Multivariate analyses of NP-TLC chromatographic retention data for grouping of structurally-related plant secondary metabolites

Multivariate Data Analysis Guided Identification of Anticancer Constituents of Spina Gleditsiae for Human Hepatoma Cells

Spina Gleditsia has been traditionally used as a lead ingredient of many formulas for cancer treatment in Traditional Chinese Medicine. This work aimed to reveal the phytochemical foundation of Spina Gleditsiae and underpin a fundamental understanding of its anticancer activities. The growth inhibition activities were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay of 7 solvent extracts of Spina Gleditsia in the human liver cancer cell line HepG2. The activities were then mapped onto the secondary metabolite profile of crude extracts by principal components analysis (PCA) of High Performance Liquid Chromatography-Ultraviolet (HPLC-UV) data. The top 5 PCA components of the map discriminated extract activities, mainly based on the differential content of 3 compounds. The identified compounds were then tested individually using cytotoxic assay on cancer cells in vitro. Principal components analysis constructed secondary metabolite mapping quickly identified functional compounds from the crude herbal extracts. (2 R,3 R)-7,3′,4′-Trihydroxy-5-methoxy-flavanonol, (2 R,3 R)-5,7,3′-trihydroxy-4′-methoxy-flavanonol, and isovitexin inhibited the growth of human liver cancer cell line growth with activities of 38.6 ± 1.9, 40.7 ± 0.9, and 41.5 ± 3.1 μg/mL, respectively, comparable with that of cisplatin (IC50: 41.6 ± 2.9 μg/mL). (2 R,3 R)-7,3′,4′-Trihydroxy-5-methoxy-flavanonol, (2 R,3 R)-5,7,3′-trihydroxy-4′-methoxy-flavanonol, and isovitexin are, for the first time, identified as the anticancer constituents of Spina Gleditsia. It thus strongly underpins a fundamental understanding of the anticancer activities of Spina Gleditsia and supports its ongoing clinical uses in China.

Ecological Insights to Track Cytotoxic Compounds among Maytenus ilicifolia Living Individuals and Clones of an Ex Situ Collection

Biodiversity is key for maintenance of life and source of richness. Nevertheless, concepts such as phenotype expression are also pivotal to understand how chemical diversity varies in a living organism. Sesquiterpene pyridine alkaloids (SPAs) and quinonemethide triterpenes (QMTs) accumulate in root bark of Celastraceae plants. However, despite their known bioactive traits, there is still a lack of evidence regarding their ecological functions. Our present contribution combines analytical tools to study clones and individuals of Maytenus ilicifolia (Celastraceae) kept alive in an ex situ collection and determine whether or not these two major biosynthetic pathways could be switched on simultaneously. The relative concentration of the QMTs maytenin (1) and pristimerin (2), and the SPA aquifoliunin E1 (3) were tracked in raw extracts by HPLC-DAD and ¹H-NMR. Hierarchical Clustering Analysis (HCA) was used to group individuals according their ability to accumulate these metabolites. Semi-quantitative analysis showed an extensive occurrence of QMT in most individuals, whereas SPA was only detected in minor abundance in five samples. Contrary to QMTs, SPAs did not accumulate extensively, contradicting the hypothesis of two different biosynthetic pathways operating simultaneously. Moreover, the production of QMT varied significantly among samples of the same ex situ collection, suggesting that the terpene contents in root bark extracts were not dependent on abiotic effects. HCA results showed that QMT occurrence was high regardless of the plant age. This data disproves the hypothesis that QMT biosynthesis was age-dependent. Furthermore, clustering analysis did not group clones nor same-age samples together, which might reinforce the hypothesis over gene regulation of the biosynthesis pathways. Indeed, plants from the ex situ collection produced bioactive compounds in a singular manner, which postulates that rhizosphere environment could offer ecological triggers for phenotypical plasticity.

Multivariate assessment of azo dyes' biological activity parameters

Lipophilicity as key molecular descriptor of potential biological activity for selected derivatives of azo dyes was determined mathematically, by using relevant software packages and by reversed-phase thin-layer chromatography (RPTLC) on C18 and cyano modified carriers in mixtures of water/n-propanol and water/acetone. The obtained chromatographic parameters, R_M⁰ and m, of the examined azo dyes were correlated with the standard measure of lipophilicity, log P, important pharmacokinetic predictors and selected toxicity parameters applying linear regression analysis. Thereby, good correlations for each applied system were obtained (average correlation coefficient, r, 0.944, 0.885 and 0.919). Also, the correlations between the studied parameters of azo dyes were examined applying two multivariate methods (Cluster Analysis and Principal Component Analysis). It was shown that the polarity of the substituent, and to a lesser extent its electronic effects has the greatest influence on the studied parameters of the azo dyes derivatives. Multivariate methods pointed out the similarity of the chromatographic retention constant, R_M⁰, with the parameters of lipophilicity, unlike the chromatographic parameter m, which exhibits better agreement with the toxicity parameters.

Mass spectrometry-driven drug discovery for development of herbal medicine

Herbal medicine (HM) has made a major contribution to the drug discovery process with regard to identifying products compounds. Currently, more attention has been focused on drug discovery from natural compounds of HM. Despite the rapid advancement of modern analytical techniques, drug discovery is still a difficult and lengthy process. Fortunately, mass spectrometry (MS) can provide us with useful structural information for drug discovery, has been recognized as a sensitive, rapid, and high-throughput technology for advancing drug discovery from HM in the post-genomic era. It is essential to develop an efficient, high-quality, high-throughput screening method integrated with an MS platform for early screening of candidate drug molecules from natural products. We have developed a new chinmedomics strategy reliant on MS that is capable of capturing the candidate molecules, facilitating their identification of novel chemical structures in the early phase; chinmedomics-guided natural product discovery based on MS may provide an effective tool that addresses challenges in early screening of effective constituents of herbs against disease. This critical review covers the use of MS with related techniques and methodologies for natural product discovery, biomarker identification, and determination of mechanisms of action. It also highlights high-throughput chinmedomics screening methods suitable for lead compound discovery illustrated by recent successes.

Liver tissue metabolic profiling and pathways of non-alcoholic steatohepatitis in rats

AIM

The mechanisms of non-alcoholic steatohepatitis (NASH) in hepatocytes are unknown. Our aim is to study the tissue metabolic profiling and pathways of NASH.

METHODS

We built rat models for simple steatosis and NASH and analyzed the liver extract using a liquid chromatograph-mass spectrometer. The acquired data were processed by multivariate principal component analysis and partial least squares discriminant analysis (PLS-DA) to obtain metabolic profiling. Orthogonal projections to latent structures DA was used to obtain metabolites capable of distinguishing NASH and steatosis. The total differences in the metabolites between groups were analyzed to determine their metabolic pathways.

RESULTS

Principal component analysis showed that the metabolic profiles of NASH and steatosis are different. The PLS-DA modeling revealed a clear separation between two groups with parameters R² Y and Q² Y all greater than 0.7. The orthogonal projections to latent structures DA model identified 171 metabolites capable of distinguishing NASH from steatosis. The identified metabolites are involved in fatty acid metabolism, tryptophan metabolism, the urea cycle, and the citric acid cycle in hepatocytes.

CONCLUSIONS

These metabolic profiles and pathways in rat hepatocytes will offer useful information when studying metabolic disorders in patients with NASH.