Biomedical subjects

Feng-Lin Hsu

Publications and source records attributed to Feng-Lin Hsu.

At least 19 recordsLinked to original sources

PubMed2007

Microbial metabolism of steviol and steviol-16alpha,17-epoxide.

Steviol (2) possesses a blood glucose-lowering property. In order to produce potentially more- or less-active, toxic, or inactive metabolites compared to steviol (2), its microbial metabolism was investigated. Incubation of 2 with the microorganisms Bacillus megaterium ATCC 14581, Mucor recurvatus MR 36, and Aspergillus niger BCRC 32720 yielded one new metabolite, ent-7alpha,11beta,13-trihydroxykaur-16-en-19-oic acid (7), together with four known related biotransformation products, ent-7alpha,13-dihydroxykaur-16-en-19-oic acid (3), ent-13-hydroxykaur-16-en-19-alpha-d-glucopyranosyl ester (4), ent-13,16beta,17-trihydroxykauran-19-oic acid (5), and ent-13-hydroxy-7-ketokaur-16-en-19-oic acid (6). The preliminary testing of antihyperglycemic effects showed that 5 was more potent than the parent compound (2). Thus, the microbial metabolism of steviol-16alpha,17-epoxide (8) with M. recurvatus MR 36 was continued to produce higher amounts of 5 for future study of its action mechanism. Preparative-scale fermentation of 8 yielded 5, ent-11alpha,13,16alpha,17-tetrahydroxykauran-19-oic acid (10), ent-1beta,17-dihydroxy-16-ketobeyeran-19-oic acid (11), and ent-7alpha,17-dihydroxy-16-ketobeyeran-19-oic acid (13), together with three new metabolites: ent-13,16beta-dihydroxykauran-17-acetoxy-19-oic acid (9), ent-11beta,13-dihydroxy-16beta,17-epoxykauran-19-oic acid (12), and ent-11beta,13,16beta,17-tetrahydroxykauran-19-oic acid (14). The structures of the compounds were fully elucidated using 1D and 2D NMR spectroscopic techniques, as well as HRFABMS. In addition, a GRE (glucocorticoid responsive element)-mediated luciferase reporter assay was used to initially screen the compounds 3-5, and 7 as glucocorticoid agonists. Compounds 4, 5 and 7 showed significant effects.

Aspergillus niger↗

PubMed2006

Biotransformation of gallic acid by Beauveria sulfurescens ATCC 7159.

Preparative-scale fermentation of gallic acid (3,4,5-trihydroxybenzoic acid) (1) with Beauveria sulfurescens ATCC 7159 gave two new glucosidated compounds, 4-(3,4-dihydroxy-6-hydroxymethyl-5-methoxy-tetrahydro-pyran-2-yloxy)-3-hydroxy-5-methoxy-benzoic acid (4), 3-hydroxy-4,5-dimethoxy-benzoic acid 3,4-dihydroxy-6-hydroxymethyl-5-methoxy-tetrahydro-pyran-2-yl ester (7), along with four known compounds, 3-O-methylgallic acid (2), 4-O-methylgallic acid (3), 3,4-O-dimethylgallic acid (5), and 3,5-O-dimethylgallic acid (6). The new metabolite genistein 7-O-beta-D-4''-O-methyl-glucopyranoside (8) was also obtained as a byproduct due to the use of soybean meal in the fermentation medium. The structural elucidation of the metabolites was based primarily on 1D-, 2D-NMR, and HRFABMS analyses. Among these compounds, 2, 3, and 5 are metabolites of gallic acid in mammals. This result demonstrated that microbial culture parallels mammalian metabolism; therefore, B. sulfurescens might be a useful tool for generating mammalian metabolites of related analogs of gallic acid (1) for complete structural identification and for further use in investigating pharmacological and toxicological properties in this series of compounds. In addition, a GRE (glucocorticoid response element)-mediated luciferase reporter gene assay was used to initially screen for the biological activity of the 6 compounds, 2-6 and 8, along with 1 and its chemical O-methylated derivatives 9-13. Among the 12 compounds tested, 11-13 were found to be significant, but less active than the reference compounds of methylprednisolone and dexamethasone.

Beauveria↗

PubMed2006

Bioactive constituents of Spatholobus suberectus in regulating tyrosinase-related proteins and mRNA in HEMn cells.

Spatholobus suberectus Dunn (Leguminosae) is a traditional Chinese herbal medicine used to treat rheumatism, anemia, menoxenia, and other disorders. The extent to which this herbal medicine is useful to skin cells, however, has not been evaluated. Constituents of the 95% ethanol extracts of the dried vine stems of S. suberectus were therefore isolated and examined for their skin-whitening capacity. A bio-guided phytochemical investigation, involving use of the mushroom tyrosinase inhibitory system, of active fractions of the extracts resulted in the isolation of 12 constituents. The structures of these constituents, which were characterized by various spectroscopic techniques, consisted of one flavone, three isoflavones, five flavanones, two flavanonols, and one chalcone. Of these constituents 3',4',7-trihydroxyflavone (1), eriodictyol (3), plathymenin (5), dihydroquercetin (6), butin (7), neoisoliquiritigenin (8), dihydrokaempferol (9), liquiritigenin (10), and 6-methoxyeriodictyol (12) represented compounds isolated for the first time from S. suberectus. These constituents were evaluated their ability to inhibit cellular tyrosinase activity and for their melanin inhibitory activity in human epidermal melanocytes (HEMn). Butin (7) was the most efficacious of these constituents and exhibited concentration-dependent effects. Western blot analysis revealed that expression of tyrosinase and tyrosinase-related proteins 1 and 2 (TRP1 and TRP2) was decreased in butin (7)-treated HEMn cells. Additionally, quantitative real-time PCR (qRT-PCR) analysis disclosed that expression of mRNAs for tyrosinase, TRP1 and TRP2 was suppressed by butin (7). It is concluded that butin (7) is the most active of the components of S. suberectus in inhibiting pigmentation and that this inhibition is exerted through inhibition of transcription of the genes encoding tyrosinase, TRP1 and TRP2.

Cell Survival↗

PubMed2006

Cosmetic applications of selected traditional Chinese herbal medicines.

Because tyrosinase catalyzes melanin synthesis, tyrosinase inhibitors are important in cosmetic skin-whitening. Oxidative stress contributes to skin aging and can adversely affect skin health, which means antioxidants active in skin cells may support skin health. We examined 25 traditional Chinese herbal medicines that might be useful for skin-whitening and skin health. Extracts (100microg/mL) were tested for cytotoxicity on human epidermal melanocytes (HEMn); 12 exhibited low cytotoxicity. Their effects on tyrosinase and melanin inhibitory activities and free radical scavenging activities were further assessed. Phenolic contents were evaluated using Folin-Ciocalteu reagent. Four herbs, Pharbitis nil, Sophora japonica, Spatholobus suberectus, and Morus alba, exhibited potent inhibitory effects on tyrosinase (IC(50) values 24.9, 95.6, 83.9, and 78.3microg/mL, respectively). Melanin inhibition was not dose-dependent. Sophora japonica (IC(50): 14.46microg/mL, 1,1-diphenyl-2-picrylhydrazyl (DPPH); 1.95microg/mL, hydroxyl radical) and Spatholobus suberectus (IC(50): 10.51microg/mL, DPPH; 4.36microg/mL, hydroxyl radical) showed good antioxidative activities and high phenolic contents (255 and 189mg of gallic acid/g extract, respectively). Among active anti-tyrosinase extracts, Sophora japonica and Spatholobus suberectus were especially potent in HEMn cells in terms of free radical scavenging effects and high phenolic contents, making them the strongest candidates for cosmetic application found in the current study.

Biphenyl Compounds↗

PubMed2006

Transformation of steviol-16alpha,17-epoxide by Streptomyces griseus and Cunninghamella bainieri.

Eight new ent-beyerane metabolites, 5-8, 12, and 14-16, and four new ent-kaurane metabolites, 3, 10, 11, and 13, together with two known metabolites, 4 and 9, were isolated from the microbial transformations of steviol-16alpha,17-epoxide using Streptomyces griseus ATCC 10137 and Cunninghamella bainieri ATCC 9244. The structures of the metabolites were characterized by IR, HRFABMS, and 1D and 2D NMR data. In addition, a GRE (glucocorticoid response element)-mediated luciferase reporter assay was used to initially screen for the biological activity of the 11 metabolites and stevioside. Steviol (1), steviol-16alpha,17-epoxide (2), ent-11alpha,13,16alpha,17-tetrahydroxykauran-19-oic acid (3), ent-17-hydroxy-16-ketobeyeran-19-oic acid (4), ent-9alpha,13-dihydroxy-16beta,17-epoxykauran-19-oic acid (10), ent-9alpha,17-dihydroxy-16-ketobeyeran-19-oic acid (12), ent-1beta,17-dihydroxy-16-ketobeyeran-19-oic acid (14), and stevioside showed significant effects; in particular, stevioside showed almost equal potency as dexamethasone.

Animals↗

PubMed2005

Promotion of hyphal growth and underlying chemical changes in Antrodia camphorata by host factors from Cinnamomum camphora.

The aim of this research was to investigate the hyphal growth-promoting factors (HGFs) of Antrodia camphorata from the host-related species, Cinnamomum camphora (CC) and the underlying chemical produced. The HGF was identified in the polysaccharide fraction of CC at levels ranging from 80 to 320 mg L(-1), and it maximally stimulated growth to 5.50 g L(-1) during a 14-day culture period compared to that of the control of 2.88 g L(-1). We also investigated the nature and chemical composition of the CC polysaccharide. Herein, size-exclusion column chromatography followed by high-performance anion-exchange chromatography after complete hydrolysis of the CC polysaccharide was performed to derive its molecular weight and sugar composition. The Mw values of the CC polysaccharide were determined to be 728.2, 187.5, 28.7, 7.5, and 1.9 kDa. Compositional analysis of the CC polysaccharide showed that galactosamine, mannose, and glucose were the major monosaccharides. Time-course studies of mycelial extracts of cultures revealed that prolonged incubation with the water-soluble extracts of CC resulted in an increase in the relative amounts of two lanostane-type compounds, i.e., dehydrosulphurenic acid and 15alpha-acetyl-dehydrosulphurenic acid, which are found in the fruiting bodies of A. camphorata. This finding offers the possibility of the reliable production of this medicinal fungus under laboratory conditions compared to its limited slow growth in nature.

Cell Extracts↗

PubMed2005

Inhibitory effects of acylated kaempferol glycosides from the leaves of Cinnamomum kotoense on the proliferation of human peripheral blood mononuclear cells.

A new chemical entity, namely kaempferol 3- O-alpha-L-[2-(Z)-p-coumaroyl-4-(E)-p-coumaroyl]rhamnopyranoside (1), and the known kaempferol 3-O-alpha-L-[2,4-di-(E)-p-coumaroyl]rhamnopyranoside (2) have been isolated from the methanolic extract of leaves of Cinnamomum kotoense. Structural elucidation of compounds 1 and 2 were achieved on the basis of spectroscopic analysis. The effects of compounds 1 and 2 on phytohemagglutinin (PHA) stimulated cell proliferation were studied towards human peripheral blood mononuclear cells (PBMC). The results indicated that compounds 1 and 2 suppressed PBMC proliferation induced by PHA with an IC50 value of 5.0 +/- 1.3 and 6.0 +/- 1.5 microM, respectively. Interleukin-2 production in activated PBMC inhibited by compounds 1 and 2 were in a concentration-dependent manner. Therefore, we suggested that compounds 1 and 2 in C. kotoense were likely the growth modulators for PBMC.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Myricetin as the active principle of Abelmoschus moschatus to lower plasma glucose in streptozotocin-induced diabetic rats.

The antihyperglycemic action of myricetin, purified from the aerial part of Abelmoschus moschatus (Malvaceae), was investigated in streptozotocin-induced diabetic rats (STZ-diabetic rats). Bolus intravenous injection of myricetin decreased the plasma glucose concentrations in a dose-dependent manner in STZ-diabetic rats. Myricetin at the effective dose (1.0 mg/kg) significantly attenuated the increase of plasma glucose induced by an intravenous glucose challenge test in normal rats. A stimulatory effect of myricetin on glucose uptake of the soleus muscles isolated from STZ-diabetic rats was obtained in a concentration-dependent manner from 0.01 to 10.0 micromol/L. The increase of glucose utilization by myricetin was further characterized using the enhancement of glycogen synthesis in isolated hepatocytes of STZ-diabetic rats. These results suggest that myricetin has an ability to enhance glucose utilization to lower plasma glucose in diabetic rats lacking insulin.

Abelmoschus↗

PubMed2004

Isosteviol acts on potassium channels to relax isolated aortic strips of Wistar rat.

Isosteviol is a derivative of stevioside, a constituent of Stevia rebaudiana, which is commonly used as a noncaloric sugar substitute in Japan and Brazil. In the present study, the role of potassium channels in the vasodilator effect of isosteviol was investigated using potassium channel blockers on isosteviol-induced relaxation of isolated aortic rings prepared from Wistar rats. Isosteviol dose-dependently relaxed the vasopressin (10(-8) M)-induced vasoconstriction in isolated aortic rings with or without endothelium. However, in the presence of potassium chloride (3x10(-2) M), the vasodilator effect of isosteviol on arterial strips disappeared. Only the inhibitors specific for the ATP-sensitive potassium (K(ATP)) channel or small conductance calcium-activated potassium (SK(Ca)) channel inhibited the vasodilator effect of isosteviol in isolated aortic rings contracted with 10(-8) M vasopressin. Also; since the isosteviol-induced relaxation was unchanged by methylene blue, a role of nitric oxide and/or endothelium in the vasodilatation produced by isosteviol could be ruled out. The obtained results indicated that vasodilatation induced by isosteviol is related to the opening of SK(Ca) and K(ATP) channels.

Animals↗

PubMed2004

Isosteviol as a potassium channel opener to lower intracellular calcium concentrations in cultured aortic smooth muscle cells.

Isosteviol is a derivative of stevioside, a constituent of Stevia rebaudiana, and is commonly used as a non-caloric sugar substitute in Japan and Brazil. The present study attempted to elucidate the role of potassium (K (+)) channels in the action of isosteviol on intracellular calcium concentrations ([Ca (2+)]i) in cultured vascular smooth muscle (A7r5) cells using the Ca (2+)-sensitive dye Fura-2 as an indicator. The increase of [Ca (2+)]i in A7r5 cells produced by vasopressin (1 micromol/L) or phenylephrine (1 micromol/L) was attenuated by isosteviol from 0.01 micromol/L to 10 micromol/L. The attenuation by isosteviol of the vasopressin- and phenylephrine-induced increase in [Ca (2+)]i was inhibited by glibenclamide, apamin and 4-aminopyridine but not by charybdotoxin. Furthermore, the inhibitory action of isosteviol on [Ca (2+)]i was blocked when A7r5 cells co-treated with glibenclamide and apamin in conjunction with 4-aminopyridine were present. Therefore, not only did the ATP-sensitive potassium (K (ATP)) channel affect the action of isosteviol on [Ca (2+)]i modulation in A7r5 cells, but also those on the small conductance calcium-activated potassium (SK (Ca)) channels and voltage-gated (Kv) channels. However, the blockers of large-conductance Ca (2+)-activated potassium channels failed to modify the inhibitory action of isosteviol on [Ca (2+)]i. The obtained results indicated that a decrease of [Ca (2+)]i in A7r5 cells by isosteviol is mainly mediated by the selective opening of K (ATP) channel or/and SK (Ca) channel. Alteration in the Kv channel also plays a critical role in the inhibitory action of isosteviol.

Animals↗

PubMed2004

Hydroxylation and glucosidation of ent-16beta-Hydroxybeyeran-19-oic acid by Bacillus megaterium and Aspergillus niger.

ent-16beta-Hydroxybeyeran-19-oic acid ( 1) has potential antihypertensive activity. To obtain novel and more-effective compounds, 1 was incubated with Bacillus megaterium ATCC 14 581 and Aspergillus niger CCRC 32 720. The structures of the metabolites were determined by HR-FAB-MS, 1D- and 2D-NMR spectral data, and enzymatic hydrolysis. Bacillus megaterium hydroxylated and glucosidated 1 to yield ent-7alpha,16beta-dihydroxybeyeran-19-oic acid ( 2), ent-16beta-hydroxybeyeran-19-oic acid alpha- D-glucopyranosyl ester ( 3), and ent-7alpha,16beta-dihydroxybeyeran-19-oic acid alpha- D-glucopyranosyl ester ( 4). Aspergillus niger hydroxylated 1 to yield ent-1beta,7alpha,16beta-trihydroxybeyeran-19-oic acid ( 5) and ent-1beta,7alpha-dihydroxy-16-oxobeyeran-19-oic acid ( 6). Metabolites 3 - 5 were characterized as new compounds. In addition, 2, 3, 5, and 6 were tested for antihypertensive effects, and we found that 5 and 6 were more potent than the parent compound 1.

Antihypertensive Agents↗

PubMed2004

Antioxidant iridoid glucosides from Wendlandia formosana.

Two new iridoid glucosides of 10-O-caffeoyl scandoside methyl ester (3), and 6-methoxy scandoside methyl ester (4) besides the known compounds of scandoside methyl ester (1), methyl deacetyl asperulosidate (2), 10-O-caffeoyl daphylloside (5), phytol (6), and ursolic acid (7) were isolated from the leaves of Wendlandia formosana. Structure elucidation of the new iridoid glucosides was based on interpretation of high-resolution 1D and 2D NMR spectral data and chemical conversions. Antioxidant activity of Compounds (1-5) against diphenylpicrylhydrazyl (DPPH) and hydroxyl radical, and peroxynitrite was reported.

Antioxidants↗

PubMed2003

Inhibition of lipopolysaccharide-induced nitric oxide production by flavonoids in RAW264.7 macrophages involves heme oxygenase-1.

The role of heme oxygenase-1 (HO-1) played in the inhibitory mechanism of flavonoids in lipopolysaccharide (LPS)-induced responses remained unresolved. In the present study, flavonoids, including 3-OH flavone, baicalein, kaempferol, and quercetin, induced HO-1 gene expression at the protein and mRNA levels in the presence or absence of LPS in RAW264.7 macrophages. This effect was associated with suppression of LPS-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) protein expression. Hemin induced HO-1 protein expression and this was associated with the suppression of LPS-induced NO production and iNOS protein expression in a dose-dependent manner. In addition, an increase in bilirubin production was found in flavonoid- and hemin-treated cells. Hemin, at the doses of 10, 20, and 50 microM, dose-dependently stimulated the flavonoid (50 microM)-induced HO-1 protein expression, and enhanced their inhibitory effects on LPS-induced NO production and iNOS protein expression. Pretreatment of the HO-1 inhibitor, tin protoporphyrin (10 microM), attenuated the inhibitory activities of the indicated flavonoids on LPS-induced NO production. Morphologic analysis showed that 3-OH flavone, baicalein, kaempferol, quercetin, hemin, and tin protoporphyrin did not cause any change in cell viability in the presence or absence of LPS. In contrast, only 3-OH flavone showed a significant inhibition of cell growth using the MTT assay. Transfection of an HO-1 vector in macrophages (HO-1/RAW264.7) resulted in a 3-fold increase in HO-1 protein compared with that the parental RAW264.7 cells. NO production mediated by LPS in HO-1 over-expressed RAW264.7 cells (HO-1/RAW264.7) was significant less than that in parental RAW264.7 cells. 3-OH Flavone, baicalein, kaempferol, and quercetin showed a more significant inhibition on LPS-induced NO production in HO-1/RAW264.7 cells than in parental RAW264.7 cells. These results provide evidence on the role of HO-1 in the inhibition of LPS-induced NO production by flavonoids. A combination of HO-1 inducers (i.e. hemin) and flavonoids might be an effective strategy for the suppression of LPS-induced NO production.

Animals↗

PubMed2003

Inhibitory activities of semicarbazide-sensitive amine oxidase and angiotensin converting enzyme of pectin hydroxamic acid.

Solutions of 100 mL of 1% commercial pectin each with a different degree of esterification (DE), DE94, DE65, and DE25, were reacted with 100 mL of 2 M alkaline hydroxylamine (pH 12.0) at room temperature for 4 or 18 h. These pectin hydroxamic acids (PHAs; DE94T4, DE94T18, DE65T4, and DE25T4) were used to test the inhibitory activities against semicarbazide-sensitive amine oxidase (SSAO) and angiotensin-converting enzyme (ACE). Compared to different DE pectins (DE94, DE65, and DE25), the PHAs of DE94T4, DE94T18, DE65T4, and DE25T4 showed different inhibition activities against SSAO or ACE. Commercial pectins with different DE values showed negligible SSAO or ACE inhibitions. The order of SSAO inhibition was DE65T4 > DE94T18 approximately DE25T4 >> DE94T4. However, the order of ACE inhibition was DE94T4 > DE94T18 >> DE65T4 > DE25T4. The SSAO activity staining or ACE-hydrolyzed products on TLC chromatogram also confirmed the inhibitory activities of PHAs against SSAO or ACE.

Amine Oxidase (Copper-Containing)↗

PubMed2003

Antihypertensive effects of tannins isolated from traditional Chinese herbs as non-specific inhibitors of angiontensin converting enzyme.

The tannins are natural polyphenols, able to precipitate water-soluble alkaloids and possess an inhibitory action on the angiotensin converting enzyme (ACE). We identified 18 polyphenolic compounds (tannins) from Chinese herbs and examined the in vitro effects of these tannins on ACE activity, including determination of the 50% inhibitory concentrations (IC50), specificity and mode of inhibition. We also assessed the in vivo inhibitory effect of the tannins on angiotensin I-induced blood pressure elevation in spontaneously hypertensive rats (SHR). Nine tannins with an IC50 <200 microM for ACE inhibitors were identified belonging to three tannin classes: caffeoylquinates, flavan-3-ols and gallotannins. In vitro, we found caffeoylquinates chelate the ACE zinc cofactor. Two of the flavan-3-ols: epigallocatechin-3-O-gallate and epigallocatechin-3-O-methylgallate, and one of gallotannin: 1, 2, 3, 4, 6-penta-O-galloyl-beta-D-glucose were non-specific inhibitors because also reduced the activity of trypsin and chymotrypsin. The ACE inhibition of 1, 2, 3, 4, 6-penta-O-galloyl-beta-D-glucose was also reduced after addition of bovine serum albumin, suggesting a non-specific mode of action. In vivo, 1,2,3,6-tetra-O-galloyl-beta-D-glucose and epigallocatechin-3-O-methylgallate had a strong dose-dependent hypotensive effect reducing the blood pressure significantly in the SHR with infusion of the angiotensin I. These findings indicate that some of the tannins isolated from herbs inhibit ACE activity non-specifically. The ACE inhibitory effect of these tannins may explain the hypotensive effects of some traditional Chinese herbs.

Angiotensin I↗

PubMed2003

Differential apoptosis-inducing effect of quercetin and its glycosides in human promyeloleukemic HL-60 cells by alternative activation of the caspase 3 cascade.

Flavonoids were demonstrated to possess several biological effects including antitumor, antioxidant, and anti-inflammatory activities in our previous studies. However, the effect of glycosylation on their biological functions is still undefined. In the present study, the apoptosis-inducing activities of three structure-related flavonoids including aglycone quercetin (QUE), and glycone rutin (RUT; QUE-3-O-rutinoside), and glycone quercitrin (QUI; QUE-3-O-rhamnoside) were studied. Both RUT and QUI are QUE glycosides, and possess rutinose and rhamnose at the C3 position of QUE, respectively. Results of the MTT assay showed that QUE, but not RUT and QUI, exhibits significant cytotoxic effect on HL-60 cells, accompanied by the dose- and time-dependent appearance of characteristics of apoptosis including an increase in DNA ladder intensity, morphological changes, apoptotic bodies, and an increase in hypodiploid cells by flow cytometry analysis. QUE, but not RUT or QUI, caused rapid and transient induction of caspase 3/CPP32 activity, but not caspase 1 activity, according to cleavage of caspase 3 substrates poly(ADP-ribose) polymerase (PARP) and D4-GDI proteins, and the appearance of cleaved caspase 3 fragments being detected in QUE- but not RUT- or QUI-treated HL-60 cells. A decrease in the anti-apoptotic protein, Mcl-1, was detected in QUE-treated HL-60 cells, whereas other Bcl-2 family proteins including Bax, Bcl-2, Bcl-XL, and Bag remained unchanged. The caspase 3 inhibitor, Ac-DEVD-FMK, but not the caspase 1 inhibitor, Ac-YVAD-FMK, attenuated QUE-induced cell death. Results of DCHF-DA assay indicate that no significant increase in intracellular peroxide level was found in QUE-treated cells, and QUE inhibited the H(2)O(2)-induced intracellular peroxide level. Free radical scavengers N-acetyl-cysteine (NAC) and catalase showed no prevention of QUE-induced apoptosis. In addition, QUE did not induce apoptosis in an mature monocytic cell line THP-1, as characterized by a lack of DNA ladders, caspase 3 activation, PARP cleavage, and an Mcl-1 decrease, compared with those in HL-60 cells. Our experiments provide evidence to indicate that the addition of rutinose or rhamnose attenuates the apoptosis-inducing activity of QUE, and that the caspase 3 cascade but not free radical production is involved.

Apoptosis↗

PubMed2003

Patatin, the tuber storage protein of potato (Solanum tuberosum L.), exhibits antioxidant activity in vitro.

The potato (Solanum tuberosum L.) tuber storage protein, patatin, was purified to homogeneity with a molecular mass of 45 kDa. The purified patatin showed antioxidant or antiradical activity by a series of in vitro tests, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (half-inhibition concentration, IC(50), was 0.582 mg/mL) scavenging activity assays, anti-human low-density lipoprotein peroxidation tests, and protections against hydroxyl radical-mediated DNA damages and peroxynitrite-mediated dihydrorhodamine 123 oxidations. Using electron paramagnetic resonance (EPR) spectrometry for hydroxyl radical detections, it was found that the intensities of the EPR signal were decreased by the increased amounts of patatin added (IC(50) was 0.775 mg/mL). Through modifications of patatin by iodoacetamide or N-bromosuccinimide, it was found that the antiradical activities of modified patatin against DPPH or hydroxyl radicals were decreased. It was suggested that cysteine and tryptophan residues in patatin might contribute to its antioxidant activities against radicals.

Animals↗

PubMed2003

Screening of 25 compounds isolated from Phyllanthus species for anti-human hepatitis B virus in vitro.

Using an HBV-producing cell line and inhibition of the expression of the HBsAg and HBeAg as antiviral indicators, a study was conducted on 25 compounds isolated from four Phyllanthus (Euphorbiaceae) plants, including P. amarus Schum. & Thonn., P. multi florus Willd., P. tenellus Roxb. and P. virgatus Forst. f. It was found that niranthin (1), nirtetralin (3), hinokinin (5) and geraniin (13) at the non-cytotoxic concentration of 50 micro m, suppressed effectively both HBsAg and HBeAg expression, with the highest inhibition at 74.3%, 45.3%; 69.6%, 33.9%; 68.1%, 52.3%; 32.1%, 46.6%, respectively. Of these, niranthin (1) showed the best anti-HBsAg activity, while the most potent anti-HBeAg activity was observed with hinokinin (5).

4-Butyrolactone↗