Relaxant effect of 6-deoxyclitoriacetal on smooth muscle preparations.

The pharmacological effect of 6-deoxyclitoriacetal (6-DA), a rotenoid compound isolated from the roots of Clitoria macrophylla Wall. (Papilionaceae), was examined on different smooth muscle preparations. 6-Deoxyclitoriacetal 0.2 mg/ml produced a significant decrease in the spontaneous contraction of isolated rat uterus. It also suppressed the contraction induced by acetylcholine 5x10(-6) M and oxytocin 5x10(-3) IU/ml. The cumulative contractile responses of rat aortic strips caused by serotonin 10(-8)-10(-4) M and norepinephrine 10(-11)-10(-7) M were reduced by 6-DA 0.4 mg/ml. In calcium free Kreb's solution, 6-DA inhibited the aortic contraction produced by a cumulative dose of calcium chloride (0.1-30 mM). In guinea-pig ileum, 6-DA 0.15 mg/ml exerted the spasmolytic activity by inhibition of the contractile response evoked by various contractile agents e.g. acetylcholine 10(-9)-10(-5) M, serotonin 10(-9)-10(-5) M and histamine 10(-9)-10(-5) M. All of the results indicated that 6-DA could induce a smooth muscle relaxant effect by interference with intracellular calcium metabolism.

Flavonoids from Ochna integerrima.

Two biflavonoids namely, 2",3"-dihydroochnaflavone and 2",3"-dihydroochnaflavone 7"-O-methyl ether, and a flavonoid glycoside, 6-gamma,gamma-dimethylallyltaxifolin 7-O-beta-D-glucoside were isolated from the leaves of Ochna integerrima.

Ardisiphenols A-C, novel antioxidants from the fruits of Ardisia colorata.

Novel alk(en)ylphenols, named ardisiphenols A--C (1--3) were isolated from the fruits of Ardisia colorata, together with known alk(en)ylresorcinols (4--6). Their structures were determined by the NMR and MS/MS analyses. All compounds showed scavenging activities towards 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and cytotoxicities against murine breast cancer cell line, FM3A.

Chemical constituents of Micromelum minutum. Isolation and structural elucidation of new coumarins.

The chemical constituents of an acetone extract of the stems of Micromelum minutum Wight et Arn (Rutaceae), collected at Nakorn-Rachasima province in Thailand, were studied. Six new coumarins, named micromarin-A (1), -B (2), -C (3), -F (4), -G (5), and -H (6), were isolated along with six known coumarins, and their structures were elucidated by chemical and spectroscopic methods.

New carbazole alkaloids from Clausena anisata with antitumor promoting activity.

Four new carbazole alkaloids, named clausamine D (1), E (2), F (3), and G (4), were isolated from Clausena anisata as inhibitors of Epstein-Barr virus early antigen activation induced by 12-O-tetradecanoylphorbol-13-acetate in Raji cells.

Antimalarial naphthoquinones from Nepenthes thorelii.

Roots of Nepenthes thorelii yielded plumbagin, 2-methylnaphthazarin, octadecyl caffeate, isoshinanolone, and droserone. In addition, seven derivatives were prepared from plumbagin. Each of these natural and semisynthetic compounds was evaluated for in vitro antimalarial potential.

Xanthones with antimalarial activity from Garcinia dulcis.

Chromatographic separation of the EtOH extract of the bark of Garcinia dulcis (Guttiferae) furnished five xanthones, viz 1,7-dihydroxyxanthone (1), 12b-hydroxy-des-D-garcigerrin A (2), 1-O-methylsymphoxanthone (3), symphoxanthone (4), and garciniaxanthone (5). These xanthones 1-5 showed inhibitory effects on the growth of Plasmodium falciparum with IC50 values of 0.96-3.88 micrograms/ml. In addition, revised 13C-NMR assignments of 3 and complete 13C-NMR assignments of 4 were obtained through analysis of their COSY, NOESY, HMQC, and HMBC spectra.

Isolation of pyropheophorbide a from the leaves of Atalantia monophylla (ROXB.) CORR. (Rutaceae) as a possible antiviral active principle against herpes simplex virus type 2.

Antiviral activity-guided isolation studies on the leaves of Atalantia monophylla (ROXB.) CORR. (Rutaceae) led to the identification of pyropheophorbide a (1), a simple chlorin derivative, from the chloroform extract (fr. B) as a possible antiviral active principle against herpes simplex virus type 2 (HSV-2). Pyropheophorbide a methyl ester (2) was also isolated from the hexane extract (fr. A).

Lycorine alkaloids from Hymenocallis littoralis.

From Hymenocallis littoralis, one new alkaloid, named littoraline, together with 13 known lycorine alkaloids and one lignan, were isolated. The structure and NMR assignments of this new alkaloid were determined by 1D and 2D NMR techniques. Littoraline showed inhibitory activity of HIV reverse transcriptase, and lycorine and haemanthamine showed potent in vitro cytotoxicity.

Bisbenzylisoquinoline alkaloids from Cyclea barbata.

Continuing studies of the alkaloidal fraction from the roots of Cyclea barbata afforded two new bisbenzylisoquinoline alkaloids, namely, (-)-2'-norlimacine [1] and (+)-cycleabarbatine [2]. The known (+)-tetrandrine-2'-beta-N-oxide [3], for which the configuration of the N-oxide function is now assigned, was identified, as were (+)-berbamine, (-)-repandine, (+)-cycleanorine, (+)-daphnandrine, (-)-curine, (+)-coclaurine, and (-)-N-methylcoclaurine.

3-hydroxycoumarin glycosides from Alyxia reinwardti var. Lucida.

Investigation of the inner bark of Alyxia reinwardti var. lucida led to the isolation of two new coumarin glycosides, 1 and 2, whose structures were determined by interpretation of their spectroscopic data, particularly NMR spectroscopy.

Cytotoxic and antimalarial alkaloids from the tubers of Stephania pierrei.

Biological evaluation of extracts prepared from the tubers of Stephania pierrei revealed cytotoxic and antimalarial activity. During the course of separation, two new aporphine alkaloids, (-)-asimilobine-2-O-beta-D-glucoside [2] and (-)-nordicentrine [8], in addition to twenty-one known isoquinoline alkaloids, were isolated. Each isolate was assessed for cytotoxic and antimalarial activities. It was found that the cytotoxicity of S. pierrei was mainly due to the presence of the aporphine alkaloids containing the 1,2-methylenedioxy group 3-10, whereas the antimalarial activity was attributed to the nonquaternary aporphine alkaloids 1, 3-10 and the tetrahydroprotoberberines possessing a phenolic functionality, 13-15, 18. None of the isolates showed a degree of selectivity comparable to that of antimalarial drugs such as chloroquine, quinine, mefloquine, and artemisinin. Comparison of the alkaloid content of S. pierrei and Stephania erecta strongly suggested separate identities for the two plants.

Cytotoxic and antimalarial alkaloids from the bulbs of Crinum amabile.

From the bulbs of Crinum amabile (Amaryllidaceae), a new alkaloid (-)-amabiline [1], together with the known alkaloids (-)-lycorine [2], (-)-buphanisine [3], (-)-augustine [4], and (+)-crinamine [5], were isolated. The structural characterization of 1 and the revised 1H- and 13C-nmr assignments of 2 are discussed. Alkaloids 2, 4, and 5 were found to be the principal cytotoxic and antimalarial constituents.

Cytotoxic and antimalarial bisbenzylisoquinoline alkaloids from Cyclea barbata.

An alkaloid extract derived from the roots of Cyclea barbata demonstrated cytotoxic and antimalarial activities, and five bisbenzylisoquinoline alkaloids, (+)-tetrandrine [1], (-)-limacine [2], (+)-thalrugosine [3], (+)-homoaromoline [4], and (-)-cycleapeltine [5], were isolated as the active principles. The complete and unambiguous assignments of the 1H- and 13C-nmr data of these substances were made by 1D and 2D nmr techniques (COSY, phase-sensitive ROESY, HETCOR, and FLOCK).

Cytotoxic and antimalarial bisbenzylisoquinoline alkaloids from Stephania erecta.

(+)-2-N-Methyltelobine [1], a new alkaloid, together with twelve known bisbenzylisoquinolines, was isolated from the tubers of Stephania erecta. The structure determination and the complete 1H- and unambiguous 13C-nmr assignments of 1 were obtained through extensive use of several 1D and 2D nmr techniques. All alkaloids inhibited the growth of cultured Plasmodium falciparum strains D-6 and W-2 and displayed nonselective cytotoxicity with a battery of cultured mammalian cells. These data were used for the calculation of selectivity indices. Relative to known antimalarial agents, these bisbenzylisoquinoline alkaloids do not appear to be promising clinical candidates at the present time.

Traditional medicinal plants of Thailand. XVII. Biologically active constituents of Plumeria rubra.

The compounds 1-6 were isolated from the heartwood of Plumeria rubra, following bioactivity-directed fractionation. Plumericin 1 and isoplumericin 2 displayed molluscicidal, cytotoxic and antibacterial activity, 4-hydroxyacetophenone 3 was weakly cytotoxic, whereas the remaining glycosidic isolates (plumieride, 4; 13-O-coumaroylplumieride, 5; protoplumericine A, 6) were inactive in all test systems.

Constituents of Michelia Rajaniana. Two new germacranolide amides.

Six components have been isolated from the bark of Michelia rajaniana, and their structures have been determined by spectroscopic analysis. Four of the components have been reported previously: The germacranolide (-)-parthenolide and the oxoaporphinoid alkaloid liriodenine have been observed as constituents of several species, and (-)-bisparthenolidine and (+)-paramicholide have been reported recently by us as constituents of Paramichelia baillonii. The two new components 3 and 4, which are novel derivatives of parthenolide and contain an unusual N-acetyl substituent at C-13, have been given the names (+)-N-acetylparthenolidine and (+)-N-acetyl-8 alpha-hydroxyparthenolidine, respectively. The crude CHCl3 extract of the bark of M. rajaniana exhibited strong cytotoxicity in the KB cell culture assay.

Traditional medicinal plants of Thailand, IX. 10-Hydroxy-11-methoxydracaenone and 7,10-dihydroxy-11-methoxydracaenone from Dracaena loureiri.

Examination of Dracaena loureiri, a Thai medicinal plant possessing anti-bacterial activity, has led to the isolation of two new representatives, 1 and 2, of a rare skeleton of homoisoflavans. Proton assignments of the two isolates were aided by extensive 2D-homonuclear chemical shift correlation and nOe difference spectroscopy. Carbon assignments were completed through the utilization of simple and sensitive one-dimensional techniques such as selective population transfer via one-bond (CSCM 1D) and selective polarization transfer via long range coupling (selective INEPT) experiments. Conformational assignments were proposed through nOe difference spectroscopy and have been established by X-ray crystallography. The absolute configuration is proposed based on the octant rule and a biogenetic pathway for this type of homoisoflavan is briefly discussed.

Constituents of Paramichelia baillonii: a new antitumor germacranolide alkaloid.

Paramichelia baillonii has been used by the natives of Northern Thailand for medicinal purposes. Four components have been isolated from the bark of this plant and their structures determined by spectroscopic means. Three of the components had been reported previously: the germacranolide epoxides (--)-dihydroparthenolide [1] and (--)-parthenolide [2] and the oxoaporphinoid alkaloid liriodenine [4]. The fourth component is an unusual new germacranolide alkaloid which has been named (--)-bisparthenolidine [3] because it was presumably formed in the plant from ammonia and two molecules of parthenolide. Parthenolide was reported previously to possess anti-tumor activity, and in the present study we report on the significant activity of the new alkaloid 3 in the KB cell culture assay.

Traditional medicinal plants of Thailand, VIII. Isoflavonoids of Dalbergia candenatensis.

Five isoflavonoids, including the new isoflavone quinone, 5-hydroxybowdichione [2], were isolated from the heartwood of Dalbergia candenatensis through bioactivity-directed fractionation.