In this work, we used the Minimum Inhibitory Concentration (MIC) technique to evaluate the antibacterial potential of the apitoxin produced by Apis mellifera bees against the causative agents of tooth decay. Apitoxin was assayed in natura and in the commercially available form. The antibacterial actions of the main components of this apitoxin, phospholipase A 2 , and melittin were also assessed, alone and in combination. The following bacteria were tested: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, Lactobacillus casei, and Enterococcus faecalis. The MIC results obtained for the commercially available apitoxin and for the apitoxin in natura were close and lay between 20 and 40µg / mL, which indicated good antibacterial activity. Melittin was the most active component in apitoxin; it displayed very promising MIC values, from 4 to 40µg / mL. Phospholipase A 2 presented MIC values higher than 400µg / mL. Association of mellitin with phospholipase A 2 yielded MIC values ranging between 6 and 80µg / mL. Considering that tooth decay affects people's health, apitoxin and its component melittin have potential application against oral pathogens.

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Usnic acid is one of the most common and abundant metabolites found in various lichen genera, which are important sources of biologically active compounds. The aim of this study was to evaluate the genotoxic and antigenotoxic potential of (+)-usnic acid (UA) by the micronucleus and comet assays in V79 cell cultures and Swiss mice. For assessment of genotoxicity, V79 cells were treated with 15, 30, 60, and 120μg/mL UA, established based on clonogenic efficiency cytotoxic assay. Swiss mice were treated with UA doses of 25, 50, 100, and 200mg/kg body weight. The same concentrations of UA were combined with methyl methanesulfonate (MMS) for evaluation of antigenotoxicity. The in vitro results demonstrated that UA induced DNA damage at concentrations of 60 and 120μg/mL in the comet assay. However, no genotoxic effect was observed in the micronucleus test using V79 cells at the concentrations tested. No genotoxic effects were observed for the different UA treatments in in vivo test system. Combined administration of UA and MMS significantly reduced the frequencies of micronuclei and DNA damage in vitro and in vivo when compared to treatment with MMS alone. Although the mechanisms underlying the protective effect of UA are not completely understood, the antioxidant activity of this metabolite may explain its protective effect against MMS-induced genotoxicity.

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Antibiotic-resistant bacteria have emerged from the widespread use of antibiotics worldwide and have prompted the search for new sources of antimicrobial substances. Pinus spp. contain several bioactive compounds consisting mainly of terpenes, terpenoids and some other aromatic and aliphatic constituents. These compounds exert important biological effects, and pine oils have found wide application in the industry. In the present study, we have evaluated the potential activity of the resin-oil of Pinus elliottii and its major compound dehydroabietic acid (DA) against multiresistant bacteria by MIC, minimum bactericidal concentration and time-kill assays. The MIC of the resin-oil of P. elliottii varied between 25 and 100 mg ml "1 . As for DA, the MIC and minimum bactericidal concentration varied between 6.25 and 50 and between 6.25 and 100 mg ml "1 , respectively. The time-kill assay conducted with DA at 6.25 mg ml "1 evidenced bactericidal activity against Staphylococcus epidermidis (American Type Culture Collection 14990) within 24 h. On the basis of these results, the resin-oil of P. elliottii and its major compound DA play an important part in the search for novel sources of agents that can act against multiresistant bacteria. INTRODUCTIONThe widespread use of antibiotics worldwide has culminated in a high prevalence of infections by antibioticresistant bacteria. Indeed, exchangeable genetic elements such as plasmids, transposons and integrons disseminate antibiotic resistance in many bacteria (Nikokar et al., 2013). The slower introduction of new chemotherapeutic drugs into the market and clinical practice over the last few years may yet be another reason for the growing number of resistant bacteria (Russell, 2002;Coelho et al., 2013). This slow-down may have caused a number of antibiotics to lose their efficacy against antibiotic-resistant organisms, making the use of drugs that are often reserved for last-line treatment necessary (Coelho et al., 2013). The overall result of the emergence of human pathogenic organisms exhibiting multidrug resistance has been the search for new antimicrobial substances from other sources, including plants (Ahmad & Beg, 2001).During the 1950s, exotic, fast-growing trees such as Pinus spp. were introduced in southern Brazil to supply wood for the paper industry and cellulose for energy production. Today, Brazil holds one of the largest planted areas in the world (Pacheco et al., 2009). A number of compounds displaying anti-inflammatory, antiparasitic, antioxidant, antimutagenic and antitumour activities, as well as the ability to regulate cancer-related proteins, have been isolated from different Pinus spp. (Tó ro et al., 2003;Karonen et al., 2004;Kwak et al., 2006;Li et al., 2007;Politeo et al., 2011). Some species are frequently used for their medicinal benefits, such as diuretic and expectorant actions, to treat diseases that include pulmonary, urinary, hepatic and hypertensive disorders (Lawless, 1992;Politeo et al., 2011). Moreover, pine oils are widely employed as fragran...