Antibacterial activity of Hibiscus rosa-sinensis L. red flower against antibiotic-resistant strains of Helicobacter pylori and identification of the flower constituents.

L.T.M. Ngan,T.T.H. Hoa,T.T. Hieu,D.T. Thanh,N.T.M. Nuong,N.T.T. Linh,N.V.M. Hoang,M.T. Tan

doi:10.1590/1414-431x2020e10889

Abstract

Utilization of plant resources for treatment of Helicobacter pylori infections is one of the appealing approaches as rapid emergence of antibiotic-resistant strains is occurring throughout the world. Ethanol extract and its fractions from Hibiscus rosa-sinensis red flower were assessed for antibacterial and urease inhibitory activities towards forty-three clinical strains and two reference strains of H. pylori. The ethyl acetate fraction exhibited the most potent bacteriostatic activity with minimum inhibitory concentrations (MICs) of 0.2-0.25 mg/mL and minimum bactericidal concentrations (MBCs) of 1.25-1.5 mg/mL against all test strains, including forty-three strains resistant to one to four antibiotics, azithromycin (MICs, 8-256 µg/mL), erythromycin (MICs, 8-128 µg/mL), levofloxacin (MICs, 8-256 µg/mL), and/or metronidazole (MICs, 8-256 µg/mL). The fraction had similar antibacterial activities toward these test strains suggesting the preparation and the antibiotics do not have a common mechanism of anti-H. pylori activity. The fraction also had stronger effects on biofilm formation, morphological conversion, and urease activity of H. pylori than the other fractions and the ethanol extract. These flower preparations were non-toxic to three human cell lines, and nine compounds were also isolated and identified from the ethyl acetate fraction. In vivo research needs to be conducted to confirm the potential usefulness of H. rosa-sinensis flower and its constituents for effective prevention and treatment of H. pylori disease.

Highlights

Helicobacter pylori, a microaerobic, Gram-negative, and spiral-shaped bacterium, is known to be a major cause of gastrointestinal diseases such as chronic active gastritis, peptic ulcer, and gastric carcinoma [1]
Antibiotic resistance of H. pylori clinical strains The antibacterial activity of six common antibiotics toward forty-three H. pylori clinical isolates is shown in Figure 1 with minimum inhibitory concentrations (MICs) breakpoints for these test antibiotics [17,18,19]
The EtOAc fraction exhibited the most potency against all forty-three clinical strains of H. pylori resistant to 1–4 test antibiotics, and two reference strains, ATCC 43504 resistant to metronidazole and ATCC 51932 susceptible to all the six test antibiotics

Summary

Introduction

Helicobacter pylori, a microaerobic, Gram-negative, and spiral-shaped bacterium, is known to be a major cause of gastrointestinal diseases such as chronic active gastritis, peptic ulcer, and gastric carcinoma [1]. (Malvaceae family), a tropical evergreen shrub with red flowers, is traditionally used for the treatment of flu and cough, bronchitis, stomach pain, dysentery and diarrhea, Anti-H. pylori activity of H. rosa-sinensis red flower and for regulation of menstruation and stimulation of blood circulation [7]. Aerial part extracts of the plant have been known to possess antiulcerogenic activity on gastric ulcers [8]. The ethanol extract and ethyl acetate fraction derived from the H. rosa-sinensis flower were found to have antibacterial activity against H. pylori ATCC 43504 and four isolated compounds (naringenin, luteolin, myricetin, and protocatechuic acid) from the fraction were proven to possess potent antibacterial properties against seven antibiotic-sensitive and -resistant strains of H. pylori [14]

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Conclusion