Total phenolic and flavonoid content and antibacterial activity of Punica granatum L. var. pleniflora flowers (Golnar) against bacterial strains causing foodborne diseases.

Arash Mahboubi,Jinous Asgarpanah,Parisa Nosrati Sadaghiyani,Mehrdad Faizi

doi:10.1186/s12906-015-0887-x

Abstract

BackgroundFlowers of Punica granatum L. (Punicaceae) var. pleniflora, known as “Golnar” in Iranian traditional medicine have been used for the prevention and treatment of foodborne diseases. In this study, antibacterial activities of ethanol extract of Golnar and its fractions were scientifically evaluated against bacteria causing foodborne diseases including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, Shigella dysantriae, and Salmonella typhi. The total phenolic and flavonoid contents of the extract and its fractions were also determined.MethodsThe antibacterial effect of the ethanol extract and its fractions were primarily evaluated by agar well diffusion and their MIC and MBC were determined by broth macro dilution method. The total phenolic and flavonoid contents of the extract and its fractions were measured based on gallic acid and rutin equivalents (GAE and RE), respectively.ResultsAfter evaluation of total phenolic and flavonoid content the chloroform fraction showed the lowest phenolic and flavonoid contents (3.8 mg GAE/g and 1.1 mg RE/g respectively) and the methanol fraction showed the highest phenolic and flavonoid contents (18.1 mg GEA/g and 3.3 mg RE/g respectively). The total phenolic and flavonoid content was positively associated with the antibacterial activities of the fractions with chloroform extract exhibiting lowest antibacterial activity against E. coli (MIC 25 mg/ml) and the methanol fraction exhibiting the highest antibacterial effect against S. aureus (MIC 0.19 mg/ml).ConclusionGolnar extract showed antibacterial activity against both Gram positive and Gram negative bacteria causing food poisoning. Therefore, the extract can be used for prevention or treatment of foodborne diseases or as preservative in the food industry.The methanol fraction with the highest phenolic and flavonoid content showed the highest antibacterial effect. This indicates that the phenolic and flavonoid compounds in the extract can be responsible for the effect.

Highlights

Flowers of Punica granatum L. (Punicaceae) var. pleniflora, known as “Golnar” in Iranian traditional medicine have been used for the prevention and treatment of foodborne diseases
We investigated the antibacterial activity of Golnar against bacteria causing foodborne diseases, based on the traditional use of Golnar as an antibacterial agent
The results showed that S. aureus (Gram positive bacteria) and Shigella dysantriae (Gram negative bacteria) could be more sensitive based on their larger inhibition zones

Summary

Introduction

Flowers of Punica granatum L. (Punicaceae) var. pleniflora, known as “Golnar” in Iranian traditional medicine have been used for the prevention and treatment of foodborne diseases. Antibacterial activities of ethanol extract of Golnar and its fractions were scientifically evaluated against bacteria causing foodborne diseases including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, Shigella dysantriae, and Salmonella typhi. The food industry is following the consumer opinions for safer additives, especially natural preservatives [2, 3]. Discovering plants and their active ingredients to prevent or cure infections, including foodborne diseases, could be a great achievement [3]. The antibacterial effects of various medicinal plants are being investigated due to the toxicological concerns associated with the synthetic antioxidants and preservatives [4, 5]

Methods

Results

Discussion

Conclusion