A new coumarin derivative (1) and 30 known compounds were isolated from Mammea siamensis and Andrographis paniculata, guided by B cell-specific Moloney murine leukemia virus insertion region 1 (BMI1) promoter inhibitory activity. Among the isolated compounds, 15 compounds showed BMI1 promoter inhibitory activity, and five compounds were found to be cytotoxic. 14-Deoxy-11,12-dehydroandrographolide (18) was highly cytotoxic to DU145 cells with an IC₅₀ value of 25.4 µM. Western blotting analysis of compound 18 in DU145 cells suggested that compound 18 suppresses BMI1 expression.

Quantitative ¹H-NMR (¹H-qNMR) is useful for determining the absolute purity of organic molecules; however, it is sometimes difficult to identify the target signal(s) for quantitation because of their overlap and complexity. Therefore, we focused on the ³¹P nucleus because of the simplicity of its signals and previously reported ³¹P-qNMR in D₂O. Here we report ³¹P-qNMR of an organophosphorus compound, sofosbuvir (SOF), which is soluble in organic solvents. Phosphonoacetic acid (PAA) and 1,4-bis(trimethylsilyl)benzene-d₄ (1,4-BTMSB-d₄) were used as reference standards for ³¹P-qNMR and ¹H-qNMR, respectively, in methanol-d₄. The purity of SOF determined by ³¹P-qNMR was 100.63 ± 0.95%, whereas that determined by ¹H-qNMR was 99.07 ± 0.50%. The average half bandwidths of the ³¹P signal of PAA and SOF were 3.38 ± 2.39 and 2.22 ± 0.19 Hz, respectively, suggesting that the T₂ relaxation time of the PAA signal was shorter than that of SOF and varied among test laboratories. This difference most likely arose from the instability in the chemical shift due to the deuterium exchange of the acidic protons of PAA, which decreased the integrated intensity of the PAA signal. Next, an aprotic solvent, dimethyl sulfoxide-d₆ (DMSO-d₆), was used as the dissolving solvent with PAA and sodium 4,4-dimethyl-4-silapentanesulfonate-d₆ (DSS-d₆) as reference standards for ³¹P-qNMR and ¹H-qNMR, respectively. SOF purities determined by ³¹P-qNMR and ¹H-qNMR were 99.10 ± 0.30 and 99.44 ± 0.29%, respectively. SOF purities determined by ³¹P-qNMR agreed with the established ¹H-qNMR values, suggesting that an aprotic solvent is preferable for ³¹P-qNMR because it is unnecessary to consider the effect of deuterium exchange.

From the less polar fraction of the MeOH extract of the leaves and twigs of Omphalea oppositifolia, five new ent-rosane-type diterpenoids, named omphalines A–E (1–5), were isolated together with one known compound, 7-keto-ent-kaurane-16β,17-diol (6), by a combination of various kinds of chromatography. The structure of omphaline A (1) was elucidated to be 19-nor-ent-rosane-4,15-diene-2β,6α-diol-3-one. Omphalines B (2), C (3), D (4), and E (5) possessed two double bonds at 5- and 15-positions, and hydroxy functional groups at 3β-, 2α,3α-, 2α,3β-, and 2α,19-positions, respectively. The absolute configuration of 1 was determined by the comparison of the experimental electronic circular dichroism (ECD) spectrum and calculated ECD spectra.

We have developed a simple and accurate method for quantifying sugars in herbal medicines, which have hitherto been difficult to quantify. Using ultra performance liquid chromatography-quadrupole-time-of-flight (UPLC-Q-TOF)-MS and two types of columns with different chemical properties, we determined the optimum conditions for separating nine sugars (fructose, galactose, glucose, mannitol, sucrose, melibiose, raffinose, manninotriose, and stachyose) commonly found in herbal medicines. Separation was completed within 10 min when an apHera NH₂ HPLC column was used, although galactose and glucose could not be separated. On the other hand, the nine sugars were completely separated within 16 min when a hydrophilic interaction chromatography (HILIC)pak VG-50 2D column was used. The calibration curves obtained using those two columns gave good linearity for the sugar standards, and the coefficient of determination was 0.995 or higher. Both columns showed excellent performance with short analysis time and high sensitivity. Using our developed method, we were able to quantify sugars in galactose-free herbal medicines within 10 min and in herbal medicines containing galactose within 16 min. We revealed that our method could be used for the analysis of sugars in Angelica acutiloba and Rehmannia glutinosa roots.

Here, we synthesized three acetogenin analogs containing pyrimidine moieties linked by amine bonds, which represent the skeleton structure of pyrimidifen, a mitochondrial complex I-inhibiting insecticide. Replacing the pyrimidine moiety linked by the amine bond remarkably enhanced growth-inhibitory activity of the analogs against several human cancer cell lines. Moreover, these analogs selectively and potently inhibited the growth of these human cancer cell lines regardless of the pyrimidine substituents. Furthermore, COMPARE analyses suggested that these analogs inhibited cancer growth by inhibiting mitochondrial complex I. Our study provides insights into the design of acetogenin analogs as novel antitumor agents.

Chemically modified nucleic acids are essential for the therapeutic application of oligonucleotides. In this study, 6′-C-spiro-thymidine exhibiting a fixed torsion angle γ was designed, synthesized, and incorporated into oligonucleotides. The conformational analysis of the 6′-C-spiro-thymidine monomer revealed that its torsion angle γ was in the +synclinal range (approx. 60°), which is similar to that in a natural RNA duplex, as expected. On the other hand, the sugar conformation of the RNA duplex is known to be predominantly an N-type, whereas that of the synthesized monomer was an S-type. The results of the UV melting analysis demonstrated that the duplex-forming ability of 6′-C-spiro-thymidine was inferior to that of natural DNA. Contrarily, 6′-C-spiro-thymidine could enhance the stability of oligonucleotides toward nucleases. Particularly, the incorporation of 6′-C-spiro-thymidine on the 3′-ends of the oligonucleotides significantly increased the nuclease resistance of the oligonucleotides.

Proteins modified in a controlled manner with artificial moieties such as fluorophores or affinity tags have been shown to be a powerful tool for functional or structural analysis of proteins. A reliable way to prepare proteins with a well-defined modification is protein synthesis. Although many successful syntheses have been reported, the poor aqueous solubility of synthetic intermediates causes difficulty in the chemical synthesis of proteins. Here we describe a solubilizing strategy for poorly soluble peptides which uses chemoselective incorporation of a hydrophilic tag onto a hydrazide in a peptide. We found that a hydrophilic tag possessing a dialkoxybenzaldehyde moiety can react with peptide hydrazides through reductive N-alkylation. No protecting groups are required for this reaction, and peptides modified in this way show enhanced solubility and consequently good peak separation during HPLC purification. The tag can be removed subsequently by treatment with trifluoroacetic acid to generate a free hydrazide, which can be converted in a one-pot reaction to a thioester for further modification. This method was validated by synthesis of a Lys₆₃-linked ubiquitin dimer derivative. This late-stage solubilization can be applied in principal to any peptide and opens the possibility of the synthesis of proteins that have previously been considered inaccessible due to their poor solubility.

Computational chemistry is useful in synthetic organic chemistry, as it can be used not only to analyze reaction mechanisms, but also to calculate biosynthetic pathways and to plan and evaluate strategies for total syntheses. Here we report the computation-guided total synthesis of vitisinol G, a resveratrol dimer.

The acetamide moiety is a general functional group present in many natural and pharmaceutical products. Herein, we report two new reagents, p-methoxybenzyl N-acetylcarbamate potassium salt (PM-BENAC-K) and 2,4-dimethoxybenzyl N-acetylcarbamate potassium salt (2,4-DM-BENAC-K), which are refined versions of the benzyl N-acetylcarbamate potassium salt (BENAC-K). These compounds, which we reported as simple equivalents of N-acetamide nucleophiles, are stable and easy-to-handle powders that react with a variety of alkyl halides and sulfonates to afford substituted products in good yields. The products were transformed into N-alkylacetamides after p-methoxybenzyloxycarbonyl (Moz) or 2,4-dimethoxybenzyloxycarbonyl (Dmoz) cleavage under mild acidic conditions. The acetyl groups in the substituted products of PM- and 2,4-DM-BENAC-Ks were removed using K₂CO₃ in methanol to afford Moz- and Dmoz-protected amines, respectively. Hence, the new BENAC-Ks acted as versatile equivalents of both N-acetamide and Moz/Dmoz-protected nitrogen nucleophiles and can be used in synthetic studies of natural and pharmaceutical products.

A number of alkaloids found in Mitragyna species belonging to the Rubiaceae family have been shown to have potent biological activity such as analgesic properties. Here, we report the asymmetric total syntheses of mitragynine, speciogynine, and 7-hydroxymitragynine, which are classified as corynantheine-type monoterpenoid indole alkaloids, isolated from Mitragyna speciosa. These syntheses were accomplished within 12 steps and in >11% total yield from commercial 3-(trimethylsilyl)propanal using an organocatalytic anti-selective Michael reaction and bioinspired transformations.

Herein, we developed secondary-alcohol-selective C–H alkylation of 1,3-butane diol by combining an acridinium photoredox catalyst and a thiophosphoric acid hydrogen atom transfer (HAT) catalyst. The use of non-coordinating solvent such as dichloromethane (DCM) improved secondary α-alkoxy C–H selectivity by lowering bond dissociation energy (BDE) through intramolecular hydrogen bonding.

Hardness is a critical quality characteristic of pharmaceutical oral jelly. In this study, the hardness was determined by using the T₂ relaxation curves measured by time-domain NMR. For sample preparation, kappa- and iota-carrageenans, and locust bean gum, were used as gel-forming agents. Ten test jellies with different gel-forming agent composition were prepared, and their hardness and T₂ relaxation curves were measured by a texture analyzer and time-domain NMR (TD-NMR). A negative correlation between T₂ relaxation time (T₂) and hardness was observed; however, it was difficult to determine the hardness directly from the T₂ value. That is probably because the T₂ relaxation curve contains information about molecular states, not only of water but also of the solute, and T₂ values calculated by single-exponential curve fitting only express one property of the test jelly. By considering this issue, partial least squares (PLS) regression analysis was performed on the T₂ relaxation curves for hardness determination of the test jellies. According to the analysis, an accurate and reliable PLS model was created that enabled accurate assessment of the hardness of the test jellies. TD-NMR enables the measurement of samples nondestructively and rapidly with low cost, and so could be a promising method for evaluation of the hardness of pharmaceutical oral jellies.

We report aryne generation from 2-triazenylarylboronic acids using an activator such as Brønsted acids, Lewis acids, and solid acids. With the use of (±)-Camphorsulfonic acid [(±)-CSA], the aryne precursors provided cycloadducts with a range of arynophiles in high yields. Aryne generated under the acidic conditions underwent chemoselective cycloaddition with a furan in the presence of a basic arynophile, namely an amine. Hammett plot analyses revealed that an aryne generation mechanism induced by (±)-CSA is distinct from the mechanism induced by silica gel.

A lot of chiral stationary phases (CSPs) have been introduced for the purpose of analytical and preparative separations of enantiomers. CSPs based on proteins and glycoproteins have unique properties among those CSPs. This review article deals with the preparation of CSPs based on proteins and glycoproteins, their chiral recognition properties and mechanisms, focusing on the CSPs investigated in our group. The dealt proteins and glycoproteins are including bovine serum albumin, human serum albumin, lysozyme, pepsin, human α₁-acid glycoprotein (AGP), chicken ovomucoid and chicken ovoglycoprotein (named chicken AGP).

Due to the importance of the RNA chemical modifications, methods for the selective chemical modification at a predetermined site of the internal position of RNA have attracted much attention. We have developed functional artificial nucleic acids that modify a specific site of RNA in a site- and base-selective manner. In addition, the copper-catalyzed azide-alkyne cycloaddition (CuAAC) has been shown to introduce additional molecules on the alkynes attached to the pyridine ring. However, it was found that some azide compounds produced the cycloadduct in lower yields. Therefore, in this study, we synthesized the pyridinyl transfer group with the alkyne attached via a polyethylene glycol (PEG) linker with a different length and optimized its structure for both the transfer and CuAAC reaction. Three new transfer groups were synthesized by introducing an alkyne group at the end of the triethylene (11), tetraethylene (12) or pentaethylen glycol linker (13) at the 5-position of the pyridine ring of (E)-3-iodo-1-(pyridin-2-yl)prop-2-en-1-one. These transfer groups were introduced to the 6-thioguanine base in the oligodeoxynucleotide (ODN) in high yields. The transfer groups 11 and 12 more efficiently underwent the cytosine modification. For the CuAAC reaction, although 7 showed low adduct yields with the anionic azide compound, the new transfer groups, especially 12 and 13, significantly improved the yields. In conclusion, the transfer groups 12 and 13 were determined to be promising compounds for the modification of long RNAs.

Cationic liposomal formulations of the telomeric G-quadruplex stabilizing ligand, 13-(2-naphthylmethoxy)berberine bromide (1), have been developed with the purpose of delivering 1 into the nucleus of cancer cells for potential telomere targeting. Berberine derivative 1 was encapsulated in various cationic lipids 2–4 by the thin film evaporation method; these lipids are cationic after amine protonation. The most appropriate liposomal berberine formulation was that of 1 and the cholesterol derived cationic lipid 4 in a weight ratio of 1 : 20 with 76.5% encapsulation efficiency of 1. Cellular uptake studies in the HeLa and HT-29 cancer cells lines showed that the liposomal berberine derivative uptake in the cells was higher and more stable than for berberine derivative 1 alone while free 1 was completely decomposed in the cells within 60 min exposure to the cells. Anticancer activity of the liposomal berberine derivative 1 based on 4 was greater than that for the free berberine derivative 1 in the MCF-7, HeLa and HT-29 cell line by 2.3-, 4.9- and 5.3-fold, respectively, and also, interestingly, superior to the anticancer drug doxorubicin against the HT29 cancer cell line.

Picrotoxinin, coriamyrtin, and tutin are representative natural products classified as picrotoxane-type sesquiterpenes and they function as strong neurotoxins. Because they possess a cis-fused 5,6-ring skeleton with a highly congested functionalization, organic chemistry researchers have pursued the development of a stereoselective synthesis method for such skeleton. This study aims to stereoselectively synthesize the cis-fused 5,6-ring skeleton with two tetrasubstituted carbons at both angular positions using a model compound. The results revealed that the desymmetrization of the 2-methyl-1,3-cyclopentanedione moiety via the DL-proline-mediated intramolecular aldol reaction of a pentanal derivative bearing an isopropenyl group and the five-membered ring at the 3- and 5-position, respectively, provided the desired cis-fused skeleton. This reaction can construct four contiguous stereogenic centers of the bicyclic skeleton with the two angular positions in good yield with high stereoselectivity. Further, this reaction was applied to the kinetic resolution of the racemate using L-proline, providing the enantiomeric pure aldol product with the desired skeleton. This method can be utilized for total synthesis of picrotoxane-type sesquiterpenes.

Two series of 2-substituted benzimidazole conjugated 1,3,4-oxadiazole derivatives were designed, synthesized and evaluated for their cytotoxic activities against the three human cancer cell lines (cervical cancer (HeLa), breast cancer (MCF-7) and lung cancer (A549)). As the results 14 compounds demonstrated consistent to stronger cytotoxicities compared to the control 5-fluorouracil (5-FU) towards the tested cell lines including 4c (HeLa); 4b, 4e, 4h, 7i–j, 7m–n, 7s (MCF-7); 7b (MCF-7, A549); 7h (HeLa, MCF-7); and 4d, 4i, 7c (HeLa, MCF-7, A549), with the IC₅₀ ranging from 2.7 to 38 µM. Notably, compound 4b illustrated almost 5-fold activity against the MCF-7 while 4d, 4i were 9- and 8-fold (HeLa), 4.5- and 13-fold (MCF-7), 4.7- and 4-fold (A549) increase in activity compared to 5-FU, respectively, and were found as lead compounds. These findings suggest that compounds 4b, 4d and 4i merit further characterization and can serve as promising scaffolds in the discovery of new potent anticancer agents.