Identification of chemosensitizing agents of colorectal cancer in Rauvolfia vomitoria using an NMR-based chemometric approach

Searching for new adjuvants of conventional chemotherapeutic approaches against colorectal cancer cells is extremely urgent. In current research, a non-targeted analytical approach was established by combining proton nuclear magnetic resonance spectroscopy with a chemometrics data mining tool to identify chemosensitizing agents from Rauvolfia vomitoria. This approach enabled the identification of potential active constituents in the initial fractionation process and provided their structural information. This strategy was validated by its application to Rauvolfia vomitoria extract exhibiting chemosensitizing activity on 5-fluorouracil against colorectal cancer cells. After the workflow, the biochemometrics analysis showed that at least 15 signals (Variable influence on projection (VIP) > 1) could have contributions in the differentiation of various fractions. Through systematic literature and database searches, we found that the most active fraction (fraction 7) exhibited the highest presence of sabazin-type and armaniline-type alkaloids, which were potential chemosensitizers as previously reported. To validate the results of the strategy, the effect of 5-FU and compounds isolated from fraction seven incubation on HCT-8 and LoVo cell vialibilty were evaluated. These results evidenced that compound β-carboline (3), 1-methyl-β-carboline (4), and lochnerine (6) could enhance the cytotoxicity of 5-fluorouracil against to Colorectal cancer cells. Besides, 21 compounds including two new compounds were isolated from Rauvolfia vomitoria. The experimental results verify the reliability of the method, and this approach provides a new and efficient tool to overcome some of the bottlenecks in natural products drug discovery.

Comparative morpho-anatomical standardization and chemical profiling of root drugs for distinction of fourteen species of family Apocynaceae

BACKGROUND

The root drugs of the family Apocynaceae are medicinally important and used in Indian Systems of Medicine (ISM). There is often a problem of misidentification and adulteration of genuine samples with other samples in the market trade. Keeping in view the adulteration problem of raw drug material, comparative macroscopic and microscopic (qualitative and quantitative) characterisation and chemical analysis (TLC and LC-MS profiling) of a total of 14 economically important root drugs of family Apocynaceae were done for practical and rapid identification. A total of 33 qualitative botanical characteristics of root samples were subjected to Principal Component Analysis (PCA) and Cluster analysis to identify taxonomically significant characteristics in the distinction of root drug samples at the species level.

RESULTS

Comparative qualitative and quantitative data on morphological, macroscopic, and microscopic characters were generated for the studied 14 species. Despite the similarity in some root characters, a combined study involving the surface, anatomical, and powder features helped distinguish root samples at the species level. The relative relationship between selected species was represented as clustering or grouping in the dendrogram. PCA analysis determined significant characters leading to species grouping and identification. Results showed that clustering of xylem vessels in cross-section, pore size, and distribution in the cut root, the shape of starch grains, the thickness of cork zone were among the most notable characters in species distinction. Chemical profiling revealed unique fingerprints and content of chemical compounds, which were significant in identification of root drug samples.

CONCLUSIONS

The comparative botanical standards and chemical profiles developed in the present study can be used as future reference standards for the quick, easy, and correct identification of root drug samples to be used in the herbal drug industry. Further, the identified significant microscopic characters have the potential for taxonomic studies in species delimitation.