Iranian propolis efficiently inhibits growth of oral streptococci and cancer cell lines

Asgharpour et al. BMC Complementary and Alternative Medicine https://doi.org/10.1186/s12906-019-2677-3 (2019) 19:266 RESEARCH ARTICLE Open Access Iranian propolis efficiently inhibits growth of oral streptococci and cancer cell lines Fariba Asgharpour1,2, Ali Akbar Moghadamnia3,4, Ebrahim Zabihi5, Sohrab Kazemi5, Amirmorteza Ebrahimzadeh Namvar6, Hemmat Gholinia7, Mina Motallebnejad8* and Hamid Reza Nouri5* Abstract Background: Propolis is a natural bee product with a wide range of biological activities that are related to its chemical composition. The present study investigated the quantification of quercetin (Q) in Ardabil ethanol extract of propolis (AEEP), and then compared its anti-bacterial, anti- biofilm and cytotoxic effects on cancer and normal cell lines. Method: In the present study, the chemical composition of AEEP was determined through the high-performance liquid chromatography (HPLC). The AEEP and its main component, quercetin (Q), were evaluated in vitro against 57 oral streptococci by a broth micro-dilution method. The biofilm formation was assessed through the crystal violet staining and MTT assays. The impact of AEEP and Q anti-proliferative effect were evaluated on the fibroblast as normal and cancer cell lines (KB and A431). Results: The Q concentration in the composition of AEEP was 6.9% of all its components. The findings indicated that the AEEP and Q were efficient against the cariogenic bacteria and were able to inhibit the S.mutans biofilm adherence at a sub-MIC concentration. Moreover, electron micrographs indicated the inhibition of biofilms compared to control biofilms. In addition, the AEEP and Q indicated a dose-dependent cytotoxic effect on A431 and KB cell lines. On the contrary, they had no cytotoxic effect on fibroblast cells. Conclusion: The results indicated that the synergistic impact of main components of AEEP was related to the inhibition of the cancer cell proliferation, cariogenic bacteria and oral biofilm formation. It may play a promising role in the complementary medicine and, it is suggested to be used as food additives. Keywords: Anti-bacterial, Anti-biofilms, Propolis, Quercetin Background The propolis is a nontoxic natural resinous substance that is produced by honeybee from diverse plants containing several chemical compounds such as flavonoids, phenolic acids, and aromatic compounds [1, 2]. The ingredient of this compound depends on its geographic origin and other factors such as collection periods by honeybees [3]. Propolis has a wide range of biological functions such as anti-microbial, anti-viral, anti-fungal, anti-inflammatory, anti-oxidative, free-radical scavenging and anti-tumor properties [2–6]. The anti-microbial * Correspondence: ; 8 Oral Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran 5 Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Full list of author information is available at the end of the article activity of propolis is considerable and it varies according to the flavonoid content [7]. The reduction of bacterial count in oral cavity effectively prevents the teeth decay [8]. Streptococcus mutans, a main acidogenic bacterium, is crucial in developing malignant cariogenesis [9]. Due to the synthesis of extracellular polysaccharides, mainly water-insoluble glucan, S. mutans can be colonized on the teeth surface and can initiate the plaque formation and dental caries [10]. Propolis can adhere to the teeth surface, and subsequently decrease the dental plaque development [11–13]. According to the emergence of multidrug resistant strains, the reduction and elimination of the pathogenic bacteria and also maintaining the normal flora are critical to prevent the teeth decay and oral diseases [14]. © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Asgharpour et al. BMC Complementary and Alternative Medicine (2019) 19:266 Recent studies indicate that ethanol extract of propolis (EEP) exerts potent anticancer activities against many tumor cells. The results revealed anticancer properties of propolis via various mechanisms such as the inhibition of cell proliferation and growth, induction of apoptosis, cell cycle arrest and induction of mitochondrial stress. Propolis contains a wide range of polyphenol and flavonoid content that strongly depends on the geographical areas, time and place of collection, climate, and the surrounding vegetation. This wide spectrum of different factors can affect the biological activity of propolis [15]. Quercetin (3,3`,4`,5,7-penta hydroxyl flavanone) is a flavonoid that can be found in different types of plants; and propolis is a one of the richest flavonoid source. Quercetin has a wide range of pharmacological properties such as the anti-inflammation and anti-oxidation; hence, it can be beneficial to the human health. Previous studies on bioactive effects of quercetin revealed that it could inhibit the growth of different microorganisms, especially gram-positive bacteria (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus and Staphylococcus epidermidis) and gram negative bacilli (Escherichia coli and Pseudomonas aeruginosa) [16–19]. Quercetin applied anti-proliferative and antitumor activities via various mechanisms such as cell cycle arrest during G0/G1 or G2/M phases of the cell cycle in leukemia, breast carcinoma and esophageal adenocarcinoma cells [20–22]. The present study aimed to investigate the quantification of quercetin (Q) in the Ardabil ethanol extract of propolis (AEEP), and then compared its anti-bacterial, antibiofilm and cytotoxic effects on cancer and normal cell lines with AEEP. Methods Preparation of Ethanolic extract of propolis Parts of crude propolis produced by Apis mellifera bees were collected in the spring of 2016 from Ardabil in Northern of Iran. 2 g of propolis dissolved with 25 ml ethanol and shacked for 2 days at room temperature. Then, it was filtered and kept in the dark place. A rotary vacuum evaporator used for ethanol removal. The ethanol extract of propolis had a brown color and extracts stored at − 20 °C. High-performance liquid chromatography (HPLC) analysis The propolis sample was analysis by HPLC consisted a chromatograph equipped with a UV detector (Knauer, Germany) and a normal-phase silica column (250 mm × 4 mm, 5 μm particle diameter, Euro (...truncated)