Effects of neolignans from the stem bark of Magnolia obovata on plant pathogenic fungi.

AIMS: To characterize antifungal principles from the methanol extract of Magnolia obovata and to evaluate their antifungal activities against various plant pathogenic fungi. METHODS AND RESULTS: Four neolignans were isolated from stem bark of M. obovata as antifungal principles and identified as magnolol, honokiol, 4-methoxyhonokiol and obovatol. In mycelial growth inhibition assay, both magnolol and honokiol displayed more potent antifungal activity than 4-methoxyhonokiol and obovatol. Both magnolol and honokiol showed similar in vivo antifungal spectrum against seven plant diseases tested; both compounds effectively suppressed the development of rice blast, tomato late blight, wheat leaf rust and red pepper anthracnose. 4-Methoxyhonokiol and obovatol were highly active to only rice blast and wheat leaf rust respectively. CONCLUSIONS: The extract of M. obovata and four neolignans had potent in vivo antifungal activities against plant pathogenic fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: Neolignans from Magnolia spp. can be used and suggested as a novel antifungal lead compound for the development of new fungicide and directly as a natural fungicide for the control of plant diseases such as rice blast and wheat leaf rust.

Anticomplement activity of terpenoids from the spores of Ganoderma lucidum.

A new lanostane-type terpenoid, lucidenic acid SP1 (1), was isolated from a CHCl(3)-soluble fraction of Ganoderma lucidum spores together with four other known compounds (2 - 5). The structure of lucidenic acid SP1 was determined to be 3 beta,7 beta-dihydroxy-4,4,14 alpha-trimethyl-11,15-dioxo-5 alpha-chol-8-en-24-oic acid by spectroscopic means including 2D-NMR. Twelve triterpenes (1-12) isolated from G. lucidum spores were investigated in vitro for their anticomplementary activity. Compounds 1 - 5 were inactive, whereas ganoderiol F (8), ganodermanondiol (9) and ganodermanontriol (10) showed a strong anticomplement activity against the classical pathway (CP) of the complement system with IC(50) values of 4.8, 41.7, and 17.2 microM, respectively. The potency of these triterpene alcohols (8-10) in inhibiting CP activity was improved when the number of hydroxymethyl groups on the side chain moiety is increased. On the other hand, the ganoderic acids 1-7, which contain a carboxyl group in the side chain, and lucidumols A and B (11, 12) had little activity on this system.

Cytotoxic mono-tetrahydrofuran ring acetogenins from leaves of Annona montana.

Further studies on leaves of Annona montana led to isolation of one iso-acetogenin, montanacin G, three pairs of acetogenins, montanacin H-J and 34-epi-montanacin H-J, together with four known acetogenins, gigantetrocins A and B, annonacin and cis-annonacin. Montanacin G belongs to the iso-acetogenin group with a terminal 2,4-trans-ketolactone unit. Montanacin H-J and 34-epi-montanacin H-J contain the rare gamma-hydroxy-gamma-methyl-gamma-lactone moiety. The cytotoxic activities of these compounds, together with previously reported acetogenins, montanacins B and C, were examined against Meth-A and LLC tumor cell lines in vitro.

Inhibitory effects of Korean plants on HIV-1 activities.

In the search for novel anti-human immunodeficiency virus type 1 (anti-HIV-1) agents from natural sources, 49 MeOH extracts of Korean plants were screened for their inhibitory effects against RNA-dependent DNA polymerase (RT) and ribonuclease H (RNase H) activities of HIV-1 reverse transcriptase and HIV-1 protease, and anti-HIV-1 activity. Regarding the HIV-1 reverse transcriptase, Agrimonia pilosa (whole plant), Cornus kousa (stem and leaf), Limonium tetragonum (root) and Mallotus japonicus (stem) showed significant inhibitory activity on RT activity with 50% inhibitory activity (IC(50)) of 8.9, 6.3, 7.5 and 11.9 microg/mL, respectively, whereas Agrimonia pilosa was also active against RNase H activity (IC(50) = 98.4 microg/mL). Four plants, namely Agrimonia pilosa (whole plant), Atractylodes japonica (root), Clematis heracleifolia (whole plant) and Syneilesis palmata (whole plant), were appreciably active (<35%) against recombinant HIV-1 protease at a concentration of 100 microg/mL. Crinum asiaticum var. japonicum (root) showed significant anti-HIV-1 activity (ED(50) = 12.5 microg/mL) with a favourable SI value of 16.

Cytotoxic alkaloids and a flavan from the bulbs of Crinum asiaticum var. japonicum.

A new pyrrolophenanthridone alkaloid, criasiaticidine A (1), was isolated from the bulbs of Crinum asiaticum var. japonicum, together with pratorimine (2), lycorine (3) and 4'-hydroxy-7-methoxyflavan (4). The structure of the new alkaloid was determined to be 4,5-etheno-9,10-dihydroxy-6-phenanthridone by spectroscopic means. The cytotoxicity of the isolated compounds 1-4 was evaluated in vitro against Meth-A (mouse sarcoma) and Lewis lung carcinoma (mouse lung carcinoma) tumor cell lines. Furthermore, 3 was examined for in vivo antitumor activity with LLC tumor cells.

Kaempferol acetylrhamnosides from the rhizome of Dryopteris crassirhizoma and their inhibitory effects on three different activities of human immunodeficiency virus-1 reverse transcriptase.

Three new kaempferol glycosides, called crassirhizomosides A (1), B (2) and C (3), were isolated from the rhizome of Dryopteris crassirhizoma (Aspidiaceae), together with the known kaempferol glycoside, sutchuenoside A (4). The structures of 1-3 were determined as kaempferol 3-alpha-L-(2,4-di-O-acetyl)rhamnopyranoside-7-alpha-L-rhamnopyranoside, kaempferol 3-alpha-L-(3,4-di-O-acetyl)rhamnopyranoside, and kaempferol 3-alpha-L-(2,3-di-O-acetyl)rhamnopyranosside-7-alpha-L-rhamnopyranoside, respectively, by chemical and spectroscopic means. Inhibitory effects of 1-4 and kaempferol on human immunodeficiency virus reverse transcriptase-associated DNA polymerase (RNA-dependent DNA polymerase and DNA-dependent DNA polymerase) and RNase H activities were investigated.

Triterpenes and lignans from Artemisia caruifolia and their cytotoxic effects on meth-A and LLC tumor cell lines.

One new triterpene, 3beta-hydroxy-29-norcycloart-24-one (1), and four new lignans, caruilignans (2-5), together with six known compounds were isolated from the aerial part of Artemisia caruifolia BUCH.-HAM. ex TOXB. Their structures were determined by various spectroscopic means. Most of the isolated lignans were moderately cytotoxic to Meth-A cells with ED50 values of 5-10 microg/ml, but not to Lowis lung carcinoma (LLC) cells. An oxime derivative of 1 showed more potent cytotoxic activity against Meth-A and LLC cells than the original triterpene 1.

Inhibition of human immunodeficiency virus type 1 reverse transcriptase and ribonuclease H activities by constituents of Juglans mandshurica.

From the stem-bark of Juglans mandshurica, two new naphthalenyl glucopyranosides, 1,4,8-trihydroxynaphthalene 1-O-[alpha-L-arabinofuranosyl-(1-->6)-beta-D-glucopyranoside] (1) and 1,4,8-trihydroxynaphthalene 1-O-beta-D-[6'-O-(3",5"-dihydroxy-4"-methoxybenzoyl)]glucopyranosi de (4), and two new alpha-tetralonyl glucopyranosides, 4 alpha,5,8-trihydroxy-alpha-tetralone 5-O-beta-D-[6'-O-(3",5"-dihydroxy-4"-methoxybenzoyl)]glucopyranosi de (7) and 4 alpha,5,8-trihydroxy-alpha-tetralone 5-O-beta-D-[6'-O-(3",4",5"-trihydroxybenzoyl)]glucopyranoside (8), were isolated together with three known naphthalenyl glucopyranosides (2, 3 and 5), one alpha-tetralonyl glucopyranoside (6), four flavonoids (9-12), and two galloyl glucopyranosides (13, 14). Amongst the isolated compounds, 1,2,6-trigalloylglucopyranose (13) and 1,2,3,6-tertagalloylglucopyranose (14) exhibited the most potent inhibition of reverse transcriptase (RT) activity with IC50 values of 0.067 and 0.040 microM, respectively, while the latter compound also inhibited ribonuclease H (RNase H) activity with an IC50 of 39 microM, comparable in potency to illimaquinone used as a positive control. 1,4,8-Trihydroxy-naphthalene 1-O-beta-D-glucopyranoside (2), 1,4,8-trihydroxynaphthalene 1-O-beta-D-[6'-O-(4"-hydroxy-3",5"-dimethoxybenzoyl)]glucopyranoside (3) and 8 showed moderate inhibition against both enzyme activities, and inhibitory potency of 2 against RNase H activity (IC50 = 156 microM) was slightly greater than that against the RT activity (IC50 = 290 microM). The inhibitory potencies of 4 alpha,5,8-trihydroxy-alpha-tetralone 5-O-beta-D-[6'-O-(4"-hydroxy-3",5"-dimethoxybenzoyl)] glucopyranoside (6), 7 and 8 against RT activity increased accompanied by an increase in the number of free hydroxyls on the galloyl residues, as represented by the IC50 values of > 500, 330 and 5.8 microM, respectively.

Screening of Korean plants against human immunodeficiency virus type 1 protease.

With the aim of finding novel anti-human immunodeficiency virus agents from natural products, 93 MeOH extracts of Korean plants were screened for their inhibitory activities against HIV-1 protease. The most potent inhibition was shown by the root of Rodiola rosea with 70.4% inhibition at a concentration of 100 microg/mL.

Inhibitory effect of triterpenes from Crataegus pinatifida on HIV-I protease.

The methanol extracts of the leaves of Crataegus pinnatifida showed potent inhibitory activities against HIV-1 protease at a concentration of 100 micrograms/ml. The subsequent fractionation and isolation of the extract gave two active compounds. Their structures were identified as uvaol (1) and ursolic acid (2) by spectral data. These active compounds inhibit HIV-1 protease with IC50 values of 5.5 and 8.0 microM, respectively.

Chitin synthase II inhibitory activity of ursolic acid, isolated from Crataegus pinnatifida.

Two triterpenoid compounds, ursolic acid and uvaol, were isolated from Crataegus pinnatifida Bunge leaves. Ursolic acid inhibits chitin synthase II from S. cerevisiae with an IC50 value of 0.84 microgram/ml and the inhibition appears to be selective for chitin synthase II, whereas uvaol has no inhibitory activity up to 280 micrograms/ml. Oleanolic acid, alpha-hederin hydrate, and betulic acid inhibited the chitin synthase II activity under the same conditions with an IC50 of 5.6, 64.3, and 98.7 micrograms/ml, respectively.

Inhibitory constituents against HIV-1 protease from Agastache rugosa.

Two diterpenoid compounds, agastanol (1) and agastaquinone (2), were isolated from the roots of Agastache rugosa (Labiatae). Compound 1 and 2 showed significant inhibitory effects against human immunodeficiency virus type 1 (HIV-1) protease activity with IC50 values of 360 and 87 microM, respectively.