Application of comprehensive NMR-based analysis strategy in annotation, isolation and structure elucidation of low molecular weight metabolites of Ricinus communis seeds

INTRODUCTION

Powder-like extract of Ricinus communis seeds contain a toxic protein, ricin, which has a history of military, criminal and terroristic use. As the detection of ricin in this "terrorist powder" is difficult and time-consuming, related low mass metabolites have been suggested to be useful for screening as biomarkers of ricin.

OBJECTIVE

To apply a comprehensive NMR-based analysis strategy for annotation, isolation and structure elucidation of low molecular weight plant metabolites of Ricinus communis seeds.

METHODOLOGY

The seed extract was prepared with a well-known acetone extraction approach. The common metabolites were annotated from seed extract dissolved in acidic solution using (1)H NMR spectroscopy with spectrum library comparison and standard addition, whereas unconfirmed metabolites were identified using multi-step off-line HPLC-DAD-NMR approach.

RESULTS

In addition to the common plant metabolites, two previously unreported compounds, 1,3-digalactoinositol and ricinyl-alanine, were identified with support of MS analyses.

CONCLUSION

The applied comprehensive NMR-based analysis strategy provided identification of the prominent low molecular weight metabolites with high confidence.

Liquid chromatography-mass spectrometry and chemometric analysis of Ricinus communis extracts for cultivar identification

INTRODUCTION

Seeds of Ricinus communis contain the toxic protein ricin, a 64 kD heterodimeric type II ribosome-inactivating protein that has been used in several high-profile poisoning incidents. The ability to determine which cultivar the toxin was isolated from via an LC-MS method would be of significant use to law enforcement and forensic agencies.

OBJECTIVE

To analyse via LC-MS and chemometrics (principal components analysis (PCA), orthogonal partial-least-squares discriminant analysis (OPLS-DA)) extracts of R. communis to identify compounds specific to a particular cultivar.

METHODS

Seeds from eight specimens of six cultivars of R. communis ('carmencita', 'dehradun', 'gibsonii', 'impala', 'sanguineus' and 'zanzibariensis') were extracted using a standard methodology. These extracts were analysed by LC-MS then subjected to chemometric analysis (PCA and OPLS-DA). Identified compounds of importance were subjected to high-resolution Fourier transform (HRFT) MS and MS/MS to elucidate their structures.

RESULTS

This analysis identified 17 ions as potential cultivar determinators. Through accurate mass measurement and MS/MS, molecular formulae for 13 ions were determined, including two known and 11 new peptides.

CONCLUSION

Unique ions in extracts of 'carmencita', 'dehradun', 'gibsonii', 'impala' and 'zanzibariensis' were identified that would allow an individual cultivar to be distinguished from other cultivars in this study. Although 'sanguineus' extracts contained no unique compounds, a unique LC-MS profile would allow for cultivar assignment.

Physiological and biochemical responses of Ricinus communis seedlings to different temperatures: a metabolomics approach

BACKGROUND

Compared with major crops, growth and development of Ricinus communis is still poorly understood. A better understanding of the biochemical and physiological aspects of germination and seedling growth is crucial for the breeding of high yielding varieties adapted to various growing environments. In this context, we analysed the effect of temperature on growth of young R. communis seedlings and we measured primary and secondary metabolites in roots and cotyledons. Three genotypes, recommended to small family farms as cash crop, were used in this study.

RESULTS

Seedling biomass was strongly affected by the temperature, with the lowest total biomass observed at 20°C. The response in terms of biomass production for the genotype MPA11 was clearly different from the other two genotypes: genotype MPA11 produced heavier seedlings at all temperatures but the root biomass of this genotype decreased with increasing temperature, reaching the lowest value at 35°C. In contrast, root biomass of genotypes MPB01 and IAC80 was not affected by temperature, suggesting that the roots of these genotypes are less sensitive to changes in temperature. In addition, an increasing temperature decreased the root to shoot ratio, which suggests that biomass allocation between below- and above ground parts of the plants was strongly affected by the temperature. Carbohydrate contents were reduced in response to increasing temperature in both roots and cotyledons, whereas amino acids accumulated to higher contents. Our results show that a specific balance between amino acids, carbohydrates and organic acids in the cotyledons and roots seems to be an important trait for faster and more efficient growth of genotype MPA11.

CONCLUSIONS

An increase in temperature triggers the mobilization of carbohydrates to support the preferred growth of the aerial parts, at the expense of the roots. A shift in the carbon-nitrogen metabolism towards the accumulation of nitrogen-containing compounds seems to be the main biochemical response to support growth at higher temperatures. The biochemical changes observed in response to the increasing temperature provide leads into understanding plant adaptation to harsh environmental conditions, which will be very helpful in developing strategies for R. communis crop improvement research.

Symbiodinium-invertebrate symbioses and the role of metabolomics

Symbioses play an important role within the marine environment. Among the most well known of these symbioses is that between coral and the photosynthetic dinoflagellate, Symbiodinium spp. Understanding the metabolic relationships between the host and the symbiont is of the utmost importance in order to gain insight into how this symbiosis may be disrupted due to environmental stressors. Here we summarize the metabolites related to nutritional roles, diel cycles and the common metabolites associated with the invertebrate-Symbiodinium relationship. We also review the more obscure metabolites and toxins that have been identified through natural products and biomarker research. Finally, we discuss the key role that metabolomics and functional genomics will play in understanding these important symbioses.

Research Front Essay: Forensic Chemistry

The author discusses the benefits for forensic science from greater engagement with basic and other applied areas of chemistry and gives examples of how his organization, the Australian Federal Police, have partnered with academia and others to promote the use of chemistry in areas of trace evidence, illicit drugs, fingerprint detection, and explosives.