Natural products chemistry in the third millennium

The main directions of Natural Products Chemistry in the Third Millennium are summarized

Recent trends and important developments in propolis research

The newest developments in propolis pharmacological research are summarized. The problem regarding biological studies, caused by the chemical variability of propolis, is discussed. The most important trends and developments in recent propolis research are outlined: biological studies performed with chemically characterized samples, bioassay-guided studies of active principles and comparative biological studies of propolis of different origin and chemical composition. These types of studies are extremely valuable with respect to propolis standardization and practical applications in therapy. They will allow scientists to connect a particular chemical propolis type to a specific type of biological activity and formulate recommendations for practitioners

Moroccan propolis: a natural antioxidant, antibacterial, and antibiofilm against Staphylococcus aureus with no induction of resistance after continuous exposure

This study was performed to evaluate the total phenols, flavonoids, and antioxidant activities of twenty-four propolis samples from different regions of Morocco. In addition, two samples were screened regarding the antibacterial effect against four Staphylococcus aureus strains. Gas chromatography coupled to mass spectra (GC-MS) analysis was done for propolis samples used in antibacterial tests. The minimum inhibitory and minimum bactericidal concentration (MIC, MBC) were determined. The potential to acquire the resistance after sequential exposure of bacterial strains and the impact of adaptation to propolis on virulence using the Galleria mellonella were evaluated. Additionally, the effects of propolis extract on the bacterial adherence ability and its ability to inhibit the quorum sensing activity were also examined. Among the twenty-four extracts studied, the samples from Sefrou, Outat el Haj, and the two samples marketed in Morocco were the best for scavenging DPPH, ABTS, NO, peroxyl, and superoxide radicals as well as in scavenging of hydrogen peroxide. A strong correlation was found between the amounts of phenols, flavonoids, and antioxidant activities. Propolis extract at the MIC value (0.36 mg/mL) significantly reduced (p < 0.001) the virulence potential of S. aureus ATCC 6538 and the MRSA strains without leading to the development of resistance in the sequence of continuous exposure. It was able to impair the bacterial biofilm formation. The results have revealed that sample 1 reduces violacein production in a concentration dependent manner, indicating inhibition of quorum sensing. This extract has as main group of secondary metabolites flavonoids (31.9%), diterpenes (21.5%), and phenolic acid esters (16.5%).Fundacao para a Ciencia e a Tecnologia (FCT) - Pest-OE/QUI/UI4023/2011info:eu-repo/semantics/publishedVersio

Stingless bees and Mangifera indica: A close relationship?

Propolis is a bee product with various biological activities and phytochemical compositions. This study was aimed to identify the chemical composition and botanical origin of Indonesian stingless bees propolis produced by Tetragonula laeviceps in Banten and Heterotrigona itama in South Kalimantan, respectively. Propolis extracts were prepared using 70% ethanol and chloroform. The extracts were analysed by GC/MS after silylation. The results showed that the studied stingless bee propolis contained a relatively high amount of sugars, probably due to the harvesting method used. Furthermore, triterpenes were found as the main constituents followed by phenolic lipids. Both samples were Mangifera indica type propolis with typical compounds, including cycloartenol, isomangiferolic acid, mangiferolic acid, ambolic acid, alk(en)ylphenols, alk(en)ylresorcinols, and anacardic acids. Therefore, M. indica might be a preferred botanical source of propolis from a tropical zone. In addition, the suctioning method in harvesting the stingless bee honey could be recommended to avoid high content of sugar and sugar derivatives

Stingless bees and Mangifera indica: A close relationship?

130-134Propolis is a bee product with various biological activities and phytochemical compositions. This study was aimed to identify the chemical composition and botanical origin of Indonesian stingless bees propolis produced by Tetragonula laeviceps in Banten and Heterotrigona itama in South Kalimantan, respectively. Propolis extracts were prepared using 70% ethanol and chloroform. The extracts were analysed by GC/MS after silylation. The results showed that the studied stingless bee propolis contained a relatively high amount of sugars, probably due to the harvesting method used. Furthermore, triterpenes were found as the main constituents followed by phenolic lipids. Both samples were Mangifera indica type propolis with typical compounds, including cycloartenol, isomangiferolic acid, mangiferolic acid, ambolic acid, alk(en)ylphenols, alk(en)ylresorcinols, and anacardic acids. Therefore, M. indica might be a preferred botanical source of propolis from a tropical zone. In addition, the suctioning method in harvesting the stingless bee honey could be recommended to avoid high content of sugar and sugar derivatives

GC-MS studies of the chemical composition of two inedible mushrooms of the genus Agaricus

<p>Abstract</p> <p>Background</p> <p>Mushrooms in the genus <it>Agaricus </it>have worldwide distribution and include the economically important species <it>A. bisporus</it>. Some <it>Agaricus </it>species are inedible, including <it>A. placomyces </it>and <it>A. pseudopratensis</it>, which are similar in appearance to certain edible species, yet are known to possess unpleasant odours and induce gastrointestinal problems if consumed. We have studied the chemical composition of these mushrooms using GC-MS.</p> <p>Results</p> <p>Our GC-MS studies on the volatile fractions and butanol extracts resulted in the identification of 44 and 34 compounds for <it>A. placomyces </it>and <it>A. pseudopratensis</it>, respectively, including fatty acids and their esters, amino acids, and sugar alcohols. The most abundant constituent in the volatiles and butanol were phenol and urea respectively. We also identified the presence of ergosterol and two Δ⁷-sterols. In addition, 5α,8α-Epidioxi-24(ξ)-methylcholesta-6,22-diene-3β-ol was isolated for the first time from both mushrooms. Our study is therefore the first report on the chemical composition of these two species.</p> <p>Conclusion</p> <p>The results obtained contribute to the knowledge of the chemical composition of mushrooms belonging to the <it>Agaricus </it>genus, and provide some explanation for the reported mild toxicity of <it>A. placomyces </it>and <it>A. pseudopratensis</it>, a phenonomenon that can be explained by a high phenol content, similar to that found in other <it>Xanthodermatei </it>species.</p

The specific chemical profile of Mediterranean propolis from Malta

Seventeen Maltese propolis samples were studied by GC–MS after silylation. They exhibited the typical Mediterranean chemical profile, rich in diterpene compounds (18–92% of TIC, GC–MS): 32 individual diterpenes were identified; 22 of them were present in each specimen. The other abundant compound group was that of sugars and sugar derivatives. In some samples, however, another compound group was observed (0–12% of TIC, GC–MS); the corresponding mass spectra were consistent with monoand sesquiterpenyl esters of substituted benzoic acids. Two new propolis constituents of this group, daucane diterpene esters of hydroxybenzoic acids, were isolated. Their origin is suggested to be Ferula communis, as they are taxonomic markers for this species. All propolis samples were active against Staphylococcus aureus but only those with high concentrations of terpenyl esters showed antifungal activity against Candida albicans. The present results confirm that Mediterranean propolis is a valuable natural product with potential to improve human health.peer-reviewe

Chemical composition and biological activities of the Black Sea algae Polysiphonia denudata (Dillw.) Kutz. and Polysiphonia denudata f. fragilis (Sperk) Woronich.

Abstract The two investigated algae had almost identical sterol composition, but there were signifi­cant differences in the com position of the polar components and especially in the composi­tion of the volatiles. P. denudata f. fragilis extracts possessed a stronger biological activity (antibacterial, antifungal and toxicity against Artemia salina). Despite the minute morpholog­ical differences between the two algae, we recommend P. denudata f. fragilis to be regarded as P. denudata subsp. fragilis