Ent-kaurenoic acid-enriched Mikania glomerata leaves-complexed ß-cyclodextrin: Pharmaceutical development and in vivo antitumor activity in a sarcoma 180 mouse model.

The extract obtained from Mikania glomerata leaves rich in ent-kaurenoic acid (ERKA) shows cytotoxic activity in vitro, but its hydrophobic nature and thermosensitivity are issues to be solved prior to in vivo antitumor studies. The purpose of this study was to investigate the antitumor activity of inclusion complexes formed between ERKA and ß-cyclodextrin (ERKA:ß-CD) in rodents. ERKA:ß-CD complexes obtained by malaxation (MX) and co-evaporation (CE) methods were firstly characterized regarding their physical properties, encapsulation efficiency, and cytotoxicity againts L929 cells. The antitumor activity study was then performed in mice with sarcoma 180 treated with saline, 5-fluouracil (5FU) and ERKA:ß-CD at 30, 100 and 300 µg/kg. The weight, volume, percentage of inhibition growth, gross and pathological features and positivity for TUNEL, ki67, NFκB and NRF2 in the tumors were assessed. Serum lactate-dehydrogenase activity (LDH), white blood cells count (WBC) and both gross and pathological features of the liver, kidneys and spleen were also evaluated. The formation of the inclusion complexes was confirmed by thermal analysis and FTIR, and they were non-toxic for L929 cells. The MX provided a better complexation efficiency. ERKA:ß-CD300 promoted significant tumor growth inhibition, and attenuated the tumor mitotic activity and necrosis content, comparable to 5-fluorouracil. ERKA:ß-CD300 also increased TUNEL-detected cell death, reduced Ki67 and NF-kB immunoexpression, and partially inhibited the serum LDH activity. No side effect was observed in ERKA:ß-CD300-treated animals. The ERKA:ß-CD inclusion complexes at 300 µg/kg displays antitumour activity in mice with low systemic toxicity, likely due to inhibition on the NF-kB signaling pathway and LDH activity.

A reliable validated high-performance liquid chromatography-photodiode array detection method for quantification of terpenes in Copaifera pubiflora, Copaifera trapezifolia, and Copaifera langsdorffii oleoresins.

The Copaifera oleoresins are widely used in folk medicine to treat various diseases. The goal of this study was to develop a validated reverse-phase high-performance liquid chromatography method with photodiode array detection (RP-HPLC-PDA) to quantify eight terpenes: ent-hardwickiic acid, ent-copalic acid, ent-7α-acetoxy hardwickiic acid, ent-16-hydroxy-3,13-clerodadiene-15,18-dioic acid, ent-5,13-labdadiene-15-oic acid, junenol, ent-kaurenoic acid, and 13E-ent-labda-7,13-dien-15-oic acid in the oleoresins of Copaifera pubiflora L. (OCP), Copaifera trapezifolia L. (OCT) and Copaifera langsdorffii L. (OCL). The linearity of the method was confirmed in the range of 20.00-500 µg.mL-1 (r2 > 0.999). The limit of quantification was between 1,05 and 16.89 µg.mL-1. Precision and accuracy ranges were found to be %RSD <0.2 and 96% to 110%, respectively. Based on the obtained results, the developed analytical method is rapid, precise, accurate, and sensitive for quantifying these terpenes in Copaifera's oleoresins.

Brazilian green propolis reduces worm burden and hepatic granuloma formation in a Schistosoma mansoni experimental murine model.

Characterized as an acute and chronic parasitic disease, schistosomiasis mansoni has as its central pathology the formation of hepatic granulomas in response to the parasite's eggs trapped in the host's liver. In recent years, research on propolis has grown; however, there is little anthelmintic work on this bee product. In the propolis scenario, Brazilian ones receive attention, with green and red propolis standing out. This study aims to evaluate in vivo the standardized extract of Brazilian green propolis (Pex) against Schistosoma mansoni. The in vivo antiparasitic activity of Pex was conducted in female BALB/c mice infected with S. mansoni and of the three groups treated with Pex (300 mg/kg); G2 (35th to 42nd dpi) reduced the total worm burden by 55.32%, followed by G3 (42nd to 49th dpi) and G4 (49th to 56th dpi), with about 46%. Furthermore, G2 significantly reduced the total egg load in the ileum (59.33%) and showed an increase in the dead eggs. Similarly, histological analysis of the livers showed a significant reduction in the number and diameter of the granulomas. Based on these results, there is an interesting schistosomicidal activity of Pex and its potential against the formation of hepatic granulomas, paving the way for more detailed studies of propolis in the animal model of schistosomiasis mansoni.

Detailed 1 H and 13 C NMR structural assignment of ent-polyalthic acid, a biologically active labdane diterpene.

In this paper, a complete 1 H and 13 C NMR data assignment of ent-polyalthic acid, a biologically active labdane-type diterpene, is presented. The assignments were carried on the basis of spectroscopic data from 1 H NMR, 13 C{1 H} NMR, gCOSY, gHMQC, and gHMBC experiments. Furthermore, a software-assisted methodology, using FOMSC3_rm_NB and NMR_MultSim programs, supported the detailed and unequivocal assignment of 1 H and 13 C signals, allowing all hydrogen coupling constants to be determined and thus clarifying all hydrogen signal multiplicities.

Sphagneticola trilobata (L.) Pruski-derived kaurenoic acid prevents ovalbumin-induced asthma in mice: Effect on Th2 cytokines, STAT6/GATA-3 signaling, NFκB/Nrf2 redox sensitive pathways, and regulatory T cell phenotype markers.

ETHNOPHARMACOLOGICAL RELEVANCE: Sphagneticola trilobata (L.) Pruski is used in traditional medicine in Brazil for inflammatory diseases treatment including asthma. The diterpene kaurenoic acid (KA) is one of its active compounds, but whether KA activity could explain the traditional use of S. trilobata in asthma is unknown. AIM: Investigate KA effect and mechanisms in asthma. METHODS: Experimental asthma was induced by ovalbumin immunization and challenge in male Swiss mice. KA (0.1-10 mg/kg, gavage) was administered 1 h before the ovalbumin challenge. Total leukocytes, eosinophil, and mast cell were counted in bronchoalveolar lavage fluid (BALF), and lung histopathology was performed. Lung mRNA expression of Th2 and regulatory T cells markers, and BALF type 2 cytokine production were quantitated. NFκB activation and oxidative stress-related components in pulmonary tissue were measured. RESULTS: KA inhibited the migration of total leukocytes and eosinophils to BALF, reduced lung histopathology (inflammatory cells and mast cells), mRNA expression of IL-33/ST2, STAT6/GATA-3 and NFκB activation in the lung, and reduced IL-33, IL-4, IL-5 production in the BALF. KA also reduced the mRNA expression of iNOS and gp91phox, and superoxide anion production accompanied by the induction of Nrf2, HO-1 and NQO1 mRNA expression, thus, exerting an antioxidant effect. Finally, KA induced nTreg-like and Tr1-like, but not Th3-like markers of suppressive T cell phenotypes in the lung tissue. CONCLUSION: KA prevents antigen-induced asthma by down-regulating Th2 and NFκB/cytokine-related pathways, and up-regulating Nrf2 and regulatory T cells' markers. Thus, explaining the ethnopharmacological use of S. trilobata for the treatment of lung inflammatory diseases.

Antiparasitic Properties of Propolis Extracts and Their Compounds.

Propolis is a bee product that has been used in medicine since ancient times. Although its anti-inflammatory, antioxidant, antimicrobial, antitumor, and immunomodulatory activities have been investigated, its anti-parasitic properties remain poorly explored, especially regarding helminths. This review surveys the results obtained with propolis around the world against human parasites. Regarding protozoa, studies carried out with the protozoa Trypanosoma spp. and Leishmania spp. have demonstrated promising results in vitro and in vivo. However, there are fewer studies for Plasmodium spp., the etiological agent of malaria and less so for helminths, particularly for Fasciola spp. and Schistosoma spp. Despite the favorable in vitro results with propolis, helminth assays need to be further investigated. However, propolis has shown itself to be an excellent natural product for parasitology, thus opening new paths and approaches in its activity against protozoa and helminths.

Green and Red Brazilian Propolis: Antimicrobial Potential and Anti-Virulence against ATCC and Clinically Isolated Multidrug-Resistant Bacteria.

Brazilian green and red propolis stand out as commercial products for different medical applications. In this article, we report the antimicrobial activities of the hydroalcoholic extracts of green (EGP) and red (ERP) propolis, as well as guttiferone E plus xanthochymol (8) and oblongifolin B (9) from red propolis, against multidrug-resistant bacteria (MDRB). We undertook the minimal inhibitory (MIC) and bactericidal (MBC) concentrations, inhibition of biofilm formation (MICB50 ), catalase, coagulase, DNase, lipase, and hemolysin assays, along with molecular docking simulations. ERP was more effective by displaying MIC and MBC values <100 µg mL-1 . Compounds 8 and 9 displayed the lowest MIC values (0.98 to 31.25 µg mL-1 ) against all tested Gram-positive MDRB. They also inhibited the biofilm formation of S. aureus (ATCC 43300 and clinical isolate) and S. epidermidis (ATCC 14990 and clinical isolate), with MICB50 values between 1.56 and 6.25 µg mL-1 . The molecular docking results indicated that 8 and 9 might interact with the catalase's amino acids. Compounds 8 and 9 have great antimicrobial potential.

The diterpene from Sphagneticola trilobata (L.) Pruski, kaurenoic acid, reduces lipopolysaccharide-induced peritonitis and pain in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Sphagneticola trilobata (L.) Pruski is a plant species belonging to the Asteraceae family. Kaurenoid acid (KA) is a diterpene metabolite and one of the active ingredients of Sphagneticola trilobata (L.) Pruski. Extracts containing KA are used in traditional medicine to treat pain, inflammation, and infection. AIM: The goal of the present study was to investigate the in vivo effects of KA (1-10 mg/kg, per oral gavage) upon LPS inoculation in mice by intraperitoneal (i.p.) or intraplantar (i.pl.; subcutaneous plantar injection) routes at the dose of 200 ng (200 µL or 25 µL, respectively). METHODS: In LPS paw inflammation, mechanical and thermal hyperalgesia MPO activity and oxidative imbalance (TBARS, GSH, ABTS and FRAP assays) were evaluated. In LPS peritonitis we evaluated leukocyte migration, cytokine production, oxidative stress, and NF-κB activation. RESULTS: KA inhibited LPS-induced mechanical and thermal hyperalgesia, MPO activity and modulated redox status in the mice paw. Pre- and post-treatment with KA inhibited migration of neutrophils and monocytes in LPS peritonitis. KA inhibited the pro-inflammatory/hyperalgesic cytokine (e.g., TNF-α, IL-1ß and IL-33) production while enhanced anti-inflammatory/analgesic cytokine IL-10 in peritoneal cavity. In agreement with the effect of KA over pro-inflammatory cytokines it inhibited oxidative stress (total ROS, superoxide production and superoxide positive cells) and NF-κB activation during peritonitis. CONCLUSION: KA efficiently dampens LPS-induced peritonitis and hyperalgesia in vivo, suggesting it as a suitable candidate to control excessive inflammation and pain during gram-negative bacterial infections and bringing mechanistic explanation to the ethnopharmacological application of Sphagneticola trilobata (L.) Pruski in inflammation and infection.

Evaluation of antileishmanial activity of harzialactone a isolated from the marine-derived fungus Paecilomyces sp.

Fractionation of extracts from the culture broth of the marine-derived fungus, Paecilomyces sp. 7A22, resulted in the isolation of the harzialactone A (HA), a known compound previously isolated from fungi of marine environments. The chemical structure of HA was determined by spectroscopic analyses. Upon evaluation of HA on antileishmanial assays against Leishmania amazonensis, HA exhibited significant activity against promastigotes forms with IC50 of 5.25 µg mL-1 and moderate activity against intracellular amastigotes with IC50 of 18.18 µg mL-1. This is the first report on the antileishmanial activity of HA, and the effects of HA presented in this work suggest that this class of compounds are suitable for future biological in vitro and in vivo studies for the search of natural products with activity against Leishmania spp. Furthermore, the present results corroborate marine-derived fungi as a promising source of natural products with antiparasitic activity.

Licochalcone a Exhibits Leishmanicidal Activity in vitro and in Experimental Model of Leishmania (Leishmania) Infantum.

The efficacy of Licochalcone A (LicoA) and its two analogs were reported against Leishmania (Leishmania) amazonensis and Leishmania (Leishmania) infantum in vitro, and in experimental model of L. (L.) infantum in vitro. Initially, LicoA and its analogs were screened against promastigote forms of L. (L.) amazonensis. LicoA was the most active compound, with IC50 values of 20.26 and 3.88 µM at 24 and 48 h, respectively. Against amastigote forms, the IC50 value of LicoA was 36.84 µM at 48 h. In the next step, the effectivity of LicoA was evaluated in vitro against promastigote and amastigote forms of L. (L.) infantum. Results demonstrated that LicoA exhibited leishmanicidal activity in vitro against promastigote forms with IC50 values of 41.10 and 12.47 µM at 24 and 48 h, respectively; against amastigote forms the IC50 value was 29.58 µM at 48 h. Assessment of cytotoxicity demonstrated that LicoA exhibited moderate mammalian cytotoxicity against peritoneal murine macrophages; the CC50 value was 123.21 µM at 48 h and showed about 30% of hemolytic activity at concentration of 400 µM. L. (L.) infantum-infected hamsters and treated with LicoA at 50 mg/kg for eight consecutive days was able to significantly reduce the parasite burden in both liver and spleen in 43.67 and 39.81%, respectively, when compared with negative control group. These findings suggest that chalcone-type flavonoids can be a promising class of natural products to be considered in the search of new, safe, and effective compounds capable to treat canine visceral leishmaniosis (CVL).

Uncovering Biological Application of Brazilian Green Propolis: A Phenotypic Screening against Schistosoma mansoni.

The chemotherapy of schistosomiasis remains centered in the use of praziquantel, however, there has been growing resistant parasites to this drug. Thus, the aim of this work was to evaluate in vitro schistosomicidal activity of the hexanes/dichloromethane 1 : 1 extract of Brazilian green propolis (Pex), as well as its major isolated compounds artepillin C, caffeic acid, coumaric acid and drupanin against Schistosoma mansoni. The Pex was active by displaying an IC50 value of 36.60 (26.26-51.13) µg mL-1 at 72 h against adult worms of S. mansoni. The major isolated compounds were inactive with IC50 values >100 µM, however, the combination of the isolated compounds (CM) in the same range found in the extract was active with an IC50 value of 41.17 (39.89-42.46) µg mL-1 at 72 h. Pex and CM induced alteration in the tegument of S. mansoni, and caffeic acid caused alteration in egg's maturation. Pex displayed in vitro activity against adult worms' and eggs' viability of S. mansoni, which opens new perspectives to better understand the synergistic and/or additive effects promoted by both Pex extract and CM against schistosomiasis features.

Kaurenoic acid and its sodium salt derivative: antibacterial activity against Porphyromonas gingivalis and their mechanism of action.

AIM: To evaluate the antibacterial activity of 12 kaurane-type diterpenes against a panel of bacteria that cause endodontic infection. METHODS & MATERIALS: We conducted tests against bacteria in the planktonic or in the sessile mode, cytotoxic assays for the most promising compounds against human normal lung fibroblast cells, and Porphyromonas gingivalis (ATCC 33277) proteomic analysis. RESULTS & CONCLUSION: Kaurenoic acid and its salt exhibited satisfactory antibacterial action against the evaluated bacteria. Proteomic analysis suggested that these compounds might interfere in bacterial metabolism and virulence factor expression. Kaurane-type diterpenes are an important class of natural products and should be considered in the search for new irrigating solutions to treat endodontic infections.

In vitro cytotoxicity and structure-activity relationship approaches of ent-kaurenoic acid derivatives against human breast carcinoma cell line.

In this study, ent-kaurenoic acid derivatives were obtained by microbial transformation methodologies and tested against breast cancer cell lines (MCF-7). A multivariate quantitative-structure activity relationship (QSAR) analysis was performed taking into account both microbial transformation derivatives and other analogues previously reported in literature to give some insight into the main features behind the cytotoxic activity displayed by kaurane-type diterpenes against MCF-7 cells. The partial least square regression (PLS) method was employed in the training set and the best PLS model was built with a factor describing 69.92% of variance and three descriptors (logP, εHOMO and εHOMO-1) selected by the Ordered Predictors Selection (OPS) algorithm. The QSAR model provided reasonable regression (Q2 = 0.64, R2 = 0.72, SEC = 0.29 and SEV = 0.33). The model was validated by leave-N-out cross-validation, y-randomization and external validation (R2pred = 0.89 and SEP = 0.27). The selected descriptors indicated that the activity was mainly related to electronic parameters (HOMO and HOMO-1 molecular orbital energies), as well as to logP. These findings suggest that higher activity values are directly related with both higher logP and frontier orbital energy values. The positive relationship between these orbitals and the activity suggests that the ent-kaurenoic acid analogues interaction with the target involves charge displacement, which is entirely consistent with the literature. Based on these findings, three compounds were proposed and one of them was synthesized and tested. The experimental result confirmed the activity predicted by the model.

Electrospray ionization tandem mass spectrometry of labdane-type acid diterpenes.

Copaifera (Leguminoseae) species produce a commercially interesting oleoresin that displays several biological activities, including antimicrobial and anti-inflammatory properties. Labdane-type diterpenes are the main chemical constituents of these oleoresins, and copalic acid is the only compound that has been detected in all Copaifera oleoresins. In this study, we investigate some aspects of the gas-phase fragmentation reactions involved in the formation of the product ions from the deprotonated compounds (-)-ent-copalic acid (1), (-)-ent-3ß-hydroxy-copalic acid (2), (-)-ent-3ß-acetoxy-copalic acid (3), and (-)-ent-agathic acid (4) by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and multiple stage mass spectrometry (MSn ). Our results reveal that the product ion with m/z 99 is common to all the analyzed compounds, whereas the product ion with m/z 217 is diagnostic for compounds 2 and 3. Moreover, only compound 4 undergoes CO2 (44 u) and acetic acid (60 u) elimination from the precursor ion. Thermochemical data obtained by computational chemistry at the B3LYP/6-31G(d) level of theory support the proposed ion structures. These data helped us to identify these compounds in a crude commercial Copaifera langsdorffii oleoresin by selective multiple reaction monitoring (MRM). Finally, a precursor ion scan (PIS) strategy aided screening of labdane-type acid diterpenes other than 1 to 4 in the same Copaifera oleoresin sample and led us to propose the structures of 8,17-dihydro-ent-agathic acid (5) and 3-keto-ent-copalic acid (6), which have not been previously reported in Copaifera oleoresins.

Antibacterial Effect of Copaifera duckei Dwyer Oleoresin and Its Main Diterpenes against Oral Pathogens and Their Cytotoxic Effect.

This study evaluates the antibacterial activity of the Copaifera duckei Dwyer oleoresin and two isolated compounds [eperu-8(20)-15,18-dioic acid and polyalthic acid] against bacteria involved in primary endodontic infections and dental caries and assesses the cytotoxic effect of these substances against a normal cell line. MIC and MBC assays pointed out the most promising metabolites for further studies on bactericidal kinetics, antibiofilm activity, and synergistic antibacterial action. The oleoresin and polyalthic acid but not eperu-8(20)-15,18-dioic provided encouraging MIC and MBC results at concentrations lower than 100 µg mL-1. The oleoresin and polyalthic acid activities depended on the evaluated strain. A bactericidal effect on Lactobacillus casei (ATCC 11578 and clinical isolate) emerged before 8 h of incubation. For all the tested bacteria, the oleoresin and polyalthic acid inhibited biofilm formation by at least 50%. The oleoresin and polyalthic acid gave the best activity against Actinomyces naeslundii (ATCC 19039) and L. casei (ATCC 11578), respectively. The synergistic assays combining the oleoresin or polyalthic acid with chlorhexidine did not afford interesting results. We examined the cytotoxicity of C. duckei oleoresin, eperu-8(20)-15,18-dioic acid, and polyalthic acid against Chinese hamster lung fibroblasts. The oleoresin and polyalthic acid were cytotoxic at concentrations above 78.1 µg mL-1, whereas eperu-8(20)-15,18-dioic displayed cytotoxicity at concentrations above 312.5 µg mL-1. In conclusion, the oleoresin and polyalthic acid are potential sources of antibacterial agents against bacteria involved in primary endodontic infections and dental caries in both the sessile and the planktonic modes at concentrations that do not cause cytotoxicity.

Biotransformation of (-)-cubebin by Aspergillus spp. into (-)-hinokinin and (-)-parabenzlactone, and their evaluation against oral pathogenic bacteria.

The biotransformation of the lignan (-)-cubebin by filamentous fungi Aspergillus terreus and Aspergillus niger is an efficient bioprocess for obtaining (-)-hinokinin and (-)-parabenzlactone. The relevance of getting (-)-hinokinin is due to its promising effect against oral pathogens, especially S. sanguinis (both MIC and MBC 12.5 µg/mL), and other previous reported effects against Chagas disease and as anti-inflammatory. The advantage of using fungal transformation is the use of non-toxic and/or non-pollutant reagents and/or solvents in comparison with semi-synthesis. Microbial transformation of (-)-cubebin is also important to evaluate its human metabolism, since Aspergillus species are capable of mimicking P450 reactions, providing possible products of the metabolism, which is important in the assessment of its efficacy and safety. Furthermore, the present study describes a reliable RP-HPLC method to perform quantification of (-)-hinokinin in fungal extracts. It is simple, fast, selective, linear, precise, accurate and robust according to validation guidelines.

Copaifera multijuga oleoresin and its constituent diterpene (-)-copalic acid: Genotoxicity and chemoprevention study.

Copaiba oleoresins are used in alternative medicine as anti-inflammatory, antitumoral, and antimicrobial treatments. (-)-Copalic acid (CA) is the major diterpene found in exudates from Copaifera species. We have examined the genotoxicity and the chemopreventive potential of Copaifera multijuga oleoresin (CM) and CA. Genotoxicity assessment was examined with the peripheral blood micronucleus test and the comet assay (male Swiss mouse hepatocytes). In the chemoprevention study, we evaluated the effects of CM and CA on the formation of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in male Wistar rat colon. Neither agent caused a significant increase in micronucleus frequency relative to controls, but the highest CM dose tested (400mg/kg b.w.) caused DNA damage in the comet assay. Both agents significantly reduced the frequency of DMH-induced ACF. Both CM and CA suppressed ACF formation and may have a protective effect against colon carcinogenesis.

Copaifera duckei Oleoresin and Its Main Nonvolatile Terpenes: In Vitro Schistosomicidal Properties.

In this article, the in vitro schistosomicidal effects of three Brazilian Copaifera oleoresins (C. duckei, C. langsdorffii, and C. reticulata) are reported. From these botanical sources, the oleoresin of C. duckei (OCd) demonstrated to be the most promising, displaying LC50 values of 75.8, 50.6, and 47.2 µg/ml at 24, 48, and 72 h of incubation, respectively, against adult worms of Schistosoma mansoni, with a selectivity index of 10.26. Therefore, the major compounds from OCd were isolated, and the diterpene, (-)-polyalthic acid (PA), showed to be active (LC50 values of 41.7, 36.2, and 33.4 µg/ml, respectively, at 24, 48, and 72 h of incubation). Moreover, OCd and PA affected the production and development of eggs, and OCd modified the functionality of the tegument of S. mansoni. Possible synergistic and/or additive effects of this balsam were also verified when a mixture of the two of its main compounds (PA and ent-labd-8(17)-en-15,18-dioic acid) in the specific proportion of 3:1 (w/w) was tested. The obtained results indicate that PA should be considered for further investigations against S. mansoni, such as, synergistic (combination with praziquantel (PZQ)) and in vivo studies. It also shows that diterpenes are an important class of natural compounds for the investigation of agents capable of fighting the parasite responsible for human schistosomiasis.

The Labdane Ent-3-Acetoxy-Labda-8(17), 13-Dien-15-Oic Decreases Blood Pressure In Hypertensive Rats / O Labdano Ácido Ent-3-Acetóxi-Labda-8(17), 13-Dieno-15-Óico Reduz Pressão Arterial Em Ratos Hipertensos

Abstract Background: Labdane-type diterpenes induce lower blood pressure via relaxation of vascular smooth muscle; however, there are no studies describing the effects of labdanes in hypertensive rats. Objective: The present study was designed to investigate the cardiovascular actions of the labdane-type diterpene ent-3-acetoxy-labda-8(17), 13-dien-15-oic acid (labda-15-oic acid) in two-kidney 1 clip (2K-1C) renal hypertension. Methods: Vascular reactivity experiments were performed in aortic rings isolated from 2K-1C and normotensive (2K) male Wistar rats. Nitrate/nitrite (NOx) measurement was performed in aortas by colorimetric assay. Blood pressure measurements were performed in conscious rats. Results: Labda-15-oic acid (0.1-300 µmol/l) and forskolin (0.1 nmol/l - 1 µmol/l) relaxed endothelium-intact and endothelium-denuded aortas from both 2K-1C and 2K rats. Labda-15-oic acid was more effective at inducing relaxation in endothelium-intact aortas from 2K pre-contracted with phenylephrine when compared to the endothelium-denuded ones. Forskolin was more potent than labda-15-oic acid at inducing vascular relaxation in arteries from both 2K and 2K-1C rats. Labda-15-oic acid-induced increase in NOx levels was lower in arteries from 2K-1C rats when compared to 2K rats. Intravenous administration of labda-15-oic acid (0.3-3 mg/kg) or forskolin (0.1-1 mg/kg) induced hypotension in conscious 2K-1C and 2K rats. Conclusion: The present findings show that labda-15-oic acid induces vascular relaxation and hypotension in hypertensive rats.

Resumo Fundamento: Diterpenos do tipo labdano induzem uma queda da pressão arterial por meio do relaxamento do músculo liso vascular; todavia, não há estudos que descrevam os efeitos de labdanos em ratos hipertensos. Objetivo: O presente estudo foi desenvolvido para investigar as ações cardiovasculares do labdano ácido ent-3-acetóxi-labda-8(17),13-dieno-15-óico (labda-15-óico) na hipertensão renal dois rins-1 clipe (2R-1C). Métodos: Foram feitos experimentos de reatividade vascular em anéis aórticos isolados de ratos machos 2R-1C e normotensos (2R). A medição de Nitrato/Nitrito (NOx) foi feita nas aortas por meio de ensaio colorimétrico. As medidas de pressão arterial foram feitas em ratos conscientes. Resultados: O ácido labda-15-óico (0,1 - 300 µmol/l) e a forscolina (0,1 nmol/l - 1 µmol/l) relaxaram as aortas com endotélio intacto e as aortas sem endotélio dos ratos 2R-1C e 2R. O labda-15-óico mostrou-se mais eficaz na indução do relaxamento em aortas com endotélio intacto de 2R pré-contraídas com fenilefrina em comparação àquelas sem endotélio. A forscolina mostrou-se mais potente do que o ácido labda-15-óico na indução do relaxamento vascular nas artérias tanto de ratos 2R-1C quanto de ratos 2R. O aumento dos níveis de NOx induzido pelo ácido labda-15-óico foi menor nas artérias de ratos 2R-1C em comparação a ratos 2R. A administração intravenosa de ácido labda-15-óico (0,3-3 mg/kg) ou forscolina (0,1-1 mg/kg) induziu hipertensão em ratos 2R-1C e 2R conscientes. Conclusão: Os presentes resultados mostram que o labda-15-óico induz relaxamento vascular e hipotensão em ratos hipertensos.