Trypanocidal activity of pimarane diterpenes from Viguiera arenaria (Asteraceae)

Diterpenoids from Acanthopanacis Cortex and their anti-inflammatory activity studies

Acanthopanacis Cortex (A.-C) with a long history of more than1000 years, has been used to treat rheumatism effectively. Nineteen diterpenoids have been isolated from A.-C, including six new compounds (1-6). Among them, compounds 7, 9-11, 13, and 17 were discovered from A.-C for the first time. The structures of 1-6 were determined by analyzing their NMR data and comparing their experimental and calculated electronic circular dichroism spectra. Moreover, the single-crystal X-ray diffraction data of 1, 2, 8, and 14 were provided. The anti-inflammatory activity of 1-5 and 7-18 on neutrophil elastase, cyclooxygenase-1 (COX-1), and cyclooxygenase-2 (COX-2) has been studied in vitro, and the results showed that 15 had almost no inhibitory effects on COX-1 at 200 μM but a significant activity against COX-2 with an IC50 of 0.73 ± 0.006 μΜ. It indicated that compound 15 can provide valuable information for the design of selective COX-2 inhibitors.

In Vitro Cytotoxic and Leishmanicidal Activity of Isolated and Semisynthetic ent-Pimaranes from Aldama arenaria

Two pimaranes ent-pimara-8(14),15-dien-19-oic acid (1: ) and ent-8(14),15-pimaradien-3β-ol (2: ), isolated from Aldama arenaria, and six semi-synthetic derivatives methyl ester of the ent-pimara-8(14),15-dien-19-oic acid (3: ), ent-pimara-8(14),15-dien-19-ol (4: ), acetate of ent-pimara-8(14),15-dien-19-ol (5: ), ent-pimara-8(14),15-dien-19-ol succinic acid (6: ), acetate of ent-8(14),15-pimaradien-3β-ol (7: ), ent-8(14),15-pimaradien-3β-ol succinic acid (8: ) were evaluated in vitro for their cytotoxic activities to childhood leukemia cell lines and leishmanicidal activity against the parasite Leishmania amazonensis. Among these compounds, 1: to 6: presented moderate cytotoxic activity, with compound 4: being the most active (GI₅₀ of 2.6 µM for the HL60 line) and the derivatives 7: and 8: being inactive. Against the parasite Leishmania amazonensis, the most promising derivative was the acetate of ent-pimara-8(14),15-dien-19-ol (5: ), with EC₅₀ of 20.1 µM, selectivity index of 14.5, and significant reduction in the parasite load. Pimarane analogues 1: , ent-pimara-8(14),15-dien-19-oic acid, and 2: , ent-8(14),15-pimaradien-3β-ol, presented different activities, corroborating the application of such molecules as prototypes for the design of other derivatives that have greater cytotoxic or leishmanicidal potential.

In vitro schistosomicidal activities of the leaf extracts from Casearia sylvestris varieties

Schistosomiasis, a tropical disease caused by flatworms, may affect the liver, spleen, bladder, and intestine. Casearia sylvestris Swartz, a medicinal plant, displays antiprotozoal, antimicrobial, antifungal, and antiulcer activities. We have evaluated the in vitro schistosomicidal activity of two C. sylvestris varieties against Schistosoma mansoni adult worms at concentrations between 12.5 and 200 μg/mL of and var. lingua . At 100 and 200 μg/mL, the ethanolic C. sylvestris var. sylvestris leaf extract enriched in casearin-like diterpenes eliminated 100% of the parasites after incubation for 72 h and 48 h, respectively, whilst the same extract at 200 μg/mL eliminated 96%, 100%, and 100% of the parasites after incubation for 24, 48, and 72 h, respectively. On the other hand, the hydroalcoholic C. sylvestris var. lingua leaf extract at 200 μg/mL eliminated 60.4 and 66.7% of the parasites after incubation for 48 and 72 h, respectively. The presence of casearin-like diterpenes and glycosylated flavonoids was confirmed based on chromatographic techniques and mass spectrometry data.

Characterization of microbial communities from rumen and large intestine of lactating creole goats grazing in arid plant communities

Arid plant communities provide variable diets that can affect digestive microbial communities of free-foraging ruminants. Thus, we used next-generation sequencing of 16S and 18S rDNA to characterize microbial communities in the rumen (regurgitated digesta) and large intestine (faeces) and diet composition of lactating creole goats from five flocks grazing in native plant communities in the Sonoran Desert in the rainy season. The bacterial communities in the rumen and large intestine of the five flocks had similar alpha diversity (Chao1, Shannon, and Simpson indices). However, bacterial community compositions were different: a bacterial community dominated by Proteobacteria in the rumen transitioned to a community dominated by Firmicutes in the large intestine. Bacterial communities of rumen were similar across flocks; similarly occurred with large-intestine communities. Archaea had a minimum presence in the goat digestive tract. We detected phylum Basidiomycota, Ascomycota, and Apicomplexa as the main fungi and protozoa. Analyses suggested different diet compositions; forbs and grasses composed the bulk of plants in the rumen and forbs and shrubs in faeces. Therefore, lactating goats consuming different diets in the Sonoran Desert in the rainy season share a similar core bacterial community in the rumen and another in the large intestine and present low archaeal communities.

In vitro anti-trypanosomal potential of kaurane and pimarane semi-synthetic derivatives

As part of the search for anti-trypanosomal agents, this work presents the production of sixteen derivatives. All of them were obtained from two natural diterpenes, one with kaurane skeleton (ent-kaurenoic acid) and other with a pimarane skeleton (ent-pimaradienoic acid). Then, the eighteen compounds were assayed against epimastigote form of Trypanosoma cruzi, with the derivatives showing increase of activity in relation to their precursors. Moreover, the most active derivative presented an IC₅₀ <12.5 µM (estimated 0.8 µM), lower than Benznidazole (IC₅₀ = 9.8 µM), used as control. The esterification of acid diterpenes showed to be an interesting way in the search for anti-trypanosomal agents.

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.

Chemical and Antimicrobial Analyses of Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood, an Endemic of the Western Balkan

A comprehensive study on essential oil and different solvent extracts of Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood (Lamiaceae) from Montenegro is reported. The gas chromatography-mass spectrometry analysis of the essential oil revealed a total of 43 components with bicyclogermacrene (23.8%), germacrene D (8%), (E)-caryophyllene (7.9%) and spathulenol (5.5%) as the major ones. Sesquiterpenoid group was found to be the most dominant one (64.8%), with 19.9% of the oxygenated forms. In the crude methanol extract of the investigated plant, obtained by Sohhlet exraction, the total phenol content was 14.7 ± 0.4 mg of GA/g, the total flavonoids were 0.29 ± 0.03% expressed as hyperoside percentage, whereas the total tannins content was 0.22 ± 0.04% expressed as pyrogallol percentage. For the antimicrobial activity determination, the following microorganisms have been used: methicillin-susceptible Staphylococcus aureus (MSSA (American Type Culture Collection (ATCC) 29213)) and methicillin-resistant S. aureus (MRSA (clinical strain)), Escherichia coli (ATCC 25922), carbapenem-susceptible Klebsiella pneumoniae (clinical strain), carbapenem-resistant K. pneumoniae (clinical strain) and Candida albicans (ATCC 14053). The essential oil showed high potency against MSSA and MRSA, both at high (~5 × 10⁵ CFU/mL) and low (~5 × 10³ CFU/mL) inoculum. With respect to MSSA, the minimal inhibitory concentration (MIC) value was 0.307 mg/mL, with bactericidal activity obtained at 0.615 mg/mL, while, in the case of MRSA, the MIC and minimal bactericidal concentration (MBC) values were 0.076 and 0.153 mg/mL, respectively. Regarding anti-Candida albicans activity, the MIC value was 2.46 mg/mL without reaching fungicidal activity. In addition to the observed essential oil efficacy, different solvent extracts were analyzed for their antimicrobial activity. Similarly to the essential oil, thehighest efficacy was observed against both MSSA and MRSA strains, at high and low inoculums, in the case of the 1,2-dichloroethane and methanol extracts. A potent fungicidal activity has been also found for the n-hexane and 1,2-dichloroethane extracts. It can be concluded that Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood provides a wide range of application in different fields such as phytochemistry, pharmacology, toxicology or pharmacognosy.

Diterpenes as lead molecules against neglected tropical diseases

Nowadays, neglected tropical diseases (NTDs) are reported to be present everywhere. Poor and developing areas in the world have received great attention to NTDs. Drug resistance, safety profile, and various challenges stimulate the search for alternative medications. Plant-based drugs are viewed with great interest, as they are believed to be devoid of side effects. Diterpenes, a family of essential oils, have showed attractive biological effects. A systematic review of the literature was carried out to summarize available evidences of diterpenes against NTDs. For this, databases were searched using specific search terms. Among the 2338 collected reports, a total of 181 articles were included in this review. Of them, 148 dealt with investigations using single organisms, and 33 used multiple organisms. No mechanisms of action were reported in the case of 164 reports. A total of 93.92% were related to nonclinical studies, and 4.42% and 1.66% dealt with preclinical and clinical studies, respectively. The review displays that many diterpenes are effective upon Chagas disease, chikungunya, echinococcosis, dengue, leishmaniasis, leprosy, lymphatic filariasis, malaria, schistosomiasis, and tuberculosis. Indeed, diterpenes are amazing drug candidates against NTDs. Copyright © 2016 John Wiley & Sons, Ltd.

Seasonal variation of the essential oil from two Brazilian native Aldama La Llave (Asteraceae) species

ABSTRACT Aldama arenaria and A. robusta are morphologically similar aromatic species that have seasonal development. The yield and chemical composition of essential oils from aerial and underground vegetative organs of these species were compared to verify the production of volatile metabolites in flowering and dormant phases of development and to identify if there are unique compounds for either species. The major compound in the essential oils from A. arenaria leaves was palustrol (16.22%) and for aerial stems was limonene (15.3%), whereas limonene (11.16%) and α-pinene (19.64%) were the major compounds for leaves and aerial stems from A. robusta, respectively. The major compound for the underground organs was α-pinene, in both species and phenological stages. High amounts of diterpenes were found especially for A. arenaria essential oils. Each analyzed species presented unique compounds, which can provide a characteristic chemical profile for both species helping to solve their taxonomic problems. This study characterized for the first time the yield and essential oil composition of A. arenaria and A. robusta, which have medicinal potential, and some of the compounds in their essential oils are unique to each one and may be useful in helping the correct identification of them.

ent-Pimarane and ent-Kaurane Diterpenes from Aldama discolor (Asteraceae) and Their Antiprotozoal Activity

Aldama discolor (syn.Viguiera discolor) is an endemic Asteraceae from the Brazilian "Cerrado", which has not previously been investigated for its chemical constituents and biological activity. Diterpenes are common secondary metabolites found in Aldama species, some of which have been reported to present potential antiprotozoal and antimicrobial activities. In this study, the known ent-3-α-hydroxy-kaur-16-en-18-ol (1), as well as three new diterpenes, namely, ent-7-oxo-pimara-8,15-diene-18-ol (2), ent-2S,4S-2-19-epoxy-pimara-8(3),15-diene-7β-ol (3) and ent-7-oxo-pimara-8,15-diene-3β-ol (4), were isolated from the dichloromethane extract of A. discolor leaves and identified by means of MS and NMR. The compounds were assayed in vitro against Trypanosoma brucei rhodesiense, T. cruzi and Leishmania donovani, Plasmodium falciparum and also tested for cytotoxicity against mammalian cells (L6 cell line). The ent-kaurane 1 showed significant in vitro activity against both P. falciparum (IC 50 = 3.5 μ M) and L. donovani (IC 50 = 2.5 μ M) and ent-pimarane 2 against P. falciparum (IC 50 = 3.8 μ M). Both compounds returned high selectivity indices (SI >10) in comparison with L6 cells, which makes them interesting candidates for in vivo tests. In addition to the diterpenes, the sesquiterpene lactone budlein A (5), which has been reported to possess a strong anti-T. b. rhodesiense activity, was identified as major compound in the A. discolor extract and explains its high activity against this parasite (100% growth inhibition at 2 μ g/mL).

HPLC-DAD phenolic profile, cytotoxic and anti-kinetoplastidae activity of Melissa officinalis

Context Melissa officinalis subsp. inodora Bornm. (Lamiaceae) has been used since ancient times in folk medicine against various diseases, but it has not been investigated against protozoa. Objective To evaluate the activities of M. officinalis against Leishmania braziliensis, Leishmania infantum and Trypanosoma cruzi as well as its cytotoxicity in fibroblast cell line. Materials and methods The fresh leaves were chopped into 1 cm(2) pieces, washed and macerated with 99.9% of ethanol for 72 h at room temperature. Antiparasitic activity of M. officinalis was accessed by direct counting of cells after serial dilution, while the cytotoxicity of M. officinalis was evaluated in fibroblast cell line (NCTC929) by measuring the reduction of resazurin. The test duration was 24 h. High-performance liquid chromatography (HPLC) was used to characterise the extract. Results The extract at concentrations of 250 and 125 μg/mL inhibited 80.39 and 54.27% of promastigote (LC50  value = 105.78 μg/mL) form of L. infantum, 80.59 and 68.61% of L. brasiliensis (LC50 value  = 110.69 μg/mL) and against epimastigote (LC50 value  = 245.23 μg/mL) forms of T. cruzi with an inhibition of 54.45 and 22.26%, respectively, was observed. The maximum toxicity was noted at 500 μg/mL with 95.41% (LC50  value = 141.01 μg/mL). The HPLC analysis identified caffeic acid and rutin as the major compounds. Discussion The inhibition of the parasites is considered clinically relevant (< 500 μg/mL). Rutin and caffeic acids may be responsible for the antiprotozoal effect of the extract. Conclusion The ethanol extract of M. officinalis can be considered a potential alternative source of natural products with antileishmania and antitrypanosoma activities.

In vitro leishmanicidal activities of sesquiterpene lactones from Tithonia diversifolia against Leishmania braziliensis promastigotes and amastigotes

Natural compounds represent a rich and promising source of novel, biologically active chemical entities for treating leishmaniasis. Sesquiterpene lactones are a recognized class of terpenoids with a wide spectrum of biological activities, including activity against Leishmania spp. In this work, a sesquiterpene lactone-rich preparation—a leaf rinse extract (LRE) from Tithonia diversifolia—was tested against promastigote forms of L. braziliensis. The results revealed that the LRE is a rich source of potent leishmanicidal compounds, with an LD₅₀ value 1.5 ± 0.50 µg·mL⁻¹. Therefore, eight sesquiterpene lactones from the LRE were initially investigated against promastigote forms of L.braziliensis. One of them did not present any significant leishmanicidal effect (LD₅₀ > 50 µg·mL⁻¹). Another had a cytotoxic effect against macrophages (4.5 µg·mL⁻¹). The five leishmanicidal compounds with the highest level of selectivity were further evaluated against intracellular parasites (amastigotes) using peritoneal macrophages. Tirotundin 3-O-methyl ether, tagitinin F, and a guaianolide reduced the internalization of parasites after 48 h, in comparison with the negative control. This is the first report on sesquiterpene lactones that have potent leishmanicidal effects on both developmental stages of L. braziliensis.

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-3β-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-3β-ol is an important metabolite in the search for new effective antimicrobial agents.

In vitro and in vivo studies of the trypanocidal activity of four terpenoid derivatives against Trypanosoma cruzi

Four terpenoid derivatives were examined for their activity against Trypanosoma cruzi. Our results show that two compounds were very active in vitro against both extra- and intracellular forms. These compounds, non-toxic for the host cells, are more effective than the reference drug benznidazole. The capacity to infect cells was negatively affected and the number of amastigotes and trypomastigotes was reduced. A wide range of ultrastructural alterations was found in the epimastigote forms treated with these compounds. Some metabolic changes occurred presumably at the level of succinate and acetate production, perhaps caused by the disturbance of the enzymes involved in sugar metabolism inside the mitochondria. In vivo results were consistent with those observed in vitro. The parasitic load was significantly lower than in the control assay with benznidazole. The effects of these products showed the reduction of the anti-T. cruzi antibodies level during the chronic stage.

Chemical and antimicrobial evaluation of supercritical and conventional Sideritis scardica Griseb., Lamiaceae extracts

Sideritis scardica Griseb., Lamiaceae (ironwort, mountain tea), an endemic plant of the Balkan Peninsula, has been used in traditional medicine in the treatment of antimicrobial infections, gastrointestinal complaints, inflammation and rheumatic disorders. This study reports a comparison between conventional (hydrodistillation HD and solvent extraction SE) and alternative (supercritical carbon dioxide SC CO₂) extraction methods regarding the qualitative and quantitative composition of the obtained extracts as analyzed by GC and GC-MS techniques and their anitimicrobial activity. Different types of extracts were tested, the essential oil EO obtained by HD, EO-CO₂ and AO-CO₂ obtained by SC CO₂ at different preasures 10 and 30 MPa, at 40 °C, respectively, and the fractions A, B, C and D obtained by successive solvent extraction (SE) A: ethanol, B: diethyl ether, C: ethyl acetate and D: n-butanol). While EO was characterized by the presence of the high percentage of oxygenated monoterpenes and sesquiterpenes (30.01 and 25.54%, respectively), the rest of the investigated samples were the most abundant in fatty acids and their esters and diterpenes (from 16.72 to 71.07% for fatty acids and their esters, and from 23.30 to 72.76%, for diterpenes). Microbial susceptibility tests revealed the strong to moderate activity of all investigated extracts against the tested microorganisms (MIC from 40 to 2,560 μg/mL). Although differences in the chemical compositions determined by GC and GC-MS analysis were established, the displayed antimicrobial activity was similar for the all investigated extracts.

Pimarane-type diterpenes: antimicrobial activity against oral pathogens

Seven pimarane type-diterpenes re-isolated from Viguiera arenaria Baker and two semi-synthetic pimarane derivatives were evaluated in vitro against the following main microorganisms responsible for dental caries: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis and Lactobacillus casei. The compounds ent-pimara-8(14),15-dien-19-oic acid (PA); ent-8(14),15-pimaradien-3beta-ol; ent-15-pimarene-8beta,19-diol; ent-8(14),15-pimaradien-3beta-acetoxy and the sodium salt derivative of PA were the most active compounds, displaying MIC values ranging from 2 to 8 microg mL(-1). Thus, this class of compounds seems promising as a class of new effective anticariogenic agents. Furthermore, our results also allow us to conclude that minor structural differences among these diterpenes significantly influence their antimicrobial activity, bringing new perspectives to the discovery of new natural compounds that could be employed in the development of oral care products.