The genus Eupatorium L . ( Asteraceae ) : A review of their antimicrobial activity

In recent years, the number of infectious diseases linked to the occurrence of bacterial and fungal resistance has increased, leading to extensive search for new drugs to treat these infections. Species of the Asteraceae family and the genus Eupatorium, have high biological potential and are used in folk medicine to treat various diseases. This review article presents the main phytochemical and biological characteristics of the Asteraceae family and the genus Eupatorium s.l., whose antimicrobial activity is promising, especially antibacterial and antifungal activity. The current review was achieved using an organized search of the scientific data published on antimicrobial activity and phytochemical of the species of the genus Eupatorium using various databases, including PubMed, ScienceDirect, Scopus, Scielo, SciFinder and Google Scholar. The species of Eupatorium are rich in terpenes, phytosterols and sesquiterpene lactones, the latter being chemotaxonomic markers of the group, with broad anticancer, antiplasmodial and antimicrobial activity, making them promising for the development of new drugs. Various species of Eupatorium seems to hold great potential for in-depth investigation for antimicrobial activities. Many species have broad folk use, with scientific confirmation of its antimicrobial properties making these plants potential sources of safer and more effective treatments.


INTRODUCTION
The family Asteraceae, belonging to the class of eudicotyledons, is one of the largest families of angiosperm plants.Its species are known for their therapeutic, cosmetic and aromatic properties and have great importance both from the environmental and economic standpoints.They have been widely studied for their anti-inflammatory, antimicrobial, anticancer, antisyphilitic, antigonorrheal and insecticidal properties (Carrillo-Hormaza et al., 2015).Biological studies of its extracts, oils and constituents for production of phytochemicals have attracting growing interdisciplinary interest from the scientific community (Garcia-Sanchez et *Corresponding author.E-mail: caiosobrinho@yahoo.com.br.al., 2011;Yang et al., 2004;Souza et al., 2007).
Among several genera of Asteraceae studied, Eupatorium L. sensu lato stands out.Numerous studies of its species have been performed and the majority showed the presence of terpenes, phytosterols and sesquiterpene lactones (Liu et al., 2015), the latter identified as promising sources for development of new drugs due to the antimicrobial, anticancer and antiplasmodial action (Albuquerque et al., 2010;Lang et al., 2002).
In a broader context, ethnobotanical and ethnopharmacological studies are very useful for investigation of new bioactive plant sources (Silambarasan and Ayyanar, 2015).Many traditional indigenous communities have longstanding contact with plant species having medicinal properties, with information being transmitted from generation to generation.This information is useful to the scientific community in studies of natural resources, as occurred in studies of Eupatorium s.l.(Silva et al., 2012;Paredes-Flores et al., 2007).
Chemical compounds with biological activity isolated from plants and used by the population through extracts are promising sources to prospect for new antimicrobial drugs.These substances may also act synergistically with other drugs, potentially improving the antibiotic action (Al-Fatimi et al., 2007).However, it is necessary to establish whether the traditional use of plants for the treatment of infectious diseases is supported by pharmacological action or merely based on folklore (Pessini et al., 2003).
One obstacle to the treatment of bacterial infections is the phenomena of resistance to antibacterial drugs, caused by the selection of resistant bacteria from exposure to chemotherapeutic agents, causing transfer of resistant gene fragments between bacterial strains and clonal spread of resistant strains among hospitalized patients (Spellberg et al., 2013).The exposure of antimicrobial compound can increase bacterial resistance also by selecting for mutation in genes that help microbes detoxify antibiotics.As for antibiotics, inadequate knowledge of the pharmacokinetic and pharmacodynamic properties, in addition to factors inherent to the patient, such as immune status and non-adherence to treatment, affect the efficiency of chemotherapy against pathogenic bacteria (Muller et al., 2015;Udy et al., 2013).
The use of natural extracts in the treatment of infectious diseases is promising, but studies on antimicrobial activity of different plant extracts should be expanded, including analysis of essential oils and their constituents in order to maximize the effect studied and to discover which chemical compound plays the main role in antimicrobial action (Danielli et al., 2013).In relation to antifungal drugs, natural products are widelyused and the results are promising (Cragg and Newman, 2013).Due to the resistance of many pathogenic microorganisms, the search for new antimicrobial agents from plants is intense (Alviano and Alviano, 2009).The relevance of these studies is based on the fact that infections of bacterial etiology, and in particular fungal infections, are aggravated in immunosuppressed individuals, due to therapy against cancer and AIDS and suppression of the immune response to prevent rejection of transplanted organs (Miceli et al., 2011).
For a comprehensive literature overview, the current review was achieved by using an organized search of the scientific data published on antimicrobial activity and phytochemical, focusing on the antibacterial and antifungal activities of the species of the genus Eupatorium.The search was conducted using the keyword search term "Eupatorium antimicrobial activity".The searches were carried out using various databases, including PubMed (http://www.ncbi.nlm.nih.gov/pubmed),Science Direct (http://www.sciencedirect.com/),Scopus (http://www.scopus.com/),Scielo (http://www.scielo.org/),SciFinder (https://scifinder.cas.org/) and Google Scholar (http://www.scholar.google.com/).
Based on these considerations, in the present paper, the antibacterial and antifungal potential of species of the genus Eupatorium s.l., were analyzed highlighting also biological properties of the Asteraceae family.

ASTERACEAE FAMILY
Asteraceae (Compositae) includes about 1600 genera and 25000 species (Petacci et al., 2012) belonging to 17 tribes and three subfamilies.It is considered by some authors as the largest family of eudicotyledonous angiosperm plants (Nakajima and Semir, 2001;Hattori and Nakajima, 2008).The Asterales order is formed by the Calyceraceae, Menyanthaceae, Goodeniaceae, Campanulaceae and Asteraceae (Judd et al., 2009).This family has been studied intensely over the past 25 years regarding morphology, anatomy, ontogeny and ecology as well as phytochemical, cytogenetic and macromolecular aspects (Hind and Beentje, 1996).

GENUS EUPATORIUM
The genus Eupatorium s.l.(tribe Eupatorieae, subtribe Eupatoriinae) was one of the most representative of the family Asteraceae, containing around 1200 species, however a detailed survey conducted by King and Robinson (1987) found that about 1010 species would be reclassified to different new genera.When interpreted in its traditional concept, this genus form a polyphyletic group.Eupatorium s.l.have been a highly artificial concept, tending to include all members of the tribe with a pappus of numerous capillary bristles, five ribs on the achene, and another appendage as long as or longer that wide (King and Robinson, 1987).This genus has been restructured and was fragmented into 80 genera.Currently, the genus Eupatorium sensu stricto containing about 45 species, distributed primarily by arctic-tertiary region (King and Robinson,1987;Bremer, 1994).
The species of this genus are used in folk medicine in different parts of the world (Albuquerque et al., 2010), like Mexico, where over 1000 medicinal plants have been used for over 400 years in folk medicine, many are in the genus Eupatorium (Garcia-Sanchez et al., 2011).
Ethnopharmacological studies of medicinal plants are important for the development of new drugs (Silambarasan and Ayyanar, 2015).The main goal is to find new bioactive substances for disease control with minimal side effects (Rodríguez and Carlini, 2003).In this context, studies have been conducted of biological activities such as toxic activity of essential oils (Albuquerque et al., 2004) and plant extracts (Rozo et al., 2008) against the larvae of Aedes aegypti and antiplasmodial activity against Plasmodium falciparum, a protozoan that causes malaria (Lang et al., 2002).
In particular, the literature contains numerous studies of the genus Eupatorium with use of plant extracts and essential oils against strains of bacteria and fungi that infect animals and plants, for development of new drugs for veterinary and human use and new herbicides.Studies were found from 1948 to 2016 with Eupatorium species.E. adenophorum, E. odoratum and E. triplinerve are the species with the most work reporting their antimicrobial potential (Table 1).

Antimicrobial activity of Eupatorium s.l.
Most studies of the antimicrobial activity involved species of Asia and Europe, with fewer studies of South American plants.This is counterintuitive, given that although countries like China, Malaysia, India, Zaire, Indonesia and Madagascar can be considered megadiverse (Sandes and Di Blasi, 2000), species of Eupatorium are particularly diverse in tropical and subtropical areas of the Americas (Zhang et al., 2008).
For antibacterial action, tests have been conducted on activity against a wide range of microorganisms, both Gram-positive and negative bacteria.For investigations of plant extracts, the most commonly used solvents are methanol, ethanol, ethyl acetate and n-hexane, used in studies the aerial parts, branches, twigs and leaves.Nevertheless, there are reports of the use of roots to obtain the essential oil of E. adenophorum Spreng.(Ahluwalia et al., 2014) and the aqueous extract of E. purpureum L. (Carlson et al., 1948;Pates Madsen, 1955), in both cases having antibacterial action.
Referring to antifungal bioassays, the studies focused on Eupatorium generally also have involved tests against bacteria.The tested fungi include filamentous fungi, dermatophytes and yeasts.Tests with dermatophytes, filamentous fungi that cause dermatophytosis are promising for the genus, with reports of activity for Eupatorium arnottianum Griseb.(Muschietti et al., 2005), Eupatorium aschenbornianum S. Schauer (García et al., 2003Rios et al., 2003), Eupatorium buniifolium Hook.and Arn.(Muschietti et al., 2005), Eupatorium japonicum Thunb.(Inouye et al., 2006), Eupatorium laciniatum Kitam.(Inouye et al., 2006) and Eupatorium odoratum L. (Taylor et al., 1996).In all these studies, extracts of plant material were used.There are few reports in the literature on the use of essential oils for susceptibility testing.As for the fungi tested, of the three genera of dermatophytes (Trichophyton, Microsporum and Epidermophyton), only two showed sensitivity and growth inhibition (Trichophyton and Microsporum), highlighting species T. rubrum and T. mentagrophytes in the genus Trichophyton.

Eupatorium adenophorum Spreng.
The species E. adenophorum [syn.Ageratina adenophora (Spreng.)R.M. King & H.Rob.], native to Mexico, is now widely distributed in the world (King and Robinson, 1970) and is used in folk medicine as an antimicrobial, antiseptic, analgesic and antipyretic (Bhattarai and Shrestha, 2009).It has also been shown to have molluscicide potential against Oncomelania hupensis, the intermediate host of Schistosoma japonicum (Zou et al., 2009).The essential oil extracted from the flowers, and roots was tested and showed inhibitory activity for the strains of Xanthomonas oryzae, Erwinia chrysanthemi, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae.Assays were performed using the disk diffusion and agar dilution methods (Ahluwalia et al., 2014).The essential oil extracted from the aerial parts was also investigated against strains of Arthrobacter protophormiae, Escherichia coli, Micrococcus luteus, Rhodococcus rhodochrous and Staphylococcus aureus.Assays were performed by broth dilution and the results showed growth inhibition for all strains tested (Kurade et  , 1994;Taylor et al., 1996;Suksamrarn et al., 2004;Chomnawang et al., 2005;Molina-Salinas et al., 2007;Gautam et al., 2007;Chomnawang et al., 2009;Sharma et al., 2013 (Bhattarai and Shrestha, 2009).Cadinene derivatives extracted from leaves of E. adenophorum showed antifungal activity against four plant pathogenic fungi strains: Rhizoctonia solani, Sclerotium rolfsii, Fusarium oxysporum and Macrophomina phaseolina.Cadinene sesquiterpenes were isolated by column chromatography and preparative thin layer chromatography.Less polar cadinene sesquiterpenes were active against S. rolfsii and polar cadinene derivatives with mono or dihydroxy groups were more inhibitory towards R. solani (Kundu et al., 2013).Ahluwalia et al. (2014) analyzed the antifungal action of the essential oil of E. adenophorum against five pathogenic fungi: Sclerotium rolfsii, Macrophomina phaseolina, Rhizoctonia solani, Pythium debaryanum and Fusarium oxysporum.They found the strongest inhibitory activity against S. rolfsii.Regarding toxicity, they evaluated the phytotoxic action of the essential oil, which inhibited the growth and seed germination of Phalaris minor Retz.and Triticum aestivum L., used for phytotoxicity assays in a dose-dependent concentration.

Eupatorium altissimum L.
In a study on the species collected in the state of Louisiana in the United States, a dichloromethane extract was tested against Mycobacterium tuberculosis bacterium, causative agent of most cases of tuberculosis (Cantrell et al., 1998).In a bioprospecting study of 550 plants collected in the states of Ohio and Oregon in the United States, action was reported on the extract of aerial parts of E. altissimum against strains of S. aureus and E. coli (Carlson et al., 1948).

Eupatorium arnottianum Griseb.
E. arnottianum [syn.Chromolaena arnottiana (Griseb.)R.M. King & H. Rob.] is an herb native to Latin America, common in the North-East and Centre of Argentina and South of Bolivia, traditionally used to treat stomach ailments (Clavin et al., 2007), against asthma, bronchitis, colds and topically in plasters for bone fractures and dislocations by healers from the bolivian altiplano (Giraoult, 1987), in addition to having anti-inflammatory and analgesic properties (Muschietti et al., 2005).
A methanol extract of the aerial parts showed antifungal activity against the dermatophytes Microsporum gypseum, Trichophyton rubrum and Trichophyton mentagrophytes according to broth microdilution tests (Muschietti et al., 2005).

Eupatorium aschenbornianum S. Schauer.
E. aschenbornianum [syn.Ageratina pichinchensis (Kunth) R.M. King & H. Rob.] is a plant traditionally used in Mexico to treat skin lesions, mouth ulcers and tumors (Rios et al., 2003).Studies of hexane and methanol extracts obtained from the aerial parts point to the antifungal potential of E. aschenbornianum against the dermatophytes, T. mentagrophytes, T. rubrum, the yeast C. albicans and the filamentous fungus Aspergillus niger (Rios et al., 2003;García et al., 2003).

Eupatorium ayapana Vent.
The leaves of E. ayapana [syn.Ayapana triplinervis (Vahl) R.M. King & H. Rob.] are used in folk medicine as a heart stimulant, laxative and anticoagulant (Gupta et al., 2002).In rainforests of South America, its leaves are used in decoctions, infusions, tea and baths as tonic, stimulant, sedative, febrifuge and anti-inflammatory, especially in Brazilian folk medicine (Melo et al., 2013).The first preliminary studies of this species were performed by Oswaldo Gonçalves de Lima, then director of the Antibiotics Institute of the University at Recife, Brazil (Lima, 1963).
The phytochemical study of petroleum ether extract showed presence of steroids, coumarins, tannins and saponins.For the species E. ayapana, the petroleum ether extract inhibited growth of bacteria B. subtilis, Staphylococcus epidermidis, S. aureus, M. luteus, E. coli, P. aeruginosa, Salmonella typhi, Shigella sp., Vibrio cholerae and Vibrio parahaemolyticus.The extract also inhibited the growth of A. niger, A. flavus, Alternaria solani and Fusarium solani, pathogenic fungi causing black mold in fruits and vegetables, deterioration by mycotoxins in grains, alternaria spot in solanaceous plants and root and stem rot, respectively (Gupta et al., 2002).
The essential oil extracted from the aerial parts, was tested by broth microdilution method and showed antifungal activity against strains fungal dermatophytes, Trichophyton rubrum.The chromatographic analysis showed 25 components, accounting for 93.84%, among them mono-and sesquiterpenes, with prevalence of sesquiterpenes (Sobrinho et al., 2016).
The modulatory activity assay was performed to determine the combined effect of the essential oil with the ketoconazole, standard antifungal drug, against strains of T. rubrum by the checkerboard technique.The combination of ketoconazole with essential oil reduced the MICs for both strains of T. rubrum indicating a synergistic effect (Sobrinho et al., 2016).

Eupatorium buniifolium Hook. ex Hook. & Arn.
E. buniifolium [syn.Acanthostyles buniifolius (Hook.ex Hook.& Arn.) R.M. King & H. Rob.] is a shrubby species widely used in folk medicine, such as to treat rheumatic pains and liver problems with tea obtained by decoction.Preparations from this plant are also used as disinfectants (Ríos et al., 1993).

Eupatorium cannabinum L.
E. cannabinum is a perennial herbaceous species distributed in the northern hemisphere, especially in Europe and North America (Senatore et al., 2001).A study of the essential oil of E. cannabinum subsp.cannabinum L. obtained from the aerial parts identified high percentage of terpenoids, such as germacrene, monocyclic sesquiterpene, found in large amounts.The oil showed antibacterial activity against strains of Grampositive bacteria (Senatore et al., 2001).
In another investigation, the extract of the aerial parts showed antimicrobial activity against strains of Grampositive and negative bacteria, the main ones tested being S. typhi, Micrococcus aureus, B. subtilis and Proteus spp.(Freerksen and Bönicke, 1951).

Eupatorium capillifolium (Lam.) Small. ex Porter & Britton
E. capillifolium is a perennial herbaceous species found in North America.It is used as food for livestock in the southeastern United States when other fodder is lacking, but it is generally considered a weed (Sellers et al., 2009).
Studies of the effect of plant extracts against pathogenic fungi are important to find new agents against fungi causing plant diseases in agricultural crops.Tabanca et al. (2010) investigated, by contact bioautography, the antifungal activity of the essential oil of E. capillifolium, which inhibited growth of the fungus Colletotrichum acutatum, the cause of strawberry anthracnose.The main constituents were thymol methyl ether (36.3%), 2,5-dimethoxy-p-cymene (20.8%) and myrcene (15.7%).

Eupatorium fortunei Turcz.
E. fortunei is a traditional Chinese medicinal herb, common in the northeastern of China, used in folk medicine to treat many diseases (Liu et al., 1992).In a study of bacteria that produce volatile sulfur compounds (VSCs) that cause halitosis, Li et al. (2010) investigated extracts of 40 plants found in China, of which 14 inhibited bacterial growth and production of VSCs.The main compounds found were hydrogen sulfide, dimethyl sulfide and methylmercaptan.Among the 14 plants that were active in the screening was E. fortunei, which was used to obtain the aqueous extract.
The methanol extract of leaves of E. glutinosum presented antibacterial activity against strains of Mycobacterium phlei, B. subtilis and S. aureus, by the disk diffusion method (Lopez et al., 2001).The antibacterial activity of the hexane extract of leaves and stems and of two isolated compounds (15-hydroxy-7labden-17-oic acid and 15-acetoxy-7-labden-17-oic acid) were investigated by diffusion in agar (Figure 2).The tests showed activity against S. aureus, B. cereus, E. coli and P. aeruginosa (El-Seedi et al., 2002).
In an antimicrobial prospecting study of plants of the Americas, the dichloromethane extract of leaves of E. havanense, collected in the state of Tamaulipas, Mexico, inhibited the growth of the pathogenic microorganisms M. tuberculosis and M. avium, the latter an opportunistic pathogen related to infections in immunocompromised individuals (Cantrell et al., 1998).

Eupatorium intermedium DC.
E. intermedium [syn.Grazielia intermedia (DC.)R.M. King and H. Rob.] is a branchy shrub, native to southern Brazil with upright growth between 1.0 to 1.5 m high and it is densely leafy until close to the inflorescences, which are composed of white flowers (Czaikoski et al., 2015).
The extracts obtained by supercritical extraction from the flowers with scCO 2 , propane and petroleum ether as solvents were tested and showed antibacterial activity against two Gram-positive bacterial strains, S. aureus and L. monocytogenes, and two Gram-negative bacterial strains, E. coli and S. typhimurium.The assays were performed using the disk diffusion method (Czaikoski et al., 2015).The extracts were effective against all bacteria strains, particularly the extract obtained with scCO 2 and compressed propane.
] is a species found in Latin America, whose common name in Argentina is "sanalotodo" or "yerba de Santa María".This species is used in folk medicine for treatment of skin infections due to its antimicrobial properties (Lancelle et al., 2009) and throat diseases (Álvarez et al., 2005).
In a study of 122 plant species from 54 families, Pérez and Anesini (1994) investigated the antibacterial activity against the microorganism S. typhi, causative agent of typhoid fever.Of the plants tested in the initial screening, E. inulaefolium showed inhibitory activity against the growth of S. typhi.In an investigation of the in vitro antimicrobial activity of Colombian angiosperms, the inhibitory activity against the microorganisms S. aureus and B. subtilis, was investigated at a concentration of 3 mg/mL, by the agar diffusion method (Sanabria-Galindo et al., 1998).In a third study, the ethyl extract of the leaves of E. inulaefolium were tested against the strains of S. aureus, E. coli and P. aeruginosa.The authors only observed growth inhibition against S. aureus, at a concentration of 50 mg/mL (Álvarez et al., 2005).

Eupatorium japonicum Thunb.
E. japonicum [syn.Eupatorium chinense L.] is a perennial herb, native to Japan, Korea and northeastern area of China.It is a medicinal herb used in folk medicine as a decoction for the treatment of measles, rheumatic bone pains, colds and cough (Roeder, 2000).
The ethyl acetate extract of the leaves and flowers of E. japonicum was used to investigate the antifungal activity against the dermatophyte T. mentagrophytes, the most common cause of Tinea pedis.At the concentration of 0.25 mg/mL, the authors observed an inhibition zone of 11 mm (Inouye et al., 2006).Sobrinho et al. 51 Eupatorium laciniatum Kitam.
E. laciniatum [syn.Eupatorium chinense L.] an annual herbal plant, native to Asia is distributed in the south of China, used in Chinese folk medicine for the treatment of cold, snakebite and inflammation (Yang et al., 2005).
The antidermatophytic activity of this plant species was tested against the fungus, T. mentagrophytes, using the ethyl acetate extract of the leaves and flowers at a concentration of 0.25 mg/mL.The extract caused an inhibition zone of 12 mm (Inouye et al., 2006).

Eupatorium laevigatum Lam.
E. laevigatum [syn.Chromolaena laevigata (Lam.)R.M. King & H. Rob.], native to South America is widely distributed in the South part of Brazil and Argentina, whose common name in Brazil is "erva-de-santa-maria" or "camara", is used in folk medicine for wound healing and as an antifungal (Maia et al., 2002).In Argentina, it is known as "caá-hú" or "doctorcito" and used in folk medicine as an anticefalalgic, analgesic, cathartic, emenagogue and purgative agent (Clavin et al., 2000).
The ethanol and hexane extracts of the leaves were tested against B. subtilis, by the agar diffusion method, with moderate results for inhibition of bacterial growth by both solvents (Schmidt et al., 2009).In a chemical and antimicrobial prospecting study, the methanol extract of the leaves of E. laevigatum showed the presence of alkaloids, steroids, phenols, tannins and flavonoids.The antimicrobial activity was performed by the broth microdilution method against strains of Gram-positive and negative bacteria, showing inhibitory activity against P. aeruginosa, B. cereus, Shigella sonnei and Salmonella enterica sorovar typhimurium (Fabri et al., 2011).

Eupatorium lindleyanum DC.
E. lindleyanum is a perennial herbaceous plant, native to China, known as "Yemazhui" and used in folk medicine to relieve fever, remove toxic substances, treat coughs, promote urination, and lower blood pressure (Xia et al., 2004).In traditional Chinese medicine, its aerial part is used as an antipyretic and detoxicant (Yang et al., 2010).
The extracts of the aerial parts obtained by use of ethanol, methanol and ethyl acetate were tested by the broth dilution method against eight bacterial strains: four Gram-positive (B.subtilis, S. aureus, B. cereus and E. faecium) and four Gram-negative (E.coli, S. typhimurium, P. vulgaris and Pseudomonas fluorescens).The extracts inhibited growth of all strains tested, with the best results for B. subtilis, S. aureus and B. cereus (Ji et al., 2008).

Eupatorium maculatum L.
Native to United States, E. maculatum known as "Joe-pye weed" is widely found in moist places, especially in calcareous soils (Goebel et al., 2012).The first report of antimicrobial activity of E. maculatum dates back to the work of Bishop and MacDonald (1951), who reported that the ethanol extract of the aerial parts showed activity against strains of Gram-positive bacteria.
In prospective study with 336 native species of the states of Minnesota and Wisconsin in the United States, ethanol extracts of leaves and stems of E. maculatum were tested against strains of S. aureus, E. coli, P. aeruginosa and C. albicans, presenting significant action only against S. aureus.The assays were performed using the disk diffusion method (Borchardt et al., 2008).
Various studies of E. odoratum have investigated the plant's antimicrobial activity against bacteria that cause various infectious diseases.Cáceres et al. (1995) observed activity against the bacterium Neisseria gonorrhoeae, which causes gonorrhea, with an excellent growth inhibition zone.
Four flavanones extracted from flowers of E. odoratum exhibited antibacterial activity against Mycobacterium tuberculosis.Flavanones were isolated by silica gel chromatography and analyzed with infrared spectroscopy and nuclear magnetic resonance (Suksamrarn et al., 2004).Chomnawang et al. (2005) tested the antiacne activity (crude extracts with chloroform and ethylacetate) against strains of Propionibacterium acnes, S. epidermidis, while Molina-Salinas et al. (2007) investigated the antibacterial activity (methanol extract; leaves, flowers and roots) against Streptococcus pneumonia and Chomnawang et al. (2009) tested it against methicillin-resistant S. aureus.
In a screening study, the aqueous leaf extract of E. odoratum was tested for their fungitoxicity against spores of Uromyces vignae and showed the better result for the inhibition of spore germination (Patil and Kamble, 2015).] is a densely branched shrub that is distributed from Bolivia and Paraguay to Patagonia in Argentina, known by the common names of "acancio" or "bejuco" (Cabrera and Correa, 1971).

Eupatorium patens
The essential oil of the leaves was tested against the microorganisms S. aureus, E. coli, B. subtillis, C. albicans and A. niger by the agar diffusion method.Only the strains of B. subtilis showed significant growth inhibition zones after incubation for 24 h (Bailac et al., 2000).

Eupatorium perfoliatum L.
Native to North America, E. perfoliatum is a medicinal herb, known as "boneset" or "thoroughwort", used in folk medicine by the native inhabitants for the treatment of fever and flu (Maas et al., 2008).The first record in the literature on the antimicrobial potential of E. perfoliatum was performed by Carlson et al. (1948).The authors found that the ether extract obtained from the aerial parts inhibited the growth of S. aureus.Later studies investigated extracts from leaves and stems using organic solvents (ethanol, ether and acetone) and water, demonstrating antimicrobial activity against C. albicans, Gram-positive and Gram-negative bacteria and Mycobacterium spp.(Bishop and MacDonald, 1951;Madsen and Pates, 1952;Liegey, 1953;Frisby et al., 1953).
In prospective study, the ethanol extract of the leaves and flowers of E. perfoliatum was tested against strains of S. aureus, E. coli, P. aeruginosa and C. albicans.The extract only had significant action against S. aureus, with inhibition zones of 11 and 7 mm for extracts of the leaves and inflorescences, respectively.The assays were performed using the disk diffusion method (Borchardt et al., 2008).

Eupatorium purpureum L.
E. purpureum is a wildflower perennial plant, native to the eastern United States, known as "joe-pye weed", "sweet joe-pye weed", and "sweetscented joe-pye weed" (Sabanadzovic et al., 2010).It is used in traditional medicine for rheumatoid arthritis and several other disease conditions (Habtemariam, 1998).
The saline extract of the stems of E. purpureum L. showed antibacterial activity against S. aureus and E. coli, by the agar diffusion method (Carlson et al., 1948).The saline extract of the leaves was also investigated against S. aureus and E. coli, with positive results by the agar diffusion method (Pates and Madsen, 1955).

Eupatorium rugosum Houtt.
E. rugosum [syn.Ageratina altissima (L.) R.M. King & H. Rob.] is a perennial herb commonly found in the midwestern and eastern United States, known as "white snakeroot" (Lee et al., 2012).The saline extract of the stems of E. rugosum showed antibacterial activity against strains of Gram-positive bacteria by the agar diffusion method (Frisby et al., 1954).

Eupatorium serratum Spreng.
E. serratum [syn.Grazielia serrata (Spreng.)R.M. King & H. Rob.], popularly known as "erva-milagrosa" or ("miraculous herb") in Brazil, is used in folk medicine to treat snake bites, as an analgesic, healing agent, antimicrobial agent and for the treatment of stomach problems, liver disorders, diabetes, cancer and bronchial asthma (Desoti et al., 2011).The hexane, methanol and ethyl acetate extracts obtained from fresh leaves of E. serratum were tested against S. aureus, M. luteus, E. coli and S. typhi.The best inhibitory halo results were produced by the methanol extract against M. luteus (Desoti et al., 2011).

Eupatorium tashiroi Hayata
E. tashiroi, native to Asia is a wild herb which has been Sobrinho et al. 53 used in a folk medicine for treating edema and hemoptysis in Taiwan (Wu et al., 1985).The aqueous extract of the entire plant was tested by the agar diffusion method against two serotypes of S. mutans, bacteria associated with the development of dental caries.The extracts inhibited bacterial growth of both serotypes (Chen et al., 1989).

Eupatorium triplinerve Vahl
E. triplinerve [syn.Ayapana triplinervis (Vahl) R.M. King & H. Rob.] commonly found in Asia is an erect perennial herb with narrow lanceolate leaves and large number of pedicelled flower-heads at the top of the branch, known as "ayapana" (Selvamangai and Bhaskar, 2012).The species was introduced in Indian as ornamental species.
In Indian, folk medicine is used as a stimulant, tonic, laxative and for the treatment of yellow fever (Unnikrishnan et al., 2014).
The antimicrobial activities of the essential oil obtained from the leaves and the stem and thymohydroquinone dimethylether were evaluated using disk diffusion assay against strains of Gram-positive and negative bacteria, showing inhibitory activity against P. aeruginosa, S. aureus, K. pneumoniae and E. coli.The essential oil showed antifungal activity against fungal strains of Penicillium chrysogenum and C. albicans; however thymohydroquinone dimethylether only inhibited the growth of P. chrysogenum (Unnikrishnan et al., 2014).

Eupatorium urticaefolium Reichard
E. urticaefolium [syn.Ageratina altissima (L.) R.M. King & H. Rob.] is a species native to North America, it is commonly found throughout the eastern half of continent.Ingestion of the plant causes a disease called trembles in livestock (Lee et al., 2010).The ethyl acetate extract of the aerial parts of E. urticaefolium inhibited the growth of S. aureus and E. coli, by the agar diffusion method (Carlson et al., 1948).

Conclusion
Thirty Eupatorium species were identified, some already reclassified to other genera.The aerial parts are the part of plant with more studies and so far the best source for anti-microbial product, being the essential oils and fixed compounds the main natural products.Most of the studies were carried by the broth microdilution and disk diffusion methods, according to Clinical and Laboratory Standards Institute (CLSI).
Microbial infections caused by bacteria and fungi are a growing public health problem, and increasingly common in routine medicine.Outbreaks of infections by methicillinresistant S. aureus in hospital and social environments have been reported in several regions of the world.Regarding fungal infections, the search for new more efficient therapies is particularly urgent considering that the available antifungal chemicals are much less than antibacterial drugs and also typically have more side effects, besides the possible development of fungal resistance.
This review shows that the Asteraceae family, and especially the genus Eupatorium s.l., contains many species with antimicrobial activity, making these plants potential sources of safer and more effective treatments.In short, Eupatorium s.l.contains a diverse array of species with antimicrobial potential.New studies involving chemical and biological bioprospecting are necessary to develop effective and less toxic herbal products.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License

Table 1 .
Species of the genus Eupatorium s.l. with antimicrobial activity.