Industrial Crops and Products 51 (2013) 355–359 Contents lists available at ScienceDirect Industrial Crops and Products journal h om epage: www.elsevier.com/locate/indcrop Seasonal changes in phenolic compounds and in the biological activities of Baccharis dentata (Vell.) G.M. Barroso T. Sartor a , V.B. Xavier b , M.A. Falcão b , C.A. Mondin c , M.A. dos Santos d , E. Cassel b , L.V. Astarita a , E.R. Santarém a,∗ a Laboratório de Biotecnologia Vegetal, Faculdade de Biociências; Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, RS 90619-900, Brazil b Laboratório de Operac ¸ ões Unitárias, Faculdade de Engenharia, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, RS 90619-900, Brazil c Faculdade de Biociências, Instituto do Meio Ambiente, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, RS 90619-900, Brazil d Laboratório de Farmacognosia, Faculdade de Farmácia, Laboratório de Farmácia Aeroespacial Joan Vernikos – Centro de Microgravidade. Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, RS 90619-900, Brazil a r t i c l e i n f o Article history: Received 26 June 2013 Received in revised form 7 September 2013 Accepted 19 September 2013 Keywords: Antimicrobial activity Antioxidant activity Flavonoids Quercetin a b s t r a c t Baccharis, a large genus of Asteraceae, has been extensively studied because of the medicinal properties of its species. The present study determined the seasonal variation of the levels of total phenolic compounds and flavonoids of Baccharis dentata, and determined the antioxidant and bactericidal potential of the plant extracts. Aerial parts of B. dentata were harvested during the seasons of 1 year. Samples of 0.1 g dry mass (DM) were extracted with aqueous methanol (80%; v/v), and used for quantification of phenolic compounds, quercetin-derived flavonoids and antioxidant activity (DPPH). Caffeic acid and the flavonoids rutin, quercetin, apigenin and kaempferol were quantified in methanolic extracts (0.5 g DM) by HPLC. The micro-dilution method was applied for the determination of the minimal inhibitory concentration (MIC) of selected bacteria strains. Concentrations of total phenolic compounds and flavonoids showed significant seasonal variation, and the antioxidant potential of extracts was related to the concentration of these compounds. Highest antioxidant activity was detected in the extracts from summer and winter plants. Concentrations of quercetin, kaempferol and apigenin were markedly higher in spring and summer plants when compared to the other seasons. This result may be related to the antibacterial activity of n- butanolic and aqueous fractions against Staphylococcus aureus. This is the first report on seasonal changes of secondary compounds and biological activities on B. dentata and might be useful to prospection of novel molecules with antioxidant and antimicrobial properties. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Baccharis L. (Asteraceae, Astereae) is a large genus of the family Asteraceae, with approximately 360 species, many of which have been used in folk medicine. The phytochemistry of the genus Bac- charis has been extensively studied and more than 150 molecules have been isolated. Several species of this genus have been inves- tigated chemically or pharmacologically for their medicinal use and for potential new drugs (Abad and Bermejo, 2007; Parejo et al., 2003). Cytotoxic and anti-inflammatory properties are com- monly reported for extracts obtained from Baccharis (Abad et al., ∗ Corresponding author at: Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Prédio 12C, Porto Alegre, RS 90619-900, Brazil. Tel.: +55 51 3353 4148; fax: +55 51 3320 3568. E-mail address: esantarem@pucrs.br (E.R. Santarém). 2006; Ferronatto et al., 2007; Rosas-Burgo et al., 2009). Different molecules with anti-tumor action have been described from leaves of Baccharis dracunculifolia (Fukuda et al., 2006). Terpenes and flavonoids are the most abundant classes of com- pounds described for the genus (Abad and Bermejo, 2007; Verdi et al., 2005). The available chemical data indicate methylated flavones and flavonols as the main classes of phenolic compounds in Baccharis species (Martinez et al., 2005). Various derivatives of quinic acid, caffeic acid, gallic acid and several flavonoids have been identified in the genus Baccharis (Marques and Farah, 2009; Tapia et al., 2004) and many studies have suggested that flavonoids exhibit biological proprieties, including anti-allergenic, antiviral, anti-inflammatory, vasodilator, and antioxidant activi- ties (Handique and Baruah, 2002; Harborne and Williams, 2000; Heim et al., 2002). Moreover, extracts from aerial parts of Baccha- ris chilco, Baccharis pentlandii, Baccharis grisebachii and Baccharis articulata, among other in the genus, were shown to be sources of 0926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2013.09.018