Biomedical subjects

Tian-Shung Wu

Publications and source records attributed to Tian-Shung Wu.

At least 19 recordsLinked to original sources

PubMed2006

Kalanchosides A-C, new cytotoxic bufadienolides from the aerial parts of Kalanchoe gracilis.

[Structure: see text] Three new compounds, kalanchosides A-C (1-3), as well as five known compounds, were isolated from the aerial parts of Kalanchoe gracilis. The compound structures were determined by spectroscopic methods. All eight isolated compounds showed significant cytotoxic activity against a panel of human tumor cell lines, with potency reaching the nanomolar range. However, only bryophyllin B (8) inhibited HIV replication in H9 lymphocyte cells.

Antineoplastic Agents, Phytogenic↗

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

Antitumor agents. 254. Synthesis and biological evaluation of novel neo-tanshinlactone analogues as potent anti-breast cancer agents.

In our previous study, neo-tanshinlactone (1) showed potent and selective anti-breast cancer activity. To explore the SAR of 1, nine analogues (15-18, 24-28) were designed and synthesized. Together with 1 and tamoxifen (TAM), all newly synthesized compounds and some intermediates were evaluated for in vitro anticancer activity against several human tumor cell lines. Compounds without a ring D did not show promising activity, while compounds with a methylated furan ring D showed better activity than those with unsubstituted furan or hydroxy-dihydrofuran rings. Among all newly synthesized compounds, compound 15 with an ethyl group at the 4-position showed the best activity and selectivity with ED50 values of 0.45 and 0.18 microg/mL against MCF-7 and ZR-75-1 (ER+) and 13.5 and 10.0 microg/mL against MDA MB-231 and HS 587-1 (ER-), respectively. Furthermore, 15 also showed potent activity against SK-BR-3 (ER-, HER2+) with an ED50 value of 0.10 microg/mL. Our preliminary SAR studies showed that a methylated furan ring D and the C-4 substituent in ring A are critical for anti-breast cancer activity. Further development of 1 and 15 as anti-breast cancer drug candidates is warranted.

Antineoplastic Agents↗

PubMed2006

Comparison of transcripts in Phalaenopsis bellina and Phalaenopsis equestris (Orchidaceae) flowers to deduce monoterpene biosynthesis pathway.

BACKGROUND: Floral scent is one of the important strategies for ensuring fertilization and for determining seed or fruit set. Research on plant scents has hampered mainly by the invisibility of this character, its dynamic nature, and complex mixtures of components that are present in very small quantities. Most progress in scent research, as in other areas of plant biology, has come from the use of molecular and biochemical techniques. Although volatile components have been identified in several orchid species, the biosynthetic pathways of orchid flower fragrance are far from understood. We investigated how flower fragrance was generated in certain Phalaenopsis orchids by determining the chemical components of the floral scent, identifying floral expressed-sequence-tags (ESTs), and deducing the pathways of floral scent biosynthesis in Phalaneopsis bellina by bioinformatics analysis. RESULTS: The main chemical components in the P. bellina flower were shown by gas chromatography-mass spectrometry to be monoterpenoids, benzenoids and phenylpropanoids. The set of floral scent producing enzymes in the biosynthetic pathway from glyceraldehyde-3-phosphate (G3P) to geraniol and linalool were recognized through data mining of the P. bellina floral EST database (dbEST). Transcripts preferentially expressed in P. bellina were distinguished by comparing the scent floral dbEST to that of a scentless species, P. equestris, and included those encoding lipoxygenase, epimerase, diacylglycerol kinase and geranyl diphosphate synthase. In addition, EST filtering results showed that transcripts encoding signal transduction and Myb transcription factors and methyltransferase, in addition to those for scent biosynthesis, were detected by in silico hybridization of the P. bellina unigene database against those of the scentless species, rice and Arabidopsis. Altogether, we pinpointed 66% of the biosynthetic steps from G3P to geraniol, linalool and their derivatives. CONCLUSION: This systems biology program combined chemical analysis, genomics and bioinformatics to elucidate the scent biosynthesis pathway and identify the relevant genes. It integrates the forward and reverse genetic approaches to knowledge discovery by which researchers can study non-model plants.

Acyclic Monoterpenes↗

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↗

PubMed2006

High-performance liquid chromatographic method for simultaneous quantification of eight major biologically active ingredients in 'Da-Chai-Hu-Tang' preparation.

A simple, sensitive and specific high-performance liquid chromatographic method has been developed for the first time to simultaneously determine the eight major biologically active ingredients, namely paeoniflorin, naringin, sennoside A, baicalin, baicalein, saikosaponin a, rhein and emodin of the Chinese herbal formula Da-Chai-Hu-Tang. The contents of these marker substances in Da-Chai-Hu-Tang extract could be easily determined within 85 min. The assay was reproducible and accurate with overall intra-day variations and accuracy of less than 2% and more than 97.9%, respectively. Results indicate that the developed HPLC assay can be successfully utilized as a quality control method for simultaneous determination of eight representative substances in Da-Chai-Hu-Tang.

Chromatography, High Pressure Liquid↗

PubMed2006

Abietane diterpene alkaloids from Salvia yunnanensis.

Nine new abietane diterpene alkaloids containing an oxazole ring, salviamines A-F (1-6) and isosalviamines C-E (7-9), together with 17 known abietane diterpenes, were isolated and characterized from the roots of Salvia yunnanensis. The structures of 1-9 were elucidated by interpretation of their spectroscopic data.

Abietanes↗

PubMed2006

C18 dibenzocyclooctadiene lignans from Kadsura philippinensis.

Four new C18 dibenzocyclooctadiene lignans, kadsuphilins A (1) and B (3), 6-epi-gomisin (2), and 1-demethylkadsuphilin A (4), along with eight known related metabolites, were isolated from an EtOAc fraction of an alcoholic extract of the aerial parts of Kadsura philippinensis growing in Taiwan. The structures of 1-4 were elucidated on the basis of spectroscopic analyses, including 2D NMR (HMQC, HMBC, and NOESY) experiments, and by comparison of their spectroscopic data with those of related metabolites. The configurations of the biphenyl and cyclooctadiene moieties were deduced from circular dichroism (CD) and NOESY NMR spectra, respectively. Some of the compounds showed radical-scavenging activity in a DPPH-HPLC method.

Biphenyl Compounds↗

PubMed2006

Antidepressant principles of the roots of Polygala tenuifolia.

[(125)I]RTI-55-membrane binding assay-guided fractionation and separation of a water-soluble extract of the roots of Polygala tenuifolia gave five new oligosaccharide derivatives, polygalatenosides A-E (1-5). The structures of these new oligosaccharides were established on the basis of spectroscopic evidence. Polygalatenosides A and B (1 and 2) showed significant inhibitory activity, with IC(50) values of 30.0 and 6.04 microM, respectively, in this membrane binding assay and acted as norepinephrine reuptake inhibitors through blocking norepinephrine transport.

Antidepressive Agents↗

PubMed2006

Melatonin attenuates the postischemic increase in blood-brain barrier permeability and decreases hemorrhagic transformation of tissue-plasminogen activator therapy following ischemic stroke in mice.

Melatonin protects against transient middle cerebral artery (MCA) occlusion and may be suited as an add-on therapy of tissue plasminogen activator (t-PA) thrombolysis. Herein, we examined whether melatonin would reduce postischemic increase in the blood-brain barrier (BBB) permeability and, therefore, attenuate the risk of hemorrhagic transformation after t-PA therapy in experimental stroke. Twelve mice were subjected to transient occlusion of the MCA for 1 hr, followed by 24 hr of reperfusion. Melatonin (5 mg/kg, i.p.) or vehicle was given at the beginning of reperfusion. BBB permeability was evaluated by quantitation of Evans Blue leakage. An additional 32 mice underwent photothrombotic occlusion of the distal MCA, and were administered vehicle or t-PA (10 mg/kg, i.v.), alone or in combination with melatonin (5 mg/kg, i.p.), at 6 hr postinsult. The animals were then killed after 24 hr for the determination of infarct and hemorrhage volumes. Relative to controls, melatonin-treated animals had significantly reduced BBB permeability (by 52%; P < 0.001). Additionally, we found that at 6 hr after photo-irradiation, either t-PA or melatonin, or a combined administration of t-PA plus melatonin, did not significantly affect brain infarction (P > 0.05), compared with controls. Mice treated with t-PA alone, however, had significantly increased hemorrhagic formation (P < 0.05), and the event was effectively reversed by co-treatment with melatonin (P < 0.05). Thus, melatonin improved postischemic preservation of the BBB permeability and a decreased risk of adverse hemorrhagic transformation after t-PA therapy for ischemic stroke. The findings further highlight melatonin's potential role in the field of thrombolytic treatment for ischemic stroke patients.

Animals↗

PubMed2006

Melatonin decreases neurovascular oxidative/nitrosative damage and protects against early increases in the blood-brain barrier permeability after transient focal cerebral ischemia in mice.

We have recently shown that melatonin decreases the late (24 hr) increase in blood-brain barrier (BBB) permeability and the risk of tissue plasminogen activator-induced hemorrhagic transformation following ischemic stroke in mice. In the study, we further explored whether melatonin would reduce postischemic neurovascular oxidative/nitrosative damage and, therefore, improve preservation of the early increase in the BBB permeability at 4 hr after transient focal cerebral ischemia for 60 min in mice. Melatonin (5 mg/kg) or vehicle was given intraperitoneally at the beginning of reperfusion. Hydroethidine (HEt) in situ detection and immunohistochemistry for nitrotyrosine were used to evaluate postischemic accumulation in reactive oxygen and nitrogen species, respectively, in the ischemic neurovascular unit. BBB permeability was evaluated by spectrophotometric and microscopic quantitation of Evans Blue leakage. Relative to controls, melatonin-treated animals not only had a significantly reduced superoxide accumulation in neurovascular units in boundary zones of infarction, by reducing 35% and 54% cytosolic oxidized HEt in intensity and cell-expressing percentage, respectively (P < 0.001), but also exhibited a reduction in nitrotyrosine by 52% (P < 0.01). Additionally, melatonin-treated animals had significantly reduced early postischemic disruption in the BBB permeability by 53% (P < 0.001). Thus, melatonin reduced postischemic oxidative/nitrosative damage to the ischemic neurovascular units and improved the preservation of BBB permeability at an early phase following transient focal cerebral ischemia in mice. The findings further highlight the ability of melatonin in anatomical and functional preservation for the ischemic neurovascular units and its relevant potential in the treatment of ischemic stroke.

Animals↗

PubMed2006

Cytotoxic arylnaphthalene lignans from Phyllanthus oligospermus.

Three new arylnaphthalene lignans, namely phyllanthusmins A-C, together with nine known compounds were isolated and characterized from the stems and roots of Phyllanthus oligospermus by a bioassay-guided purification. The structures of the new compounds were elucidated by means of spectroscopic data interpretation. Among them, phyllanthusminA displayed significant cytotoxicity against KB and P-388 cancer cell lines.

Benzodioxoles↗

PubMed2006

Constituents from the leaves of Phellodendron amurense and their antioxidant activity.

Three new coumarins, phellodenols F-H (1-3) and a new glutaric acid derivative, phellodendric acid-A (4) were isolated from the leaves of Phellodendron amurense together with twenty-nine known compounds. Extensive 1D and 2D NMR experiments and other spectroscopic studies were employed to determine the structures of 1-4. The isolated compounds were screened for their antioxidant activity through DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) radical scavenging assay. Compounds quercetin, quercetin-3-O-beta-D-glucoside, quercetin-3-O-beta-D-galactoside and kaempferol-3-O-beta-D-glucoside demonstrated significant radical scavenging activity comparable to vitamin E.

Antioxidants↗

PubMed2006

Delayed treatment with nicotinamide inhibits brain energy depletion, improves cerebral microperfusion, reduces brain infarct volume, but does not alter neurobehavioral outcome following permanent focal cerebral ischemia in Sprague Dawley rats.

Delayed treatment with nicotinamide (NAm) reduces infarction induced by middle cerebral artery occlusion (MCAO) in rats. This study explored some potential mechanisms by which delayed NAm treatment may confer protection in the brain of Sprague-Dawley rats following permanent MCAO (pMCAO). NAm (500 mg/kg) or vehicle was given 2 h after the onset of pMCAO. Cortical microperfusion, brain and rectal temperature were serially measured. Neurobehavioral examinations were performed at 24 h post-ischemia followed by sacrifice for histologic assessment. Some rats were also sacrificed at 4 h post-ischemia for analyses of ATP, ADP, AMP, and adenosine. Permanent MCAO induced spontaneous hyperthermia and a sharp decrease in cortical microperfusion, ATP concentration, and the sum of adenine nucleotides (p < 0.05). At 4 h post-ischemia, NAm improved ATP recovery, the sum of adenine nucleotides (p < 0.05) and attenuated the ischemia-induced systemic hyperthermia (p < 0.05) without affecting brain temperature or cortical microperfusion. At 24 h, NAm improved cortical microperfusion in the ischemic hemisphere and reduced total infarct volume (p < 0.05), but did not affect behavioral scores. The data suggest that NAm attenuated brain damage following pMCAo initially by improving cerebral bioenergetic metabolism during the sub-acute phase of ischemia, followed by a delayed improvement in microvascular perfusion.

Adenine↗

PubMed2005

Cinnamophilin reduces oxidative damage and protects against transient focal cerebral ischemia in mice.

Acute neuroprotective effects of cinnamophilin (CINN; (8R, 8'S)-4, 4'-dihydroxy-3, 3'-dimethoxy-7-oxo-8, 8'-neolignan), a novel antioxidant and free radical scavenger, were studied in a mouse model of transient middle cerebral artery (MCA) occlusion. CINN was administered intraperitoneally either 15 min before (pretreatment) or 2 h after the onset of MCA occlusion (postischemic treatment). Relative to vehicle-treated controls, animals pretreated with CINN, at 20-80 mg/kg, had significant reductions in brain infarction by 33-46% and improvements in neurobehavioral outcome. Postischemic administration with CINN (80 mg/kg) also significantly reduced brain infarction by 43% and ameliorated neurobehavioral deficits. Additionally, CINN administration significantly attenuated in situ accumulation of superoxide anions (O2-) in the boundary zones of infarct at 4 h after reperfusion. Consequently, CINN-treated animals exhibited significantly decreased levels of oxidative damage, as assessed by immunopositive reactions for 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxynonenal (4-HNE), and the resultant inflammatory reactions at 24 h post-insult. It is concluded that CINN effectively reduced brain infarction and improved neurobehavioral outcome following a short-term recovery period after severe transient focal cerebral ischemia in mice. The finding of a decreased extent of reactive oxygen species and oxidative damage observed with CINN treatment highlights that its antioxidant and radical scavenging ability is contributory.

Animals↗

PubMed2005

A rapid and simple determination of protoberberine alkaloids in cortex phellodendri by 1H NMR and its application for quality control of commercial traditional Chinese medicine prescriptions.

Huangbai (cortex Phellodendri, the dried bark of Phellodendron amurense or Phellodendron chinense) is one of the important traditional Chinese medicines. Protoberberine alkaloids were reported to contribute to the biological activity of this species. A highly specific and sensitive method using (1)H NMR has been developed for the quantitative determination of protoberberine alkaloids in Phellodendron species and their commercial traditional Chinese medicine prescriptions. In the region of delta 8.6-8.9, the signals of H-13 of berberine (1) and palmatine (2), were well separated from other signals in methanol-d(4). The quantity of the compounds was calculated by the relative ratio of the integral values of the target peak of each compound to the known amount of internal standard anthracene. This method allows rapid and simple quantization of protoberberine alkaloids from Phellodendron species or the more complex commercial prescriptions in 5 min without any pre-purification steps. The recoveries of berberine and palmatine from P. amurense were in the range of 95-106%. Limit of detection (LOD) and limit of quantitation (LOQ) of them were 1.0 and 1.8 microg/mL, respectively. The advantages of the method were that no reference compounds are required for calibration curves, the quantification could be directly realized on a crude extract, the better selectivity for protoberberine alkaloids and a very significant time-gain could be achieved, in comparison to conventional HPLC methods, for instance.

Alkaloids↗

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

Constituents of Vittaria anguste-elongata and their biological activities.

Twelve new compounds, vittarin-A (1), -B (2), -C (3), -D (4), -E (5), -F (6), 3-O-acetylniduloic acid (7), ethyl 3-O-acetylniduloate (8), methyl 4-O-coumaroylquinate (9), vittarilide-A (10), and -B (11), and vittariflavone (12), as well as 20 known compounds have been isolated from the whole plant of Vittaria anguste-elongata. The structures of these compounds were determined by spectroscopic and chemical transformation methods. 5,7-Dihydroxy-3',4',5'-trimethoxyflavone (18) displayed moderate cytotoxicity against human lung carcinoma and central nervous system carcinoma cell lines with inhibition of 89 and 61% at a concentration of 58 microM, respectively. Vittarilide-A (10) and -B (11) and ethyl 4-O-caffeoylquinate (14) exhibited moderate DPPH radical scavenging activity with IC50 values of 91, 290, and 234 microM, respectively.

Antineoplastic Agents, Phytogenic↗