Omar Malagón

Chemical composition of essential oils of two species of the Lamiaceae family: Scutellaria volubilis and Lepechinia paniculata from Loja, Ecuador

Scutellaria volubilis and Lepechinia paniculata belong to the Lamiaceae family of species. They are used widely in traditional medicine in Ecuador. The physical properties and chemical composition of the essential oils from the aerial part of Scutellaria volubilis in its foliation – flowering stage and Lepechinia paniculata in its flowering phase have been studied after their hydrodistillation. The components of these essential oils were investigated by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detection (GC/FID) techniques. Thirty-seven components were determined in the essential oil of S. volubilis. The principal constituents were found to be sesquiterpene hydrocarbons: germacrene D (20.4%), β-caryophyllene (17.5%), α-humulene (14.7%) and β-bisabolene (5.8%). Thirty-four components were identified in the essential oil of L. paniculata, the principal groups were sesquiterpene hydrocarbons such as aromadendrene (24.6%), viridiflorene (12.4%), β-selinene (7.4%) and valencene (6.7%). The monoterpene hydrocarbons were present in lower amounts as well as β-phellandrene (6.9%) and (7.7%). Oxygenated monoterpenes and sesquiterpenes contribute below 5% in both species. This is the first report on the chemical composition of this species.

Sesquiterpene lactones from Gynoxys verrucosa and their anti-MRSA activity

ETHNOPHARMACOLOGICAL RELEVANCE Because of its virulence and antibiotic resistance, Staphylococcus aureus is a more formidable pathogen now than at any time since the pre-antibiotic era. In an effort to identify and develop novel antimicrobial agents with activity against this pathogen, we have examined Gynoxys verrucosa Wedd (Asteraceae), an herb used in traditional medicine in southern Ecuador for the treatment and healing of wounds. MATERIALS AND METHODS The sesquiterpene lactones leucodine (1) and dehydroleucodine (2) were extracted and purified from the aerial parts of Gynoxys verrucosa, and their structure was elucidated by spectroscopic methods and single-crystal X-ray analysis. The in vitro anti-microbial activity of Gynoxys verrucosa extracts and its purified constituents was determined against six clinical isolates including Staphylococcus aureus and Staphylococcus epidermidis strains with different drug-resistance profiles, using the microtiter broth method. RESULTS Compound 1 has very low activity, while compound 2 has moderate activity with MIC(50)s between 49 and 195 μg/mL. The extract of Gynoxys verrucosa has weak activity with MIC(50)s between 908 and 3290 μg/mL. CONCLUSIONS We are reporting the full assignment of the (1)H NMR and (13)C NMR of both compounds, and the crystal structure of compound 2, for the first time. Moreover, the fact that compound 2 has antimicrobial activity and compound 1 does not, demonstrates that the exocyclic conjugated methylene in the lactone ring is essential for the antimicrobial activity of these sesquiterpene lactones. However, the weak activity observed for the plant extracts, does not explain the use of Gynoxys verrucosa in traditional medicine for the treatment of wounds and skin infections.

Dehydroleucodine, a Sesquiterpene Lactone from Gynoxys verrucosa, Demonstrates Cytotoxic Activity against Human Leukemia Cells

The sesquiterpene lactones dehydroleucodine (1) and leucodine (2) were isolated from Gynoxys verrucosa, a species used in traditional medicine in southern Ecuador. The activity of these compounds was determined against eight acute myeloid leukemia (AML) cell lines and compared with their activity against normal peripheral blood mononuclear cells. Compound 1 showed cytotoxic activity against the tested cell lines, with LD50 values between 5.0 and 18.9 μM. Compound 2 was inactive against all of the tested cell lines, demonstrating that the exocyclic methylene in the lactone ring is required for cytotoxic activity. Importantly, compound 1 induced less toxicity to normal blood cells than to AML cell lines and was active against human AML cell samples from five patients, with an average LD50 of 9.4 μM. Mechanistic assays suggest that compound 1 has a similar mechanism of action to parthenolide (3). Although these compounds have significant structural differences, their lipophilic surface signatures show striking similarities.

Chemical composition, antifungal and antibacterial activity of the essential oil from Baccharis latifolia (Ruiz & Pav.) Pers. (Asteraceae) from Loja, Ecuador

The essential oil of aerial parts of Baccharis latifolia (asteraceae) growing wild in Ecuador was obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS) and GC/flame ionization detector (GC/FID). Twenty-nine compounds, representing 90.91% of the oil, were identified. The major components were limonene (33.72%), -phellandrene (10.32%), sabinene (10.28%), β-pinene (6.99%) and α-pinene (5.44%). The antifungal and antibacterial activities were determined by the broth microdilution method. The essential oil from B. latifolia exhibited activity only against Trichophyton rubrum (ATCC 28188) and Trichophyton mentagrophytes (ATCC 28185).

Structures and biological significance of lactarane sesquiterpenes from the European mushroom Russula nobilis

The results of the first investigation on secondary metabolites occurring in intact and damaged fruiting bodies of Russula nobilis growing in Europe, are reported. Intact mushrooms contain fatty acid esters of velutinal, while three new sesquiterpenoids, russulanobilines A–C, along with eight known ones were isolated from extracts of injured fruiting bodies. The structures of the new compounds were elucidated on the basis of spectral data, molecular modeling, and 13C NMR spectra calculation. This pattern of sesquiterpenes constitutes a new variant of a chemical defense machinery which protects mushrooms against predators, parasites, and microorganisms.

Antifungal activity of raw extract and flavanons isolated from Piper ecuadorense from Ecuador

The MeOH extract of Piper ecuadorense Sodiro, Piperaceae, was chosen for metabolite isolation and elucidation due to the strong antifungal activity exhibited, measured by means of the broth microdilution method. Two known flavonoids: pinostrobin (1) and pinocembrin (2) were isolated from 4.16 g. of dichloromethane extract by column chromatography, using a gradient of hexane/EtOAc. A total of 20 mg of 1 were obtained from the fraction eluted with hexane-EtOAc 95:5 v/v, and 100 mg of 2 were obtained from the fraction eluted with hexane-EtOAc 85:15 v/v. The MIC values of the MeOH extract was 31.25 µg/mL for Trichophyton mentagrophytes ATCC® 28185 and 62.5 µg/mL for Trichophyton rubrum ATCC® 28188. The MIC value of pinocembrin was 125 µg/mL for Trichophyton mentagrophytes ATCC® 28185 and Trichophyton rubrum ATCC® 28188. Pinostrobin in antifungal test was not active against fungi tested.

Composition of the Essential Oils of Artemisia sodiroi Hieron., Siparuna eggersii Hieron., Tagetes filifolia Lag. and Clinopodium nubigenum (Kunth) Kuntze from Loja Ecuador

Abstract The chemical composition of the essential oils from fresh leaves of four species (Artemisia sodiroi, Siparuna eggersii, Tagetes filifolia and Clinopodium nubigenum), grown wild in the southern Ecuador (province of Loja), was examined through the GC-MS analysis. In the essential oil of A. sodiroi, the oxygenated monoterpenes were the main group of components, especially sabinyl acetate (65.8 %), while the essential oil of S. eggersii was mainly composed by the oxygenated sesquiterpenes among which the epicurzerenone (29.9 %) was the most representative. Conversely, the aromatic hydrocarbons predominated in the oils of T. filifolia and C. nubigenum, with (E)-anethole (72.6 %) and carvacryl acetate (38.1 %) as the main components, respectively.

Phytochemical researches and antimicrobial activity of Clinopodium nubigenum Kunth (Kuntze) raw extracts

The essential oil of the species Clinopodium nubigenum (Kunth) Kuntze, Lamiaceae, was analyzed by GC-MS and GC-FID, taking into account the more recent literature. Among the seventy compounds identified, the majority are oxygenated monoterpenoids. The essential oil, tested for antimicrobial activity, resulted effective in vitro against Candida albicans. From the aqueous MeOH extract of the aerial parts of the plant two nonvolatile compounds, named schizonepetoside A and schizonepedoside C, have been isolated. They are rare glycosyl terpenoids, which were previously isolated from only one plant, but never found before in the genus Clinopodium.

Antibacterial and cytotoxic activity from the extract and fractions of a marine derived bacterium from the Streptomyces genus

Abstract Context: Marine natural products are a rich source of potent, selective, and structurally novel compounds. Marine bacteria are considered the most promising source of biologically active compounds which can be applied to treat a wide range of diseases. Objective: The current study was designed to establish the bases for a future marine exploration in the Ecuadorian coast based on the molecular identification of a marine bacterium and its potential use as an antibacterial or cytotoxic compounds source. Materials and methods: Isolation and characterization of the marine bacterium were carried out through microbiological methods from desiccated sediment. Molecular identification was made by means of 16S rDNA analysis. MIC was measured by the microdilution broth method against six pathogenic bacteria: two Gram positive and four Gram negative strains. Cytotoxicity was evaluated by Crystal violet assay against breast adenocarcinoma (MCF7) and ductal carcinoma (T47D and ZR-75-30). Results: Our present study has shown that EtOAc extract and fraction A1 obtained from marine Streptomyces sp. revealed the maximal antibacterial and cytotoxic activity. Enterococcus faecalis was found to be more sensitive strain (MIC 0.78 μg/ml) than the other five bacteria tested. ZR-75-30 and T47D cell lines were found to be more sensitive (IC50 value, 31.88 ± 0.05 and 68.35 ± 0.12 μg/ml) than adenocarcinoma MCF7 (IC50 value was 83.65 ± 0.06 μg/ml). Discussion and conclusion: The results obtained herein indicate that EtOAc extract of Streptomyces sp. has shown a strong antibacterial activity as well as moderate cytotoxic activity which make it a good candidate for metabolite isolation.

CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF ESSENTIAL OILS FROM AZORELLA SPINOSA (APIACEAE) AGAINST WILD PHYTOPATHOGENIC BACTERIA

The aim of the present investigation was to appraise variation in the chemical composition and antimicrobial activity against phytopatogenic bacterial of essential oils from Azorella spinosa . Three samples of A. spinosa were collected in different date in the same area. The essential oils were obtained for hydro-destillation using a Clevenger-type apparatus. The chemical composition of essential oils were analysed using Gas chromatography-mass spectrometry showed variation in the yield and composition, the main detected compounds were monoterpenes such as limonene (10.66-12.30%), tricyclene (10.81-16.99%) and sabinene (9.10-11.49%), the most abundant sesquiterpene was γ-gurjenene (5.48-8.47%). The biological activity of essential oils from A. spinosa against wild phytopatogenic microorganisms showed selectivity over Pseudomonas syringae . This is the first report of the essential oil composition of A. spinosa , and confirms that natural products obtained from aromatic plants represent an important source of bioactive molecules that could be used as new alternatives for the treatment of phytopatogenic bacteria infections.