honey solutions regarding different times of their incubation at room temperature. a, b, c, d, e means sharing the same letter (within one time) are not significantly different from control (p > 0.05).

Fig. 3

Growth curve of S. aureus and B. cereus during incubation with 15%, 20% and 25% (w/v) honey concentrations. C—control (S. aureus or B. cereus), 1–2—questionable honey samples, 3–12—honeydew honey, M-1—Manuka honey 100 MGO. Legend: Control - Black filled circle, 1 - orange filled triangle, 2 - dark green filled triangle, 3 - blue filed circle, 4 - purple filled circle, 5 - light green filled square, 6 - dark blue filled square, 7 - brown filled circle, 8 - dark green filled circle, 9 - dark blue filled circle, 10 - red filled square, 11 - dark green filled square, 12 - blue filled square, M-1 - red filled circle.

Fig. 4

Growth curve of E. coli and S. enterica during incubation with 15%, 20% and 25% (w/v) honey concentrations. C—control (E.coli or S. enterica), 1–2—questionable honey samples, 3–12—honeydew honey; M-1—Manuka honey 100 MGO. Legend: Control - Black filled circle, 1 - orange filled triangle, 2 - dark green filled triangle, 3 - blue filed circle, 4 - purple filled circle, 5 - light green filled square, 6 - dark blue filled square, 7 - brown filled circle, 8 - dark green filled circle, 9 - dark blue filled circle, 10 - red filled square, 11 - dark green filled square, 12 - blue filled square, M-1 - red filled circle.

Fig. 5

Double-layer phage assay technique for enumeration of virus surrogates.

Fig. 6

Viral particles reduction after 2 h of incubation with 50% honey samples. (A) Bacteriophage phi6; (B) bacteriophage phiX174. Control samples without honey, 3,7 honeydew honey, M4 Manuka honey, df dilution factor.

Fig. 7

Antiviral potential of honey samples against different bacteriophages: (A)—phi6; (B)—MS2; (C)—T7; and (D)—phiX174. 3,4,7,9—honeydew honey, M-3—Manuka honey. Plaque-forming units (PFU) were calculated after 2,4,8,12,24 h of honey extract (50%) incubation with bacteriophages. phi6, MS2, T7, phiX174 bars—positive controls (PFU of viral particles in STM buffer without addition of honey). *Sharing asterisk symbol are significantly different from control (p < 0.05) (t test); no columns on the graph mean complete virus inhibition by the tested extracts.