The 13C-NMR spectra of oils containing γ-linolenic acid

A new antiprotozoal compound from Calendula officinalis

A new phytoconstituent; (6Z,9Z)-heptadeca-6,9-diene-5,11-dione (1) was isolated from Calendula officinalis methanol extract. The structure of 1 was determined based on the analysis of NMR spectra and HRESIMS. It was tested for antimicrobial and antiprotozoal activities. Compound 1 showed leishmanicidal activity against L. donovani amastigote with an IC₅₀ of 16.4394 µM and IC₉₀ of 28.9015 µM and a weak antitrypanosomal activity with an IC₅₀ of 37.6136 µM. The cytotoxicity of 1 was evaluated using standard experimental procedures against THP1 cells and no cytotoxicity was observed indicating its selectivity and safety.Supplemental data for this article can be accessed here.

Unconventional Constituents and Shared Molecular Architecture of the Melanized Cell Wall of C. neoformans and Spore Wall of S. cerevisiae

The fungal cell wall serves as the interface between the cell and the environment. Fungal cell walls are composed largely of polysaccharides, primarily glucans and chitin, though in many fungi stress-resistant cell types elaborate additional cell wall structures. Here, we use solid-state nuclear magnetic resonance spectroscopy to compare the architecture of cell wall fractions isolated from Saccharomyces cerevisiae spores and Cryptococcus neoformans melanized cells. The specialized cell walls of these two divergent fungi are highly similar in composition. Both use chitosan, the deacetylated derivative of chitin, as a scaffold on which a polyaromatic polymer, dityrosine and melanin, respectively, is assembled. Additionally, we demonstrate that a previously identified but uncharacterized component of the S. cerevisiae spore wall is composed of triglycerides, which are also present in the C. neoformans melanized cell wall. Moreover, we identify a tyrosine-derived constituent in the C. neoformans wall that, although it is not dityrosine, is a non-pigment constituent of the cell wall. The similar composition of the walls of these two phylogenetically distant species suggests that triglycerides, polyaromatics, and chitosan are basic building blocks used to assemble highly stress-resistant cell walls and the use of these constituents may be broadly conserved in other fungal species.

Solid-state NMR spectroscopy identifies three classes of lipids in Cryptococcus neoformans melanized cell walls and whole fungal cells

A primary virulence-associated trait of the opportunistic fungal pathogen Cryptococcus neoformans is the production of melanin pigments that are deposited into the cell wall and interfere with the host immune response. Previously, our solid-state NMR studies of isolated melanized cell walls (melanin "ghosts") revealed that the pigments are strongly associated with lipids, but their identities, origins, and potential roles were undetermined. Herein, we exploited spectral editing techniques to identify and quantify the lipid molecules associated with pigments in melanin ghosts. The lipid profiles were remarkably similar in whole C. neoformans cells, grown under either melanizing or nonmelanizing conditions; triglycerides (TGs), sterol esters (SEs), and polyisoprenoids (PPs) were the major constituents. Although no quantitative differences were found between melanized and nonmelanized cells, melanin ghosts were relatively enriched in SEs and PPs. In contrast to lipid structures reported during early stages of fungal growth in nutrient-rich media, variants found herein could be linked to nutrient stress, cell aging, and subsequent production of substances that promote chronic fungal infections. The fact that TGs and SEs are the typical cargo of lipid droplets suggests that these organelles could be connected to C. neoformans melanin synthesis. Moreover, the discovery of PPs is intriguing because dolichol is a well-established constituent of human neuromelanin. The presence of these lipid species even in nonmelanized cells suggests that they could be produced constitutively under stress conditions in anticipation of melanin synthesis. These findings demonstrate that C. neoformans lipids are more varied compositionally and functionally than previously recognized.

Effect of methionine on production of naphthoquinones in Impatiens balsamina root cultures and detection of some secondary metabolites

CONTEXT

Lawsone, lawsone methyl ether and 3,3'-methylelnebislawsone are the main active compounds of Impatiens balsamina L. (Balsaminaceae). These compounds possess various pharmacological activities that have been shown to assist with the treatment of skin diseases.

OBJECTIVE

This work focused on increased naphthoquinone production in I. basamina root cultures using methionine feeding.

MATERIALS AND METHODS

I. balsamina root cultures were maintained in liquid Gamborg's B5 medium supplemented with 0.1 mg/L α-naphthalene acetic acid, 0.1 mg/L kinetin, 1.0 mg/L 6-benzyladenine and 20 g/L sucrose. The effect of methionine concentration (50, 100, 300, 500 and 1000 mg/L) on naphthoquinone production of I. basamina root cultures was determined. Isolation of secondary metabolites from I. balsamina root cultures was also carried out.

RESULTS AND DISCUSSION

Feeding of 300 mg/L methionine to the root cultures at the beginning of the growth cycle increased the production of 3,3'-methylelnebislawsone almost two-fold (0.63 mg/g dry weight, compared to the control group 0.32 mg/g dry weight). Optimization of the feeding conditions showed that adding 500 mg/L methionine to a 21-day old root cultures increased production of lawsone methyl ether and 3,3'-methylenebislawsone up to 2.6- and 3.1-fold higher, respectively, compared to the controls. In addition, various pharmacologically interesting secondary metabolites were isolated from I. balsamina root cultures, such as a flavonoid, luteolin, a naphthoquinone, 2,3-dihydroxy-1,4-naphthoquinone, and a triterpenoid, echinocystic acid. This is the first report of the occurrence of these compounds in this plant.

High-resolution nuclear magnetic resonance spectroscopy--applications to fatty acids and triacylglycerols

During the past two decades, nuclear magnetic resonance spectroscopy (NMR) has played an ever-increasing role in the structural determination of fatty acids, fatty acid derivatives and analogues, and in the analysis of the structures of triacylglycerols including the quantitative analysis of lipid mixtures. This article discusses some of the results obtained through the application of the NMR technique to lipid molecules and reviews the literature. To maintain brevity, this article does not cover the underlying theory of NMR spectroscopy as numerous books devoted to modern NMR spectroscopy have been published.

Comparison of the grignard deacylation TLC and HPLC methods and high resolution 13C-NMR for the sn-2 positional analysis of triacylglycerols containing gamma-linolenic acid

There is increasing evidence that the fatty acid, gamma-linolenic acid (GLA) is the effective component found in evening primrose oil (EPO) which has been shown to bring about clinical improvement in a number of disease conditions. The two major triacylglycerols (TAGs) in EPO are trilinolein (LLL) and a TAG species containing one GLA and two linoleic (LA) fatty acid chains. This latter TAG, called dilinoleoyl-mono-gamma-linolenin (DLMG or Oenotheral), makes up about 15% by weight of EPO and accounts for over one-half of the total amount of GLA present in EPO. Although DLMG is comprised of three possible isomers, the abbreviation is used to represent the naturally occurring mixture of these isomers. We have isolated DLMG from EPO and also prepared its three possible isomers, sn-GLL, sn-LGL and sn-LLG, and carried out the sn-2 positional analysis using three different approaches, namely, Grignard deacylation TLC and HPLC methods and high resolution 13C-NMR spectroscopy. The results of the sn-2 positional analysis for both the natural and synthetic TAGs containing LA and GLA in this study using the three approaches are all in very good agreement. This indicates that the three positional analysis methods are valid within their acceptable error margin and can be used with confidence in determining the fatty acid composition of the sn-2 position. Given the increased availability of NMR spectrometers this method might prove to be the easiest and most convenient in determining the sn-2 position for oil or TAG samples that contain a small number of different fatty acids providing all the 13C-NMR carbonyl resonances are well resolved.