A group of naturally occurring substances containing nitrogen is widely distributed in plants as well as in fungi, animal, marine organisms, and insects, and many exhibit significant biological activity. These natural products with a huge variety of chemical structures include antibiotics, antitumor agents, immunostimulants, drugs affecting the cardiovascular and central nervous systems, analgesics etc. The diverse activities and low natural abundance of this group of natural products when coupled with their molecular complexity warrant development of new and efficient synthetic methods and strategy for the total synthesis of these products, in particular alkaloids. The purpose of this review is to describe some of our achievements in the total synthesis of the naturally-occurring bases including the Dendrobatid alkaloids pumiliotoxin B and allopumiliotoxin A, the anitibiotic streptazolin, the tricyclic marine alkaloids isolated from the ascidians such as fasicularin, lepadiformine, and cylindricine C, and the dimeric monoterpene alkaloid incarvillateine as well as the formal total synthesis of the spirocyclic marine alkaloids halichlorine and pinnaic acid, which are isolated from the Japanese marine sponge and the Okinawan bivalve, respectively.

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Nineteen new derivatives (2—20) of the naturally occurring compound, goniothalamin (1), were prepared by chemical modification and semi-synthetic methods. The antitumor activities of these derivatives and goniothalamin were evaluated in vitro against human tumor cell lines, and most of them showed an inhibitory effect against HL-60 cancer cells. The derivatives 10-nitro-goniothalamin (2) and 10-amino-goniothalamin (4) gave selective inhibition concentration (IC₅₀) of 1.10 and 1.14 μg/ml, respectively, against human stomach cancer SGC-7901 cells, while that of etoposide (vp-16) as the positive control was 6.07 μg/ml. Finally, the partition coefficients, logP (π values), of these derivative molecules, were evaluated by calculating the additive approximate organic fragment logP value.

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High-performance liquid chromatography with evaporative light scattering detection (HPLC/ELSD) was established for simultaneous determination of seven major bioactive components of Qingkailing injection including adenosine, geniposide, chlorogenic acid, baicalin, ursodeoxycholic acid, cholic acid, and hyodeoxycholic acid. The proposed method was applied to analyze ten various Qingkailing injections and produced data with acceptable linearity, repeatability, precision and accuracy having a limit of detection (LOD) of 10—50 ng. In comparison with UV detection, HPLC/ELSD permits the determination of non-chromophoric compounds without prior derivatization, and shows good compatibility to the multi-components of complex analytes. The proposed method is a useful alternative for routine analysis in the quality control of traditional Chinese medicine.

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The intercalation reaction of diclofenac sodium (DFS) with layered inorganic compounds, γ-titanium phosphate (γ-TiP), proton type titanium oxide (H-TiO₂) and sodium type synthetic mica (Na-TSM), was examined on. The direct reaction of DFS in ethanol–water mixed solvent resulted in the large amount accommodation of DFS. The amount of intercalated DFS was the order of γ-TiP>H-TiO₂>Na-TSM corresponding to the order of acidity. The intercalation using phospholiopids was also examined to assist the intercalation reaction. However, the amount of intercalated DFS was rather small in comparison with those in the direct reaction. DFS accommodated in γ-TiP dissolved into neutral and basic buffer solution stoichiometry while scarcely dissolved in the acidic solution. The mechanism of the intercalation and reverse dissolution was successfully accounted according to the ion-exchange mechanism between Na⁺ in DFS and H⁺ in γ-TiP. The dissolution from tablet of DFS/γ-TiP intercalation compound was examined by using a disintegrator. It was found that the dissolution rate appropriately controlled by mixing the disintegrator. The present results suggested the different possibilities in the clinical field to use layered inorganic compounds such as drug delivery system (DDS).

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Six novel selenium-containing polyphenolic acid esters were synthesized and evaluated as antioxidants and 5-lipoxygenase inhibitors. Synthesis of the title compounds involved the Mitsunobu reaction of polyphenolic acids (4—8, 14) with 2-phenylselenoethanol (3). Compounds 22, 23, and 25 were found to be very effective antioxidants and 5-lipoxygenase inhibitors with activity comparable to or better than caffeic acid (3,4-dihydroxycinnamic acid) phenethyl ester (CAPE).

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A new ulopyranose isolated from aqueous extract of roots and rhizomas of Psacalium peltatum has been determined to have hypoglycemic activity at doses of 100 mg/kg, comparable to that of tolbutamide and insulin in alloxan diabetic mice. The skeletal structure of the new compound was established by spectral analysis.

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To find efficient methods to evaluate oxidative stress in mouse skin caused by X-ray irradiation, several markers and methodologies were examined. Hairless mice were irradiated with 50 Gy X-rays and skin homogenates or skin strips were prepared. Lipid peroxidation was measured using the skin homogenate as the level of thiobarbituric acid reactive substances. The level of lipid peroxidation increased with time after irradiation and was twice that of the control at 78 h. ESR spectra of skin strips showed a clear signal for the ascorbyl radical, which increased with time after irradiation in a manner similar to that of lipid peroxidation. To measure levels of glutathione (GSH) and its oxidized forms (GSSG) simultaneously, two HPLC methods, sample derivatization with 1-fluoro-2,4-dinitrobenzene and detection with a UV detector (method A) and no derivatization and detection with an electrochemical detector (method B), were compared and the latter was found to be better. No significant change was observed within 24 h after irradiation in the levels of GSH and GSSG measured by method B. The GSH/GSSG ratio may be a less sensitive parameter for the evaluation of acute oxidative stress caused by X-ray irradiation in the skin. Monitoring the ascorbyl radical seems to be a good way to evaluate oxidative stress in skin in vivo.

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The 80% aqueous acetone extract from the whole plant of Saussurea medusa MAXIM. was found to inhibit rat lens aldose reductase (IC₅₀=1.4 μg/ml). From this extract, flavonoids, lignans, and quinic acid derivatives were isolated together with two new ionone glycosides, saussureosides A and B. Their absolute stereostructures were elucidated on the basis of chemical and physicochemical evidence including the application of modified Mosher's method. In addition, some isolates were found to show an inhibitory effect on aldose reductase.

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Biotransformations of the sesquiterpene ketone nootkatone (1) from the crude drug Alpiniae Fructus and grapefruit oil, and the sesquiterpene hydrocarbon valencene (2) from Valencia orange oil were carried out with microorganisms such as Aspergillus niger, Botryosphaeria dothidea, and Fusarium culmorum to afford structurally interesting metabolites. Their stereostructures were established by a combination of high-resolution NMR spectral and X-ray crystallographic analysis and chemical reaction. Metabolic pathways of compounds 1 and 2 by A. niger are proposed.

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Various thieno[3,4-b]indolizine derivatives having an allylthio or propargylthio group at the 3-position were prepared and their intramolecular arene–π interactions were investigated. Their ¹H-NMR spectra showed significant low-field shifts (δ 0.10—0.34 ppm) to the 5-proton on the thieno[3,4-b]indolizine ring, and this effect was the reverse to that observed in 3-(arylmethylthio)thieno[3,4-b]indolizines. However, their UV spectra exhibited a characteristic absorption band due to the arene–π interaction near 430 nm and these values were almost similar to those for arene–arene interaction of 3-arylmethylthio derivatives though their molar extinction coefficients were largely varied by the 3-substituents. Furthermore, both types of gauche conformations in which the intramolecular arene–π interactions are possible in one form and impossible in the other were confirmed by X-ray analyses of some compounds.

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We investigated the superoxide anion scavenging effects of thirteen 2-amino-1,3-selenazoles using a highly sensitive quantitative chemiluminescence method. At 166 μM, the 2-amino-1,3-selenazoles scavenged in the range of 14.3 to 96.7% of O₂⁻. 2-Piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole exhibited the strongest superoxide anion-scavenging activity among the 2-amino-1,3-selenazoles. The 50% inhibitory concentrations (IC₅₀) of 2-piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole were determined to be 4.03 μM and 92.6 μM, respectively. Thus, these compounds acted in vitro as effective O₂⁻ scavengers.

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The purpose of this study is to examine whether molecular dynamics (MD) simulations using a commercially available software for personal computers can estimate the glass transition temperature (T_g) of amorphous systems containing pharmaceutically-relevant excipients. MD simulations were carried out with an amorphous matrix model constructed from isomaltoheptaose, and the T_g estimated from the calculated density versus temperature profile was compared with the T_g measured by differential scanning calorimetry (DSC) for freeze-dried isomalto-oligomer having an average molecular weight close to that of isomaltoheptaose. The T_g values determined by DSC were lower by 10 to 20 K than those extrapolated from the T_g values estimated by MD simulation. Fragility parameter was estimated to be 56 and 51 from MD simulation and from DSC measurement, respectively. Thus, the results suggest that MD simulation can provide approximate estimates for the T_g and fragility parameter of amorphous formulations. However, a reduction of the cooling rate, achievable by sufficiently elongating the simulation duration, is necessary for more accurate estimation.

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A rapid and reliable solid-phase extraction method for HPLC analysis of opium alkaloids from Papaver plants was established. Fifty mg of dried and powdered plant sample was extracted with 5 ml of 5% acetic acid for 30 min under sonication. After centrifugation, 3 ml of the supernatant was loaded on a reversed-phase cation-exchange solid-phase extraction cartridge. After seriate washings with 0.1 M hydrochloric acid and methanol, alkaloids were eluted with a mixture of 28% ammonia and methanol (1 : 19). The eluate was concentrated under nitrogen stream at 40 °C and the residue was dissolved in 50% aqueous methanol for high performance liquid chromatographic analysis. With this solid-phase extraction method, the recovery of morphine, codeine, oripavine, thebaine, papaverine, noscapine and sanguinarine was from 99.94 to 112.18% when the standard alkaloids were added to the plant samples. Opium alkaloids of a variety of genus Papaver plants cultivated in a field and phytotron were analyzed by this method.

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Seventeen saponins isolated from the root of Pulsatilla koreana were examined for their in vitro cytotoxic activity against the human solid cancer cell lines, A-549, SK-OV-3, SK-MEL-2, and HCT15, using the SRB assay method, and their in vivo antitumor activity using BDF1 mice bearing Lewis lung carcinoma (LLC). The saponins 5—17, with a free acidic functional group at C-28 of aglycon, exhibited moderate to considerable cytotoxic activity, however, the saponins 1—4, esterified with a trisaccharide at C-28 of aglycon, did not exhibit cytotoxic activity (ED₅₀; >300 μM). Among them, oleanolic acid 3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-α-L-arabinopyranoside (10) exhibited the most potent cytotoxic activity (ED₅₀; 2.56, 2.31, 1.57, 8.36 μM, respectively). In vivo test, hederagenin 3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-α-L-arabinopyranoside (6, Inhibition Ratio, IR; 66.9%) exhibited more potent antitumor activity than taxol (IR; 35.8%) and doxorubicin (IR; 62.1%). Also, hedragenin 3-O-β-D-glucopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside (17, IR; 50.3%) exhibited potent antitumor activity. These two saponins were identically comprised of a hederagenin aglycon moiety and a sugar sequence O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside at C-3 of the hederagenin, suggesting that the two elements are essential factors for the antitumor activity.

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Pregnenolone (1) and pregnenolone acetate (2) were incubated with the fungi Cunninghamella elegans, Rhizopus stolonifer and Gibberella fujikuroi. Incubation of 1 with C. elegans yielded metabolites, 3β,7β,11α-trihydroxypreg-5-en-20-one (3), 3β,6α,11α,12β,15β-pentahydroxypreg-4-en-20-one (4) and 3β,6β,11α-trihydroxypreg-4-en-20-one (5), while incubation with G. fujikuroi yielded two known metabolites, 3β,7β-dihydroxypregn-5-en-20-one (6) and 6β,15β-dihydroxypreg-4-ene-3,20-dione (7). Metabolites 4 and 5 were found to be new. Fermentation of 2 by C. elegans yielded four known oxidative metabolites, 1, androsta-1,4-diene-3,17-dione (8), 6β,15β-dihydroxyandrost-4-ene-3,17-dione (9) and 11α,15β-dihydroxypreg-4-ene-3,20-dione (10). Fermentation of 2 with R. stolonifer yielded two known metabolites, 11α-hydroxypreg-4-ene-3,20-dione (11) and 7. Compounds 1—11 were screened for their cholinesterase inhibitory activity in a mechanism-based assay.

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2-Alkyl-5-hydroxychromones (2-alkyl-5-hydroxy-4-oxo-4H-1-benzopyran) and 3-alkoyl-2-alkyl-5-hydroxychromones (3-alkoyl-2-alkyl-5-hydroxy-4-oxo-4H-1-benzopyran) were prepared in one-step and one pot reaction by condensation of 2′,6′-dihydroxyacetophenone with an alkoyl chloride in the presence of K₂CO₃.

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Formosadimers A, B, and C, together with one known compound, sugikurojin B, have been isolated from the bark of Calocedrus macrolepis var. formosana. Formosadimers A, B, and C, and sugikurojin B are dimers of the abietane-O-abietane type. Their structures were elucidated principally based on spectroscopic data.

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Phenylbutenoids 1—6 isolated previously from the CHCl₃ extracts of the rhizomes of Zingiber cassumunar, were evaluated for their cyclooxygenase-2 (COX-2) inhibitory activity along with a new isolate, 7 from the n-BuOH extracts of this plant. The COX-2 inhibitory assay was performed by measuring prostaglandin E₂ production in lipopolysaccharide-stimulated mouse macrophage RAW 264.7 cells. Two phenylbutenoid dimers, 1 and 2, exhibited considerable activity with IC₅₀ values of 2.71 and 3.64 μM. Two phenylbutenoid monomers, 3 and 4, showed moderate activity (IC₅₀ 14.97, 20.68 μM, respectively). The other three phenylbutenoids, 5—7, were found to be inactive. Compound 7 was elucidated as a new phenylbutenoid glycoside, namely, (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-O-β-D-glucopyranoside by spectral analysis including various 1D- and 2D-NMR experiments.

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A phytochemical investigation on the aerial parts of Lindelofia stylosa has resulted in the isolation of seven phenyl propanoids 1—7. This includes three analogs of lithospermic acid 1—3, along with rosmarinic acid (4) and its ester derivatives 5—7. Compound 1 was identified as a new natural product. These compounds were studied for their antioxidant properties.

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Method for rapid quantitative analysis of incarvillateine in Incarvillea sinensis by high-performance liquid chromatography (HPLC) has been developed. The sample preparation involves solid phase extraction (SPE) with a mixed-mode reversed-phase and cation-exchange cartridge. The linear calibration range for incarvillateine was 0.002—0.5 mg/ml. The limit of detection was 0.35 μg/ml (S/N=3). Intra- and interday precisions were less than 0.36% (n=6) and 1.61% (n=18), respectively. The recovery of incarvillateine was 97.61—102.44% with the relative standard deviation (RSD) ranging from 0.63 to 1.93% (n=3). This method was proposed as a simple, rapid and accurate method for quantitative determination of incarvillateine content in various samples of Incarvillea sinensis collected from different areas of China.

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Twelve natural bis-spirolabdane-type diterpenoids, including eight new, named leoheteronones A—E (3, 6, 8, 9, 11), 15-epileoheteronones B (7), D (10), and E (12), and four known leopersin B (1), 15-epileopersin B (2), leopersin C (4), and 15-epileopersin C (5), together with hispanone (13) and galeopsin (14) were isolated from the aerial parts of the medicinal plant Leonurus heterophyllus SW. (Lamiaceae) grown in Vietnam. Their structures were determined by spectroscopic analyses. The current study emphasized the accumulation of C-15 oxygenated bis-spirolabdane-type diterpenoids of both 13R and 13S configurations in L. heterophyllus.

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Using the HPLC/DAD/ESI/MS method, the qualitative and quantitative analysis of senkyunolide A (SA) in the rhizomes of Ligusticum chuanxiong (Rhizoma chuanxiong; CX) and roots of Angelica sinensis (DG) was established. As a result, it was found that SA is a characteristic standard compound for the quality evaluation and chemical differentiation between CX and DG. Methanol was chosen in the preparation of standard solutions and extraction of samples based on the stability data. The identity of SA in CX and DG was unambiguously determined based on the quasimolecular ions in ESI-MS. A comprehensive validation of the method, including sensitivity, linearity, reproducibility and recovery, was conducted using the optimized chromatographic conditions. The linear calibration curve was acquired with R²>0.999 and limit of detection (S/N=3) was estimated to be 12.5 μg/g. The reproducibility was evaluated by repeated sample injection and replicated analysis of samples with the relative standard deviation (RSD) value found within 0.68%. The recovery rates of SA varied within the range of 96.91—101.50% with RSD less than 2.38%. In the present work, the contents of SA were quantified within 3.94—9.14 mg/g and 0.108—0.588 mg/g for 12 batches each of CX and DG. The results demonstrated that SA is a useful standard compound for the quality evaluation and chemical differentiation between CX and DG. The analytical procedure is precise and reproducible and thus suitable for the analysis of a large number of samples.

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Fresh Houttuynia cordata THUNB. is a Chinese materia medica generally used in Chinese medicine therapy. It possesses the actions of clearing heat, eliminating toxins, reducing swelling, discharging pus and relieving stagnation. However, dry H. cordata has traditionally been used in clinical application instead of the fresh counterpart. In this paper, the chemical profiles of H. cordata were established using fingerprinting techniques. A modified GC-MS method was developed in the comparison of fingerprints among fresh and dry herbs of H. cordata. It was shown that the varieties, as well as relative levels of chemical components, in the fresh herb were more abundant than in the dry counterpart. Fingerprinting profiles were found to be consistent for fresh herbs acquired from various production areas, but the relative abundance of peaks were varied. Besides, the chemical components among different medicinal portions of fresh herbs were found to be inconsistent. The developed fingerprint can be successfully applied to distinguish between fresh and dry herbs, as well as determining differentiation among different medicinal portions.

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Novel sialosyl donors, 4-pentenoic acid ester of N-acetylneuraminic acids (Neu5Ac) (1a) and 4-pentenyl glycoside of Neu5Ac (1b) were successfully prepared from the corresponding per-O-acetylated 2-hydroxy and 2-chloro derivatives of Neu5Ac, respectively and applied to the synthesis of O-sialosides.

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(−)-Ephedrine (EP) and (+)-Pseudoephedrine (PEP) in Jiketing granule were separated by TLC, RP-HPLC, GC, HPLC-MS, and the chromatographic phenomenon was interpreted by the topological indices. The observed chromatographic separations of investigated components were compared. This comparison indicated that simply methods as C₁₈ RP-HPLC and GC are the more effective techniques, and more suitable than others for this preparation, for the separation of two alkaloids.

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A rapid, sensitive and selective spectrophotometric method has been developed for the quantitative determination of dapsone (DAP) and metoclopramide hydrochloride (MCP) in both pure and dosage forms. Individual and simultaneous methods are based on the diazo coupling reaction of these drugs with benzoylacetone (BAC) in alkaline medium. The resulting azo dyes exhibit maximum absorption at 437 and 411 nm with a molar absorptivity of 4.14×10⁴ and 2.97×10⁴ l mol⁻¹ cm⁻¹ for DAP and MCP, respectively. Simultaneous determination of DAP and MCP was developed utilizing first-order digital derivative spectrophotometry. All variables have been optimized. No interferences were observed from drug excipients and the validity of the methods was tested against reference methods.

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We have developed a highly regioselective synthesis of heterocycles via palladium-catalyzed annulation reaction of heteroatom-substituted allenes. Various aryl halides were reacted and one regioisomer was observed exclusively in all reactions. In addition, subsequent functionalizations of annulated products were carried out using alkyl metal reagents, and the introduction of alkyl moieties was accomplished.

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(Cyanomethylene)tributylphosphorane (CMBP), which promoted the alkylation of various nucleophiles (HA) with alcohols (ROH) to give RA (Mitsunobu-type reaction), was prepared in two steps starting from chloroacetonitrile.

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Post-biotinylation of the alkyl azide derivative of trifluoromethyl phenyldiazirine (TPD) was elucidated to apply a photoaffinity biotinylation technique. A photo-modified polyvinilidene difluoride (PVDF) membrane was used as a photolabeled component and we introduced biotin by Staudinger–Bertozzi ligation. The 15 pmol amount of biotinylated reagent was still effective for the visualization of cross-linked product on the matrix. The results show the potential utility of alkyl azide carrying TPD derivatives in the application of photoaffinity biotinylation, which could be useful for the ligands with tight structural requirements.

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Nootkatone (2), the most important and expensive aromatic of grapefruit, decreases the somatic fat ratio, and thus its demand is increasing in the cosmetic and fiber sectors. A sesquiterpene hydrocarbon, (+)-valencene (1), which is cheaply obtained from Valencia orange, was biotransformed by the green algae Chlorella species and fungi such as Mucor species, Botryosphaeria dothidea, and Botryodiplodia theobromae to afford nootkatone (2) in high yield.

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