1 Antioxidant and antimicrobial activities on uropathogenic bacteria of Asteraceae medicinal plants Trinh Canh Phan 1 , Thao Thi Thanh Le 1 , Ha Tran Viet Hoang 1 , TuAnh Nguyen 1 1 Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh 700000, Vietnam. Correspondence should be addressed to Trinh C. Phan; phancanhtrinh@ump.edu.vn Abstract Antimicrobial and DPPH-scavenging assay were analyzed on nine Asteraceae species collected from Southest in Vietnam. Crude extracts from Taraxacum officinale, Chrysanthemum morifolium, Ageratum conyzoides, Tagetes erecta and essential oils from Ageratum conyzoides, Helianthus annuus, Artemisia vulgaris have antimicrobial activity on tested microorganisms ssential oils of displayed effect on Candida spp. and Gram possitive bacteria, meanwhile, crude extracts expressed the inhibitory ability on bacteria. Ethyl acetate fraction from Ageratum conyzoides showed the most potent effect on urinary clinical strains E coli and K pneumoniae with MIC at 1 25-10 mg ml and 5-12 5 mg ml, respectively All ethanol crude extracts exhibited strong reducing power indicating on the TLC plate. The results of the DPPH scavenging assay showed that Tagetes erecta extract had the lowest IC 50 17 280 g ml and 2 5 times higher than vitamin C 7 321 g ml This study revealed that A. conyzoides has good potential against uropathogenic E. coli and K. pneumoniae, and could therefore be applicable of prophylactic urinary tract infection. 1. Introduction In recent years, the antibiotic resistance has become more complex, putting mankind into the post- antibiotic period. Many clinical Enterobacteriaceae strains such as Escherichia coli and Klebsiella pneumoniae have extended-spectrum beta-lactamase (ESBL) and carbapenem resistant Enterobacteriaceae (CRE) [1-3]. It is the important problem for both microbiologists and clinicians. Especially, polymyxin plasmid-mediated resistance gene (mcr-1) was observed in E. coli strains, which was isolated from animals and inpatients with infection during 2011-2014, in China [4]. Moreover, it is with deep concern that mcr-1 could be transferred to K. pneumoniae and Pseudomonas aeruginosa via transformation [4]. In 2016, the first report about mcr-1 gene in a patient with urinary infections in Pennsylvania, the United States was shown by Jennifer Abbasi [5]. In urinary infections, many reports show that E. coli, K. pneumoniae is the leading causative agents. In addition, Staphylococcus saprophyticus, Enterococcus faecalis, group B Streptococcus, Proteus mirabitis, Pseudomonas aeruginosa, Staphylococcus aureus and Candida spp. is also aetiology [6-9]. Herbal extracts and their essential oils have used as foods such as floral teas, beverages, functional foods, bakery products; and traditional medicines in many years, with minimal known “side- effects” on human health. Using herbal remedies might help to reduce dependence on antibiotic therapies and minimizing antibiotic resistance phenomenon [10]. The Asteraceae family (Compositae) is a widespread family of flowering plants, including 32,913 species names, belonging to 1,911 plant genera, distributed in 13 subfamilies [11]. The tropics, subtropics and temperate regions is the natural habitats of Asteraceae species [12]. As chemical . CC-BY-ND 4.0 International license (which was not certified by peer review) is the author/funder. It is made available under a The copyright holder for this preprint this version posted December 28, 2019. . https://doi.org/10.1101/2019.12.25.888404 doi: bioRxiv preprint