Oficinas multitemáticas: Estudantes como protagonistas na popularização da ciência em Feira de Santana -BA / Multi-thematic workshops: Students as protagonists in the popularization of science in Feira de Santana -BA / Talleresmultitemáticos: los estudiantes como protagonistas de la divulgación científica en Feira de Santana ­BA

Objetivo: estimular estudantes a serem protagonistas de ações que fomentassem na sua comunidade a popularização das ciências através de oficinas pedagógicas temáticas, colocando-os como construtores dos saberes, assim como, fortalecendo o papel extensionista da Universidade. Método:As atividades tiveram a participação de 80 alunos e foram desenvolvidas no Departamento de Ciências Biológicas (DCBIO) da Universidade Estadual de Feira de Santana (UEFS), pelos docentes do NUPEECBio, discentes e monitores. Foi realizada na SNCT (2019) com estudantes do Ensino Fundamental (6° e 7° ano) utilizando oficinas multitemáticas em Ciências. Após essa etapa, foram aplicados questionários e a avaliação qualitativa usando a Escala Likert para realizar uma avaliação qualitativa sobre a participação e adesão dos estudantes. Resultados:A análise dos dados em conjunto nos permitiu avaliar o grau de satisfação, percepção e cognição dos estudantes após cada oficina, demonstrando que as estratégias utilizadas foram exitosas. Conclusão:nessa experiência de interface Universidade e Escola básica, foi possível perceber a relevância da junção de atividades teóricas/práticas por meios de oficinas interdisciplinares no despertamento de curiosidade, motivação e receptividade dos estudantes.

Objective: to encourage students to take the lead in actions that would promote the popularization of science in their community through themed pedagogical workshops, placing them as builders of knowledge, as well as strengthening the university's extension role. Method: 80 students took part in the activities, which were carried out at the Department of Biological Sciences (DCBIO) of the State University of Feira de Santana (UEFS) by NUPEECBio teachers, students and monitors. It was held during SNCT (2019) with elementary school students (6th and 7th grade) using multi-thematic science workshops. After this stage, questionnaires and the Likert Scale were applied to carry out a qualitative assessment of student participation and adherence. Results:Analyzing the data together allowed us to assess the degree of satisfaction, perception and cognition of the students after each workshop, demonstrating that the strategies used were successful. Conclusion: in this experience of the interface between university and elementaryschool, it was possible to see the relevance of combining theoretical/practical activities through interdisciplinary workshops in arousing curiosity, motivation and receptivity in the students.

Objetivo: incentivar a los estudiantes a protagonizar acciones que promuevan la popularización de la ciencia en su comunidad a través de talleres educativos temáticos, convirtiéndolos en constructores de conocimiento y fortaleciendo el papel de extensión de la universidad. Método: 80 estudiantes participaron en las actividades, que se llevaron a cabo en el Departamento de Ciencias Biológicas (DCBIO) de la Universidad Estatal de Feira de Santana (UEFS) por profesores, estudiantes y monitores de NUPEECBio. Se llevó a cabo durante el SNCT (2019) con estudiantes de la escuela primaria (6º y 7º grado) utilizando talleres de ciencias multitemáticas. Después de esta etapa, se aplicaron cuestionarios y la Escala de Likert para llevar a cabo una evaluación cualitativa de la participación y la adhesión de los estudiantes. Resultados: El análisis conjunto de los datos nos permitió evaluar el grado de satisfacción, percepción y cognición de los alumnos luego de cada taller, demostrando que las estrategias utilizadas fueron exitosas. Conclusión: en esta experiencia de interfaz entre la universidad y la escuela primaria, fue posible constatar la importancia de la combinación de actividades teórico/prácticas a través de talleres interdisciplinares para despertar curiosidad, motivacióny receptividad en los alumnos.

Nitrobenzoates and Nitrothiobenzoates with Activity against M. tuberculosis.

Esters of weak acids have shown improved antimycobacterial activity over the corresponding free acids and nitro benzoates in particular have previously shown to have a very intriguing activity. To expand the potential of nitro-derivatives of benzoic acid as antimycobacterial drugs and explore the effects of various structural features on the activity of these compounds, we have obtained a library of 64 derivatives containing esters and thioesters of benzoates and studied their activity against M. tuberculosis, the stability of the compounds, their activation by mycobacterial enzymes and the potential cytotoxicity against human monocytic THP-1 cell line. Our results showed that the most active compounds are those with an aromatic nitro substitution, with the 3,5-dinitro esters series being the most active. Also, the greater antitubercular activity for the nitro derivatives was shown to be unrelated to their pKa values or hydrolysis rates. Given the conventional relationship between nitro-containing substances and toxicity, one might anticipate that the great antimicrobial activity of nitro compounds would be associated with high toxicity; yet, we have not found such a relationship. The nitrobenzoate scaffold, particularly the 3,5-dinitrobenzoate scaffold, merits further investigation, because it has the potential to generate future antimycobacterial agents with improved activity.

Benzoic Acid Derivatives as Prodrugs for the Treatment of Tuberculosis.

One interesting approach to fight tuberculosis is the use of prodrugs that often have shown improved biological activities over drugs with poor absorption or difficulty to cross membranes. Previous studies demonstrate that weak acids such as benzoic acid, present antimycobacterial activity. Moreover, esters of those acids revealed to be a viable alternative since they may diffuse more easily through the cell membranes. Previously we showed that mycobacteria can easily activate benzoic acid esters by conversion to the corresponding acid. Since Zhang postulated that the activity of the acids can be dependent on their pKa, we set up to synthesize a library of benzoates with different electron withdrawing groups (4-chloro, 2,6-dichloro, 3,5-dichloro, 4-nitro, and 3,5 dinitro), to modulate pKa of the liberated acid and different alkoxy substituents (propyl, hexyl, and phenyl) to modulate their lipophilicity, and tested the activity of the esters and the corresponding free acids against mycobacteria. We also studied the activation of the esters by mycobacterial enzymes and the stability of the compounds in buffer and plasma. We concluded that all the benzoates in our study can be activated by mycobacterial enzymes and that the phenyl and hexyl esters presented higher activity than the corresponding free acids, with the nitrobenzoates, and especially the dinitrobenzoates, showing very interesting antitubercular activity that deserve further exploration. Our results did not show a correlation between the activity and the pKa of the acids.

New records of Meiothecium boryanum (Müll.Hal.) Mitt. (Sematophyllaceae, Bryophyta) in Brazil / Novas ocorrências de Meiothecium boryanum (Müll.Hal.) Mitt. (Sematophyllaceae, Bryophyta) no Brasil

During the review of species of the Sematophyllaceae family deposited in national herbaria, it was possible to expand the occurrence record of Meiothecium boyanum (Müll.Hal.) Mitt. in Brazil. Currently, the confirmed occurrence of the species is limited to the States of Bahia, Goiás, Rio de Janeiro, Rio Grande do Sul and São Paulo, although only the State of Bahia is mentioned in Flora e Funga do Brasil 2022. With this work, the species had its record confirmed for Minas Gerais and Pernambuco States.

Durante a revisão de espécies da família Sematophyllaceae depositadas em herbários nacionais foi possível ampliar o registro de ocorrência de Meiothecium boryanum (Müll.Hal.) Mitt. no Brasil. Atualmente a ocorrência confirmada da espécie se limita aos Estados da Bahia, Goiás, Rio de Janeiro, Rio Grande do Sul e São Paulo, embora seja citada apenas o Estado da Bahia no Flora e Funga do Brasil 2022. Com este trabalho, a espécie teve seu registro confirmado também para os estados de Minas Gerais e Pernambuco.

Activation of benzoate model prodrugs by mycobacteria. Comparison with mammalian plasma and liver hydrolysis.

Due to difficulties in drug penetration in M. tuberculosis, a prodrug approach based on mycobacterial activation appears as a promising strategy to increase the delivery of antitubercular drugs to the target microorganisms. Esters have been successful used by us and others to deliver drugs to mycobacteria, however because very little is known about the metabolic hydrolysis of esters by mycobacteria in connection with prodrug activation, we decided to study the process further. For that we selected a series of 13 benzoates with different chain lengths and ramifications in the alkoxy side as model prodrugs and examined their hydrolysis by a mycobacterial homogenate, comparing the results with those obtained parallelly in human plasma and in total rat liver homogenate. In all biological media, the benzoates with a linear alkyl group showed a parabolic dependence between log(k) and logP (or the number of carbons of the linear alkyl chain) that reached a maximal value for the n-butyl chain. Considering linear correlations for the total number of compounds between log(k) and chosen descriptors, for mycobacterial esterases, pKa of the leaving alcohol (pKaLG) seem to be the most important descriptor. Plasma esterases seem to be quite sensitive to the Taft polarity parameter σ* and also to pKaLG and less sensitive to steric effects. Liver esterases seem to be more sensitive to the Taft steric descriptor ESc. Lipophilicity correlates weakly with log(k) in all the 3 media, however, is more important when one looks for mycobacterial activation selectivity in relation to plasma metabolism or in relation to liver homogenate metabolism. The importance of lipophilicity increases further when biparametric expressions are considered. We showed that it is easy to activate a wide variety of benzoate esters using a mycobacterial homogenate. The data also suggest that with careful design is possible to obtain tuberculostatic prodrug esters sensitive to mycobacterial hydrolases while reasonably resistant to plasma and liver hydrolysis. One important observation is that mycobacterial hydrolysis is less affected by bulky substituents than liver homogenate or plasma hydrolysis. tert-Butyl is probably the substituent in the alkoxy side that seems more adequate to resist simultaneously plasma and liver metabolism, while allowing activation by mycobacterial esterases. Hexyl is also a good option for the medicinal chemist if a linear alkoxy chain is needed.

Esters of Pyrazinoic Acid Are Active against Pyrazinamide-Resistant Strains of Mycobacterium tuberculosis and Other Naturally Resistant Mycobacteria In Vitro and Ex Vivo within Macrophages.

Pyrazinamide (PZA) is active against major Mycobacterium tuberculosis species (M. tuberculosis, M. africanum, and M. microti) but not against M. bovis and M. avium. The latter two are mycobacterial species involved in human and cattle tuberculosis and in HIV coinfections, respectively. PZA is a first-line agent for the treatment of human tuberculosis and requires activation by a mycobacterial pyrazinamidase to form the active metabolite pyrazinoic acid (POA). As a result of this mechanism, resistance to PZA, as is often found in tuberculosis patients, is caused by point mutations in pyrazinamidase. In previous work, we have shown that POA esters and amides synthesized in our laboratory were stable in plasma (M. F. Simões, E. Valente, M. J. Gómez, E. Anes, and L. Constantino, Eur J Pharm Sci 37:257-263, 2009, http://dx.doi.org/10.1016/j.ejps.2009.02.012). Although the amides did not present significant activity, the esters were active against sensitive mycobacteria at concentrations 5- to 10-fold lower than those of PZA. Here, we report that these POA derivatives possess antibacterial efficacy in vitro and ex vivo against several species and strains of Mycobacterium with natural or acquired resistance to PZA, including M. bovis and M. avium. Our results indicate that the resistance probably was overcome by cleavage of the prodrugs into POA and a long-chain alcohol. Although it is not possible to rule out that the esters have intrinsic activity per se, we bring evidence here that long-chain fatty alcohols possess a significant antimycobacterial effect against PZA-resistant species and strains and are not mere inactive promoieties. These findings may lead to candidate dual drugs having enhanced activity against both PZA-susceptible and PZA-resistant isolates and being suitable for clinical development.

Development of a method to investigate the hydrolysis of xenobiotic esters by a Mycobacterium smegmatis homogenate.

One of the main problems in combating tuberculosis is caused by a poor penetration of drugs into the mycobacterial cells. A prodrug approach via activation inside mycobacterial cells is a possible strategy to overcome this hurdle and achieve efficient drug uptake. Esters are attractive candidates for such a strategy and we and others communicated previously the activity of esters of weak organic acids against mycobacteria. However very little is known about ester hydrolysis by mycobacteria and no biological model is available to study the activation of prodrugs by these microorganisms. To begin filling this gap, we have embarked in a project to develop an in vitro method to study prodrug activation by mycobacteria using Mycobacterium smegmatis homogenates. Model ester substrates were ethyl nicotinate and ethyl benzoate whose hydrolysis was monitored and characterized kinetically. Our studies showed that in M. smegmatis most esterase activity is associated with the soluble fraction (cytosol) and is preserved by storage at 5°C or at room temperature for one hour, or by storage at -80°C up to one year. In the range of homogenate concentrations studied (5-80% in buffer), k(obs) varied linearly with homogenate concentration for both substrates. We also found that the homogenates showed Michaelis-Menten kinetics behavior with both prodrugs. Since ethyl benzoate is a good substrate for the mycobacterial esterases, this compound can be used to standardize the esterasic activity of homogenates, allowing results of incubations of prodrugs with homogenates from different batches to be readily compared.

Lipophilic pyrazinoic acid amide and ester prodrugs stability, activation and activity against M. tuberculosis.

Pyrazinamide (PZA) is active against M. tuberculosis and is a first line agent for the treatment of human tuberculosis. PZA is itself a prodrug that requires activation by a pyrazinamidase to form its active metabolite pyrazinoic acid (POA). Since the specificity of cleavage is dependent on a single bacterial enzyme, resistance to PZA is often found in tuberculosis patients. Esters of POA have been proposed in the past as alternatives to PZA however the most promising compounds were rapidly degraded in the presence of serum. In order to obtain compounds that could survive during the transport phase, we synthesized lipophilic ester and amide POA derivatives, studied their activity against M. tuberculosis, their stability in plasma and rat liver homogenate and also their activation by a mycobacterial homogenate. The new lipophilic ester prodrugs were found to be active in concentrations 10-fold lower than those needed for PZA to kill sensitive M. tuberculosis and also have a suitable stability in the presence of plasma. Amides of POA although more stable in plasma have lower activity. The reason can probably be found in the rate of activation of both types of prodrugs; while esters are easily activated by mycobacterial esterases, amides are resistant to activation and are not transformed into POA at a suitable rate.

Structure-activity relationships for dipeptide prodrugs of acyclovir: implications for prodrug design.

A series of water-soluble dipeptide ester prodrugs of the antiviral acyclovir (ACV) were evaluated for their chemical stability, cytotoxicity, and antiviral activity against several strains of Herpes Simplex-1 and -2, vaccinia, vesicular stomatitis, cytomegalovirus and varicella zoster viruses. ACV dipeptide esters were very active against herpetic viruses, independently of the rate at which they liberate the parent drug. Their minimum cytotoxic concentrations were above 100 microM and the resulting MCC/EC(50) values were lower than those of ACV. When comparing the reactivity of Phe-Gly esters and amides (ACV, zidovudine, paracetamol, captopril and primaquine) in pH 7.4 buffer it was found that the rate of drug release increases with drug's leaving group ability. Release of the parent drug from Phe-Gly in human plasma is markedly faster than in pH 7.4 buffer, thus suggesting that the dipeptide-based prodrug approach can be successfully applied to bioactive agents containing thiol, phenol and amine functional groups.

Kinetics and mechanism of hydrolysis of N-acyloxymethyl derivatives of azetidin-2-one.

The pH-independent, acid-catalyzed and base-catalyzed hydrolyses of N-acyloxymethylazetidin-2-ones all occur at the ester function. The pH-independent hydrolysis involves rate-limiting alkyl C-O fission and formation of an exocyclic beta-lactam iminum ion. This iminium ion is then trapped by water at the exocyclic iminium carbon atom, rather than at the beta-lactam carbonyl carbon atom, to form the corresponding N-hydroxymethylazetidin-2-ones. Calculations carried out at the B3LYP/6-31+G(d) level of theory also support that nucleophilic attack by water takes place at the exocyclic carbon rather than at the beta-lactam carbonyl carbon of the iminium ion. The mechanism for the acid-catalyzed pathway involves a preequilibrium protonation, probably at the beta-lactam nitrogen, followed by rate-limiting alkyl C-O fission with formation of an exocyclic iminum ion. The base-catalyzed hydrolysis involves rate-limiting hydroxide attack at the ester carbonyl carbon. These results imply formation of a beta-lactam system containing a positively charged amide nitrogen atom that hydrolyzes via a pathway that preserves the beta-lactam structure in the product and provide further evidence that cleavage of the beta-lactam C-N bond is not as facile as is commonly imagined.