Avaliação da atividade antibacteriana, citotóxica e antioxidante da espécie vegetal Opuntia cochenillifera (L. ) Mill / Evaluation of antibacterial, cytotoxic, and antioxidant activity of the plant species Opuntia cochenillifera (L. ) Mill

RESUMO O presente estudo teve como objetivo avaliar a atividade antibacteriana, antioxidante e citotóxica da espécie Opuntia cochenillifera (L.) Mill. Foi realizada a prospecção fitoquímica e espectroscopia de absorção de infravermelho (IV) dos extratos etanólicos brutos e frações dos cladódios grande e pequeno. A atividade antioxidante foi avaliada pelo método da capacidade sequestradora de radicais livres utilizando o radical sintético 2,2-difenil-1-picrilhidrazila (DPPH). A atividade citotóxica foi obtida através do método colorimétrico do Metiltetrazolium (MTT). Já a atividade antibacteriana foi avaliada pelo método de microdiluição em caldo para determinar a concentração inibitória mínima (CIM) frente às estirpes bacterianas Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa e Escherichia coli. A prospecção fitoquímica revelou principalmente a presença de fenóis, esteroides livres, alcaloides, alcanos, além de outras classes químicas. O IV apresentou grupos funcionais como alcanos, carbonilas, grupos de metila, duplas ligações de carbono, grupamentos alquilamina, entre outros. Sobre a citotoxicidade na concentração de 100 μg/mL, os dois extratos brutos, todas as frações do cladódio grande e as frações de clorofórmio e metanol do cladódio pequeno não apresentaram toxicidade. Os extratos brutos e frações do cladódio grande e pequeno, não demonstraram atividade antibacteriana e nem antioxidante. Esses resultados podem fornecer suporte para pesquisas futuras, visando outras atividades biológicas da presente espécie vegetal.

ABSTRACT The purpose of this study was to evaluate the antibacterial, antioxidant, and cytotoxic activity of Opuntia cochenillifera (L.) Mill. A phytochemical screening and infrared (IR) absorption spectroscopy were performed in the crude ethanolic extracts and fractions of large and small cladodes. The antioxidant activity was evaluated through the qualitative method of free-radical scavenging capacity using the synthetic radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The cytotoxic activity was obtained by the cell viability assay using methyl thiazolyl tetrazolium (MTT). Antibacterial activity was evaluated by broth microdilution method to determine the minimum inhibitory concentration (MIC) against the bacterial strains Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. The phytochemical screening mainly revealed the presence of phenols, flavonoids, free steroids, alkaloids, alkanes, and other chemical classes. The IR spectroscopy presented functional groups such as alkanes, carbonyls, methyl groups, carbon double bonds, and alkylamino groups, among others. Regarding cytotoxicity in the concentration of 100 μg/mL, neither the crude extracts, the fractions of the large cladode, nor the chloroform and methanol fractions of small cladode presented toxicity. The crude ethanolic extracts and fractions of large and small cladode showed no antibacterial or antioxidant activity. These results may provide support for future research aimed at other biological activities of this plant species.

Expression of the chemokine receptor CXCR4 on lymphocytes of leprosy patients

Leprosy is caused by Mycobacterium leprae, which induces chronic granulomatous infection of the skin and peripheral nerves. The disease ranges from the tuberculoid to the lepromatous forms, depending on the cellular immune response of the host. Chemokines are thought to be involved in the immunopathogenesis of leprosy, but few studies have investigated the expression of chemokine receptors on leukocytes of leprosy patients. In the present study, we evaluated 21 leprosy patients (M/F: 16/5) with a new diagnosis from the Dermatology Outpatient Clinic of the University Hospital, Federal University of Minas Gerais. The control group was composed of 20 healthy members (M/F: 15/5) of the community recruited by means of announcements. The expression of CCR2, CCR3, CCR5, and CXCR4 was investigated by flow cytometry on the surface of peripheral blood lymphocytes. There was a decrease in percentage of CD3+CXCR4+ and CD4+CXCR4+ lymphocytes in the peripheral blood of leprosy patients (median [range], 17.6 [2.7-41.9] and 65.3 [3.9-91.9], respectively) compared to the control group (median [range], 43.0 [3.7-61.3] and 77.2 [43.6-93.5], respectively). The percentage of CD4+CXCR4+ was significantly lower in patients with the tuberculoid form (median [range], 45.7 [0.0-83.1]) of the disease, but not in lepromatous patients (median [range], 81.5 [44.9-91.9]). The CXCR4 chemokine receptor may play a role in leprosy immunopathogenesis, probably directing cell migration to tissue lesions in tuberculoid leprosy patients.

Estudo fitoquímico preliminar e bioensaio toxicológico frente a larvas de Artemia salina Leach. de extrato obtido de frutos de Solanum lycocarpum A. St.-Hill (Solanaceae) / Phytochemical screening and toxicological bioassay with brine shrimp larvae (Artemia salina Leach) of an extract obtained from fruits of Solanum lycocarpum A. St-Hill

Neste trabalho, avaliou-se o perfil fitoquímico e a toxicidade preliminar frente a larvas de Artemia salina do extrato etanólico de frutos de Solanum lycocarpum. O extrato foi submetido à análise fitoquímica preliminar para identificação das principais classes de metabolitos secundários presentes e testado frente a larvas de A. salina para obtenção das concentrações letais médias (CL50%). Os testes fitoquímicos demonstraram a presença de fenóis, taninos, saponinas, alcalóides e esteroides livres. O extrato foi fracionado em diferentes solventes para a avaliação da toxicidade frente à A. salina, apresentando considerável citotoxicidade na fração hidroalcoólica (CL50% = 285,546 µg/mL).

The phytochemical profile of ethanolic extract of Solanum lycocarpum fruits was analyzed and preliminary toxicity tests were performed against brine shrimp larvae. The extract was subjected to preliminary phytochemical analysis to identify the main classes of secondary metabolites and tested against the larvae of A. salina to obtain the median lethal concentrations (LC50%). The phytochemical tests showed the presence of phenols, tannins, saponins, alkaloids and free steroids. The extract was fractionated with various solvents for toxicity testing against the larvae and the hydroalcoholic fraction showed considerable cytotoxicity (CL50% = 285.546 µg/mL).