Dionéia Camilo Rodrigues de Oliveira

Antimicrobial activity of flavonoids and steroids isolated from two Chromolaena species

The crude extracts (dichloromethanic and ethanolic) and some compounds (8 flavonoids and 5 steroids) isolated from Chromolaena squalida (leaves and stems) and Chromolaena hirsuta (leaves and flowers) have been evaluated against 22 strains of microorganisms including bacteria (Gram-positive and Gram-negative) and yeasts. All crude extracts, flavonoids and steroids evaluated have been shown actives, mainly against Gram-positive bacteria.

Antimicrobial Activity of Kaurane Diterpenes against Oral Pathogens

Two kaurane diterpenes, ent-kaur-16(17)-en-19-oic acid (KA) and 15-β-isovaleryloxy-entkaur- 16(17)-en-19-oic acid (KA-Ival), isolated from Aspilia foliacea, and the methyl ester derivative of KA (KA-Me) were evaluated against oral pathogens. KA was the most active compound, with MIC values of 10 μg mL-1 against the following microorganisms: Streptococcus sobrinus, Streptococcus mutans, Streptococcus mitis, Streptococcus sanguinis, and Lactobacillus casei. However, KA did not show significant activity against Streptococcus salivarius and Enterococcus faecalis, with MIC values equal to 100 and 200 μg mL-1, respectively. Our results show that KA has potential to be used as a prototype for the discovery of new effective anti-infection agents against microorganisms responsible for caries and periodontal diseases. Moreover, these results allow to conclude that minor structural differences among these diterpenes significantly influence their antimicrobial activity, bringing new perspectives to studies on the structure-activity relationship of this type of metabolites with respect to caries and periodontal diseases.

Pharmacological comparison of the vasorelaxant action displayed by kaurenoic acid and pimaradienoic acid.

The vascular effects of two natural occurring diterpenes from the kaurane and pimarane classes were compared. The diterpenes ent‐kaur‐16‐en‐19‐oic acid (kaurenoic acid; KA) and ent‐pimara‐8(14), 15‐dien‐19‐oic acid (pimaradienoic acid; PA) were tested for their antispasmodic activity on isolated rat aorta. Vascular reactivity experiments, using standard muscle bath procedures, showed that KA and PA (both at 50 and 100 μm) inhibited phenylephrine and KCl‐induced contraction in both endothelium‐intact and endothelium‐denuded rat aortic rings, with PA being more effective than KA. These compounds also reduced CaCl2‐induced contraction in Ca2+‐free solution containing KCl (30 mm). Again, PA produced a greater reduction in CaCl2‐induced contraction than KA. PA (1–300 μm) and KA (1–450 μm) concentration dependently relaxed endothelium‐denuded aortic rings pre‐contracted with KCl (maximum relaxation 102.31 ± 6.94% and 82.71 ± 1.40%, respectively). Similarly, the relaxation induced by KA on aortic rings pre‐contracted with phenylephrine (73.06 ± 3.68%) was less pronounced than that found for PA (102.21 ± 3.64%). Incubation of endothelium‐denuded rings for different periods showed that at 50 μm, KA and PA achieved maximum inhibitory activity on KCl‐induced contraction after incubation for 60 (53.48 ± 5.83%) and 30 min (83.89 ± 2.12%), respectively. At 100 μm, KA and PA inhibited KCl‐induced contraction, with a maximum after incubation for 30 min (73.58 ± 5.30% and 92.07 ± 1.20%, respectively). The maximum inhibition induced by PA at both concentrations tested was greater than that induced by KA. The results provide evidence that structural differences between diterpenes, independent of the C‐19 carboxylic acid site, influence selectivity for voltage‐operated Ca2+ channels and rate of equilibrium with the target site for their vasorelaxant action in rat aortic rings.

DOSY NMR applied to analysis of flavonoid glycosides from Bidens sulphurea.

2D DOSY 1H NMR has proved to be a useful technique in the identification of the molecular skeleton of the four major compounds of ethyl acetate extract of aerial parts of Bidens sulphurea (Asteraceae). The combination of this technique with HPLC, mass spectrometry and other NMR techniques enabled the identification of four flavonoid glycosides: quercetin‐3‐O‐β‐D‐galactopyranoside, quercetin‐3‐O‐β‐D‐glycopyranoside, quercetin‐3‐O‐α‐L‐arabinofuranoside and quercetin‐3‐O‐β‐D‐rhamnopyranoside. Copyright

Differences in secondary metabolites from leaf extracts of Mikania glomerata Sprengel obtained by micropropagation and cuttings

GC analysis of the dichloromethane extracts obtained from cultivated specimens of Mikania glomerata Sprengel possibilited to verify that cuttings technique led to production of kaurenoic acid and coumarin while the same results have not been observed by propagation process using in vitro techniques.

Role of the carboxylic group in the antispasmodic and vasorelaxant action displayed by kaurenoic acid

The present work describes the investigation of the role of the carboxylic group in the structure‐activity relationship of the diterpene ent‐kaur‐16‐en‐19‐oic acid (kaurenoic acid, KA) in inhibiting rat aorta contraction. For this purpose the methylation of the C‐19 carboxyl group of KA was carried out. The effects of the obtained ent‐methyl‐kaur‐16‐en‐19‐oate (KAMe) were compared with those induced by KA. Vascular reactivity experiments showed that KA (50 and 100 μm) concentration‐dependently inhibited KCl‐induced contraction in both endothelium‐intact and denuded rat aortic rings. On the other hand, KAMe attenuated KCl‐induced contraction at 100 μm, but not at 50 μm. KA also reduced CaCl2‐induced contraction in Ca2+‐free solution containing KCl (30 mM). Again, KAMe produced a less accentuated reduction in CaCl2‐induced contraction than that induced by the acid KA. KAMe (1–450 μm) concentration‐dependently relaxed KCl‐pre‐contracted rings (percentages of relaxation 82.57±1.65 and 70.55±4.71, respectively) with denuded endothelium. Similarly, the relaxation induced by KA on phenylephrine (Phe)‐pre‐contracted rings (73.06±3.68%) was more pronounced than that found for KAMe (53.68±4.75%). Pre‐incubation of denuded rings for different periods with KA and KAMe showed that the equilibrium periods required by each compound to achieve its maximal inhibitory response on KCl‐induced contraction are different. Collectively, our results provide functional evidence that methylation of the C‐19 carboxyl group of KA reduces but does not abolish the antispasmodic activity displayed by KA. Additionally, we showed that the equilibrium period is a critical step for the inhibitory effect displayed by kaurane‐type diterpenes.

Trypanocidal and antifungal activities of p-hydroxyacetophenone derivatives from Calea uniflora (Heliantheae, Asteraceae).

The dichloromethane extract of underground parts of Calea uniflora (Heliantheae, Asteraceae) exhibited trypanocidal and antifungal activities. Four p‐hydroxyacetophenone derivatives were isolated as the main compounds: 2‐senecioyl‐4‐(hydroxyethyl)‐phenol (1), 2‐senecioyl‐4‐(angeloyloxy‐ethyl)‐phenol (2), and two new derivatives, 2‐senecioyl‐4‐(methoxyethyl)‐phenol (3) and 2‐senecioyl‐4‐(pentadecanoyloxyethyl)‐phenol (4). 1 and 4 were active towards Trypanosoma cruzi trypomastigotes, reducing their number by 70 and 71% at 500 μg mL−1, whereas 2 and 3 were inactive. All the compounds tested showed antifungal activity with minimal inhibitory concentration values between 500 and 1000 μg mL−1 against pathogenic Candida spp. and dermatophytes. The isolation, structure elucidation, NMR spectral assignments and bioactivity results of these compounds are reported.

Kaurene diterpenes and other chemical constituents from Mikania stipulacea (M. Vahl) willd

Phytochemical study of Mikania stipulacea yielded lupeol, a-amyrin, stigmasterol, b-sitosterol, campesterol, b-sitosteryl glucopyranoside, stigmasteryl glucopyranoside, the coumarin isoscopoletin, and vanillic, cinnamoylgrandifloric and ent-kaurenoic acids, besides two new diterpene acids: ent-9a-hydroxy-15b-E-cinnamoyloxy-16-kauren-19-oic and ent-9a-hydroxy-15b-Z-cinnamoyloxy-16-kauren-19-oic. IR, 1H and 13C NMR and MS spectroscopic analyses were used for the identification of these compounds.

Anticariogenic properties of ent-pimarane diterpenes obtained by microbial transformation.

In the present work, the anticariogenic activities of three pimarane-type diterpenes obtained by fungal biotransformation were investigated. Among these metabolites, ent-8(14),15-pimaradien-19-ol was the most active compound, displaying very promising MIC values (ranging from 1.5 to 4.0 μg mL−1) against the main microorganisms responsible for dental caries: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, and Lactobacillus casei. Time kill assays performed with ent-8(14),15-pimaradien-19-ol against the primary causative agent S. mutans revealed that this compound only avoids growth of the inoculum in the first 12 h (bacteriostatic effect). However, its bactericidal effect is clearly noted thereafter (between 12 and 24 h). The curve profile obtained by combining ent-8(14),15-pimaradien-19-ol and chlorhexidine revealed a significant reduction in the time necessary for killing S. mutans compared with each of these two chemicals alone. However, no synergistic effect was observed using the same combination in the checkerboard assays against this microorganism. In conclusion, our results point out that ent-8(14),15-pimaradien-19-ol is an important metabolite in the search for new effective anticariogenic agents.

Transdermal Delivery of Ketoprofen: The Influence of Drug–Dioleylphosphatidylcholine Interactions

PurposeConsidering that most inflammatory diseases occur locally and near the body surface, transdermal delivery of non-steroidal anti-inflammatory drugs (NSAIDs) may be an interesting strategy for delivering these drugs directly to the diseased site. To optimize ketoprofen (KP) transdermal delivery we investigated the influence of dioleylphosphatidylcholine (DOPC) on skin permeation.Materials and MethodsThe formulations studied were: i) a physical mixture of KP and DOPC and ii) DOPC and KP complex, in a molar ratio of 1:3, obtained by dissolution of the components in chloroform followed by drying under a N2 atmosphere. Both systems were dispersed in mineral oil and the in vitro percutaneous was assayed by absorption using a flow through diffusion cell. Differential Scanning Calorimetry (DSC) and 1H NMR studies were carried out to characterize KP and DOPC interactions. Geometry optimizations using Density Functional Theory and semiempirical methods, as well as a flexible docking procedure were carried out to obtain a binding model for KP with DOPC. KP solubility and partition studies in the formulations, as well as skin irritation and hypersensitivity assays were also carried out.ResultsDSC determinations in the complex showed enthalpy and temperature depressions, indicating KP and DOPC interaction. In addition, dipole–dipole interactions between the KP carboxylic acid and OH groups in phospholipids were shown by 1H NMR studies. Based on the NMR studies, a KP–DOPC binding model is proposed, in which KP is involved by the two long aliphatic chains of the phospholipid. Solubility studies indicated that DOPC improved drug solubility. KP permeation was enhanced by both formulations tested, but the complex also increased its skin uptake. Such behavior could be attributed to the solubilizing, melting and enhancing effects of DOPC. Skin irritation and hypersensitivity were not significantly changed compared to control, suggesting that the formulation may be therapeutically explored for KP transdermal delivery.