Fragmentation pattern of amides by EI and HRESI: study of protonation sites using DFT-3LYP data.

Amides are important natural products which occur in a few plant families. Piplartine and piperine, major amides in Piper tuberculatum and P. nigrum, respectively, have shown a typical N-CO cleavage when analyzed by EI-MS or HRESI-MS. In this study several synthetic analogs of piplartine and piperine were subjected to both types of mass spectrometric analysis in order to identify structural features influencing fragmentation. Most of the amides showed an intense signal of the protonated molecule [M + H]+ when subjected to both HRESI-MS and EI-MS conditions, with a common outcome being the cleavage of the amide bond (N-CO). This results in the loss of the neutral amine or lactam and the formation of aryl acylium cations. The mechanism of N-CO bond cleavage persists in α,ß-unsaturated amides because of the stability caused by extended conjugation. Computational methods determined that the protonation of the piperamides and their derivatives takes place preferentially at the amide nitrogen supporting the dominant the N-CO bond cleavage.

In vitro synergistic interaction between amide piplartine and antimicrobial peptide dermaseptin against Schistosoma mansoni schistosomula and adult worms.

Schistosomiasis is one of the world's major public health problems, and praziquantel is the only available drug to treat this notable neglected disease. Drug combinations have been considered an important strategy for treatment of infectious diseases, which might enhance therapeutic efficacy and delaying resistance. In this study, we have examined the in vitro activities of the amide piplartine and the antimicrobial peptide dermaseptin 01 administered singly or in combination against Schistosoma mansoni of different ages including 3-hour-old and 7-day-old schistosomula and 49-day-old adult schistosomes as well as on egg output by adult worms. We calculated the median lethal concentrations (LC(50)) of 7.87 and 17.99 µM on 49-day-old adults, 11.02 and 71.58 µM on 7-day-old schistosomula, and 70.87 and 98.42 µM on 3-hour-old schistosomula for piplartine and dermaseptin, respectively. Most Piplartine/dermaseptin combinations showed synergistic effect, with combination index (CI) values less than 0.9 when S. mansoni adults or schistosomula were simultaneously incubated with both drugs in vitro; synergy between these two compounds was also indicated using isobolograms. Additionally, we observed alterations on the tegumental surface of schistosomula and adult schistosomes by means of laser scanning confocal microscopy. Furthermore, egg laying of surviving worms was considerably more reduced when exposed to the piplartine/dermaseptin combinations than each drug alone, and this inhibition was irreversible. This is the first report on the synergistic effect between piplartine and dermaseptin against S. mansoni and opens the route to further studies (e.g. in vivo) to characterize this combination in greater detail.

Molluscicidal and ovicidal activities of plant extracts of the Piperaceae on Biomphalaria glabrata (Say, 1818).

Schistosomiasis is a tropical disease caused by Schistosoma and occurs in 54 countries, mainly in South America, the Caribbean region, Africa and the eastern Mediterranean. Currently, 5 to 6 million Brazilian people are infected and 30,000 are under infection risk. Typical of poor regions, this disease is associated with the lack of basic sanitation and very frequently to the use of contaminated water in agriculture, housework and leisure. One of the most efficient methods of controlling the disease is application of molluscicides to eliminate or to reduce the population of the intermediate host snail Biomphalaria glabrata. Studies on molluscicidal activity of plant extracts have been stimulated by issues such as environmental preservation, high cost and recurrent resistance of snails to synthetic molluscicides. The aim of this study was to determine the molluscicide action of extracts from Piperaceae species on adult and embryonic stages of B. glabrata. Fifteen extracts from 13 Piperaceae species were obtained from stems, leaves and roots. Toxicity of extracts was evaluated against snails at two different concentrations (500 and 100 ppm) and those causing 100% mortality at 100 ppm concentration were selected to obtain the LC90 (lethal concentration of 90% mortality). Piper aduncum, P. crassinervium, P. cuyabanum, P. diospyrifolium and P. hostmannianum gave 100% mortality of adult snails at concentrations ranging from 10 to 60 ppm. These extracts were also assayed on embryonic stages of B. glabrata and those from P. cuyabanum and P. hostmannianum showed 100% ovicidal action at 20 ppm.

Molluscicidal and ovicidal activities ofplant extracts of the Piperaceae onBiomphalaria glabrata (Say, 1818)

Schistosomiasis is a tropical disease caused by Schistosoma and occurs in 54countries, mainly in South America, the Caribbean region, Africa and the easternMediterranean. Currently, 5 to 6 million Brazilian people are infected and 30,000are under infection risk. Typical of poor regions, this disease is associated withthe lack of basic sanitation and very frequently to the use of contaminated water in agriculture, housework and leisure. One of the most efficient methods of controlling the disease is application of molluscicides to eliminate or to reduce the population of the intermediate host snail Biomphalaria glabrata. Studies on molluscicidal activity of plant extracts have been stimulated by issues such as environmental preservation, high cost and recurrent resistance of snails tosynthetic molluscicides. The aim of this study was to determine the molluscicideaction of extracts from Piperaceae species on adult and embryonic stages ofB. glabrata. Fifteen extracts from 13 Piperaceae species were obtained from stems, leaves and roots. Toxicity of extracts was evaluated against snails at two different concentrations (500 and 100ppm) and those causing 100% mortality at 100ppm concentration were selected to obtain the LC90 (lethal concentration of 90% mortality). Piper aduncum, P. crassinervium, P. cuyabanum, P. diospyrifolium and P. hostmannianum gave 100% mortality of adult snails at concentrations ranging from 10 to 60 ppm. These extracts were also assayed on embryonic stages of B. glabrata and those from P. cuyabanum and P. hostmannianum showed 100%ovicidal action at 20ppm.

Lycopene entrapped in human albumin protects 2'-deoxyguanosine against singlet oxygen damage.

The generation of electronically excited molecular oxygen 1O2 has been shown to occur in several biological systems, such as photooxidation of a variety of biological compounds and xenobiotics ("photodynamic action") and also enzymatic reactions. The high reactivity of 1O2 with unsaturated compounds, sulfides and amino groups arises from its electrophilicity and relatively long lifetime. Thus, biological targets for 1O2 having the above functional groups include unsaturated fatty acids, proteins, enzymes and DNA. There is interest in the role of nutrition in the prevention and pathogenesis of cancer. Epidemiological studies in humans have suggested that carotenoids aid in cancer prevention. Lycopene and oxycarotenoids are present at significant levels in cells and plasma. Extensively conjugated biomolecules such as carotenoids act largely on physical quenching of 1O2 and in much lesser extent on chemical reaction. In this study we observed the protective effect of beta-carotene and lycopene entrapped in human albumin (HSA) against the oxidative 1O2 attack of 2'-deoxyguanosine (dGuo). Photosensitization with methylene blue associated with Chelex resine or Polymer-Rose bengal (Sensitox) and thermodecomposition of water-soluble endoperoxide 3,3'-(1,4-naphthylidene)dipropionate were employed to generate 1O2. The detection of 8-oxo-7,8-dihydro-2'-deoxyguanosine(8-oxodGuo) and 4-hydroxy-8-oxo-7,8-dihydro-2'-deoxyguanosine(4-OH-8-oxodGuo) were performed using reversed phase HPLC with UV, electrochemical detection and by electrospray ionization mass spectrometry. Results showed a significant decrease in the amount of 8-oxodGuo in the presence of lycopene. The percentages of 4-OH-8-oxodGuo and 8-oxodGuo measured were 50% and 70% lower than the control, respectively. These data indicate that carotenoids entrapped in albumin can be an efficient quencher of 1O2 and may be of interest in protecting against the deleterious effect of this excited state molecule.