Amentoflavone inhibits the induction of nitric oxide synthase by inhibiting NF-kappaB activation in macrophages.

Amentoflavone is a bi-flavonoid compound with anti-fungal and anti-inflammatory activities. We isolated amentoflavone from Selaginella tamariscina (Selaginellaceae) and studied its effects on nuclear factor-kappaB (NF-kappaB)-mediated inducible nitric oxide synthase (iNOS) gene expression in RAW 264.7 cells. Amentoflavone inhibited the production of nitric oxide in a concentration-dependent manner and also blocked the lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS). To clarify the mechanistic basis for its inhibition of iNOS induction, we examined the effect of amentoflavone on the transactivation of iNOS gene by luciferase reporter activity using -1.59 kb flanking region. Amentoflavone potently suppressed the reporter gene activity. The LPS-induced activation of NF-kappaB was also found to be significantly blocked by amentoflavone, but AP-1 activation was unaffected. Furthermore, the nuclear translocation of p65 by LPS was inhibited by amentoflavone. NF-kappaB activation is controlled by the phosphorylation and subsequent degradation of I-kappaBalpha, and the cytosolic degradation of I-kappaBalpha was found to be inhibited by amentoflavone. These findings suggest that the inhibition of LPS-induced NO formation by amentoflavone is due to its inhibition of NF-kappaB by blocking I-kappaBalpha degradation, which may be the mechanistic basis of the anti-inflammatory effects of amentoflavone.

HIV-1 integrase inhibitory phenylpropanoid glycosides from Clerodendron trichotomum.

Seven phenylpropanoid glycosides named acteoside (1), acteoside isomer (2), leucosceptoside A (3), plantainoside C (4), jionoside D (5), martynoside (6), and isomartynoside (7) were isolated from Clerodendron trichotomum. Compounds 1 and 2 showed potent inhibitory activities against HIV-1 integrase with IC50 values of 7.8 +/- 3.6 and 13.7 +/- 6.0 microM, respectively.

Isolation of virus-cell fusion inhibitory components from Eugenia caryophyllata.

The fractionation of Eugenia caryophyllata (Myrtaceae) guided by the syncytia formation inhibition assay led to the isolation of four tannins (eugeniin, casuarictin, 1,3-di-O-galloyl-4,6-(S)-hexahydroxydiphenoyl-beta-D-glucopyranose, and tellimagrandin I), and two chromones (biflorin and isobiflorin). Among the isolated compounds, tellimagrandin (4) showed a significantly high inhibitory activity on the syncytia formation with an IC50 value of 16.12 +/- 1.98 micrograms/ml.

7-feruloylloganin: an iridoid glucoside from stems of Lonicera insularis.

A new iridoid glucoside, 7-feruloylloganin (1), was isolated from stems of Lonicera insularis, along with six known lignans including (-)-pinoresinol, 9alpha-hydroxypinoresinol, balanophonin, erythro-1-(4-hydroxy-3-methoxyphenyl)-2-[4-[2-formyl-(E)-vinyl]-2-methoxyphenoxy]-propane-1,3-diol, threo-1-(4-hydroxy-3-methoxyphenyl)-2-[4-[2-formyl-(E)-vinyl]-2-methoxyphenoxy]-propane-1,3-diol and buddlenol A. The structure of 1 was determined by analyses of 2D NMR (1H-1H COSY, HMQC and HMBC) and HRFABMS.

A new prenylated flavonol from the roots of Sophora flavescens.

A new prenylated flavonol, sophoflavescenol (1), together with five known flavonoids, kurarinol, kushenol K, kushenol H, trifolirhizin, and kuraidin, were isolated from the roots of Sophora flavescens. The structure of 1 was determined by spectroscopic analysis. Among the five known flavonoids, kurarinol, kushenol K, and kushenol H showed weak antiviral activity against Herpes simplex virus types I and II.

A cytotoxic pennogenin glycoside from Majanthemum dilatatum.

A cytotoxic pennogenin glycoside, pennogenin 3-O-alpha-L-rhamnopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[ alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (1) was isolated from the whole herb of Majanthemum dilatatum. Compound 1 showed potent cytotoxic activity against human cancer cell lines.

A new flavonol glycoside gallate ester from Acer okamotoanum and its inhibitory activity against human immunodeficiency virus-1 (HIV-1) integrase.

Bioassay-directed chromatographic fractionation of an ethyl acetate extract of the leaves of Acer okamotoanum using HIV-1 integrase afforded a new acylated flavonol glycoside, quercetin 3-O-(2",6"-O-digalloyl)-beta-D-galactopyranoside (1), together with six known flavonol glycosides and three known phenolic compounds. The structure of the new compound was determined by spectroscopic methods. The most active compounds were quercetin 3-O-(2"-galloyl)-alpha-L-arabinopyranoside (6) and 1, which exhibited IC50 values of 18.1 +/- 1.3 and 24.2 +/- 6.6 micrograms/mL, respectively, against HIV-1 integrase.

Anti-herpetic activity of various medicinal plant extracts.

In order to find antiviral compounds againstHerpes simplex virus type I (HSV-1) and II (HSV-2) from natural products, a convenient virus-induced cytopathic effect (CPE) inhibition assay was introduced. More than 300 fractions were prepared by solvent fractionation from sixty collected plants or purchased herbal medicines, and their anti-herpetic activities were evaluated. Among them, several medicinal plants showed potent anti-herpetic activity. Selective indexes (SI) of the EtOAc extract of Caraganae Radix (Caragana sinica) against HSV-1 and HSV-2 were more than 8.06 and 24.79, SI of the MeOH extract ofAcer okamotoanum leaves were 3.92 and 3.51, SI of the CH(2)Cl(2) extract of Veratri Rhizoma et Radix (Veratrum patulum) were 5.49 and 1.31 and SI of the MeOH extract of aerial part of Osmundae Rhizoma (Osmunda japonica) were more than 3.45 and 1.25, respectively.

Inhibition of gp 120-CD4 interaction by various plant extracts.

Various assay methods have been developed to evaluate the effectiveness of substances against human immunodeficiency virus (HIV). One of them is the Syncytia formation inhibition assay, which is based on the inhibition of the interaction between the HIV-1 envelope protein gp 120 and the cellular membrane protein CD4. A variation of this assay using recombinant virus vPE 16 and CD4(+) HeLa cell was developed to find anti-HIV compounds in natural products that inhibit gp 120-CD4 binding. VPE 16 expresses glycoprotein gp 160, which is glycosylated then processed into gp 120 and gp 41 on its envelope. A total of 50 plant extracts were screened with this system. Extracts from Calicarpa japonica and Sedum sarmentosum were among those that showed strong inhibition of the gp 120-CD4 interaction.