Polyprenylated Benzophenones from Brazilian Red Propolis: Analytical Characterization and Anticancer Activity.

The present work describes the extraction of a polyprenylated benzophenone-rich extract from Brazilian red propolis (ERPB), the development and validation of an RP-HPLC-UV method to characterize it, and its evaluation against breast cancer cell lines MCF-7 and MDA-MB-231, as well as the normal counterpart MCF-10 A. A mixture of gutifferone E and xanthochymol (1+2), and isolated oblongifolin B (3) were used as chemical standards for ERPB and were also evaluated. The concentrations of 1+2 and 3 corresponded to 16.68 % and 42.25 % of the total content of the extract, respectively, and the validation parameters evaluated were satisfactorily met. The cytotoxic effects of ERPB were assessed, and the obtained IC50 values were 19.58 µg/mL (MCF-10 A), 11.56 µg/mL (MCF-7), and 5.22 µg/mL (MDA-MB-231). In conclusion, ERPB exhibits promising cytotoxic effects on the tested breast cell lines. However, further investigation to elucidate its potential therapeutic applications and safety profile should be conducted.

A validated ultra-performance liquid chromatography with tandem mass spectrometry method for the quantification of Brazilian green propolis main compounds.

Brazilian green propolis is used in folk medicine because of its various biological properties. The hydroalcoholic extract of Brazilian green propolis is characteristic for possessing several pharmacological properties. Phytochemical investigations have attributed some of these properties to the presence of compounds, which were chosen as analytical markers. This paper reports the development and analytical validation using UPLC-MS/MS in MRM mode. Veratraldehyde was used as an internal standard in qualitative and quantitative analyses of the extracts. Relative standard deviation values obtained for intra-day and inter-day precision were lower than 4%. Of the five parameters for robustness, wavelength detection and flow rate were the critical ones. Limits of detection and quantification ranged from 0.300 to 39.500 ng.mL-1 and from 1.400 to 85.00 ng.mL-1, respectively. The recoveries were between 94.00 and 119.00%, with relative standard deviation values around 5.0%. The developed method is precise, sensitive, and reliable for analysing Brazilian green propolis.

Population Pharmacokinetic of the Diterpenes ent-Polyalthic Acid and Dihydro-ent-Agathic Acid from Copaifera Duckei Oil Resin in Rats.

Copaifera duckei oleoresin is a plant product extensively used by the Brazilian population for multiple purposes, such as medicinal and cosmetic. Despite its ethnopharmacological relevance, there is no pharmacokinetic data on this important medicinal plant. Due to this, we determined the pharmacokinetic profile of the major nonvolatile compounds of C. duckei oleoresin. The diterpenes ent-polyalthic acid and dihydro-ent-agathic acid correspond to approximately 40% of the total oleoresin. Quantification was performed using LC-MS/MS, and the validated analytical method showed to be precise, accurate, robust, reliable, and linear between 0.57 and 114.74 µg/mL plasma and 0.09 to 18.85 µg/mL plasma, respectively, for ent-polyalthic acid and dihydro-ent-agathic acid, making it suitable for application in preclinical pharmacokinetic studies. Wistar rats received a single 200 mg/kg oral dose (gavage) of C. duckei oleoresin, and blood was collected from their caudal vein through 48 h. Population pharmacokinetics analysis of ent-polyalthic and dihydro-ent-agathic acids in rats was evaluated using nonlinear mixed-effects modeling conducted in NONMEN software. The pharmacokinetic parameters of ent-polyalthic acid were absorption constant rate = 0.47 h-1, central and peripheral apparent volume of distribution = 0.04 L and 2.48 L, respectively, apparent clearance = 0.15 L/h, and elimination half-life = 11.60 h. For dihydro-ent-agathic acid, absorption constant rate = 0.28 h-1, central and peripheral apparent volume of distribution = 0.01 L and 0.18 L, respectively, apparent clearance = 0.04 L/h, and elimination half-life = 3.49 h. The apparent clearance, central apparent volume of distribution, and peripheral apparent volume of distribution of ent-polyalthic acid were approximately 3.75, 4.00-, and 13.78-folds higher than those of dihydro-ent-agathic.

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.

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.

A validated HPLC-UV method for the analysis of phenolic compounds in Brazilian red propolis and Dalbergia ecastaphyllum.

Propolis is a natural product produced from the interaction between bees and plants. Brazilian red propolis results from Apis mellifera collection of resins from two plant species, being Dalbergia ecastaphyllum(L.) Taub, Fabaceae, the primary botanical source, containing isoflavonoids and other characteristic phenolic compounds. Several biological activities of Brazilian red propolis and their isolated compounds have been described in the literature. However, to our knowledge, there are no validated analytical methods for the analysis and standardization of products derived from this type of propolis reported in the literature. We developed a reverse-phase high-performance liquid chromatography analytical method for the detection and quantification of nine red propolis chemical markers: liquiritigenin, calycosin, isoliquiritigenin,formononetin, vestitol, neovestitol, medicarpin, biochanin A, and 7-O-methylvestitol, present in Brazilian red propolis extracts and D. ecastaphyllum. The developed method was also applied to the analyses of D. ecastaphyllum samples and seasonal analysis of Brazilian red propolis. Good detection response, linearity, precision, and robustness were obtained by the method, being reliable for the quality control of Brazilian red propolis extracts, raw propolis, plant material, and their derived products. The red propolis chemical markers were present in D. ecastaphyllum stems at lower concentrations. The seasonal analysis of Brazilian red propolis extract showed higher phenolic compound concentration on periods of the rainy season with higher humidity and lower solar radiation.

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.

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.

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.

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.

In vitro Evaluation of Copaifera oblongifolia Oleoresin Against Bacteria Causing Oral Infections and Assessment of Its Cytotoxic Potential.

The oral cavity, which harbors more than 750 bacterial species, is one of the most diverse sites of the human body. Some of these bacteria have been associated with oral diseases, such as dental caries and endodontic infections. We report on the antimicrobial and cytotoxic activities of Copaifera oblongifolia oleoresin against bacteria that cause caries and endodontic infections. The aim of this study is to determine the minimum (MIC) and the bactericidal (MBC) inhibitory concentrations as well as the biofilm inhibition ability (through determination of MBIC50) of the C. oblongifolia oleoresin. This study also investigated the bactericidal kinetics (time-kill curves) and the synergistic effect of the C. oblongifolia oleoresin. Additionally, this study evaluated the cytotoxic activity of the oleoresin toward V79 cells by means of the colony-forming assay. The C. oblongifolia oleoresin gave promising MIC and MBC values, which ranged from 25 to 200 µg/mL. Analysis of the MBIC50values of the oleoresin revealed it displayed biofilm inhibitory activity against all the assayed bacteria. Analysis of the bactericidal kinetics showed different behaviors of the oleoresin against the tested bacteria at the different time intervals and concentrations assayed in this study. An additive effect of the oleoresin with chlorhexidine dihydrochloride occurred only for S. mitis and A. actinomycetemcomitans. The C. oblongifolia oleoresin showed cytotoxic activity at concentrations ≥ 625 µg/mL.

Pimaradienoic Acid Inhibits Carrageenan-Induced Inflammatory Leukocyte Recruitment and Edema in Mice: Inhibition of Oxidative Stress, Nitric Oxide and Cytokine Production.

Pimaradienoic acid (PA; ent-pimara-8(14),15-dien-19-oic acid) is a pimarane diterpene found in plants such as Vigueira arenaria Baker (Asteraceae) in the Brazilian savannas. Although there is evidence on the analgesic and in vitro inhibition of inflammatory signaling pathways, and paw edema by PA, its anti-inflammatory effect deserves further investigation. Thus, the objective of present study was to investigate the anti-inflammatory effect of PA in carrageenan-induced peritoneal and paw inflammation in mice. Firstly, we assessed the effect of PA in carrageenan-induced leukocyte recruitment in the peritoneal cavity and paw edema and myeloperoxidase activity. Next, we investigated the mechanisms involved in the anti-inflammatory effect of PA. The effect of PA on carrageenan-induced oxidative stress in the paw skin and peritoneal cavity was assessed. We also tested the effect of PA on nitric oxide, superoxide anion, and inflammatory cytokine production in the peritoneal cavity. PA inhibited carrageenan-induced recruitment of total leukocytes and neutrophils to the peritoneal cavity in a dose-dependent manner. PA also inhibited carrageenan-induced paw edema and myeloperoxidase activity in the paw skin. The anti-inflammatory mechanism of PA depended on maintaining paw skin antioxidant activity as observed by the levels of reduced glutathione, ability to scavenge the ABTS cation and reduce iron as well as by the inhibition of superoxide anion and nitric oxide production in the peritoneal cavity. Furthermore, PA inhibited carrageenan-induced peritoneal production of inflammatory cytokines TNF-α and IL-1ß. PA presents prominent anti-inflammatory effect in carrageenan-induced inflammation by reducing oxidative stress, nitric oxide, and cytokine production. Therefore, it seems to be a promising anti-inflammatory molecule that merits further investigation.

Synthesis and biological evaluation of polyalthic acid derivatives for the treatment of neglected diseases.

Polyalthic acid is a naturally occurring diterpene found in copaiba oil, one of the most popular natural medicines in the Amazon. Based on the reported antileishmanial activity of copaiba oil, a series of amides and diols derivatives of polyalthic acid were synthesized and tested against Leishmania donovani and Trypanosoma brucei. Polyalthic acid was active in both assays with IC50 ranging from 3.87 to 8.68 µg/mL. The compound with best antileishmanial activity was 2 h (IC50=3.84 µg/mL) and compound 2c showed the best antitrypanosomal activity with an IC50 of 2.54 µg/mL.

RP-HPLC analysis of manool-rich Salvia officinalis extract and its antimicrobial activity against bacteria associated with dental caries

In this paper we screened the dichloromethane extract from the aerial parts of Salvia officinalis L., Lamiaceae, against a representative panel of microorganisms that cause caries, conducted a bioassay-guided fractionation to establish themselves the most active metabolite (manool) and determined the Salvia officinalis fraction with the manool highest concentration to be used to activate an ingredient in oral care products such as toothpastes and mouthwashes. Both manool and S. officinalis extract showed very promising minimal inhibitory concentration values (between 6.24 and 31.36 µg.ml-1) and time kill curves against the primary causative agents of dental caries (Streptococcus mutans) revealed that, at twice its minimal bactericidal concentration (12.48 µg.ml-1), manool required 6 h to completely kill the bacteria. Salvia officinalis extract at twice its minimal bactericidal concentration (31.36 µg.ml-1 ) needed 12 h. The results achieved with Salvia officinalis extract motivated us to develop and validate an analytical RP-HPLC method to detect and determine manool in this extract. The validation parameters were satisfactorily met and evaluated allows us to consider the developed method suitable for use in different labs. In conclusion, our results evidenced that the manool-rich S. officinalis extract can be considered an analytically validated alternative to develop novel and effective antimicrobial agents against the main bacteria responsible for dental caries.

Biotransformation of ent-pimaradienoic acid by cell cultures of Aspergillus niger.

Microbial transformation stands out among the many possible semi-synthetic strategies employed to increase the variety of chemical structures that can be applied in the search for novel bioactive compounds. In this paper we obtained ent-pimaradienoic acid (1, PA, ent-pimara-8(14),15-dien-19-oic acid) derivatives by fungal biotransformation using Aspergillus niger strains. To assess the ability of such compounds to inhibit vascular smooth muscle contraction, we also investigated their spasmolytic effect, along with another five PA derivatives previously obtained in our laboratory, on aortic rings isolated from male Wistar rats. The microbial transformation experiments were conducted at 30°C using submerged shaken liquid culture (120 rpm) for 10 days. One known compound, 7α-hydroxy ent-pimara-8(14),15-dien-19-oic acid (2), and three new derivatives, 1ß-hydroxy ent-pimara-6,8(14),15-trien-19-oic acid (3), 1α,6ß,14ß-trihydroxy ent-pimara-7,15-dien-19-oic acid (4), and 1α,6ß,7α,11α-tetrahydroxy ent-pimara-8(14),15-dien-19-oic acid (5), were isolated and identified on the basis of spectroscopic analyses and computational studies. The compounds obtained through biotransformation (2-5) did not display a significant antispasmodic activity (values ranging from 0% to 16.8% of inhibition); however the previously obtained diterpene, methyl 7α-hydroxy ent-pimara-8(14),15-dien-19-oate (8), showed to be very effective (82.5% of inhibition). In addition, our biological results highlight the importance to study the antispasmodic potential of a large number of novel diterpenes, to conduct further structure-activity relationship investigations.

In vitro antimicrobial activity of plant-derived diterpenes against bovine mastitis bacteria.

We evaluated the antibacterial activity of three diterpenes isolated from natural sources against a panel of microorganisms responsible for bovine mastitis. ent-Copalic acid (CA) was the most active metabolite, with promising MIC values (from 1.56 to 6.25 µg mL-1) against Staphylococcus aureus (ATCC and clinical isolate), Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus dysgalactiae. We conducted time-kill assays of CA against S. aureus, a commensal organism considered to be a ubiquitous etiological agent of bovine mastitis in dairy farms worldwide. In the first 12 h, CA only inhibited the growth of the inoculums (bacteriostatic effect), but its bactericidal effect was clearly noted thereafter (between 12 and 24 h). In conclusion, CA should be considered for the control of several Gram-positive bacteria related to bovine mastitis.

Pimarane-type diterpenes obtained by biotransformation: antimicrobial properties against clinically isolated Gram-positive multidrug-resistant bacteria.

The present study describes the antimicrobial activity of five pimarane-type diterpenes obtained by fungal biotransformation against several nosocomial multidrug-resistant bacteria. Among the investigated metabolites, ent-8(14),15-pimaradien-3ß-ol was the most active compound, with very promising minimal inhibitory concentration values (between 8.0 and 25.0 µg mL(-1)). Time-kill assays using this metabolite against Staphylococcus aureus (HCRP180) revealed that this compound exerted its bactericidal effect within 24 h at all the evaluated concentrations (8.0, 16.0, and 24.0 µg mL(-1)). When this metabolite was associated with vancomycin at their minimal bactericidal concentration values, the resulting combination was able to drastically reduce the number of viable strains of S. aureus within the first 6 h, compared with these chemicals alone. The checkerboard assays conducted against this microorganism did not evidence any synergistic effects when this same combination was employed. In conclusion, our results point out that ent-8(14),15-pimaradien-3ß-ol is an important metabolite in the search for new effective antimicrobial agents.