Identifying the compounds that can distinguish between Saposhnikovia root and its substitute, Peucedanum ledebourielloides root, using LC-HR/MS metabolomics

Previously, we established a ¹H NMR metabolomics method using reversed-phase solid-phase extraction column (RP-SPEC), and succeeded in distinguishing wild from cultivated samples of Saposhnikoviae radix (SR), and between SR and its substitute, Peucedanum ledebourielloides root (PR). Herein, we performed LC-HR/MS metabolomics using fractions obtained via RP-SPEC to identify characteristic components of SR and PR. One and three characteristic components were respectively found for SR and PR; these components were isolated with their m/z values and retention times as a guide. The characteristic component of SR was identified as 4'-O-β-D-glucosyl-5-O-methylvisamminol (1), an indicator component used to identify SR in the Japanese Pharmacopoeia. In contrast, the characteristic components of PR were identified as xanthalin (2), 4'-O-β-D-apiosyl (1 → 6)-β-D-glucosyl-5-O-methylvisamminol (3), and 3'-O-β-D-apiosyl (1 → 6)-β-D-glucosylhamaudol (4) based on spectroscopic data such as 1D- and 2D-NMR, MS, and specific optical rotation. Among them, 4 is a novel compound. For the correlation between the NMR metabolomics results in the present and our previous report, only 1 and 2 were found to correlate with the chemical shifts, and the other compounds had no correlation. As the chemical shifts for compounds 1, 3, and 4 were similar to each other, especially for the aglycone moiety, they could not be distinguished because of the sensitivity and resolution of ¹H NMR. Accordingly, combining NMR and LC/MS metabolomics with their different advantages is considered useful for metabolomics of natural products. The series of methods used in our reports could aid in quality evaluations of natural products and surveying of marker components.

The origin identification method for crude drugs derived from arthropods and annelids using molecular biological techniques

We evaluated whether the origins of crude drugs derived from arthropods and annelids could be identified using molecular biological techniques. DNA was extracted from 20 crude drugs prepared from different animals using a commercial kit with added phenol treatment. The target regions used to identify origin were the mitochondrial 16S ribosomal RNA (rRNA), 12S rRNA, and cytochrome oxidase subunit I (COI) gene regions. Extracted DNA was amplified by polymerase chain reaction, and then sequenced by the Sanger method. The aligned sequences were compared with all available sequences using BLAST to estimate the origins of the crude drugs. The origin of crude drugs used in this study could be estimated using this method. The COI region was the best for identifying origin among three regions examined, based on the success rate of PCR amplification and analysis. Moreover, the 12S rRNA region was also useful for origin identification, with the exception of the earthworm. However, the origin of some crude drugs could not be strictly identified due to matches to various species in all three regions. One likely cause was that the species of origin of a crude drug has not been registered in DNA databases. We found that even the same crude drug from the same pharmaceutical company had different origins by production lot or import source country. Therefore, this method is useful not only for DNA-based origin identification but also quality control of production lots.

1H NMR-based metabolomic analysis coupled with reversed-phase solid-phase extraction for sample preparation of Saposhnikovia roots and related crude drugs

¹H NMR-based metabolomics has been applied in research on food, herbal medicine, and natural products. Although excellent results were reported, samples were directly extracted with a deuterated solvent (e.g., methanol-d₄ or D₂O) in most reports. As primary metabolites account for most of the results, data for secondary metabolites are partially reflected. Consequently, secondary metabolites tend to be excluded from factor loading analysis, serving as a significant unfavorable feature of ¹H NMR-based metabolomics when investigating biologically active or functional components in natural products and health foods. Reversed-phase solid-phase extraction column (RP-SPEC) was applied for sample preparation in ¹H NMR-based metabolomics to overcome this feature. The methanol extract from Saposhnikoviae radix (SR), an important crude drug, was fractionated with RP-SPEC into 5% methanol-eluting fractions, and the remaining fraction was collected. Each fraction was subjected to ¹H NMR-based metabolomics and compared to results from conventional ¹H NMR-based metabolomics. Based on principal component analysis (PCA) and partial least squares projections to latent structures discriminant analysis (PLS-DA), the 5% methanol fraction and conventional method reflected the amount of saccharides such as sucrose on the PC1/PLS1 axes, and wild and cultivated samples were discriminated along those axes. The remaining fraction clearly distinguished SR from Peucedanum ledebourielloides root. The compounds responsible for this discrimination were deemed falcarindiol derivatives and other unidentified secondary metabolites from the s-plot on PLS-DA. The secondary metabolites from original plants were, therefore, presumed to be concentrated in the remaining fraction by RP-SPEC treatment and strongly reflected the species differences. The developed series is considered effective to perform quality evaluation of crude drugs and natural products.

Establishment of widely applicable DNA extraction methods to identify the origins of crude drugs derived from animals using molecular techniques

We established widely applicable DNA extraction methods to identify the origins of crude drugs derived from animals. Twenty-one samples including 17 kinds of crude drug derived from animals were examined. DNA was extracted from most of the crude drugs by adjustment of the QIAamp^® DNA Mini Kit. DNA extraction was performed successfully using phenol to remove impurities after applying a proteinase treatment. DNA extraction was performed successfully by decalcification treatment using ethylenediaminetetraacetic acid (EDTA), before applying the proteinase treatment for crude drugs having high calcium content, such as those from oyster shell and cuttlefish bone. DNA could not be extracted from sea-ear shell using the EDTA decalcification treatment, but was extracted successfully using a TBONE EX KIT. The mitochondrial 16S ribosomal RNA (rRNA) gene region was amplified, and Basic Local Alignment Search Tool (BLAST) analysis was performed after sequencing. Polymerase chain reaction (PCR) products of approximately 600 bp in length were obtained from all samples except donkey glue, one of the two seahorses, and longgu. Drug origins were determined in all samples by sequence analysis based on the BLAST results, and match rates were >97 %. Moreover, 16 samples had a match rate >99 %. Our DNA extraction methods were widely applicable to evaluation of many crude drugs derived from animals, and proved very useful for identifying the origins of such drugs.

13C-NMR-based metabolic fingerprinting of Citrus-type crude drugs

Five Citrus-type crude drugs (40 samples) were classified using ¹³C-NMR spectra-based metabolomics. The following eight metabolites were identified from the loading plots of multivariate analysis of the ¹³C-NMR spectra; naringin, neohesperidin, narirutin, synephrine, sucrose, α-glucose, β-glucose, and limonene. ¹³C-NMR spectra-based metabolic fingerprinting is a promising strategy for classifying crude drugs.

Search of new cytotoxic crude materials against human oral squamous cell carcinoma using 1H NMR-based metabolomics

BACKGROUND

The 5-year survival rate of the oral cancer patients has remained at approximately the 50% level during the past 30 years, possibly due to the poor tumor-selectivity of conventional anticancer drugs. This prompted us to search new plant extracts that have higher cytotoxicity against cancer cells than normal cells.

MATERIALS AND METHODS

Two human oral squamous cell carcinoma cell lines (HSC-2 and HSC-4) and two normal oral cells (gingival and periodontal ligament fibroblasts; HGF and HPLF) were incubated for 48 h with various concentrations of crude plant extract and the viable cell number was determined by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The 50% cytotoxic concentration (CC50) was determined from the dose-response curve. Tumor-specificity (TS) was determined by the following equation: TS=mean CC50 (normal cells)/mean CC50 (cancer cell lines). Metabolic profiling techniques based on (1)H nuclear magnetic resonance (NMR) were applied to gain the chemical structural insight for cytotoxicity induction.

RESULTS

Among 24 plant extracts, Camptotheca acuminate leaf, a well-known source for camptothecin, showed the highest TS value (88.3), followed by Vitis s.p.p. (>3.5), Sasa veitchii (>2.3) and Phellodendron amurense (>2.1), whereas other plant extracts showed much lower TS value (<2). These cytotoxic extracts made cluster on principal component analysis (PCA) score plot.

CONCLUSION

The TS value determined by the present method seems to reflect the anti-tumor potential of each plant extract, while a part of the cytotoxic compounds present in these extracts may have common chemical structures.