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A p-quinone analog having the komaroviquinone pharmacophore fused with a more conformationally flexible cycloheptane ring, was semisynthesized from natural demethlsalvicanol isolated from Perovskia abrotanoides via four steps in 26% overall yield. The IC 50 for the antitrypanosomal activity of the analog was 0.55 µM.

A new alkaloid, stemona-lactam S, and a known alkaloid, tuberostemospiroline, were isolated from the roots of Stemona tuberosa LOUR. (Stemonaceae). Their structures and absolute stereochemistry were established by X-ray crystallography and vibrational circular dichroism.

A phytochemical study on the bark of Neisosperma oppositifolia (Apocynaceae) yielded two new beta-carboline indole alkaloids, oppositinines A (1) and B (2), together with five known alkaloids, isoreserpiline, isocarapanaubine, vobasine, 10-methoxydihydrocorynantheol-N-oxide, and ochropposinine oxindole. Structural elucidation of 1 and 2 was performed using 2D NMR methods. Oppositinines A (1) and B (2) showed potent vasorelaxant effects on the rat aorta.

Fourteen new bisnor- and norditerpene dilactones, makilactones E-R, having a 7alpha : 8alpha-epoxy-9,11-enolide substructure, were isolated from a methanolic extract of the root and the bark of Podocarpus macrophyllus D. DON (Podocarpaceae) with thirteen known bisnor- and norditerpenoids, and the structures of those new bisnor- and norditerpenoids were determined on the basis of their spectroscopic studies. Of the thirteen known ones isolated, the structures of two, i.e., podolactone B and inumakilactone B, were revised on the basis of X-ray crystallographic analysis and spectroscopic analysis. Many of the compounds of this type isolated in this study showed potent cytotoxic activities against P388 murine leukemia cells.

Two new sempervirol type diterpenes, inumakiols A, B, and six new totarol type diterpenes, inumakiols C-H, were isolated from a methanolic extract of bark of Podocarpus macrophyllus (Podocarpaceae), along with one known abietane, two known totarol type diterpenes, and one known totarol type diterpene dimer. The structures of the new compounds were elucidated by the spectroscopic methods. Some of them possessed antibacterial activity against oral pathogenic microorganisms with minimum inhibitory concentration (MIC) values ranging from 3.1 to 25 ppm.

Two new bicyclic hexapeptides, RA-XXIII and RA-XXIV, were isolated from the roots of Rubia cordifolia L. (Rubiaceae). Their structures were determined by the analysis of their 2D NMR spectra, chemical methods, and X-ray crystallography. The IC50 values of RA-XXIII and RA-XXIV against P-388 leukemia cells were 0.16 and 0.48 microg/ml, respectively.

Nine new triterpenoids, 1-9, were isolated from the cortex of Cedrela sinensis (Meliaceae), together with six known compounds, sapelin E acetate, grandifoliolenone, azadirone, bourjotinolone A, piscidinol A, and hispidol B. The structures of 1-9 were determined by the 2D NMR experiments, chemical methods, and X-ray crystallography.

Isetexane diterpene analogues were semisynthesized from demethylsalvicanol isolated from Perovskia abrotanoides (Labiatae). The structure and cytotoxic activity relationships (SAR) of the natural parent diterpene, demethylsalvicanol, and its semisynthetic analogues were studied by using P388 murine leukemia cells.

Two new phenylpropanoid glycosides, scrophulosides A (1) and B (2), were isolated from the rhizomes of Neopicrorhiza scrophulariiflora (Scrophulariaceae), along with two known compounds, androsin (3) and picroside I. Their structures were elucidated on the basis of both chemical and spectroscopic data.

A new sesquiterpene lactone named coriarin was isolated from achenes (seeds) of Coriaria japonica (Coriariaceae) along with known constituents tutin, dihydrotutin and corianin, and its structure was deduced on a spectroscopic basis. The structure of coriarin was finally confirmed by the base-catalized chemical conversion of tutin into coriarin, in which the lactone ring linkage was transposed from C-3 to C-2. Chemical investigation of sarcocarps was also undertaken in parallel, but neither sesquiterpene lactones nor related constituents were obtained. The results indicate that sesquiterpene lactones occur only in achenes of C. japonica berry, as is the case in other Coriaria species.

Two new cangorosin A type triterpene dimers, which composed of two triterpene units jointed by two ether linkages between the A and B rings, were isolated from the Brazilian medicinal plant "xuxuá" (Maytenus chuchuhuasca). Structures of new isolates, xuxuasins A (1) and B (2), were established based on several spectroscopic evidences.

Nine regioisomeric and stereoisomeric triterpene dimers, namely xuxuarine Falpha (1), isoxuxuarine Falpha (2; cangorosin B), 7,8-dihydroisoxuxuarine Falpha (3), isoxuxuarine Gbeta (4), 7,8-dihydroisoxuxuarine Galpha (5), isoxuxuarine Ebeta (6), 7alpha-hydroxyisoxuxuarine Ealpha (7), 7',8'-dihydroxuxuarine Aalpha (8), and 7',8'-dihydroxuxuarine Dbeta (9), were isolated from the Brazilian medicinal plant "xuxuá" (Maytenus chuchuhuasca). Their structures have been elucidated based on several spectroscopic analyses including 2D-NMR experiments, MS spectra and CD spectral studies.

Two new cyclic peptides were isolated from the fruit peels of Citrus medica var. sarcodactylis SWINGLE. Their structures were elucidated as cyclo(-Gly-Asp-Leu-Thr-Val-Tyr-Phe-) and cyclo(-Gly-Leu-Pro-Trp-Leu-Ile-Ala-Ala-) by intensive two-dimensional (2D) NMR analysis and chemical evidence.

Nitrated gitoxins (4) and bufotoxin homologues with various lengths of alkyl chain at C-3 of the steroid nucleus (10) were prepared from gitoxin (1). The pharmacological activities of the resulting compounds (4 and 10) were evaluated by measurement of inhibitory effect on NA+, K(+)-adenosine triphosphatase (ATPase) prepared from dog kidney, positive inotropic effect (PIE) on isolated guinea-pig papillary muscle preparations, and the effect on smooth muscle using the mesenteric artery from spontaneously hypertensive rats. Most of the compounds showed a smaller contractile effect on the arterial muscle. Among these compounds, gitoxin 3"-nitrate (4g) exhibited the most desirable biological activities, such as PIE comparable to that of 1, 1.25 times wider concentration-dependent range than 1, and lack of contractile activity on vascular muscle.

Restrained molecular dynamics calculation in vacuo using AMBER force field implemented in MacroModel/Batchmin showed a major solution conformation in dimethyl sulfoxide-d6 of pseudostellarin D, cyclo(Gly-Tyr-Gly-Pro-Leu-Ile-Leu-). This is a cyclic heptapeptide isolated from Pseudostellaria heterophylla possessing characteristics of a beta-bulge motif with three intramolecular hydrogen bonds, two beta-turns (one type I at Pro4 and Leu5 residues, and one type II at Leu7 and Gly1 residues) and all trans amide bonds. The solution form of pseudostellarin D, which was homologous to that observed in the solid state, was also supported by Monte Carlo simulation study.

Antitumor activities on Sarcoma 180A of a series of cyclic pentapeptides, astins, isolated from the roots of Aster tataricus, were examined. The activities on various congeners of the dichlorinated proline residues prepared by chemical conversion and a hepatic microsomal biotransformation in rats suggested that 1,2-cis dichlorinated proline residues of astins A, B and C play an important role in the antitumor activity of astins.

Conformational analysis of antitumor cyclic pentapeptides, astins A (1) and C (3), was made by a combination of NMR and computational techniques. These results indicated that the backbone conformations of 1 and 3, with lower activity than astin B (2), were different from that of 2. The backbone conformation together with a cis 3,4-dichlorinated proline residue was considered to play an important role in the antitumor activities of astins.

The ethanolic extract of the root bark of Melia azedarach exhibited cytotoxic activity against lymphocytic leukemia P388 cell lines in vitro. Systematic fractionation of the extract monitored by cytotoxic bioassay led to the isolation of two new azadirachtin-type limonoids, 1-tigloyl-3-acetyl-11-methoxymeliacarpinin (1) and 1-acetyl-3-tigloyl-11-methoxymeliacarpinin (2), together with three highly cytotoxic sendanin-type limonoids, 29-isobutylsendanin (3), 12-hydroxyamoorastin (4) and 29-deacetylsendanin (5). The acetylated derivatives of 4 also underwent cytotoxic bioassay.

A new peptide called astin J (1) was isolated from the roots of Aster tataricus. The structure was elucidated by spectroscopic methods and chemical transformation from a cyclic pentapeptide, astin C, isolated from A. tataricus to the analogous acyclic peptide, 2. Antileukemic activities of the series of acyclic peptides are also described.

Two flavonoids, 3,5,6,7,8,3',4'-heptamethoxyflavone (HEPTA) and natsudaidain isolated from Citrus plants (Rutaceae), produced a positive inotropic effect (PIE) on guinea-pig papillary muscle. Natsudaidain (pD2 4.98 +/- 0.07) was more potent than HEPTA (pD2 4.33 +/- 0.08), but the maximum PIE of HEPTA was greater than that of natsudaidain. The PIE of HEPTA was completely inhibited by reserpinization of the guinea pig, and partially inhibited by metoprolol and carbachol. The carbachol inhibition was omitted by atropine. The mechanism of PIE of HEPTA is accounted for catecholamine release from cardiac tissue.

The ethanolic extract of Rabdosia trichocarpa leaves showed antibacterial activity against cariogenic mutans streptococci and periodontopathic Porphyromonas gingivalis. Chromatographic separation and purification of the extract afforded ten diterpenes, including one novel ent-kauren type compound named trichoranin. Some of these compounds possess potent antibacterial activity against these oral micro-organisms, indicating that these diterpenes may be useful natural substances for the maintenance of oral health.

A novel [Ile7]surfactin (1), which showed anti-human immunodeficiency virus activity, has been isolated from Bacillus subtilis natto. Structural and conformational analysis of the peptide backbone of [Ile7]surfactin was conducted by a combination of various two-dimensional (2D) nuclear magnetic resonance (NMR), circular dichroism (CD) spectroscopy and simulated annealing calculations, compared with a known [Leu7]surfactin (2). Both surfactins were shown to exist in different conformational states in both polar and apolar solvents.

Further investigation of the roots of Rubia cordifolia resulted in the isolation of four new naphthohydroquinones and two naphthohydroquinone dimers, and one known naphthohydroquinone, one naphthoquinone, two anthraquinones and one naphthohydroquinone dimer. The structures of these compounds were established by various chemical and spectroscopic methods including two dimensional NMR techniques. Also, the isolated compounds were submitted to a bio-assay for cytotoxic and antitumor activity.

Two novel tropoloisoquinoline alkaloids, Pareirubrines A and B, have been isolated as antileukemic substances from Cissampelos pareira (Menispermaceae), together with the same skeleton alkaloids, grandirubrine and isoimerubrine. Their structures were elucidated by nuclear magnetic resonance (NMR) studies, and their solid state tautomeric forms were examined by X-ray crystallographic analysis.

A number of RA-VII derivatives having various amino acids including proline (6), pipecolic acid (11), norvaline (12), ornithine (14), aspartic acid (15) and methionine (20) in place of Ala2 have been synthesized from RA-X methyl ester (3) and evaluated for cytotoxicity to P388 leukemia and KB cells in vitro. Comparison of the cytotoxicity of these compounds suggests that the polarity and the length of the 2nd amino acid residue affect the activity. An NMR study revealed that, in solution, 6 and 11 are locked in one conformational state, corresponding to conformer A of RA-VII.

Conformational analysis of antileukemic tropoloisoquinoline alkaloids isolated from Cissampelos pareira was conducted by thermodynamic proton nuclear magnetic resonance (1H NMR) studies. The line-broadening of one of methoxy methyl signals can be explained by the tropolone ring-puckering process. Analysis by dynamical simulated annealing and modified neglect of differential overlap (MNDO) calculations also supported puckering of tropolone ring system.

Several aromatic ring substituent modified RA derivatives were prepared from RA-VII (1), RA-V (8) and RA-II (11), and evaluated for cytotoxicity against P388 leukemia and KB cells. In terms of IC50 values, the C zeta methoxyl group of Tyr-3 greatly influenced the activities, while the substituents at the C zeta position of Tyr-6 were less important. One of the derivatives, Tyr-6-C zeta-deoxyRA-V (9, P388, IC50, 0.0025 micrograms/ml) was nearly as active as RA-VII (1, 0.0013 micrograms/ml), and also expressed promising anti-P388 in vivo activity (test/control = 171%, at 25 mg/kg).

Five cytostatic sesquiterpenes, desoxo-narchinol-A (1), nardosinone (2), debilon (3), nardosinonediol (4) and kanshone A (5), were isolated from the roots and rhizomes of Nardostachys chinensis (Valerianaceae). The steric structure of 1 was determined by nuclear Overhauser effects (NOEs) and the exciton chirality method. All five showed cytotoxic activity against P-388 cells and the structure-activity relationship of 1 was also discussed.

Two novel antitumor chlorine- and alloThr-containing cyclic pentapeptides, named astins A and B, both of which were isomers and took a cis configuration in one of the amide bonds, were isolated from Aster tataricus together with astin C. Their structures were solved by spectroscopic analysis and chemical degradation.

We optimized HPLC conditions for the first time to achieve satisfactory separation of six surfactins, two of which were novel, isolated from Bacillus subtilis natto. Peptide sequences were analyzed by sophisticated MS-MS analysis, performed with a pair of two surfactins with different fatty acid substitutions. Fragment peaks were divided into two series; one was a series of the ions which carried fatty acid, and thus were characterized by the fatty acid mass difference, and the other was a series of the ions which consisted of pure peptide and thus showed a superimposable pattern between a pair of surfactins.

1H NMR spectroscopy has been used to demonstrate specific binding of rat 80S ribosomes to the major conformer of an antitumor bicyclic hexapeptidic glucoside, RA-XII, isolated from Rubia cordifolia, in a fast exchange process.

The methanolic extract of Swartzia polyphylla DC. heartwood had antibacterial activity against cariogenic bacteria, the mutans Streptococci. The chromatographic purification of the extract afforded seven flavonoids. Among them, three known isoflavanones, dihydrobiochanin A, ferreirin and darbergioidin, and one new isoflavanone, 5,2',4'-trihydroxy-7-methoxyisoflavanone (dihydrocajanin) had potent antibacterial activity against cariogenic bacteria. This effect was not detected on isoflavone derivatives. A comparative antibacterial study of various flavonoids was further performed, and their structure-activity relationship was discussed.

Metabolites of antitumor cyclic hexapeptides, RA-VII and -X which were isolated from Rubia cordifolia were studied by hepatic microsomal biotransformation in rats and in bile juice of rabbits to which these drugs were administered intravascularly. Their structures and conformations were elucidated by two-dimensional nuclear magnetic resonance techniques, temperature effect on NH protons and nuclear Overhauser effect experiments. Specific N-demethylation of Tyr-3, O-demethylation and hydroxylation at aromatic rings of Tyr-3 and -5 were observed. Compared with metabolites of RA-VII, most of RA-X was excreted unchanged in the bile juice. Relationship among their structures, conformations and antitumor activities is also discussed.

Four new bicyclic hexapeptides, named as RA-XI, -XII, XIII and -XIV were isolated from Rubia cordifolia and showed potent antitumor activities against P-388. The structures were elucidated from spectroscopic and chemical evidences. RA-XII, XIII and -XIV were proved to be unique bicyclic hexapeptidic glucosides.

Using high-resolution proton nuclear magnetic resonance (1H-NMR) and carbon-13 nuclear magnetic resonance (13C-NMR) experiments, we have assigned three discernible configurational isomers observed in dimethyl sulfoxide-d6 (DMSO-d6) for an antitumor cyclic hexapeptide, RA-VII isolated from Rubia cordifolia. The largest isomer, amounting to 64%, has been assigned as conformer A with only a cis configuration between Tyr-5 and Tyr-6. The second configurational isomer, accounting for 32%, has adopted cis configurations between both Tyr-5 and Tyr-6 and between Ala-2 and Tyr-3. The third isomer, amounting to 4%, was determined to have cis configurations for all of the three N-methyl amide bonds.

Three aromatic compounds (2-4) possessing a carbomethoxyl group or a dimethoxyphthaloyl group, prepared by the Diels-Alder reaction of the cardiac glycoside, proscillaridin (1), with dimethyl acetylenedicarboxylate and methyl propiolate, were transformed into alcohols, carboxylic acids and amides. The biological activities of the resulting derivatives were evaluated by the use of Na+, K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) from dog kidney and isolated guinea-pig papillary muscle. Although the biological activities of the resulting derivatives were less potent than that of 1, a para-substituted benzylalcohol (5), methylbenzamides (9a and 10a), and ethylbenzamides (9b and 10b) inhibited the activity of Na+,K(+)-ATPase almost as potently as naturally occurring cardiac glycosides such as digoxin and digitoxin.

The Diels-Alder reactions of a cardiac glycoside, proscillaridin (1), with some dienophiles were investigated. The reaction of 1 with alkenes such as methyl vinyl ketone and methyl acrylate afforded 3-oxo-2-oxabicyclo[2.2.2]oct-7-enes (2-5) and para-substituted benzene derivatives (6 and 7), while 1 reacted with alkynes (3-butyn-2-one, methyl propiolate) to yield para- or meta-substituted benzene derivatives (6-9). The biological activities of the resulting derivatives were evaluated by the use of isolated guinea-pig papillary muscle preparations and Na+,K(+)-adenosine triphosphatase (ATPase) preparation from dog kidney. Among the proscillaridin derivatives, compounds 4 and 7 moderately inhibited Na+,K(+)-ATPase activity. Furthermore, the concentration range of 7 over which its positive inotropic effect on guinea-pig papillary muscle preparations, increased from 5% to 95% of maximum was broader than that of 1, i.e., concentration dependency was maintained over a greater range of concentration.

Taspine has been isolated as a cytotoxic substance from Sangre de Grado, sap of Croton palanostigma (Euphorbiaceae), by bioassay guided fractionation. The cytotoxicity (IC50) of taspine was found to be 0.39 microgram/ml against KB cells and 0.17 microgram/ml against V-79 cells.

Casearins G-R, new cytotoxic clerodane diterpenes have been isolated from the leaves of Casearia sylvestris Sw. (Flacourtiaceae). Their structures have been elucidated by spectroscopic methods and chemical conversions, and their structure-activity relationships have been discussed.

New antitumor clerodane diterpenes, named casearins A-F, have been isolated from the leaves of Casearia sylvestris Sw. (Flacourtiaceae). These structures have been completely elucidated by two dimensional nuclear magnetic resonance, circular dichroism spectroscopy, X-ray analysis, and chemical evidences.

The chemical constituents of Japanese mistletoes, Taxillus yadoriki Danser, Taxillus kaempferi Danser, and Korthalsella japonica Engler, epiphyting to different host trees were compared, and the antimicrobial and hypotensive properties of some isolated flavonoids were examined. Two known flavonoid glycosides, hyperin and quercitrin, were isolated from Taxillus yadoriki Danser, together with fatty acids, phytosterol, and phytosterol-glucoside. There was remarkable variation of contents of quercitrin among the plants on different host trees. From Taxillus kaempferi Danser, fatty acids, phytosterol, phytosterol-glucoside, quercetin, avicularin, and taxillusin were isolated, and quercitrin and hyperin were also identified. There was no remarkable variation of compositions of flavonoid glycosides among the plants on different host trees. A known flavone glycoside, chrysoeriol-4'-O-glucoside, was isolated from Korthalsella japonica Engler, together with fatty acids, phytosterol, oleanolic acid, and phytosterol-glucoside. Chrysoeriol-4'-O-glucoside is contained in this plant irrespective of the host trees.

The effects of structure around the 3- and 5-alkoxycarbonyl groups and the 2-carbamate groups of 4-(2,3-dichlorophenyl)-2-carbamoyloxymethyl dihydropyridine derivatives were investigated, concerning their vasodilating action, plasma level, hypotensive action and acute toxicity. High negative linear correlation was found between the plasma levels and the number of C atoms in esterifying alkyl groups in 3- and 5-positions of the dihydropyridine ring. High plasma levels and effective hypotensive action were found in compounds having lower alkyls as esterifying groups of 3- and 5-carboxyl groups, among 2-unsubstituted derivatives.