Improved quantitative analysis of tenuifolin using hydrolytic continuous-flow system to build prediction models for its content based on near-infrared spectroscopy.

This study used two types of analyses and statistical calculations on powdered samples of Polygala root (PR) and Senega root (SR): (1) determination of saponin content by an independently developed quantitative analysis of tenuifolin content using a flow reactor, and (2) near-infrared spectroscopy (NIR) using crude drug powders as direct samples for metabolic profiling. Furthermore, a prediction model for tenuifolin content was developed and validated using multivariate analysis based on the results of (1) and (2). The goal of this study was to develop a rapid analytical method utilizing the saponin content and explore the possibility of quality control through a wide-area survey of crude drugs using NIR spectroscopy. Consequently, various parameters and appropriate wavelengths were examined in the regression analysis, and a model with a reasonable contribution rate and prediction accuracy was successfully developed. In this case, the wavenumber contributing to the model was consistent with that of tenuifolin, confirming that this model was based on saponin content. In this series of analyses, we have succeeded in developing a model that can quickly estimate saponin content without post-processing and have demonstrated a brief way to perform quality control of crude drugs in the clinical field and on the market.

Near-Infrared Metabolic Profiling for Discrimination of Apricot and Peach Kernels.

Apricot and Peach Kernels are commercial crude drugs used in many formulas of traditional Japanese medicine, Kampo. Although their applications are quite different, it is difficult to distinguish them using conventional methods such as HPLC. The study aimed at near-infrared (NIR) metabolic profiling to discriminate Apricot and Peach Kernels (Armeniacae Semen and Persicae Semen) collected from Japanese markets. A fast, simple, non-destructive, and robust NIR measurement of kernel surface with no sample pre-treatment was achieved in situ. Principal component analysis and orthogonal partial least squares discriminant analysis (OPLS-DA) models showed discrimination between the two crude drugs with good fitting and prediction values. These results indicate that NIR metabolic profiling is useful for discriminating Apricot and Peach Kernels based on their chemical constituents using a simple and non-destructive procedure.

Preparation of Tenuifolin from Polygala senega L. Root Using a Hydrolytic Continuous Flow System under High-Temperature, High-Pressure Conditions.

An improved process for preparing tenuifolin (presenegenin 3-ß-d-glucopyranoside) from the root of Polygala senega L. was developed. A crude saponin mixture extracted from P. senega was subjected to hydrolysis, and the reactivity of compounds in the extract was controlled by utilizing the combination of a flow reactor and experimental design. In addition, column chromatography with HP 20, a synthetic polystyrenic adsorbent, allowed the gram-scale preparation of tenuifolin in a continuous manner with fewer steps. This approach shortens the total time required for gram-scale preparation from 16 to 5 h in a continuous manner while improving the yield from 0.59% to 2.08% (w/w).

Efficient synthesis of diverse C-3 monodesmosidic saponins by a continuous microfluidic glycosylation/batch deprotection method.

Triterpene and steroid saponins have various pharmacological activities but the synthesis of C-3 monodesmosidic saponins remains challenging. Herein, a series of C-3 glycosyl monodesmosidic saponins was synthesized via the microfluidic glycosylation of triterpenoids or steroids at the C-3 position, without the formation of orthoester byproducts, and subsequent deprotection of the benzoyl (Bz) group. This microfluidic glycosylation/batch deprotection sequence enabled the efficient synthesis of C-3 saponins with fewer purification steps and a shorter reaction time than conventional batch synthesis and stepwise microfluidic glycosylation. Furthermore, this system minimized the consumption of the imidate donor. Using this reaction system, 18 different C-3 saponins and 13 different C-28-benzyl-C-3 saponins, including 8 new compounds, were synthesized from various sugars and triterpenes or steroids. Our synthetic approach is expected to be suitable for further expanding the C-3 saponin library for pharmacological studies.

Metabolic fingerprinting for discrimination of DNA-authenticated Atractylodes plants using 1H NMR spectroscopy.

Identifying different species of the genus Atractylodes which are commonly used in Chinese and Japanese traditional medicine, using chromatographic approaches can be difficult. 1H NMR metabolic profiling of DNA-authenticated, archived rhizomes of the genus Atractylodes was performed for genetic and chemical evaluation. The ITS region of the nuclear rDNA was sequenced for five species, A. japonica, A. macrocephala, A. lancea, A. chinensis, and A. koreana. Our samples had nucleotide sequences as previously reported, except that part of the A. lancea cultivated in Japan had a type 5, hybrid DNA sequence. Principal component analysis (PCA) using 1H NMR spectra of extracts with two solvent systems (CD3OD, CDCl3) was performed. When CDCl3 extracts were utilized, the chemometric analysis enabled the identification and classification of Atractylodes species according to their composition of major sesquiterpene compounds. The 1H NMR spectra using CD3OD contained confounding sugar peaks. PCA removal of these peaks gave the same result as that obtained using CDCl3 and allowed species distinction. Such chemometric methods with multivariate analysis of NMR spectra will be useful for the discrimination of plant species, without specifying the index components and quantitative analysis on multi-components.

Oleanolic acid 3-glucoside, a synthetic oleanane-type saponin, alleviates methylmercury toxicity in vitro and in vivo.

Methylmercury (MeHg) is one of the most toxic environmental pollutants, presenting a serious health hazard worldwide. In this study, we examined the potential of derivatives of oleanolic acid (OA), such as OA 3-glucoside, OA 28-glucoside, and OA 3,28-diglucoside, to mitigate MeHg toxicity in vitro and in vivo. We found that OA 3-glucoside suppressed the cellular MeHg uptake by 63.4% compared with that of the control and improved the cell viability from 75.4% to 107.9% upon exposure to cytotoxic MeHg in Caco-2 cells. To verify the anti-MeHg activity of OA 3-glucoside, mice were orally administered MeHg (0, 1.0, or 5.0 mg kg-1·d-1), with or without OA 3-glucoside, and then mercury accumulation was measured in various organs of the mice. The mice co-treated with MeHg and OA 3-glucoside showed significantly lower mercury content in organs such as the cerebrum, cerebellum, liver, kidney, and spleen, with 83.1%, 68.7%, 71.7%, 82.1%, and 18.2% of those in the OA 3-glucoside-untreated group, respectively. This suggested OA 3-glucoside had the potential as an anti-MeHg compound, owing to its ability to suppress the distribution of MeHg into organs. Supporting this hypothesis, the mice treated with MeHg and OA 3-glucoside showed a tendency to survive one day longer than the control mice. Our findings suggest OA 3-glucoside administration alleviates the toxicity of MeHg by suppressing MeHg accumulation in organs.

Total Synthesis of (±)-Phomoidride†D.

Described herein is a synthetic strategy for the total synthesis of (±)-phomoidride D. This highly efficient and stereoselective approach provides rapid assembly of the carbocyclic core by way of a tandem phenolic oxidation/intramolecular Diels-Alder cycloaddition. A subsequent SmI2 -mediated cyclization cascade delivers an isotwistane intermediate poised for a Wharton fragmentation that unveils the requisite bicyclo[4.3.1]decene skeleton and sets the stage for synthesis completion.

Anti-steatosis compounds from leaves of Mallotus furetianus.

There is no drug administration-approved therapy for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this study, eight compounds, gallic acid (1), methyl gallate (2), corilagin (3), 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (4), repandinin B (5), (Z)-3-hexenyl-ß-D-glucopyranoside (6), (+)-lyoniresinol-3α-O-α-L-rhamnopyranoside (7) and mallophenol A (8) were isolated from the active fractions of Mallotus furetianus. Three compounds, (6, 7 and 8) revealed potent anti-steatosis activity in the oleic acid (OA)-induced steatosis cell model, with the minimum effective concentration of 0.05 (6), 0.0005 (7) and 0.0005 (8) µg/mL, which were much lower than the control compound, fibrate (72.4 µg/mL).

Phellilane L, Sesquiterpene Metabolite of Phellinus linteus: Isolation, Structure Elucidation, and Asymmetric Total Synthesis.

A new cyclopropane-containing sesquiterpenoid, phellilane L (1), was isolated from the medicinal mushroom Phellinus linteus ("Meshimakobu" in Japanese), a member of the Hymenochaetaceae family and a well-known fungus that is widely used in East Asia. The planar structure of 1 was determined on the basis of spectroscopic analysis. The authors achieved the first total synthesis of 1. Our protecting group-free synthesis features a highly stereoselective one-pot synthesis involving an intermolecular alkylation/cyclization/lactonization strategy for construction of the key cyclopropane-γ-lactone intermediate. Additionally, our synthesis determined the absolute configuration of phellilane L (1).

Corrigendum: γ-Ionylidene-type sesquiterpenoids possessing antimicrobial activity against Porphyromonas gingivalis from Phellinus linteus and their absolute structure determination.

This corrects the article DOI: 10.1038/ja.2017.35.

Corrigendum: Iminimycin A, the new iminium metabolite produced by Streptomyces griseus OS-3601.

This corrects the article DOI: 10.1038/ja.2015.142.

Inhibition of UDP-glucuronosyltransferase (UGT)-mediated glycyrrhetinic acid 3-O-glucuronidation by polyphenols and triterpenoids.

Glycyrrhetinic acid (GA) is an active metabolite of glycyrrhizin, which is a main constituent in licorice (Glycyrrhiza glabra). While GA exhibits a wide variety of pharmacological activities in the body, it is converted to a toxic metabolite GA 3-O-glucuronide by hepatic UDP-glucuronosyltransferases (UGTs). To avoid the development of the toxic metabolite-induced pseudohyperaldosteronism (pseudoaldosteronism), there is a limitation in maximum daily dosage of licorice and in combined usage of other glycyrrhizin-containing natural medicine. In this study, we investigated the inhibitory effects of various polyphenols and triterpenoids on the UGT-mediated GA 3-O-glucuronidation. In human liver microsomes, UGT-mediated GA glucuronidation was significantly inhibited by protopanaxadiol with an IC50 value of 59.2 µM. Isoliquiritigenin, rosmarinic acid, alisol B, alisol acetate, and catechin moderately inhibited the GA glucuronidation with IC50 values of 96.4 µM, 125 µM, 160 µM, 163 µM, and 164 µM. Other tested 19 polyphenols and triterpenoids, including liquiritigenin, did not inhibit UGT-mediated GA glucuronidation in human liver microsomes. Our data indicate that relatively higher dosage of licorice can be used without a risk of developing pseudohyperaldosteronism in combination of natural medicine containing protopanaxadiol such as Panax ginseng. Furthermore, supplemental protopanaxadiol and isoliquiritigenin might be useful in preventing licorice-inducing pseudoaldosteronism.

Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions.

We report the first synthesis of a series of bisdesmosidic oleanolic acid saponins using microflow reactor Comet X-01 via a continuous flow glycosylation-batch deprotection sequence. The main results of this study can be summarized as follows: (1) The microfluidic glycosylation of oleanolic acid at C-28 was achieved in quantitative yield and was applied to the synthesis of six C-28-monoglycosidic saponins. (2) The microfluidic glycosylation of oleanolic acid at C-3 was achieved in good yield without orthoester byproduct formation and was applied to the synthesis of three bisdesmosidic saponins. (3) The continuous synthesis of saponins via a microfluidic glycosylation-batch deprotection sequence was achieved in four steps involving two purifications. Thus, the continuous microfluidic glycosylation-deprotection process is expected to be suitable for the preparation of a library of bisdesmosidic oleanolic acid saponins for in vivo pharmacological studies.

Syntheses and mucosal adjuvant activity of simplified oleanolic acid saponins possessing cinnamoyl ester.

A series of new simplified oleanolic acid saponins with a glycosyl ester moiety at C28, were efficiently prepared. Furthermore, the effect of nasal administration of the synthetic oleanolic acid saponins on the nasal anti-influenza virus antibody titer against secondary nasal inoculation of the influenza split vaccine was examined. The result revealed cinnamoyl saponin as a suitable candidate vaccine adjuvant.

Iminimycin A, the new iminium metabolite produced by Streptomyces griseus OS-3601.

A new natural product, designated iminimycin A, was isolated from the cultured broth of a streptomycin-producing microbial strain, Streptomyces griseus OS-3601, via a physicochemical screening method using HP-20, silica gel and ODS column chromatographies and subsequent preparative HPLC. Iminimycin A is an indolizidine alkaloid, containing of an unusual iminium group and a cyclopropane ring with a triene side chain. The absolute configuration of iminimycin A was elucidated by NMR studies and electronic circular dichroism analysis. Iminimycin A shows anti-bacterial activity against Bacillus subtilis, Kocuria rhizophila and Xanthomonas campestris pv. orizae, and cytotoxic activity against HeLa S3 and Jurkat cells with IC50 values of 43 and 36 µM, respectively.

Asymmetric Total Synthesis of Indole Alkaloids Containing an Indoline Spiroaminal Framework.

The total synthesis of the indole alkaloids, neoxaline, oxaline and meleagrin A, all containing a unique indoline spiroaminal framework, was accomplished through the stereoselective introduction of a reverse prenyl group to the congested benzylic carbon of furoindoline, a two-pot transformation of indoline (containing three nitrogen atoms at appropriate positions) to the featured indoline spiroaminal framework, and elimination of carbonate assisted by the adjacent imidazole moiety to construct the (E)-dehydrohistidine. The absolute stereochemistry of neoxaline was elucidated through our total synthesis. In addition, we evaluated the bioactivity, especially the anti-infectious properties, of neoxaline and oxaline, and of some synthetic intermediates.

Aogacillins A and B produced by Simplicillium sp. FKI-5985: new circumventors of arbekacin resistance in MRSA.

Aogacillins A and B, capable of overcoming arbekacin resistance in methicillin-resistant Staphylococcus aureus (MRSA), were isolated from a culture broth of Simplicillium sp. FKI-5985. Their structures were elucidated by NMR spectroscopic studies and ECD analyses. The aogacillins possessed a novel carbon skeleton, including a ß-keto-γ-methyliden-δ-lactone ring connected to a 2-ethyl-6-methylcyclohexane ring by spiro conjugation.

Asymmetric total synthesis of neoxaline.

A first asymmetric total synthesis and determination of the absolute configuration of neoxaline has been accomplished through the highly stereoselective introduction of a reverse prenyl group to create a quaternary carbon stereocenter using (-)-3a-hydroxyfuroindoline as a building block, construction of the indoline spiroaminal via cautious stepwise oxidations with cyclizations from the indoline, assembly of (Z)-dehydrohistidine, and photoisomerization of unnatural (Z)-neoxaline to the natural (E)-neoxaline as the key steps.