In this work, a search for antimicrobial agents against multi-drug resistant (MDR) bacteria was undertaken. It involved two natural diterpenes of different basic skeletons, named ent-kaurenoic acid and ent-pimaradienoic acid, that were used as precursors to access 28 semi-synthetic derivatives that were also submitted to biological assays. All 30 substances were assayed against a set of seven clinically isolated MDR bacteria, including three Staphylococcus aureus strains. Results classified both natural compounds as promising bactericidal antimicrobial agents against these MDR bacteria, especially for their performance in time-kill curve assay, improving on the positive control vancomycin. Moreover, di-hydro ent-pimaradienoic acid, obtained as one of the derivatives, also displayed promising minimum inhibitory concentration (MIC) values against the microorganism set, proving optimum activity against S. aureus strains. Thereby, this work also yielded a promising semi-synthetic bacteriostatic antimicrobial agent against MDR S. aureus. Furthermore, the study was carried out with 30 structures in order to verify the veracity and scope of Urzúa’s hypothesis about the structure-activity relationship between diterpenes and antimicrobial action. Our results are 93% in agreement with this hypothesis.

The labdane diterpenes copalic acid, 3β-acetoxy-copalic acid, 3β-hydroxy-copalic acid and ent-agathic acid were isolated from Copaifera langsdorffii oleoresin. These four compounds were submitted to structural modifications by reduction with hydrogen/palladium, esterification with diazomethane, esterification with methanol/sulfuric acid and conversion into sodium salt, furnishing 15 compounds. All compounds were assayed in vitro against Mycobacterium tuberculosis (H37Rv, ATCC 27294). The four compounds displayed minimum inhibitory concentration (MIC) value of 125 µg mL-1, and were not considered active. A methylated derivative of compound 3β-hydroxy-copalic acid, and a sodium salt of copalic acid displayed MIC values of 25 µg mL-1 (71.7 µM) and 6.25 µg mL-1 (19.2 µM), respectively. The sodium salt of copalic acid stood out by displaying similar activity in comparison with streptomycin (MIC 6.25 µg mL-1) and a better activity compared to µM value of pyrazinamide (MIC 3.12 µg mL-1; 25.34 µM). Therefore, the methylated derivative of compound 3β-hydroxy-copalic acid and the sodium salt of copalic acid should be considered for further studies.

This work describes the phytochemical study of the extracts from aerial parts of Tibouchina candolleana as well as the evaluation of the antimicrobial activity of extracts, isolated compounds, and semi-synthetic derivatives of ursolic acid against endodontic bacteria. HRGC analysis of the n-hexane extract of T. candolleana allowed identification of b-amyrin, a-amyrin, and b-sitosterol as major constituents. The triterpenes ursolic acid and oleanolic acid were isolated from the methylene chloride extract and identified. In addition, the flavonoids luteolin and genistein were isolated from the ethanol extract and identified. The antimicrobial activity was investigated via determination of the minimum inhibitory concentration (MIC) using the broth microdilution method. Amongst the isolated compounds, ursolic acid was the most effective against the selected endodontic bacteria. As for the semi-synthetic ursolic acid derivatives, only the methyl ester derivative potentiated the activity against Bacteroides fragilis.

A atividade antimicrobiana de Aegiphila sellowiana Cham., Lamiaceae, contra patógenos da cavidade bucal foi avaliada empregando-se o método de microdiluição em caldo, segundo o protocolo CLSI M7-A7, utilizando-se clorexidina como controle positivo. O extrato etanólico bruto das partes aéreas de A. sellowiana, obtido por maceração, exibiu atividade contra os microrganismos testados neste trabalho, entretanto, os valores de CIM (concentração inibitória mínima) aumentaram após a partição com n-hexano, diclorometano e acetato de etila. Entre as frações testadas, a fração n-hexânica foi a mais efetiva contra os patógenos bucais avaliados, com valores de CIM entre 140 e 350 µg/mL-1. Dados obtidos por CG-EM revelaram que ésteres de ácidos graxos, esteróides e hidrocarbonetos sesquiterpênicos alifáticos são os constituintes majoritários desta fração. Embora esses compostos possam ser os responsáveis pela atividade da fração n-hexânica, outros constituintes químicos presentes nas frações em diclorometano, acetato de etila e hidroalcoólica podem potencializar suas atividades no extrato bruto.

The antimicrobial activity of Aegiphila sellowiana Cham., Lamiaceae, against oral pathogens is reported. The Minimal Inhibitory Concentrations (MICs) for inhibiting the microorganisms growth were determined using the broth microdilution method from the CLSI M7-A7 protocol. Chlorhexidine was used as the positive control. The ethanol crude extract of the aerial parts of A. sellowiana exhibited activity against the microorganisms tested in this work; however, the activity decreased after partition with n-hexane, dichloromethane, and ethyl acetate. Among the tested fractions, the n-hexane fraction was found to be the most effective against the evaluated oral pathogens. GC-MS analysis of this latter fraction revealed that fatty acids esters, steroids, and aliphatic sesquiterpene hydrocarbons are its major constituents. These compounds may be responsible for the activity of the n-hexane fraction, but other chemical constituents of the dichloromethane, ethyl acetate, and hydroalcoholic fraction may potentialize their activities in the crude extract.

O estresse sistêmico induzido pelo exercício libera substâncias bioativas determinantes da mobilização neutrofílica. A crioterapia diminui a reação inflamatória e atenua a elevação da perfusão sanguínea induzida pelo exercício. O objetivo deste trabalho foi analisar a influência da hipotermia decorrente da crioimersão corporal (CIC) imediata ao esforço físico agudo nas concentrações neutrofílicas e linfocíticas no sangue. Os ratos do grupo controle (AI) foram mantidos em repouso enquanto os do grupo AII foram submetidos ao protocolo de CIC a 10ºC por 10 minutos. Enquanto os animais dos grupos BI, BII, BIII e BIV realizaram o esforço físico agudo (EFA) em água a 31ºC durante 100 minutos com sobrecarga corpórea de 5% do peso corporal, os dos grupos CI, CII, CIII e CIV foram submetidos ao EFA seguido imediatamente de CIC. Nos grupos B e C, os animais foram sacrificados nos períodos de 06 (I), 12 (II), 24 (III) e 48 (IV) horas posteriores ao EFA. Através da microscopia óptica realizou-se a contagem dos neutrófilos e linfócitos. Utilizou-se do Teste T Student para análise estatística considerando-se nível de significância p < 0,05. Observou-se uma significativa neutrofilia nos grupos AII, BI, BII, BIII, BIV, CI, CII e CIII em relação a AI, diferentemente do grupo CIV, que apresentou quantidade de neutrófilos igual ao grupo controle. Os valores de linfócitos nos grupos BII, BIII, BIV, CI e CII foram significativamente menores do que AI, e nos grupos AII, BI, CIII e CIV foram iguais a AI. A neutrofilia e a linfopenia posteriores ao intenso exercício agudo são mantidas por 48 horas ou mais, porém, mediante a aplicação da crioimersão corporal imediata ao exercício, são normalizadas em 24 horas.

Systemic stress induced by exercise increases bioactive substances in plasma which leads to neutrophilic mobilization. Cryotherapy causes a decrease in the inflammatory reaction and attenuates high blood perfusion after exercise. The objective of this work was to analyze the influence of cold water immersion (CWI) after acute exercise on neutrophil and lymphocyte mobilization. A control group of rats (AI) was kept at rest and a second group (AII) was submitted to CWI at 10º C for 10 minutes. The animals of Groups BI, BII, BIII and BIV were submitted to acute exercise which consisted in swimming in water at 31º C for 100 minutes with a load equivalent to 5% of the body weight. Groups CI, CII, CIII and CIV were submitted to CWI immediately after acute exercise. The animals were sacrificed at 6 (I), 12 (II), 24 (III) and 48 (IV) hours after the exercise and neutrophil and lymphocyte cells were counted for all groups by optic microscopy. The Student t-test was used for statistical analysis with a significance level of p< 0.05. A significant increase in the number of neutrophils was observed in Groups AII, BI, BII, BIII, BIV, CI, CII and CIII compared to AI. The neutrophil count of the CIV Group was similar to the Control Group. There was a significant drop in the number of lymphocytes in Groups BII, BIII, BIV, CI and CII when compared to Group AI. The lymphocyte count of Groups AII, BI, CIII and CIV were similar to the Control Group. The changes in neutrophil and lymphocyte counts caused by acute exercise were reverted to normal at 24 hours by cold water immersion.