Evaluation of the antimicrobial and antioxidant activities of essential oils, extracts and their main components from oregano from Madeira Island, Portugal

Origanum vulgare subsp. virens growing wild in Madeira Island, Portugal was studied within the ongoing investigations on polymorphic Lamiaceae species. The antimicrobial activity of the essential oils and n-hexane extracts of origanum was determined against 10 strains of bacteria and yeasts, found as human pathogenic or food spoilage microorganisms. The essential oils, n-hexane extracts and isolated compounds showed moderately activity, compared to standard antibiotics, inhibiting all tested bacteria except Pseudomonas aeruginosa. The most sensitive microorganism was Mycobacterium smegmatis, reaching MIC ¼ 25 mg mL 1 . The results obtained suggest a potential application of these oils in pre venting the human pathogenic and food spoilage due to microorganism’s growth. The essential oils and n-hexane extracts have greater RSC than polar extracts, probably due to the high contents in thymol, which demonstrated the highest activity in the DPPH assay. All studied origanum samples showed a large content in non-esterified 1-hexacosanol, C26H54O, accumulated mainly in bracts and flowersinfo:eu-repo/semantics/publishedVersio

Chemical composition and bioactivity of essential oils and extracts from Oregano from Madeira Island, Portugal

In the course of ongoing investigations on polymorphic Lamiaceae species, we studied Origanum vulgare spp. virens growing wild in several locations of Madeira Island, Portugal. Variation in essential oil composition with climate conditions was studied. The antimicrobial activity of the various essential oils was determined against 10 strains of bacteria and yeasts, usually found as human pathogenic or food contaminants. The essential oils inhibited all the bacteria tested excepting for P. aeruginosa. The most sensitive microorganism was M. smegmatis with MIC = 25 µg ml-1 for two of the oils. The results of this study suggest a potential application of these oils in preventing the human pathogenic and food contaminant microorganisms growth. Radical scavenging capacity of essential oils and solvent extract (hexane, chloroform, ethyl acetate and methanol) were also determined, since interest of oregano resides in both non polar and polar fractions, all known by their very high antioxidant activity. From the hexane fraction, we obtained a large amount of 1-hexacosanol, C26H54O, a long chain alcohol, which was previously extracted in the non-esterified form only from Hygrophila erecta.info:eu-repo/semantics/publishedVersio

Antimicrobial activity of steady state cultures of Bacillus sp CCMI 1051 against wood contaminant fungi

The effect of changing dilution rate (D) on Bacillus sp. CCMI 1051 at dilution rates between 0.1 and 0.55 h−1 in a glucose-limited medium was studied. Biomass values varied between 0.88 and 1.1 g L−1 at D values of 0.15–0.35 h−1. Maximal biomass productivity was found to be 0.39 g L−1 h−1, obtained at D= 0.35 h−1 and corresponding to a 54.4% conversion of the carbon into cell mass. The highest rate of glucose consumption was 4.45 mmol g−1 h−1 occurring at D= 0.4 h−1. The glucose concentration inside the chemostat was below the detection level starting to accumulate around 0.4 h−1. Growth inhibition of fifteen strains of fungi by the broth of the steady-state cell-free supernatants was assessed. Results showed that the relative inhibition differ among the target species but was not influenced by the dilution rate changing

Environmental dynamics of Bacillus amyloliquefaciens CCMI1051 antifungal activity under different nitrogen patterns

Abstract Aims: The aim of this study was to evaluate the influence of environmental conditions on the antifungal activity of the Bacillus sp. CCMI 1053 cultures. Methods and Results: The electrospray ionization mass spectra (ESI-MS) analysis was used to detect the active peptides produced by Bacillus amyloliquefaciens CCMI 1051 cultures in a glucose-containing medium to which four different nitrogen sources were added. The cultures produced different patterns of Bacillus sporulation and distinct antifungal activity of the cell-free culture broths. Conclusions: The highest sporulation obtained corresponds to higher antifungal activity when it is formed after 3 days of microbial growth. The antifungal activity against Trichoderma harzianum CCMI 783 is more influenced by the concentration on the nitrogen source than the culture time of incubation. The association of nitrogen concentration and the time of incubation is particularly relevant in the expression of the antifungal activity. Significance and Impact of the Study: The present findings allow the reduction of the use of chemical pesticides and to limit some plant diseases. The association of the nitrogen source and the time of incubation is a novelty, which would improve the production of secondary metabolites. Both economical and environmental benefits arise from the study

Environmental dynamics of Bacillus amyloliquefaciens CCMI1051 antifungal activity under different nitrogen patterns

Aims: The aim of this study was to evaluate the influence of environmental conditions on the antifungal activity of the Bacillus sp. CCMI 1053 cultures. Methods and Results: The electrospray ionization mass spectra (ESI-MS) analysis was used to detect the active peptides produced by Bacillus amyloliquefaciens CCMI 1051 cultures in a glucose-containing medium to which four different nitrogen sources were added. The cultures produced different patterns of Bacillus sporulation and distinct antifungal activity of the cell-free culture broths. Conclusions: The highest sporulation obtained corresponds to higher antifungal activity when it is formed after 3 days of microbial growth. The antifungal activity against Trichoderma harzianum CCMI 783 is more influenced by the concentration on the nitrogen source than the culture time of incubation. The association of nitrogen concentration and the time of incubation is particularly relevant in the expression of the antifungal activity. Significance and Impact of the Study: The present findings allow the reduction of the use of chemical pesticides and to limit some plant diseases. The association of the nitrogen source and the time of incubation is a novelty, which would improve the production of secondary metabolites. Both economical and environmental benefits arise from the study

Localization and ecological significance of oroidin and sceptrin in the Caribbean sponge Agelas conifera

The Caribbean sponge Agelas conifera was found to produce a mixture of previously described bromopyrrole alkaloids of which oroidin (1) and sceptrin (2) were predominant. This sponge harboured large populations of heterotrophic bacteria but no photosynthetic symbionts (cyanobacteria). However, 1 and 2 were not associated with the bacteria but with the sponge cells as shown by their distribution in enriched cell fractions obtained by differential centrifugation and Ficoll density gradients. Spherulous cells, found in great abundance in the sponge ectosome, were assumed to be involved in the production of 1 and 2. The target compounds were detected, although in small amounts, in short-term cultures of sponge cells, validating the possibility of a continuous cell culture source. Laboratory assays showed that organic sponge extracts affected the behaviour of the coral Madracis mirabilis in causing closure and retraction of the polyps at concentrations of the combined compounds 1 and 2 (1:3.3) as low as 0.7 mg/l (0.0125% of the concentration in whole sponges). At higher concentrations (1.4 mg/l) no recovery of the polyps occurred. The extracts, at almost natural concentrations of 1 and 2, deterred feeding by the predatory reef fish Stegastis partitus, supporting other reported research. In field experiments, wounding induced a sharp increase of 1 and 2 in the sponge tissues but prolonged predator exclusion by caging and forced confrontation with coral neighbours did not yield measurable changes in 1 and 2 concentrations. All sponges were found to release measurable amounts of bromopyrrole alkaloids in seawater conditioned for 30 min. Crude and fractionated sponge extracts and pure sceptrin (2) were active against bacteria, yeast and filamentous fungi. Taken together, these results support a role of oroidin (1) and sceptrin (2) in defence mechanisms against predators and possibly against space competitors and invaing and fouling organisms. © 2003 Elsevier Science Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Synthesis of flavonoid-type compounds from methyl dehydroabietates

The synthesis of new flavone-type compounds bearing several chiral centres, 12- and 14-(2'-chromonyl)dehydroabietates, are reported. This synthesis started from the aldol condensation of methyl 12- and 14-formyldehydroabietates with 2'-hydroxyacetophenones in order to prepare the corresponding chalcone-type compounds, which were then transformed in the expected flavone-type compounds by cyclodehydrogenation with DMSO and a catalytic amount of iodine. All compounds were exhaustively characterised by NMR and MS techniques.FCT/FEDER - Organic Chemistry Research UnitFCT/FEDER - PRAXIS XXI/BD/15786/9