Biomedical subjects

Ping-Chung Kuo

Publications and source records attributed to Ping-Chung Kuo.

15 recordsLinked to original sources

PubMed2006

Total synthesis and biological evaluation of viscolin, a 1,3-diphenylpropane as a novel potent anti-inflammatory agent.

Total synthesis of viscolin, an anti-inflammatory 1,3-diphenylpropane isolated from Viscum coloratum, employing the Wittig reaction is reported. Key steps in the synthesis of viscolin depend on the selection of protecting groups to maintain the para hydroxyl group that is the most critical chemical structure influencing the biological activity of viscolin and the utilization of microwave-assisted Wittig olefination reaction. Anti-inflammatory potency of the synthetic viscolin, its precursor product 16, and its analogue 17, through their effects on reactive oxygen species (ROS), nitric oxide (NO), and pro-inflammatory cytokine production in leukocytes and microglial cells were evaluated. Excellent inhibition of ROS and NO production in inflammatory cells could confer the synthetic viscolin to be a potent anti-inflammatory agent for the treatment of oxidative stress-induced diseases.

Animals↗

PubMed2006

Physanolide A, a novel skeleton steroid, and other cytotoxic principles from Physalis angulata.

[reaction: see text] A novel withasteroid, physanolide A (1), with an unprecedented skeleton containing a seven-membered ring, and two new physalins, physalins U (2) and V (3), were isolated from Physalis angulata. The structures were elucidated from spectroscopic analysis, and plausible biosynthetic pathways were postulated. Physalins B (4), D (5), and F (6) showed strong cytotoxicity against multiple tumor cell lines, including KB, A431, HCT-8, PC-3, and ZR751, with EC(50) values less than 4 microg/mL.

Animals↗

PubMed2005

Isolation of a natural antioxidant, dehydrozingerone from Zingiber officinale and synthesis of its analogues for recognition of effective antioxidant and antityrosinase agents.

In the present study, the antioxidative and inhibitory activity of Zingiber officinale Rosc. rhizomes-derived materials (on mushroom tyrosinase) were evaluated. The bioactive components of Z. officinale rhizomes were characterized by spectroscopic analysis as zingerone and dehydrozingerone, which exhibited potent antioxidant and tyrosinase inhibition activities. A series of substituted dehydrozingerones [(E)-4-phenyl-3-buten-2-ones] were prepared in admirable yields by the reaction of appropriate benzaldehydes with acetone and the products were evaluated in terms of variation in the dehydrozingerone structure. The synthetic analogues were examined for their antioxidant and antityrosinase activities to probe the most potent analogue. Compound 26 inhibited Fe2+-induced lipid peroxidation in rat brain homogenate with an IC50 = 6.3+/-0.4 microM. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quencher assay, compounds 2, 7, 17, 26, 28, and 29 showed radical scavenging activity equal to or higher than those of the standard antioxidants, like alpha-tocopherol and ascorbic acid. Compound 27 displayed superior inhibition of tyrosinase activity relative to other examined analogues. Compounds 2, 17, and 26 exhibited non-competitive inhibition against oxidation of 3,4-dihydroxyphenylalanine (L-DOPA). From the present study, it was observed that both number and position of hydroxyl groups on aromatic ring and a double bond between C-3 and C-4 played a critical role in exerting the antioxidant and antityrosinase activity.

Animals↗

PubMed2005

Phenanthroindolizidine alkaloids from the stems of Ficus septica.

In addition to six known phenanthroindolizidine alkaloids, eight new alkaloids, namely, ficuseptines B-D (1-3), 10R,13aR-tylophorine N-oxide (4), 10R,13aR-tylocrebrine N-oxide (5), 10S,13aR-tylocrebrine N-oxide (6), 10S,13aR-isotylocrebrine N-oxide (7), and 10S,13aS-isotylocrebrine N-oxide (8), were isolated from a methanol extract of the stems of Ficus septica. The structures of the new compounds were elucidated by means of spectroscopic data interpretation. Cytotoxicity of some of these alkaloids was assessed in vitro using the HONE-1 and NUGC cell lines.

Alkaloids↗

PubMed2004

Terpenoids of Aristolochia and their biological activities.

Aristolochia is an important genus widely used in traditional medicine. During the past two decades, this genus has attracted much interest and has been the subject of numerous chemical and pharmacological studies. It is a rich source of aristolochic acids, which are unique to this genus, and of terpenoids. The nature of these terpenoids are reviewed in this article together with some bioactivity data in an effort to highlight the rapid development in the field of phytochemistry of the Aristolochia species.

Aristolochia↗

PubMed2004

Cytotoxic and antimalarial constituents from the roots of Eurycoma longifolia.

Sixty-five compounds were isolated from the roots of Eurycoma longifolia and characterized by comprehensive analyses of their 1D and 2D NMR, and mass spectral data. Among these isolates, four quassinoid diterpenoids were reported from natural sources for the first time, namely eurycomalide A (1), eurycomalide B (2), 13beta, 21-dihydroxyeurycomanol (3), and 5alpha, 14beta, 15beta-trihydroxyklaineanone (4). Screening of cytotoxicity, anti-HIV and antimalarial activity of these isolated compounds was also furnished by in vitro assays. Compounds 12, 13, 17, 18, 36, 38, 59, and 62 demonstrated strong cytotoxicity toward human lung cancer (A-549) cell lines, however, 12, 13, 17, 38, 57, 58, and 59 exhibited strong cytoxicity toward human breast cancer (MCF-7) cell lines. Compounds 57 and 58 displayed potent antimalarial activity against the resistant Plasmodium falciparum. The thorough studies on the stereochemistry of the different quassinoid diterpenoids provide a clear reference to the scientists who are interested on this field.

Animals↗

PubMed2004

The alkaloids and other constituents from the root and stem of Aristolochia elegans.

Two new aristolactams, aristolactam E (1) and aristolactam-AIIIa-6-O-beta-D-glucoside (2), three novel benzoyl benzyltetrahydroisoquinoline ether N-oxide alkaloids, aristoquinoline A (3), aristoquinoline B (4), and aristoquinoline C (5), and a new biphenyl ether, aristogin F (6), together with 62 known compounds have been isolated from the root and stem of Aristolochia elegans Mast. The structures of the new natural products were established on the basis of spectral evidence. Some of the isolated compounds were examined for their antioxidative and antityrosinase activities. Occurrence of the isoquinolones, biphenyl ethers, and benzoyl benzyltetrahydroisoquinoline ether alkaloids in the same plant indicated the definite possibility of these metabolites as biotransformation intermediates of bisbenzyltetrahydroisoquinoline alkaloids. This can be useful to solve the catabolic process of bisbenzyltetrahydroisoquinoline alkaloids.

Alkaloids↗

PubMed2004

Flavonoids and coumarins from Leaves of Phellodendron chinense.

Three new compounds, phellodensin G, phellodenols D and E have been isolated from the leaves of Phellodendron chinense Schneid (Rutaceae), together with thirteen known compounds. Their structures were established by means of spectroscopic analysis, including extensive 2D NMR and mass spectra.

Coumarins↗

PubMed2004

New neolignans from Spiraea formosana.

Phytochemical investigation on the ethanol extract from the stems of Spiraea formosana has resulted in the isolation of four new neolignans, named spiraformin-A, -B, -C and -D (1-4), together with thirty five known compounds. Their structures were established primarily on the basis of 1D and 2D NMR spectral and chemical transformation methods.

Drugs, Chinese Herbal↗

PubMed2003

Constituents from the leaves of Phellodendron amurense var. wilsonii and their bioactivity.

Two new dihydroflavonols, phellodensin-A (1) and phellodensin-C (2); three new coumarins, phellodenol-A (3), phellodenol-B (4), and phellodenol-C (5); one new chlorophyll, phellophyll-a (6); and one new phenyllactate, (2R)-sodium 3-phenyllactate (7), in addition to 35 known compounds have been isolated from the leaves of Phellodendron amurense var. wilsonii. The structures of the new compounds were established based on 1D, 2D NMR and mass spectral analyses. The stereochemistry at the C-2, C-3, and C-2' ' positions of new dihydroflavonol 1 was determined by CD spectroscopy. The known compounds were identified by comparison with authentic samples. The antioxidant and antityrosinase activities were also described.

Antioxidants↗

PubMed2003

Acetophenone derivatives from Acronychia pedunculata.

Chemical investigation on the stem and root bark of Acronychia pedunculata has resulted in the isolation of five new acetophenones, namely, acronyculatins A (1), B (2), C (3), D (4), and E (5). The structures of these metabolites were established on the basis of their 1D and 2D NMR spectroscopic and mass spectrometric data and by CD spectroscopy. The antioxidant and antityrosinase activities of these five metabolites and acrovestone (6) were evaluated. Among these compounds, 6 showed marginal antioxidant and antityrosinase activities.

Acetophenones↗

PubMed2003

Cytotoxic and antimalarial beta-carboline alkaloids from the roots of Eurycoma longifolia.

Three new [n-pentyl beta-carboline-1-propionate (1), 5-hydroxymethyl-9-methoxycanthin-6-one (2), and 1-hydroxy-9-methoxycanthin-6-one (3)] and 19 known beta-carboline alkaloids were isolated from the roots of Eurycoma longifolia. The new structures were determined by comprehensive analyses of their 1D and 2D NMR and mass spectral data and by chemical transformation. These compounds were screened for in vitro cytotoxic and antimalarial activities, and 9-methoxycanthin-6-one (4) and canthin-6-one (5) demonstrated significant cytotoxicity against human lung cancer (A-549) and human breast cancer (MCF-7) cell lines.

Alkaloids↗

PubMed2003

Flavonoids from Andrographis viscosula.

Phytochemical investigation of the whole plant of Andrographis viscosula has led to the isolation of three new 2'-oxygenated flavonoids, (2R)-5-hydroxy-7,2',3'-trimethoxyflavanone (1), 7,2',5'-trimethoxyflavone (2), 5,7,2',3'-tetramethoxyflavone (3), and eight known flavones, 5,7,2'-trimethoxyflavone (4), 5,7,2',4',5'-pentamethoxyflavone (5), echioidinin (6), 5,2',6'-trihydroxy-7-methoxyflavone (7), 5-hydroxy-7,2'-dimethoxyflavone (8), echioidin (9), echioidinin 5-O-glucoside (10), and 5,2',6'-trihydroxy-7-methoxyflavone 2'-O-glucoside (11). The structures of 1-11 were elucidated by physical and spectral methods, including extensive 2D NMR studies. The presence of 2'-oxygenated flavonoids is apparently restricted to Andrographis species in Acanthaceae. Therefore, 2'-oxygenated flavonoids are regarded as chemotaxonomic markers of Andrographis genus in the Acanthaceae family.

Andrographis↗

PubMed2003

Cytotoxic anthraquinones from the stems of Rubia wallichiana Decne.

From the stems of Rubia wallichiana DECNE, thirty-four structurally related compounds were isolated and identified. Three of them, namely rubiawallin-A (1), -B (2), and -C (3), constitute the first report of their occurrence from the natural source. Their structures were determined by comprehensive analyses of their 1D and 2D NMR, and electron impact (EI) mass spectral data. Furthermore, an in vitro screening of cytotoxicity of the isolated compounds was also evaluated. Among the testing compounds, 1-hydroxy-2-hydroxymethyl-3-methoxyanthraquinone (4) demonstrated most effective cytotoxicity towards Hepa-3B and Colo-205 cells.

Anthraquinones↗

PubMed2002

Constituents from the root and stem of Aristolochia elegans.

Four new tetralones, aristelegone-A (1), aristelegone-B (2), aristelegone-C (3), and aristelegone-D (4); one new isoquinoline, pericampylinone-A (5); four new biphenyl ethers, aristogin-A (6), aristogin-B (7), aristogin-D (8), and aristogin-E (9); three new lignans, aristelegin-A (10), aristelegin-B (11), and aristelegin-C (12); and a new dimer, aristolin (13), have been isolated from the root and stem of Aristolochia elegans. The structures were established on the basis of 1D and 2D NMR and mass spectral data. This is the first report of isoquinolones and biphenyl ethers from this plant which may be representative units for the formation of bisbenzylisoquinoline alkaloids that are common metabolites of Aristolochia species. Aristolin (13) is also the first report of a diterpene linked with an aristolochic acid.

Alkaloids↗