Antifungal and antibiofilm activities of the essential oil of leaves from Lippia gracilis Schauer against phytopathogenic fungi.

AIMS: This study aimed to evaluate the antifungal and antibiofilm effects of essential oil (EO) from leaves of Lippia gracilis and its major constituents, thymol and carvacrol, against phytopathogenic fungi. METHODS AND RESULTS: The leaves of L. gracilis were hydrodistilled to obtain the EO and the chemical composition was determined by GC/MS analysis. The antifungal activity of EO of L. gracilis was evaluated on the vegetative and mycelial growth of Colletotrichum gloeosporioides, Colletotrichum lindemuthianum, Fusarium oxysporum and Fusarium solani. In addition, the ability of the oil to inhibit fungal biofilm formation was assessed by total biomass quantification using crystal violet staining, analysis of metabolic activity, and scanning electron microscopy (SEM). Moreover the antifungal and antibiofilm activities of the monoterpenes, thymol and carvacrol, present in EO of L. gracilis were evaluated against F. oxysporum. The analysis of the chemical composition of EO extracted from L. gracilis, revealed the presence of monoterpenes (94·13%), which included carvacrol (48·57%) and thymol (7·78%), and 4 sesquiterpenes (3·74%). In general, EO showed significant antifungal activity and inhibited the formation of fungal biofilms. Furthermore, thymol and carvacrol showed significant antifungal and antibiofilm activities against F. oxysporum. SEM images showed structural changes in fungal morphology upon treatment with EO of L. gracilis. CONCLUSION: The results presented in this study showed promising antifungal and antibiofilm effects of EO of L. gracilis and its major components, carvacrol and thymol. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings indicate that the EO extracted from L. gracilis, and the monoterpenes, carvacrol and thymol have a great potential as antifungal and antibiofilm agents. Furthermore, this is the first report of the antibiofilm activity of the EO of L. gracilis and its major components against phytopathogenic fungi.

In vivo and in vitro effects of pentavalent antimony on mouse liver cytochrome P450s.

Pentavalent antimonial (Sb5+) drugs such as meglumine antimoniate (MA) are the mainstay treatment of leishmaniases in developing countries. The effects of these compounds on drug-metabolizing enzymes have not been characterized and their potential pharmacokinetic interactions with other drugs are therefore unknown. The present study investigated whether treatment with MA (300 mg Sb5+/kg body weight/day, subcutaneously) for 24 days affected the activities of cytochrome P450 (CYP)1A (ethoxyresorufin- O-deethylase), CYP2A5 (coumarin 7-hydroxylase), CYP2E1 ( p-nitrophenol-hydroxylase), CYP2B9/10 (benzyloxy-resorufin- O-debenzylase), or CYP3A11 (erythromycin- N-demethylase) in the livers of Swiss Webster (SW) and DBA-2 male and female mice. The results showed that CYP2A5-, CYP2E1-, and CYP3A11-catalyzed reactions were unaffected by MA treatment. A decrease in CYP2B9/10 activity was noted in DBA-2 females (but not males) and was not observed in SW males or females. However, repeated MA administration reduced mouse liver CYP1A activity. CYP1A2 messenger RNA (mRNA) levels were not affected by MA and in vitro exposure of mouse liver microsomes to Sb3+ and Sb5+ did not reduce CYP1A activity. These findings suggested that in vivo treatment with Sb5+ drugs depressed CYP1A activity, without downregulating CYP1A2 mRNA expression. Since in vitro treatment of liver microsomes failed to inhibit CYP1A activity, this effect may require intact cells.

Diagnosis and epidemiology of canine leishmaniasis in southeastern Bahia, Brazil.

Leishmaniasis is a disease caused by protozoa of the genus Leishmania. Two distinct forms are recognized: visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). In the Americas, the causative agent of VL is L. infantum chagasi, whereas L. braziliensis is principally responsible for CL. Domestic dogs constitute the main source of VL in urban environments, and have also been implicated in CL epidemiology. We carried out molecular and serological surveys to detect Leishmania infection in dogs from the municipality of Ituberá in Bahia, Brazil. Furthermore, we identified risk factors associated with illness in dogs from this locality. Blood samples were collected from 399 dogs and tested using an indirect immunofluorescence assay (IFA) and polymerase chain reaction (PCR) to detect Leishmania spp antibodies and L. infantum chagasi and L. braziliensis DNA, respectively. Dogs were clinically evaluated and tissue samples from those exhibiting skin lesions were examined for parasites. In addition, the dog owners completed an epidemiological questionnaire to identify factors associated with infection. Skin lesions consistent with CL were found on 37 (9.3%) of the evaluated animals, but parasitological examination was negative for all samples. The IFA returned positive results for 60 (15%) dogs. PCR identified DNA from L. braziliensis in 86 (21.6%) animals, where as all samples proved negative for L. infantum chagasi. The 134 dogs (33.6%) testing positive using IFA and/ or PCR were considered infected, and of these, only 13 demonstrated skin lesions. Animals from rural areas were 3.39-times more likely to be infected compared to those in urban environments.

Canine hepatozoonosis in southeastern Bahia, Brazil.

In Brazil, canine hepatozoonosis is a tick-borne subclinical hemoparasitosis caused by a protozoa Hepatozoon canis and is highly prevalent in dogs in rural areas. An epizootiological study was conducted to investigate the prevalence of H. canis in the canine population of Ituberá, Bahia, and to analyze any associated risk factors. Blood samples were collected from 380 dogs and determined the presence of the protozoan by performing capillary blood smear and polymerase chain reaction (PCR). Epizootiological data were collected by asking dog owners to answer a structured questionnaire. H. canis gamonts were not detected in the blood smears. However, PCR detected H. canis in 163/380 (42.9%) dogs examined. Physical examination and anamnesis indicated 105 (64.4%) positive asymptomatic dogs. Hematological alterations were observed in 115 (70.5%) infected dogs. No clinical, hematological, or epizootiological variable was found to be significantly associated to the infection. In conclusion, the high prevalence of H. canis infection in local dogs may be because of the peri-urban features of this municipality. Moreover, to the best of our knowledge, this study the first study to report H. canis infection in the State of Bahia.