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Phytochemical Investigations of Costa Rican Marcgraviaceae and Development of Insecticide SynergistsCarballo Arce, Ana F. 10 December 2013 (has links)
Substances of natural and synthetic origin were studied using analytical, bioassay guided isolation, metabolomics and medicinal chemistry techniques. In a section focused on the plant family Marcgraviaceae, a validated method for the quantification of six pentacyclic triterpenes (α and β Amyrin lupeol, ursolic acid, betulin and betulinic acid) in the Souroubea spp was developed. Quantification of the triterpenes in the crude extracts was achieved using HPLC-APCI mass selective detection. The calibration curves for the five triterpenes evaluated were highly linear (r2 >0.993) and percentage recovery from spiked samples were greater than 94% for all compounds. The LOD for betulinic acid was 0.01 µg for betulinic acid on column and LOQ was 0.03 µg. The method was successfully applied to 41 crude extracts from leaf and stem of Souroubea spp, from two locations in Costa Rica. The method is suitable for quality control of raw materials used in the manufacture of natural health products. The use of modern metabolomic techniques, UHPLC-QTOF allowed the identification of five putative makers that can potentially be used in distinguishing between the two Souroubea species.
The validated method was used in the quantification of the above triterpenes in a total of thirteen Marcgraviaceae species collected in Costa Rica. It was established that betulinic acid and β- Amyrin could be used as makers for this family of tropical vines. These same thirteen plants extracts were evaluated in antifungal and quorum sensing inhibition bioassays. Marcgravia nervosa was the only species that showed significant activity in both bioassays. Bioassay guided fractionation of the crude ethanolic extract of M. nervosa led to the identification of 2-methoxynaphthoquinone as the bioactive compound responsible for the bioactivity. The crude leaf ethanolic extract from M. nervosa showed a significant inhibition of QS comparable or somewhat better than D. pulchra extracts with the M. nervosa extract showing stronger inhibiting QS with a halo of 21.8mm, more than D. pulcra extracts which generated a halo of 15.9mm. The active quinone has a MIC of 85 µM against Saccharomyces cerevisiaBY4741 (haploid) and 100 µM against Saccharomyces cerevisiae BY4743 (diploid) compared to berberine (positive control) with a MIC 600 µM for both strains. This quinone is not present in any of the other twelve species of Marcgraviaceae available to us.
In work focusing on organic synthesis, a total of 57 semi-synthetic derivatives of dillapiol, safrol and piperonal were prepared and evaluated for their inhibitory activity in a CYP 3A4 bioassay to assess their potential use as pesticide synergists. The synergistic activity of dillapiol has been improved 45 fold; analog 31 has an IC50 = 0.2 µM compared with dillapiol IC50= 9.18 µM. A number of other compounds structurally related to 31 showed similar levels of activity.
A screening of a compound library identified the amino sulfoxide 3 as a potential lead for the design of a selective connexin blocker with potential application in the treatment of spinal cord injuries. The use of X-ray crystallography permitted the correction of the original structure assigned to 3. Once the structure was corrected a total of 6 analogs were prepared. Compound 3 has the highest inhibition of GJIC whereas compound 8 and compound 2, reduced anionic hemi-channel activity. Compound 2 also reduced the cationic activity of the hemi-channels.
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Phytochemical Investigations of Costa Rican Marcgraviaceae and Development of Insecticide SynergistsCarballo Arce, Ana F. January 2013 (has links)
Substances of natural and synthetic origin were studied using analytical, bioassay guided isolation, metabolomics and medicinal chemistry techniques. In a section focused on the plant family Marcgraviaceae, a validated method for the quantification of six pentacyclic triterpenes (α and β Amyrin lupeol, ursolic acid, betulin and betulinic acid) in the Souroubea spp was developed. Quantification of the triterpenes in the crude extracts was achieved using HPLC-APCI mass selective detection. The calibration curves for the five triterpenes evaluated were highly linear (r2 >0.993) and percentage recovery from spiked samples were greater than 94% for all compounds. The LOD for betulinic acid was 0.01 µg for betulinic acid on column and LOQ was 0.03 µg. The method was successfully applied to 41 crude extracts from leaf and stem of Souroubea spp, from two locations in Costa Rica. The method is suitable for quality control of raw materials used in the manufacture of natural health products. The use of modern metabolomic techniques, UHPLC-QTOF allowed the identification of five putative makers that can potentially be used in distinguishing between the two Souroubea species.
The validated method was used in the quantification of the above triterpenes in a total of thirteen Marcgraviaceae species collected in Costa Rica. It was established that betulinic acid and β- Amyrin could be used as makers for this family of tropical vines. These same thirteen plants extracts were evaluated in antifungal and quorum sensing inhibition bioassays. Marcgravia nervosa was the only species that showed significant activity in both bioassays. Bioassay guided fractionation of the crude ethanolic extract of M. nervosa led to the identification of 2-methoxynaphthoquinone as the bioactive compound responsible for the bioactivity. The crude leaf ethanolic extract from M. nervosa showed a significant inhibition of QS comparable or somewhat better than D. pulchra extracts with the M. nervosa extract showing stronger inhibiting QS with a halo of 21.8mm, more than D. pulcra extracts which generated a halo of 15.9mm. The active quinone has a MIC of 85 µM against Saccharomyces cerevisiaBY4741 (haploid) and 100 µM against Saccharomyces cerevisiae BY4743 (diploid) compared to berberine (positive control) with a MIC 600 µM for both strains. This quinone is not present in any of the other twelve species of Marcgraviaceae available to us.
In work focusing on organic synthesis, a total of 57 semi-synthetic derivatives of dillapiol, safrol and piperonal were prepared and evaluated for their inhibitory activity in a CYP 3A4 bioassay to assess their potential use as pesticide synergists. The synergistic activity of dillapiol has been improved 45 fold; analog 31 has an IC50 = 0.2 µM compared with dillapiol IC50= 9.18 µM. A number of other compounds structurally related to 31 showed similar levels of activity.
A screening of a compound library identified the amino sulfoxide 3 as a potential lead for the design of a selective connexin blocker with potential application in the treatment of spinal cord injuries. The use of X-ray crystallography permitted the correction of the original structure assigned to 3. Once the structure was corrected a total of 6 analogs were prepared. Compound 3 has the highest inhibition of GJIC whereas compound 8 and compound 2, reduced anionic hemi-channel activity. Compound 2 also reduced the cationic activity of the hemi-channels.
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INFLUENCE OF A SYNERGIST ON THE DISSOCIATION OF HYDRATES FORMED IN THE PRESENCE OF THE KINETIC INHIBITOR POLY VINYL CAPROLACTAMGulbrandsen, Ann Cecilie, Svartaas, Thor Martin 07 1900 (has links)
Laboratory tests have been performed using a stirred cell where SI and SII gas hydrates have been formed
under the presence of the kinetic inhibitor Poly Vinyl Caprolactam (PVCap) and INHIBEX. The latter is a
mixture containing 50wt% PVCap 2k and 50wt% butyl glycol. The effect of PVCap is enhanced by the
presence of butyl glycol; the latter acts as a synergist for the former. Dissociation temperatures were
obtained and compared for hydrates formed 1) in presence of PVCap and 2) in presence of INHIBEX. The
effect of INHIBEX concentration on the temperature of dissociation was also investigated. Systems
containing INHIBEX dissociated at lower temperatures than the corresponding systems with only PVCap
present. Furthermore, 3000 ppm INHIBEX mixtures were found to have higher dissociation temperatures
than 1500 ppm INHIBEX mixtures.
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