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Biomedical subjects

Quan-Bin Han

Publications and source records attributed to Quan-Bin Han.

At least 19 recordsLinked to original sources
PubMed2006

ent-Abietane diterpenoids from Isodon rubescens var. rubescens.

ent-Abietane diterpenoids, hebeiabinins A-F (1-5), together with seven known diterpenoids were isolated from leaves of Isodon rubescens var. rubescens. The structures of 1-5 were established on the basis of spectroscopic analyses, including application of 2D NMR spectroscopic techniques. The diterpenoids isolated were evaluated for the cytotoxicity against A549, HT-29, and K562 tumor cells. Compound 5 was the most active with IC(50) value of 0.91 microM against A549 cells.

Abietanes↗
PubMed2006

Maoecrystal Z, a cytotoxic diterpene from Isodon eriocalyx with a unique skeleton.

[structure: see text] A novel diterpene with an unprecedented tetracyclic 6,7:8,15-di-seco-7,20-olide-6,8-cyclo-ent-kaurane skeleton, named maoecrystal Z (1), has been isolated from the leaves of a Chinese medicinal herb, Isodon eriocalyx (Labiatae). Its structure was determined by comprehensive NMR and MS spectroscopic analysis coupled with single-crystal X-ray crystallographic diffraction. Compound 1 exhibited comparable inhibitory effect against human K562 leukemia, MCF7 breast, and A2780 ovarian tumor cells with IC(50) = 2.90, 1.63, and 1.45 microg/mL and with camptothecin and paclitaxel as the positive controls.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Diterpenoids from Isodon species and their biological activities.

Isodon species (Labiatae) are widely distributed plants, many of which are used in folk medicine. Over the past twenty years, they have received considerable phytochemical and biological attention. Thestructures of their many diterpenoids constituents, especially those with an ent-kaurane skeleton, have been elucidated. The significant phytochemical and pharmacological diterpenoids form the subject of this review. There are 290 references.

Diterpenes↗
PubMed2006

A pair of novel cytotoxic polyprenylated xanthone epimers from gamboges.

Two new polyprenylated xanthone epimers were isolated from gamboges of Garcinia hanburyi, and identified by detailed spectroscopic analysis as 30-hydroxygambogic acid (2a) and its (2S)-epimer 30-hydroxyepigambogic acid (2b). Both compounds exhibited significant cytotoxicities against the human leukemia K562/S and the corresponding doxorubicin-resistant K562/R cell lines (Table 2).

Cell Line, Tumor↗
PubMed2006

Cytotoxic ent-kauranoids from Isodon parvifolius.

Three new ent-kaurane diterpenoids, parvifoline Z (1), parvifoline AA (2), and parvifoline AB (3), together with 14 known compounds, were isolated from the leaves of Isodon parvifolius. The structures of the new compounds were elucidated by 1D- and 2D-NMR spectroscopy and mass spectrometry, and by comparison with known compounds. These three new diterpenoids included three types of ent-kauranoids, namely, C(20)-non-oxygenated-ent-kauranoid, 7,20-cyclo-ent-kauranoid and 6,7-seco-ent-kauranoid-7,20-olide. Compounds 1 and 2 exhibited significant cytotoxicities against A549, HT-29, and K562 cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Ent-abietane and ent-labdane diterpenoids from Isodon parvifolius.

A phytochemical investigation on the leaves of Isodon parvifolius yielded three new ent-abietanoids parvifolines L-N (1-3), together with five known ent-abietanoids (4-8) and one known ent-labdane diterpenoid (9). Their structures were determined on the basis of extensive spectroscopic analysis.

Abietanes↗
PubMed2006

Cytotoxic polyprenylated xanthones from the resin of Garcinia hanburyi.

Thirteen xanthones (1-13) were isolated from the resin of Garcinia hanburyi. Among them, two new compounds (namely gaudichaudic acid, and isogambogenic acid, 1, 2), and one new natural product (deoxygaudichaudione A, 3) were identified on the basis of extensive spectral evidence including detailed 2D NMR data. Ten of these xanthones were tested for their cytotoxicities against human leukemia K562 (K562/S) and doxorubicin-resistant K562 (K562/R) cell lines, and showed similar inhibitory effects on both cell lines, suggesting that this group of polyprenylated xanthones might not be multidrug resistance (MDR) substrates.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Quality assessment of fructus psoraleae.

Two newly-reported benzofuran glycosides, named psoralenoside and isopsoralenoside, along with two major coumarins, psoralen and isopsoralen, were simultaneously determined in twenty-three samples of Fructus Psoraleae collected from different growth areas in China. The quantitative method was validated, and the mean recovery rates from fortified samples (n=5) of psoralenoside, isopsoralenoside, psoralen and isopsoralen, were 96.5%, 97.1%, 100.7%, and 99.3% with variation coefficient of 3.1%, 3.6%, 2.3%, and 2.2%, respectively. An interesting biotransformation relationship between the glycosides and the coumarins was revealed on the basis of the quality analysis results. It was also suggested that psoralenoside and isopsoralenoside should be used as key quality markers for Fructus Psoraleae, together with the commonly used psoralen and isopsoralen.

Benzofurans↗
PubMed2005

Structure and anti-HIV activity of micrandilactones B and C, new nortriterpenoids possessing a unique skeleton from Schisandra micrantha.

Two new highly oxygenated nortriterpenoids with a unique norcycloartane skeleton, micrandilactones B and C, were isolated from Schisandra micrantha; micrandilactone C exhibited an EC50 value of 7.71 microg/mL (SI > 25.94) against HIV-1 replication with minimal cytotoxicity, and the potent anti-HIV-1 activity and unique structural features of make it a promising lead for therapeutic development of a new generation of anti-HIV drug.

Animals↗
PubMed2005

Novel mechanism of inhibition of nuclear factor-kappa B DNA-binding activity by diterpenoids isolated from Isodon rubescens.

The development of specific inhibitors that can block nuclear factor-kappaB (NF-kappaB) activation is an approach for the treatment of cancer, autoimmune, and inflammatory diseases. Several diterpenoids, oridonin, ponicidin, xindongnin A, and xindongnin B were isolated from the herb Isodon rubescens. These compounds were found to be potent inhibitors of NF-kappaB transcription activity and the expression of its downstream targets, cyclooxygenase-2 and inducible nitric-oxide synthase. The mechanisms of action of the diterpenoids against NF-kappaB are similar, but significant differences were also identified. All of the diterpenoids directly interfere with the DNA-binding activity of NF-kappaB to its response DNA sequence. Oridonin and ponicidin have an additional impact on the translocation of NF-kappaB from the cytoplasm to nuclei without affecting IkappaB-alpha phosphorylation and degradation. The effect of these compounds on the interaction of NF-kappaB with consensus DNA sequences is unique. Different inhibitory effects were observed when NF-kappaB bound to various DNA sequences. Both p65/p65 and p50/p50 homodimers, as well as p65/p50 heterodimer association with their responsive DNA, were inhibited. Kinetic studies on NF-kappaB-DNA interaction indicate that the diterpenoids decrease the B(max app) but have no effect on K(d app). This suggests that this class of compounds interacts with both p65 and p50 subunits at a site other than the DNA binding site and subsequently modulates the binding affinity of the transcription factor toward DNA with different NF-kappaB binding sequences. The diterpenoid structure could therefore serve as a scaffold for the development of more potent and selective NF-kappaB inhibitors that target regulated gene transcription.

Animals↗
PubMed2005

Authentication and quantitative analysis on the chemical profile of cassia bark (cortex cinnamomi) by high-pressure liquid chromatography.

Cassia bark or cortex cinnamomi, the dried stem bark of Cinnamomum cassia Presl. (Lauraceae), is a popular natural spice and a commonly used herb in traditional Chinese medicine. However, adulterants are frequently found in the market. In this study, 44 samples of Cassia bark including bark from seven related Cinnamomum species were collected from fields and market. Four characteristic components, cinnamaldehyde, cinnamic acid, cinnamyl alcohol, and coumarin were determined by RP-HPLC, and a fingerprint comprised of five markers was established. These results showed that cassia barks contained high contents of cinnamaldehyde (13.01-56.93 mg/g). The highest content of cinnamaldehyde (up to 93.83 mg/g) was found in debarked cortex, which is traditionally regarded as having the best quality in local herb shops. In contrast, the adulterants from the other Cinnamomum species, C. wilsonii Camble, C. japonicum Sieb., C. mairei Levl. and C. burmanii (Nees) Blume, contained low contents of cinnamaldehyde (<2.00 mg/g). The content of cinnamaldehyde in C. loureirii Nees was comparable to that in C. cassia. It is suggested that five characteristic peaks by HPLC are suitable for distinguishing genuine cassia bark from the adulterants and could be applied in the quality control of this commodity.

Acrolein↗
PubMed2005

Ent-kauranoids from Isodon rubescens var. taihangensis.

Two new compounds, rubescensins Q and R (1 and 2), and a new acetonide derivative (3) of lasiodonin, together with thirteen known analogues, oridonin (4), ponicidin (5), wikstroemioidin B (6), lasiodonin (7), lasiokaurin (8), enmenol (9), 1-O-beta-D-glucopyranosyl-enmenol (10), trichokaurin (11), the acetonide of maoyecrystal F (12), rabdoternins A-D (13-16), have been isolated from Isodon rubescens var. taihangensis. The structures of the new compounds were elucidated on the basis of spectroscopic methods, especially the 2D NMR spectral analysis. Compound 3 exhibited cytotoxicity against K562, Bcap37, CA, CNE, BIU87, BGC823, and HeLa cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Stability and cytotoxicity of gambogic acid and its derivative, gambogoic acid.

In this study, the stability of gambogic acid (GA), a polyprenylated xanthone with potent cytotoxicities against various cancer cell lines, was evaluated under several experimental conditions including addition of acids, alkalis and organic solvents. GA was stable when dissolved in acetone, acetonitrile, and chloroform, even when acids were added. However, a new derivative was produced after GA was stored in the methanol solution for a week at room temperature. The addition of alkalis could increase the rate of this chemical transformation. This derivative was determined to be gambogoic acid (GOA) by the HPLC-MS comparison with the known compound. GOA was proposed to be the product of neuclophilic addition of methanol to the olefinic bond at C-10 of GA. Furthermore, when these two compounds were tested for their cytotoxicity, GOA showed significantly weaker inhibitory effects than GA. It was therefore deduced that the alpha,beta-unsaturated carbonyl moiety at C-10 contributed to the cytotoxicity of gambogic acid.

Antineoplastic Agents↗
PubMed2005

Complete NMR assignments of the antibacterial biflavonoid GB1 from Garcinia kola.

From the antibacterial fraction of the roots of Garcinia kola, 3'',4',4''',5,5'',7,7''-heptahydroxy-3,8''-biflavanone (GB1) was isolated as the major constituent, whose interesting conformations were studied on the basis of its 1D and 2D NMR spectra obtained at different temperatures and in different solvents. GB1 showed antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) with MIC of 32 and 128 microg/ml, respectively.

Biflavonoids↗
PubMed2004

Coriatone and corianlactone, two novel sesquiterpenes from Coriaria nepalensis.

Both coriatone (1). a novel highly oxygenated picrotoxane-type sesquiterpene, and corianlactone (2). with an unprecedented sesquiterpene basic skeleton, named coriane, were isolated from Coriaria nepalensis Wall. The structures of 1 and 2 were determined by analysis of their two-dimensional NMR data, and the structure of 2 was confirmed by X-ray analysis. Compounds 1 and 2 showed no remarkable inhibitory activity toward K(562) cells. They are cytotoxic with IC(50) > 50 microg/mL (cis-platinim: IC(50) = 0.49 microg/mL).

Crystallography, X-Ray↗
PubMed2004

Diterpenoids from Isodon melissoides.

Nine new diterpenoids, melissoidesins M-U (1-9), along with five known analogues, melissoidesin F (10), xindongnin B (11), melissoidesin G (12), melissoidesin E (13), and dawoensin A (14), were isolated from the aerial parts of Isodon melissoides. The structures of new compounds were elucidated by analysis of spectral evidence including extensive 2D NMR data. Compounds 2, 3, 7, 11, 12, and 14 showed cytotoxicity against the human tumor BGC-823 cell line with IC(50) values less than 10 microg/mL, respectively.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Cytotoxic ent-kaurane diterpenoids from Isodon rubescens var. rubescens.

Five new ent-kauranoids, xindongnins C - G ( 1 - 5), together with five known ones, xindongnins A and B ( 6 and 7), melissoidesin G ( 8), dawoensin A ( 9), and glabcensin V ( 10), were isolated from the leaves of Isodon rubescens var. rubescens, and structurally elucidated. Compounds 1, 4, and 6 - 10 showed inhibitory effects against human tumor K562 cells with IC (50) values ranging from 0.3 to 7.3 microg/mL. The structure of 6 was revised on the basis of its 2D-NMR spectral data.

Antineoplastic Agents, Phytogenic↗