Synthesis, biological evaluation, and correlation of cytotoxicity versus redox potential of 1,4-naphthoquinone derivatives.

A series of 1,4-naphthoquinone derivatives of lawsone (1), 6-hydroxy-1,4-naphthoquinone (2), and juglone (3) were synthesized by alkylation, acylation, and sulfonylation reactions. The yields of lawsone derivatives 1a-1k (type A), 6-hydroxy-1,4-naphthoquinone derivatives 2a-2j (type B), and juglone derivatives 3a-3h (type C) were 52-99%, 53-96%, and 28-95%, respectively. All compounds were tested in vitro for the cytotoxicity against human oral epidermoid carcinoma (KB) and cervix epithelioid carcinoma (HeLa) cells and their structure-activity relationship was studied. Compound 3c was found to be most potent in KB cell line (IC50 = 1.39 µM). Some compounds were evaluated for DNA topoisomerase I inhibition. Compounds 2c, 3, 3a, and 3d showed topoisomerase inhibition activity with IC50 values of 8.3-91 µM. Standard redox potentials (E°) of all naphthoquinones in phosphate buffer at pH 7.2 were examined by means of cyclic voltammetry. A definite correlation has been found between the redox potentials and inhibitory effects of type A compounds.

New Hirsutinolide-Type Sesquiterpenoids from Vernonia cinerea Inhibit Nitric Oxide Production in LPS-Stimulated RAW264.7 Cells.

Phytochemical investigation of ethanol extracts from two Taiwanese collections of Vernonia cinerea resulted in the isolation of eighteen hirsutinolide-type sesquiterpenoids, including seven new ones designated as vernolides E - K (1: -7: ). All structures were determined by a combination of detailed spectroscopic analyses (NMR and MS) and comparison with reported data. In an in vitro anti-inflammatory assay, compounds 3, 7, 9, 11: , and 14: exhibited strong inhibitory activities toward NO production by LPS-induced RAW264.7 macrophages, with IC50 values of 1.18, 0.85, 0.66, 0.71 and 0.45 µM, respectively, without affecting cellular viability at 40 µM. Preliminary structure-activity relationships indicate that the ester groups at C-8 and C-13 may enhance inhibition of NO production.

Triterpene acids from Euscaphis japonica and assessment of their cytotoxic and anti-NO activities.

Six new triterpenoids, euscaphic acids G-L (1-6), along with nine known triterpene acids, and two known lignans were isolated from the ethanolic extract of the twigs of Euscaphis japonica. This is the first report concerning 1α,3ß-dihydroxy-12-oleanen-28-oic acid isolated from a natural source. The structures of the new compounds were established by spectroscopic analysis. The cytotoxic and anti-NO production activities for the isolates are also evaluated and discussed; compound 1, hederagenin (11), and arjunic acid (12) showed significant cytotoxicity against NCI-H460 cells, HT-29 cells, and CEM cells (IC50 = 1.64 ± 0.87, 2.11 ± 1.54, 1.73 ± 0.64 µM, respectively). Some of the isolated triterpenoids showed marginal inhibitions on NO production induced by LPS.

Cytotoxic polyisoprenyl benzophenonoids from Garcinia subelliptica.

Six new polyisoprenyl benzophenonoids, (+/-)-garcinialiptone A (1, 2), garcinialiptone B (3), (-)-cycloxanthochymol (4), garcinialiptone C (5), and garcinialiptone D (6), along with three known compounds, xanthochymol (7), isoxanthochymol (8), and cycloxanthochymol (9), were isolated from the fruits of Garcinia subelliptica. The structures of 1-6 were elucidated by spectroscopic analysis. Biological evaluation showed that all compounds 1-9 exhibited cytotoxic activity against a small panel of human tumor cell lines (A549, DU145, KB, vincristine-resistant KB).

Antioxidant and anti-inflammatory phenylpropanoid derivatives from Calamus quiquesetinervius.

Eight new phenylpropanoid derivatives [quiquesetinerviusides A (1), B (2), C (3), D (4), and E (5), as well as quiquesetinerviusins A (6), B (7), and C (8)] and seven known compounds (8-15), were isolated from an EtOAc extract of Calamus quiquesetinervius stems. The structures of 1-8 were elucidated on the basis of 1D- and 2D-NMR spectroscopic data analysis. Bioassay results showed that 1-5 possess weak DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, but potent (·)OH radical scavenging activity (IC(50) 3.6-8.4 µM). Of the tested isolates, compounds 4-6 and 9 showed potent inhibition (IC(50) 9.2-29.5 µM) of LPS-stimulated NO production when compared with a positive control substance, quercetin (IC(50) 34.5 µM).

Flavanone and diphenylpropane glycosides and glycosidic acyl esters from Viscum articulatum.

Seven new compounds including three flavanone glycosides, visartisides A-C (1-3), three glycoside acyl esters, visartisides D-F (4-6), and one diphenylpropane glycoside, (4'-hydroxy-2',3',6',3''-tetramethoxy-1,3-diphenylpropane)-4''-O-beta-d-glucopyranoside (7), along with four known flavanone glycosides (8-11) were isolated from the leaves and stems of Viscum articulatum. The structure elucidation of 1-7 was based on spectroscopic data analysis. Biological evaluation showed that 1, 2, and 10 exhibited antioxidant activity using a DPPH method and that compounds 1, 3, and 11 were active in a lipopolysaccharide-induced nitric oxide assay.

Triterpenoidal saponins from Hydrocotyle sibthorpioides.

Oleanane-type triterpenoidal saponins, hydrocosisaponins A-F (1-6), along with a known saponin, hydrocotyloside VII (7), were isolated from Hydrocotyle sibthorpioides. Their structures were established on the basis of spectroscopic analyses including NMR spectroscopic techniques ((13)C, (1)H, COSY, HMQC, HMBC, TOCSY and NOESY). Biological evaluation established that saponins possessing four sugar units (three d-glucoses and one l-arabinose) (4-7) exhibited moderate cytotoxicity against KB, Daoy and WiDr human tumor cell lines.

Four New C19 Homolignans, Schiarisanrins A, B, and D and Cytotoxic Schiarisanrin C, from Schizandra arisanensis.

Four new C(19) homolignans with a 5,4'-butano-2,4-cyclohexadienone-6-spiro-3'-(2',3'-dihydrobenzo[b]furan) skeleton, schiarisanrin A, schiarisanrin B, schiarisanrin D, and cytotoxic schiarisanrin C, were isolated from Schizandra arisanensis. Their structure and stereochemistry have been established by spectral and single-crystal X-ray analysis. Schiarisanrin C has cytotoxic activity with ED(50) values of 0.36, 7.1, 4.9, and 5.7 &mgr;g/mL, respectively, against KB epidermoid carcinoma of nasopharynx, COLO-205 colon carcinoma, HEPA hepatoma, and HELA cervix tumor cells.

Naturally Occurring Cytotoxic [3'→8″]-Biflavonoids from Podocarpus nakaii.

Bioassay-guided fractionation of the EtOH extract of the dried twigs of Podocarpus nakaii Hayata (Podocarpaceae), endemic plant in Taiwan has resulted in isolation of four [3'→8″]-biflavonoid derivatives, amenotoflavone (AF), podocarpusflavone-A (PF), II-4″,I-7-dimethoxyamentoflavone (DAF), and heveaflavone (HF). Their structures were determined by physical and extensive spectroscopic analyses such as (1)H, (13)C, (1)H-(1)H COSY, HMQC, and HMBC, as well as comparison with literature values. Compounds PF and DAF showed significant inhibitions against DLD, KB, MCF-7, HEp-2 tumor cell lines (ED50 ca. 4.56-16.24 µg/mL) and induced cell apoptosis in MCF-7 via mainly sub-G1/S phase arrest. Furthermore, these compounds exhibited moderate Topoisomerase I inhibitory activity.

Antioxidative Flavonol Glucuronides and Anti-HBsAg Flavonol from Rotala rotundifolia.

Two new flavonol glucuronides, quercetin 3-O-ß-D-2″-acetylglucuronide (1) and quercetin 3-O-ß-D-2″-acetylglucuronide methyl ester (2), along with four known flavonoids (3-6) were isolated from the whole parts of Rotala rotundifolia. The structures of 1 and 2 were elucidated by application of various spectroscopic methods, including 1D and 2D NMR techniques. Biological evaluation showed that all of isolated flavonoid compounds have potent anti-oxidative activities by DPPH and superoxide anion methods, and kaempferol (3) and quercetin (4) exhibited significant anti-HBV activity assayed by anti-HBsAg production. The HPLC fingerprint with photodiode array detection (HPLC-DAD) for quality control of R. rotundifolia partitioned EtOAc layer was also established.

New isoflavonoid glycosides and related constituents from astragali radix ( Astragalus membranaceus ) and their inhibitory activity on nitric oxide production.

Twenty-four secondary metabolites, including 16 isoflavonoids, 7 astragalasides, and 1 benzoquinone, have been isolated from the roots of Astragalus membranaceus (Astragali radix). Among these isolated isoflavonoids, (-)-methylinissolin 3-O-ß-d-(6'-acetyl)-glucoside (1), (-)-methylinissolin 3-O-ß-d-{6'-[(E)-but-2-enoyl]}-glucoside (2), and calycosin 7-O-ß-d-(6''-acetyl)-glucoside (3) have been identified as new compounds on the basis of spectroscopic analysis; (-)-methylinissolin 3-O-ß-d-glucoside (4) was isolated from the natural products for the first time. The nitric oxide (NO) production inhibitory activity of the major compounds has been assessed in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. To identify A. membranaceus, a fingerprint method was developed by using a high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) method. Furthermore, characteristic peaks for the 11 major compounds in the chromatogram were unambiguously confirmed.

Evaluation of caffeic acid amide analogues as anti-platelet aggregation and anti-oxidative agents.

A series of amides of caffeic acid were synthesized and evaluated for their anti-platelet and anti-oxidative activities. N-(2-Bromo-phenyl)-3-(3,4-dihydroxy-phenyl)-acrylamide (12) and N-(3-Bromo-phenyl)-3-(3,4-dihydroxy-phenyl)-acrylamide (13) exhibited potent inhibitory activity (IC(50)=5.8 and 6.7 microM, respectively) against arachidonic acid-induced (AA) platelet aggregation, comparable with invalid caffeic acid. Most of the synthesized caffeic acid anilides exhibited the promising anti-platelet aggregation in AA-induced assay and anti-oxidative activities. This study also exhibited that caffeic anilides displayed more potent anti-oxidative activity in the radical scavenging activity assay than trolox and vitamin E.

Cytotoxic phenylpropanoid glycosides from the stems of Smilax china.

Bioassay-guided fractionation of an ethanol extract of Smilax china led to the isolation of nine phenylpropanoids including six new compounds, smilasides A-F (1-6), and three known phenylpropanoids, smiglaside E, heloniosides B, and 2',6'-diacetyl-3,6-diferuloylsucrose. Structural elucidation of isolates 1-6 was based on spectroscopic data analysis. These new phenylpropanoids were evaluated against several human tumor cell lines.

Antihepatitis activity (anti-HBsAg and anti-HBeAg) of C19 homolignans and six novel C18 dibenzocyclooctadiene lignans from Kadsura japonica.

Bioassay-directed fractionation of the EtOAc extract of Kadsura japonica has led to the isolation of six new C18 dibenzocyclooctadiene lignans, schizanrins I, J, K, L, M, N, along with four known C19 homolignans, taiwanschirins A, B, C, and heteroclitin F. The elucidations of the new structures were based on spectral analysis. Bioassay evaluation against human type B hepatitis revealed that taiwanschirins A and B showed strong activity for anti-HBsAg and a medium effect for anti-HBeAg at 25 microg/mL (12.9 and 11.9 microM for taiwanschirins A and B, respectively).

DNA topoisomerase I inhibitor, ergosterol peroxide from Penicillium oxalicum.

Recently, we found that the MeOH extract of Penicillium oxalicum showed inhibitory activity towards DNA topoisomerase I. Subsequently, ergosterol peroxide, ergosterol, palmitoleic acid, and linoleic acid were isolated from the cultured mycelia of P. oxalicum. The structural determinations were based on physical and spectral analyses. Biological evaluation revealed that ergosterol peroxide inhibited the relaxation of supercoiled DNA (pBR322) induced by DNA topoisomerase I, and also showed marginal, selective cytotoxic activity against human colon tumor cells [COLO-205 (ED50=8.56 microg/mL].

The anti-HBsAg (human type B hepatitis, surface antigen) and anti-HBeAg (human type B hepatitis, e antigen) C18 dibenzocyclooctadiene lignans from Kadsura matsudai and Schizandra arisanensis.

The C(18) dibenzocyclooctadiene lignans including three novel schizanrin F (1), G (2), H (3), along with the known kadsurarin (4), were isolated from Kadsura matsudai. A new C(19) homolignan named schiarisanrin E (5), together with the known C(18) lignans, gomisin B (6), G (7) and (+)-gomisin K(3) (8) were obtained from Schizandra arisanensis. Gomisin B, G and (+)-gomisin K(3) showed moderate to strong activity for antihepatitis in anti-HBsAg (human type B hepatitis, surface antigen) and/or anti-HBeAg (human type B hepatitis, e antigen) tests. The structural elucidations of new compounds 1-3 and 5 were based on two-dimensional (2D) NMR techniques including COSY, HMQC, HMBC, NOESY and CD spectra. Preliminary structure-activity relationship studies for these isolated lignans are also discussed.