Ocotea daphnifolia: phytochemical investigation, in vitro dual cholinesterase inhibition, and molecular docking studies

This study aimed to evaluate the anticholinesterase activities of extracts and fractions of Ocotea daphnifolia in vitro and characterize its constituents. The effects of hexane, ethyl acetate, and ethanolic extracts on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity were determined with a spectrophotometry assay. All extracts inhibited cholinesterase activity, and the ethanolic extract (2 mg/mL) exhibited the highest inhibition of both enzymes (99.7% for BuChE and 82.4% for AChE). The ethanolic extract was fractionated by column chromatography resulting in 14 fractions that were also screened for their anticholinesterase effects. Fraction 9 (2 mg/mL) showed the highest activity, inhibiting AChE and BuChE by 71.8% and 90.2%, respectively. This fraction was analyzed by high-performance liquid chromatography high-resolution mass spectrometry which allowed the characterization of seven glycosylated flavonoids (containing kaempferol and quercetin nucleus) and one alkaloid (reticuline). In order to better understand the enzyme-inhibitor interaction of the reticuline toward cholinesterase, molecular modeling studies were performed. Reticuline targeted the catalytic activity site of the enzymes. Ocotea daphnifolia exhibits a dual cholinesterase inhibitory activity and displays the same pattern of intermolecular interactions as described in the literature. The alkaloid reticuline can be considered as an important bioactive constituent of this plant.

Anti-tick effect and cholinesterase inhibition caused by Prosopis juliflora alkaloids: in vitro and in silico studies / Efeito carrapaticida e inibição da acetilcolinesterase por alcaloides de Prosopis juliflora: estudos in vitro e in silico

Abstract We investigated the in vitro acaricide activity of the methanolic extract (ME) and alkaloid-rich fraction (AF) of Prosopis juliflora on Rhipicephalus microplus and correlated this effect with acetylcholinesterase (AChE) inhibition. The acaricide activity was evaluated using adult and larval immersion tests. Also, we studied the possible interaction mechanism of the major alkaloids present in this fraction via molecular docking at the active site of R. microplus AChE1 (RmAChE1). Higher reproductive inhibitory activity of the AF was recorded, with effective concentration (EC50) four times lower than that of the ME (31.6 versus 121 mg/mL). The AF caused mortality of tick larvae, with lethal concentration 50% (LC50) of 13.8 mg/mL. Both ME and AF were seen to have anticholinesterase activity on AChE of R. microplus larvae, while AF was more active with half-maximal inhibitory concentration (IC50) of 0.041 mg/mL. The LC-MS/MS analyses on the AF led to identification of three alkaloids: prosopine (1), juliprosinine (2) and juliprosopine (3). The molecular docking studies revealed that these alkaloids had interactions at the active site of the RmAChE1, mainly relating to hydrogen bonds and cation-pi interactions. We concluded that the alkaloids of P. juliflora showed acaricide activity on R. microplus and acted through an anticholinesterase mechanism.

Resumo A atividade carrapaticida in vitro do extrato metanólico (EM) e da fração de alcaloides (FA) de Prosopis juliflora foi investigada, frente ao Rhipicephalus microplus, e relacionada com a inibição da enzima acetilcolinesterase (AChE). A predição in silico das interações de alcaloides dessa fração com a AChE1 de R. microplus (RmAChE1) foi realizada por acoplamento molecular. A atividade carrapaticida foi avaliada, utilizando-se os ensaios de imersão de adultos e larvas. Maior efeito sobre parâmetros reprodutivos de teleóginas foi verificado para a FA, com valor de Concentração Efetiva 50% (CE50) (31.6 mg/mL), quatro vezes menor do que o valor do EM (121 mg/mL). A FA induziu mortalidade de larvas (Concentração Letal de 50% - CL50 = 13,8 mg/mL). A inibição da atividade da AChE de larvas do carrapato foi observada para EM e FA, sendo a FA mais ativa (Concentração Inibitória 50%- CI50 de 0,041mg/mL). As análises químicas da FA permitiram a identificação dos alcaloides prosopina (1), juliprosinina (2) e juliprosopina (3). No ensaio in silico, observou-se que esses alcaloides podem interagir com o sítio ativo da RmAChE1, principalmente por ligações de hidrogênio e interações cátion-pi. Os alcaloides de P. juliflora têm atividade carrapaticida contra R. microplus, atuando através do mecanismo anticolinesterásico.

Acaricidal activity of Amburana cearensis on the cattle tick Rhipicephalus (Boophilus) microplus / Atividade acaricida de Amburana cearensis frente ao Rhipicephalus (Boophilus) microplus

ABSTRACT: This experiment was carried out to study the bioacaricidal activity of Amburana cearensis against engorged females of Rhipicephalus (Boophilus) microplus. The crude ethanolic extract from the leaves of A. cearensis was submitted to partition with organic solvents (hexane, chloroform and ethyl acetate) in order of increasing polarity; and evaluated using three treatments at concentrations of 5, 10 and 25mg ml-1. To evaluate the acaricidal activity, engorged females were submitted to the adult immersion test. Parameters analyzed were the weight of females; weight of egg mass; percentage of hatch; reproductive efficiency; expected rate of reproduction; and efficacy. For each extract and concentrating fraction, tests were performed in triplicate. Among all fractions, the hexane (2.5%) achieved the best results in all parameters analyzed: 52.7% of inhibition of oviposition; 39% of hatching rate; 3,271 index of reproductive efficiency; and 67.0% effectiveness. The extract obtained gradual dose response with increasing concentration; and could be used as an aid in the control of R. (B.) microplus therapy.

RESUMO: O objetivo deste estudo foi avaliar a atividade acaricida in vitro de Amburana cearensis contra fêmeas ingurgitadas de Rhipicephalus (Boophilus) microplus. O extrato etanólico bruto das folhas de A. cearensis foi submetido à partição com solventes orgânicos (hexano, clorofórmio e acetato de etila) em ordem crescente de polaridade. Foram realizadas três diluições, nas concentrações de 5, 10 e 25mg ml-1. Para avaliar a atividade carrapaticida, fêmeas teleóginas foram submetidas ao teste de imersão de fêmeas ingurgitadas. Os parâmetros analisados foram peso das fêmeas, peso da massa de ovos, porcentagem de eclosão, eficiência reprodutiva, índice de reprodução esperada e eficácia. Para cada extrato, fração e concentração, os testes foram realizados em triplicata. Dentre as frações, a hexânica (2,5%) apresentou os melhores resultados para todos os parâmetros analisados, alcançando 52,7% de inibição da oviposição; 39,0% de porcentagem de eclosão; 3.271 de índice de eficiência reprodutiva; e 67% de eficácia. O extrato obteve uma dose resposta gradual com o aumento da concentração; podendo ser utilizado como terapia auxiliar no controle do R. (B.) microplus.

In vitro photoprotective effects of Marcetia taxifolia ethanolic extract and its potential for sunscreen formulations

AbstractThe species Marcetia taxifolia (A. St.-Hil.) DC., Melastomataceae, which is endemic of the rupestrian fields of northeastern Brazil, contains a significant amount of flavonoids. In this work, the potential of the ethanolic extract of M. taxifolia as the active principle in a sunscreen photoprotection (UV-A and UV-B) formulation was investigated. The Liquid Chromatography High Performance-Diode Array Detector quantification (quercetin), total flavonoid content, antioxidant activity through 2.2-diphenyl-1- picrylhydrazil method, photoprotective activity against UV-B and UV-A radiation in vitro (spectrophotometric method) and potential for eye irritation using the methodology of the hen egg test-chorioallantoic membrane were performed in the extract. After that, the formulations were prepared using different concentrations of active ethanolic extract (5, 10, 20 and 30%) and the evaluation of the sun protection factor was carried out using the same methodology used for the crude extract. The crude extract showed UV-A photoprotection and low eye irritation in the hen egg test-chorioallantoic membrane test. All formulations containing M. taxifolia extract had ≥ 6 sun protection factor. Its shows the possibility to use this extracts as a sunscreen in pharmaceutical preparations.

Fenóis totais, flavonoides totais e atividade antioxidante de Selaginella convoluta (Arn. ) Spring (Selaginellaceae) / Total phenols, total flavonoids and antioxidant activity of Selaginella convoluta (Arn. ) Spring (Selaginellaceae)

Selaginella convoluta é uma espécie conhecida no Nordeste do Brasil como “jericó”, e bastante utilizada na medicina popular para tratamento de doenças. Este estudo teve como objetivo determinar o teor de compostos fenólicos e avaliar a atividade antioxidante in vitro do extrato etanólico e das frações obtidas por partição de S. convoluta. O conteúdo de fenóis totais foi determinado pelo método de Folin-Ciocalteu. O teor de flavonoides totais também foi avaliado. A atividade antioxidante dos extratos foi avaliada usando o método do sequestro do radical DPPH e inibição da auto-oxidação do sistema β-caroteno-ácido linoleico e comparada com os compostos de referência ácido ascórbico, BHA, BHT, quercetina e pirogalol. O conteúdo fenólico total foi de 209,90 ± 19,84 e 61,13 ± 2,50 mg equivalente de ácido gálico/g para os extratos AcOEt e EEB, respectivamente. O conteúdo de flavonoides totais foi de 155,70 ± 6,21 e 62,13 ± 4,10 para os dois extratos, respectivamente. Os extratos AcOEt e EEB apresentaram boas atividades antioxidantes. BHA foi o antioxidante mais efetivo, com um valor de IC50 de 1,62 ± 0,69 μg/mL. Os resultados obtidos mostram que S. convoluta pode ser uma boa fonte de compostos fenólicos antioxidantes. Estudos posteriores serão realizados para se chegar ao isolamento e identificação dos principais constituintes fenólicos dos extratos.

Selaginella convoluta is a species of "spike moss" (an order of pteridophytes) known in Northeast Brazil as "jericó" and widely used in popular medicine to treat several diseases. Phenolic compounds were determined in extracts of whole Selaginella convoluta plants. The total phenolics content was determined by the Folin-Ciocalteu method. Total flavonoid content was also measured. Antioxidant activities of the extracts were assayed by DPPH radical scavenging and inhibition of β-carotene-linoleic acid bleaching and compared with ascorbic acid, BHA, BHT, quercetin and pyrogallol, used as reference compounds. The total phenolics contents of ethyl acetate (EtOAc) and crude ethanol extract (CEE) were 209.90 ± 19.84 and 61.13 ± 2.50 mg of gallic acid equivalent/g, respectively. The total flavonoids contents were 155.70 ± 6.21 and 62.13 ± 4.10 mg of catechin equivalent/g for the two extracts, respectively. The EtOAc and CEE extracts exhibited good antioxidant activities. BHA was the most effective antioxidant, with an IC50 of 1.62 ± 0.69 μg/ml. The results show that S. convoluta could be a good source of antioxidant phenolics. Further research will be carried out to achieve the isolation and identification of the main phenolic constituents of the extracts.

Anthraquinones from the bark of Senna macranthera

2-acetyl physcion (2-acetyl-1,8-dihydroxy-6-methoxy-3-methyl-9,10-anthraquinone, 2), a rare anthraquinone, was isolated from Senna macranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). The chemical structure was elucidated and all ¹H and 13C NMR chemical shifts were assigned by NMR one- (¹HNMR, {¹H}-13CNMR, and APT-13CNMR) and two (COSY, NOESY, HMQC and HMBC) dimensional of this natural compound. Furthermore, the minor anthraquinones chrysophanol (3), chrysophanol-8-methyl ether (4) and physcion (5) were characterized by GC-MS analysis. The occurrence of the anthraquinones 3-5 confirms that S. macranthera is a typical representative of the genus Senna.

2-acetil-fisciona (2-acetil-1, 8-di-hidróxi-6-metóxi-3-metil-9, 10-antraquinona, 2), uma antraquinona rara, foi isolada de Senna acranthera var. nervosa (Vogel) H.S. Irwin & Barneby (Fabaceae). estrutura química foi elucidada e todos os deslocamentos químicos de RMN ¹H e 13C foram atribuídos através de RMN uni- (RMN¹H, {¹H}-RMN-13C e APT-RMN13C) e bi- (COSY, NOESY, HMQC e HMBC) dimensional deste composto natural. Adicionalmente, as antraquinonas minoritárias crisofanol (3), crisofanol-8-metil éter (4) e fisciona (5) foram caraterizadas pela análise de CG-EM. A ocorrência das antraquinonas 3-5 confirma que S. macranthera é uma típica representante do gênero Senna.

Evaluation of anthelmintic activity of liquid waste of Agave sisalana (sisal) in goats / Avaliação da atividade anti-helmíntica do resíduo líquido de Agave sisalana (sisal) em caprinos

It was evaluated the anthelmintic activity of Agave sisalana (sisal) juice against gastrointestinal nematodes and its potential toxic effects in goats. In vitro tests showed more than 95 percent reduction in larval counts of the genus Haemonchus spp. at concentrations between 86.5 and 146.3 mg.mL-1. In vivo the percent reduction of larvae of the fourth (L4) and fifth (L5) stages of Haemonchus, Oesophagostomum and Trichostrongylus was less than 95 percent in groups GI and GII, and between 80 and 90 percent in group GIII. A. sisalana juice at the concentrations tested in vitro was effective against gastrointestinal nematodes in goats; however, its anthelmintic efficacy was reduced when administered to animals.

Foi avaliada a atividade anti-helmíntica do suco de Agave sisalana (sisal) contra nematódeos gastrintestinais e possíveis efeitos tóxicos em caprinos. Nos testes in vitro, encontrou-se redução superior a 95 por cento na contagem de larvas do gênero Haemonchus spp. nas concentrações entre 86,5 e 146,3 mg.mL-1. In vivo, o percentual de redução de larvas de quarto (L4) e quinto (L5) estágios de Haemonchus, Oesophagostomum e Trichostrongylus foi inferior a 95 por cento para o GI e GII, e entre 80 e 90 por cento para o GIII. O suco de A. sisalana nas concentrações testadas in vitro foi efetivo contra nematódeos gastrintestinais de caprinos, apresentando, no entanto, reduzida eficácia anti-helmíntica quando administrado nos animais.

Caracterização morfoanatômica de folhas e caules de Microlicia hatschbachii Wurdack, Melastomataceae

Este trabalho apresenta o estudo morfoanatômico das folhas e caules de Microlicia hatschbachii Wurdack, Melastomataceae. Esta espécie possui folhas elípticas a oval-elípticas, margem inteira, ápice agudo e base simétrica e arredondada. A lâmina foliar é anfiestomática, com estômatos do tipo anisocítico e anomocítico, a epiderme é uniestratificada, com células isodiamétricas em secção transversal, e presença de inúmeros tricomas glandulares. O mesofilo é do tipo isobilateral com feixe vascular bicolateral envolvido por algumas células esclerenquimáticas na nervura central. O caule tem secção quadrangular a circular e epiderme unisseriada, com tricomas similares aos da folha. Drusas de oxalato de cálcio foram encontradas nas folhas e no caule.

This work shows the morpho-anatomical study of leaf and stem of Microlicia hatschbachii Wurdack (Melastomataceae). Its leaves are elliptic to oval-elliptic, with entire margin, acute apex and rounded symmetrical base. The leaf blade is amphistomatical with anisocytic and anomocytic stomata, in transection the epidermis is uniseriate with isodiametric cells and presence of several glandular trichomes. The mesophyll is isobilateral with bicollateral vascular bundles surrounded by some sclerenchymatic cells in midrib. The stem has a quadrangular to circular transection and uniseriate epidermis with trichomes like ones of leaf. Several druses of calcium oxalate are found in the leaf and stem.

Rubrofusarina, um policetídeo natural inibidor da topoisomerase II-α humana / Rubrofusarin, a natural polyketide as new human topoisomerase II-α inhibitor

Este trabalho descreve o efeito inibitório de rubrofusarina (5,6-diidroxi-8-metoxi-2-metilbenzo[g]cromen-4-ona, 1) sobre a enzima DNA topoisomerase II-α humana. Rubrofusarina mostrou total inibição da enzima topisomerase II-α na concentração de 120 µM. Este resultado é semelhante ao observado com etoposida, utilizada como controle positivo. Para a realização deste teste, rubrofusarina foi isolada de Senna macranthera var. nervosa (Voguel) Irwin & Barnebyem e caracterizada por métodos espectroscópicos, incluindo RMN 2D, do produto natural bem como de seu derivado monoacetilado.

This work describes the inhibitory effect of rubrofusarin (5,6-dihydroxy-8-methoxy-2-methylbenzo[g]cromen-4-one, 1) against human DNA topoisomerase II-α. The results for relaxation assays showed total inhibition of topisomerase II-α by rubrofusarin at 120 µM. This result is comparable to the one observed with etoposide as positive control. For this study, rubrofusarin was isolated from Senna macranthera var. nervosa (Voguel) Irwin & Barnebyem and characterized by spectral data, including 2D NMR, as well as its acetylated derivative.

Antimicrobial activity of wax and hexane extracts from Citrus spp. peels

Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin) from C. limon.

Complete ¹H and 13C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- (¹HNMR, {¹H}-13C NMR, and APT-13C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete ¹H and 13C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated.

Os flavonóis 8-hidroxi-3, 4', 5, 6, 7-pentametoxiflavona (1) e 8-hidroxi-3, 3', 4', 5, 6, 7-hexametoxiflavona (2) foram isolados em mistura a partir de uma amostra comercial de Citrus aurantifolia. A determinação estrutural e a inequívoca atribuição dos sinais de deslocamento químico dos átomos de hidrogênio e carbono destes compostos naturais foram realizadas através da análise dos espectros de RMN 1D e 2D, incluindo COSY, NOESY, HMQC e HMBC. Em adição, a atividade antifúngica destes compostos contra fungos patogênicos também foiinvestigada.