Márcio Luis Andrade e Silva

In vitro antileishmanial, antiplasmodial and cytotoxic activities of phenolics and triterpenoids from Baccharis dracunculifolia D. C. (Asteraceae)

Baccharis dracunculifolia (Asteraceae), the most important plant source of the Brazilian green propolis (GPE), displayed in vitro activity against Leishmania donovani, with an IC(50) value of 45 microg/mL, while GPE presented an IC(50) value of 49 microg/mL. Among the isolated compounds of B. dracunculifolia, ursolic acid, and hautriwaic acid lactone showed IC(50) values of 3.7 microg/mL and 7.0 microg/mL, respectively. Uvaol, acacetin, and ermanin displayed moderate antileishmanial activity. Regarding the antiplasmodial assay against Plasmodium falciparum, BdE and GPE gave similar IC(50) values (about 20 microg/mL), while Hautriwaic acid lactone led to an IC(50) value of 0.8 microg/mL (D6 clone).

Purification, biochemical characterisation and partial primary structure of a new α-amylase inhibitor from Secale cereale (rye)

Plant alpha-amylase inhibitors show great potential as tools to engineer resistance of crop plants against pests. Their possible use is, however, complicated by the observed variations in specificity of enzyme inhibition, even within closely related families of inhibitors. Better understanding of this specificity depends on modelling studies based on ample structural and biochemical information. A new member of the alpha-amylase inhibitor family of cereal endosperm has been purified from rye using two ionic exchange chromatography steps. It has been characterised by mass spectrometry, inhibition assays and N-terminal protein sequencing. The results show that the inhibitor has a monomer molecular mass of 13,756 Da, is capable of dimerisation and is probably glycosylated. The inhibitor has high homology with the bifunctional alpha-amylase/trypsin inhibitors from barley and wheat, but much poorer homology with other known inhibitors from rye. Despite the homology with bifunctional inhibitors, this inhibitor does not show activity against mammalian or insect trypsin, although activity against porcine pancreatic, human salivary, Acanthoscelides obtectus and Zabrotes subfasciatus alpha-amylases was observed. The inhibitor is more effective against insect alpha-amylases than against mammalian enzymes. It is concluded that rye contains a homologue of the bifunctional alpha-amylase/trypsin inhibitor family without activity against trypsins. The necessity of exercising caution in assigning function based on sequence comparison is emphasised.

Antiprotozoal, schistosomicidal, and antimicrobial activities of the essential oil from the leaves of Baccharis dracunculifolia.

Baccharis dracunculifolia DC. (Asteraceae), popularly known as ‘alecrim do campo’, is a native plant from Brazil used in folk medicine as febrifuge, anti‐inflammatory, antiseptic, and to treat skin sores. Also, B. dracunculifolia is the most important plant source of the Brazilian green propolis, which is recognized for its antiseptic and antiprotozoal activities. This study aimed at investigating the in vitro antiprotozoal, schistosomicidal, and antimicrobial activities of the essential oil from the leaves of B. dracunculifolia. The essential oil was obtained by hydrodistillation and analyzed by GC and GC/MS, which allowed the identification of 14 compounds, mainly oxygenated sesquiterpenes, such as (E)‐nerolidol (33.51%) and spathulenol (16.24%). The essential oil showed activity against promastigote forms of Leishmania donovani, with IC50 values of 42 μg/ml. The essential oil displayed high activity in the schistosomicidal assay, since all pairs of Schistosoma mansoni adult worms were dead after incubation with the essential oil (10, 50, and 100 μg/ml). B. dracunculifolia essential oil was neither cytotoxic against Vero cells, nor active in the antimicrobial and antiplasmodial assays.

Halogenated indole alkaloids from marine invertebrates.

This review discusses the isolation, structural elucidation, and biological activities of halogenated indole alkaloids obtained from marine invertebrates. Meridianins and related compounds (variolins, psammopemmins, and aplicyanins), as well as aplysinopsins and leptoclinidamines, are focused on. A compilation of the 13C-NMR spectral data of these selected natural indole alkaloids is also provided.

Antimicrobial activity of Syzygium cumini (Myrtaceae) leaves extract

The antimicrobial activity of Syzygium cumini leaves extract, known as “jambolao”, was evaluated. The crude hydroalcoholic extract was active against Candida krusei (inhibition zone of 14.7 ± 0.3 mm and MIC = 70 µg/ mL), and against multi-resistant strains of Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus.

Estudo comparativo de técnicas de screening para avaliação da atividade anti-bacteriana de extratos brutos de espécies vegetais e de substâncias puras

In this work, the effectiveness of four screening techniques (three techniques of the diffusion method and one microdilution broth method) were compared. Evaluated were the ethanolic and dichloromethanic extracts of Miconia rubiginosa (Melastomataceae) against six standard bacteria (ATCC). The results showed statistical disagreement among the three diffusion techniques. Among the diffusion techniques, the well technique displayed the best result. However the microdilution broth method demonstrated to be the most adequate method to evaluate the antibacterial activity of plant crude extracts and pure compounds when compared to the other methodologies.

In-vitro trypanocidal activity evaluation of crude extract and isolated compounds from Baccharis dracunculifolia D. C. (Asteraceae)

We have performed a trypanocidal bioactivity‐guided study of Baccharis dracunculifolia (Asteraceae), the main botanical origin of Brazilian green propolis. The leaf rinse extract of B. dracunculifolia, at a concentration of 3.0 mg mL−1, displayed 100% lysis of trypomastigote forms of the Y strain of Trypanosoma cruzi (2 times 106 parasites mL−1). The chromatographic fractionation of the leaf rinse, using several techniques, afforded the isolation of the compounds isosakuranetin (1), aromadendrin‐4′‐methylether (2), baccharis oxide (3), ferulic acid (4), dihydrocinnamic acid (5), 3‐prenyl‐4‐(dihydrocinnamoyloxy)‐cinnamic acid (6), and friedelanol (7). The chemical structures of all compounds were established by UV‐vis, 1H and 13C NMR data analysis in comparison with the literature. Compounds 1 and 3 were the most active in the trypanocidal assay, showing IC50 values (inhibitory concentration required for 50% inhibition) of 247.6 and 249.8 μM, respectively. Compounds 2, 4, and 6 displayed moderate activity, whilst compounds 5 and 7 were inactive.

Antimicrobial activity of Rosmarinus officinalis against oral pathogens: relevance of carnosic acid and carnosol.

The in vitro inhibitory activity of crude EtOH/H2O extracts from the leaves and stems of Rosmarinus officinalis L. was evaluated against the following microorganisms responsible for initiating dental caries: Streptococcus mutans, S. salivarius, S. sobrinus, S. mitis, S. sanguinis, and Enterococcus faecalis. Minimum inhibitory concentrations (MIC) were determined with the broth microdilution method. The bioassay‐guided fractionation of the leaf extract, which displayed the higher antibacterial activity than the stem extract, led to the identification of carnosic acid (2) and carnosol (3) as the major compounds in the fraction displaying the highest activity, as identified by HPLC analysis. Rosmarinic acid (1), detected in another fraction, did not display any activity against the selected microorganisms. HPLC Analysis revealed the presence of low amounts of ursolic acid (4) and oleanolic acid (5) in the obtained fractions. The results suggest that the antimicrobial activity of the extract from the leaves of R. officinalis may be ascribed mainly to the action of 2 and 3.

In vitro antileishmanial and antimalarial activities of tetrahydrofuran lignans isolated from Nectandra megapotamica (Lauraceae)

Seven tetrahydrofuran lignans, isolated from Nectandra megapotamica (Lauraceae), were evaluated for their in vitro antileishmanial and antimalarial activities. Among the evaluated compounds, machilin‐G (1a) and veraguensin (2a) showed the highest antileishmanial activities, displaying for both compounds an IC50 value of 18 µg/mL and an IC90 value of 36 µg/mL, while galgravin (1b), nectandrin‐A (1c), nectandrin‐B (1d), calopeptin (2b) and ganshisandrine (3) were inactive against Leishmania donovani. In the antimalarial assay against Plasmodium falciparum, it was observed that calopeptin (2b) displayed moderate activity, with IC50 values of 3800 ng/mL (D6 clone) and 3900 ng/mL (W2 clone), while the lignans 1a–1d, 2a and 3 were inactive. In order to compare the effect on the parasites with toxicity to mammalian cells, the cytotoxic activity of the isolated compounds were evaluated against the Vero cells, showing that all evaluated tetrahydrofuran lignans exhibited no cytotoxicity at the maximum dose tested. Copyright

In vivo Analgesic and Anti-Inflammatory Activities of Ursolic Acid and Oleanoic Acid from Miconia albicans (Melastomataceae)

The aim of this work was to use in vivo models to evaluate the analgesic and anti-inflammatory activities of ursolic acid (UA) and oleanoic acid (OA), the major compounds isolated as an isomeric mixture from the crude methylene chloride extract of Miconia albicans aerial parts, in an attempt to clarify if these compounds are responsible for the analgesic properties displayed by this plant. Ursolic acid inhibited abdominal constriction in a dose-dependent manner, and the result obtained at a content of 40 mg kg-1 was similar to that produced by administration of acetylsalicylic acid at a content of 100 mg kg-1. Both acids reduced the number of paw licks in the second phase of the formalin test, and both of them displayed a significant anti-inflammatory effect at a content of 40 mg kg-1. It is noteworthy that the administration of the isolated mixture, containing 65% ursolic acid/35% oleanolic acid, did not display significant analgesic and anti-inflammatory activities. On the basis of the obtained results, considering that the mixture of UA and OA was poorly active, it is suggested that other compounds, rather than UA and OA, should be responsible for the evaluated activities in the crude extract, since the crude extract samples displayed good activities.