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One hundred methanolic plant extracts were screened for antiviral activity against seven viruses. Twelve extracts were found to have antiviral activity at the non-cytotoxic concentrations tested. The extracts of Rosa nutkana and Amelanchier alnifolia, both members of the Rosaceae, were very active against an enteric coronavirus. A root extract of another member of the Rosaceae, Potentilla arguta, completely inhibited respiratory syncytial virus. A Sambucus racemosa branch tip extract was also very active against respiratory syncytial virus while the inner bark extract of Oplopanax horridus partially inhibited this virus. An extract of Ipomopsis aggregata demonstrated very good activity against parainfluenza virus type 3. A Lomatium dissectum root extract completely inhibited the cytopathic effects of rotavirus. In addition to these, extracts prepared from the following plants exhibited antiviral activity against herpesvirus type 1: Cardamine angulata, Conocephalum conicum, Lysichiton americanum, Polypodium glycyrrhiza and Verbascum thapsus.

The methanolic extract of the seeds of Arctium lappa was found to show inhibitory activity against prostate cancer cell lines. Bioactivity-guided fractionation of a 95% ethanol extract from the seeds of A. lappa led to the isolation of seven compounds: β-sitosterol (1), daucosterol (2), lappaol C (3), lappaol A (4), and arctignan E (5), lappaol F (6), and arctiin (7). Their structures were elucidated by UV, IR, MS, and NMR data, as well as by comparison with those of the literature. Compounds 3–7 were studied for their cytotoxicity using a prostate cancer cell line. Compounds 3, 4, and 6 showed activity against the LNCaP prostate cancer cell line with IC50 values of 8, 16, and 40 µg/mL, respectively.

The alcohol extract or Rhodiola rosea has been shown to cause 42 ± 3.2% inhibition of acetylcholine esterase (AChE) when tested at 10 g/L. This AChE inhibition provides a physiological explanation for the reported mental and memory enhancing properties of Rhodiola rosea extracts. Active guided fractionation indicated a multitude of components which are responsible for this plants AChE inhibition. Two flavonoid glycosides (gossypetin-7-O-L-rhamnopyranoside and rhodioflavonoside) were isolated and shown to cause 58 ± 15% and 38 ± 4% AChE inhibition respectively when tested at 5 g/L. In view of this new enzymatic activity and previous clinical work indicating memory and mental enhancing properties with no indication of toxicity, this plant needs to be researched for its potential at treating memory impairing disorders such as Alzheimer’s disease.

Strong antiviral and antimicrobial activities were detected in methanolic extracts of 24 plants used medicinally in the treatment of skin infections in four different regions of Colombia. Thirteen extracts displayed activity against herpes simplex virus (HSV) whereas none was active against poliovirus. The antiviral activity was indicated by a total inhibition of viral cytopathic effects (CPE) at a non-cytotoxic concentration of the extract. The most potent extract was obtained from Byrsonima verbascifolia (L.) HBK. which showed anti-HSV activity at a concentration as low as 2.5 microg/ml. Antimicrobial screening was conducted using the disc diffusion assay against Klebsiella pneumoniae, Escherichia coli, Streptococcus faecalis, Mycobacterium phlei, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium and the human pathogenic yeast, Candida albicans. Anti-Candida activity was observed for Piper lanceaefolium HBK. and Juglans neotropica Diels. Twenty-two extracts displayed activity against Gram-positive bacteria whereas none was active against the Gram-negative species. We concluded that these Colombian medicinal plants represent an untapped source of potentially useful antivirals and are worthy of further study.

Activity guided fractionations led to the isolation of two antitumor compounds 5 alpha,8 alpha-epidioxy-24(R)-methylcholesta-6,22-dien-3 beta-D-glucopyranoside and 5,6-epoxy-24(R)-methylcholesta-7,22-dien-3 beta-ol from the methanol extract of Cordyceps sinensis. Two previously known compounds, ergosteryl-3-O-beta-D-glucopyranoside and 22-dihydroergosteryl-3-O-beta-D-glucopyranoside were also isolated. The structures of hitherto unknown sterols were established by 1D and 2D NMR spectroscopic techniques with the former synthesized in order to confirm the identity of the sugar moiety by chemical correlation. The glycosylated form of ergosterol peroxide was found to be a greater inhibitor to the proliferation of K562, Jurkat, WM-1341, HL-60 and RPMI-8226 tumor cell lines by 10 to 40% at 10 micrograms/ml than its previously identified aglycone, 5 alpha,8 alpha-epidioxy-24(R)-methylcholesta-6,22-dien-3 beta-ol.

Centipeda minima, a herb used medicinally to treat sinus infections in Nepal, was found to contain three antibacterial sesquiterpene lactones, identified as 6-O-methylacrylylplenolin, 6-O-isobutyroylplenolin, and 6-O-angeloylplenolin. 6-O-Methylacrylylplenolin had not been previously isolated from C. minima. All three had activity against Bacillus subtilis and Staphylococcus aureus, with 6-O-isobutyroylplenolin being the most active.

Ombuin (7,4'-dimethyl quercetin) (10 μg ml -1 , for 12 wk), glycyrrhizin/ quercetin (80 μg ml -1 and 10 μg ml -1 respectively, for 18 wk), ribavirin (10 μg ml -1 , for 12 wk) and quercetin/ribavirin (10 μg ml -1 each, for 9-12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ ribavirin treatment when tested by ISEM, herbaceous host indexing, RT-PCR, and immunocapture RT-PCR. A sensitive immunocapture RT-PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.

Two new (3 and 5), as well as three known (1, 2, and 4), polyynes were isolated from Devil's Club (Oplopanax horridus; Araliaceae), a medicinal plant of North America. The structures were established by 1H and 13C NMR. The absolute configurations of 2 and 5 were determined by application of Mosher's method. All the polyynes exhibited significant anti-Candida, antibacterial, and antimycobacterial activity, with an ability to kill Mycobacterium tuberculosis and isoniazid-resistant Mycobacterium avium at 10 micrograms/disk in a disk diffusion assay.

Natural products from both plants and fungi exhibit light-mediated or photodynamic biological activity against viruses, microorganisms, cells and insects. We review new aspects of the photochemistry and photobiology of natural products, including their potential as therapeutic agents, with a focus on publications from 1991 to 1996. The effect of ultraviolet and visible light on the biological activity of polyynes (including their sulfur-derivatives), quinones, alkaloids, furocoumarins, furochromones, porphyrins and some miscellaneous compound classes is summarized. Significant advances in this field have been made in the photochemistry of the 1,2-dithiin polyynes (thiarubrines), the visible light-mediated antiviral activity and protein kinase C inhibition of the perylenequinone pigments (hypericin, hypocrellins) and the phototoxicity of plant-derived porphyrins (pheophorbides).

We report the results of the first screening of 89 seaweeds collected from British Columbia, Canada, and Korea for antiviral activity. Various concentrations of methanol extracts of dried algae were tested against 100 plaque-forming units of herpes simplex virus type 1 and Sindbis virus in Vero cell monolayers. Eleven extracts inhibited both viruses, and 22 extracts were active against only one of the viruses. Thus, in total 37% of the species were active, and only two of these extracts also showed cytotoxicity at the concentrations tested. The antiviral activities were proportionately more frequent in the Korean extracts (56% compared with 27% of Canadian extracts), but in general the more potent extracts were of Canadian origin. Analipus japonicus was the most potent anti-herpes species, and the Korean species of Codium fragile was the most potent against both viruses. This high yield of antiviral extracts illustrates the potential of seaweeds as a resource for bioactive compounds. Key words: seaweeds, algal extracts, antiviral activities.

Thiarubrine A, an antimicrobial and nematocidal 1,2-dithiin polyyne has been reported to be a constituent of Aspilia leaves swallowed whole by chimpanzees. Aspilia samples were analyzed for the presence of thiarubrine A and other sulfur-containing polyynes using high-performance liquid chromatography (HPLC) and an antifungal bioassay. Thiarubrines A, B, D, and E and their corresponding thiophenes were not present in the leaves of three Aspilia species including A. mossambicensis and A. rudis, which are swallowed by chimpanzees at Mahale Mountains National Park and Gombe National Park, Tanzania. Antifungal activity, indicative of the presence of thiarubrines, was not detected in Aspilia leaf samples. Small amounts of thiarubrines A and B, and thiophenes A and B were found in A. mossambicensis roots. Analysis of three North American taxa found high concentrations of thiarubrines and thiophenes in the roots of Eriophyllum lanatum and Chaenactis douglasii, and the roots and leaves of Ambrosia chamissonis.

One hundred methanol plant extracts were screened for antibiotic activity against Mycobacterium tuberculosis and Mycobacterium avium. Nineteen extracts exhibited some activity against M. tuberculosis and 16 extracts showed some activity against M. avium. Thirteen of these 19 active extracts were traditionally used by First Nations peoples to treat tuberculosis. Extracts made from Heracleum maximum (Umbelliferae) roots, Moneses uniflora (Ericaceae), aerial parts, and Oplopanax horridus (Araliaceae) inner bark completely inhibited the growth of both organisms at a concentration equivalent to 20 mg dried plant material/disc. Extracts of Alnus rubra (Betulaceae) bark and catkins, Empetrum nigrum (Empetraceae) branches, Glehnia littoralis (Umbelliferae) roots, and Lomatium dissectum (Umbelliferae) roots completely inhibited the growth of both M. tuberculosis and M. avium at a concentration equivalent to 100 mg dried plant material/disc.

Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity. At the concentration of 5 µg of methanol extract in 25µL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase, one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula) of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal) have been found to inhibit PCR at level as low as 0.5 µg in 25µL of PCR reaction mixture.

When applied in a mixed inoculum with tomato ringspot nepovirus (TomRSV), flavonoids and related compounds inhibited infectivity in Chenopodium quinoa. Compounds that showed strong anti-viral activity were: quercetin, quercetin 3-methyl ether, quercetin 7-methyl ether, quercetin 3,7,3′4′-tetramethyl ether, galangin 3-methyl ether, morin, robinin, quercetin 3,7,4′-trimethyl ether, quercetin 7,4′-dimethyl ether, 7,4′-di-O-benzol-quercetin 7-hydroxy-3,4′-dimethyl flavone, 6,3′-dihydroxy-4′-methyl aurone and fisetin 4′-methyl ether. Quercetin applied at a concentration of 5 μg ml−1 caused 70% inhibition of local lesion development. When quercetin was applied to leaves prior to inoculation, there was only slight induced resistance to infection. Quercetin at 5 μg ml−1 did not affect virus multiplication in protoplasts prepared from cucumber cotyledons and transfected with viral-RNA. In meristematic tip cultures, quercetin reduced virus titre by up to 89% over a period of 36 weeks whereas ribavirin caused a 25% reduction over the same period. It is proposed that flavonoids interfere with an early event in the virus life cycle resulting in decreased infectivity and titre in tissue culture.

Research on the ethnobotany of Mestizos in Suni Miraño in 1994 documented 60 plant species used for medicinal purposes. Some cultural data on traditional healing and etiology were also collected. Of these 60 species, 31 were submitted to antibacterial and antifungal assays in the presence and absence of UV light and a number of species were shown to be active.

In a screening of plants used traditionally in Nepal to treat diseases that could be caused by viruses, twenty-one methanol extracts from twenty species were quantitatively assayed for activity against three mammalian viruses: herpes simplex virus, Sindbis virus and poliovirus. Assays were performed in ultraviolet (UV)-A or visible light, as well as dark, and cytotoxicity was also noted. Impressive antiviral activities were exhibited by species of Bauhinia (Fabaceae), Carissa (Apocynaceae), Milletia (Fabaceae), Mallotus (Fabaceae), Rumex (Polygonaceae), Streblus (Moraceae), Terminalia (Combretaceae) and Tridax (Asteraceae). The Carissa extract was the most active, showing activity against all three viruses at a concentration of 12 micrograms/ml. Many of the other extracts showed partial inactivation of one or more test viruses.

The antimicrobial properties of some traditional Carrier herbal preparations were evaluated using an agar dilution method. Pitch preparations were screened against known human pathogens: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus fumigatus. The results indicated definite antimicrobial activity in the pitch preparations of Picea glauca and Pinus contorta and provide a starting point for pharmacognostic evaluation of these species. In addition, cytoxicity assays, to test the anticancer activity of methanolic extracts of Alnus incana and Shepherdia canadensis against mouse mastocytoma cells, were shown to be positive.

The primary metabolic fate of phyenylalanine, following its deamination in plants, is conscription of its carbon skeleton for lignin, suberin, flavonoid, and related metabolite formation. Since this accounts for approximately 30-40% of all organic carbon, an effective means of recycling the liberated ammonium ion must be operative. In order to establish how this occurs, the uptake and metabolism of various 15N-labeled precursors (15N-Phe, 15NH4Cl, 15N-Gln, and 15N-Glu) in lignifying Pinus taeda cell cultures was investigated, using a combination of high performance liquid chromatography, 15N NMR, and gas chromatograph-mass spectrometry analyses. It was found that the ammonium ion released during active phenylpropanoid metabolism was not made available for general amino acid/protein synthesis. Rather it was rapidly recycled back to regenerate phenylalanine, thereby providing an effective means of maintaining active phenylpropanoid metabolism with no additional nitrogen requirement. These results strongly suggest that, in lignifying cells, ammonium ion reassimilation is tightly compartmentalized.

The antiviral activities of some naturally occurring anthraquinones, bianthrones, and hypericin derivatives were compared by the end-point CPE (viral cytopathic effects) method and plaque assays. Under optimal conditions of exposure to light, hypericin, 7,7'-dichlorohypericin and 5,7-dichloroemodin exhibited strong inhibitory activity against HSV-1 (herpes simplex virus type 1) in both assays. Partial inactivation of the virus was shown by emodin, 7-chloroemodin and 7-chloro-1-O-methylemodin; the bianthrones and other anthraquinones were found to be inactive. Antiviral activity appeared to be positively correlated with increasing substitution of chlorine in the anthraquinone structure. In the absence of light, only hypericin and 7,7'-dichlorohypericin displayed detectable activity.

An improved bioautographic agar overlay method was developed for the detection of antimicrobial compounds from crude plant extracts using phenol red and a tetrazolium compound as dyes to improve resolution. This method worked successfully with a wide variety of microorganisms including a number of Gram-positive and Gram-negative bacteria and fungi. Phenol red and the test organisms were incorporated directly into nutrient agar that was overlayed onto a thin layer chromatogram of plant extracts. In the case of bacteria, after spraying with thiazolyl blue (methylthiazolyltetrazolium chloride), dark red coloured inhibition zones appeared against blue background. Satisfactory results were obtained even with those compounds which were present in very small quantities. This method proved to be useful for activity-guided fractionation or for target-directed isolation of the active constituents of plants.

The discovery of porphyric insecticides was a direct fallout of the discovery and development of photodynamic herbicides. Tetrapyrrole-dependent photodynamic herbicides are compounds that force green plants to accumulate undesirable amounts of metabolic intermediates of the chlorophyll and heme metabolic pathways, namely, tetrapyrroles. In light, the accumulated tetrapyrroles photosensitize the formation of singlet oxygen that kills treated plants by oxidation of their cellular membranes. Demonstration of the potential for tetrapyrrole accumulation in insects was achieved by spraying T. ni larvae with δ-aminolevulinic acid (ALA) and 2,2-dipyridyl (Dpy). Treated larvae were placed overnight in darkness at 28°C in order to allow for tetrapyrrole accumulation. Extraction of treated, dark-incubated larvae with ammoniacal acetone, followed by spectrofluorometric examination of the larval extract, revealed the accumulation of massive amounts of protoporphyrin IX (Proto). A high degree of correlation wa...

The methanol extract of the bark of Alnus rubra showed antimicrobial activity against Gram-positive and Gram-negative bacteria. Diarylheptanoid and its glycoside (oregonin) were identified as the two constituents responsible for this activity.

The antimicrobial activity of the methanol extract and isolated constituents of Rhus glabra (Anacardiaceae), a species used in folk medicine by North American native people, was evaluated against 11 microorganisms, including gram-positive and gram-negative bacteria. The extract was subsequently fractionated and monitored by bioassays leading to the isolation of three antibacterial compounds, the methyl ester of 3,4,5-trihydroxybenzoic acid (methyl gallate) (minimal inhibition concentration (MIC) 12.5 micrograms/ml), 4-methoxy-3,5-dihydroxybenzoic acid (MIC 25 micrograms/ml) and gallic acid (MIC > 1000 micrograms/ml). The first two compounds are reported here for the first time from Rhus glabra. Their structures were established using spectroscopic and chemical methods.

Crude extracts of several Trichilia species (Meliaceae) were evaluated for their behavioral and physiological effects on the polyphagous lepidopterans Peridroma saucia and Spodoptera litura . A majority of extracts of nine Trichilia species, collected primarily from Costa Rica, significantly deter larval growth of P. saucia . Extracts of wood and bark are generally more active than those of foliage. Effects of various tissue extracts from T. connaroides on P. saucia and S. litura were comparatively studied. Extracts of bark, the most active tissue compared to those of wood, seed, exocarp and leaf, reduced larval growth of P. saucia and S. litura by 50% at dietary concentrations of 29.1 and 185.1 ppm, respectively. The limonoid hirtin, a constituent of Trichilia hirta , significantly inhibited larval growth of P. saucia in a dose-dependent manner, with a dietary EC 50 (effective concentration to inhibit growth by 50% relative to controls) of 13.0 ppm. Hirtin and various extracts from T. connaroides significantly reduced larval growth and consumption rates, as well as dietary utilization, indicating that these substances possess both behavioral effects and post-ingestive toxicity.

Crude foliar extracts of 19 species of Aglaia (Meliaceae), mostly of Indo-Malaysian origin, were screened for larval growth inhibiting and insecticidal effects on the polyphagous lepidopteran Peridroma saucia (Noctuidea). Extracts of at least seven of these species significantly reduce larval growth of P. saucia. Aglaia odorata yielded the most inhibitory extracts, but there is significant (35-fold) geographical variation in the bioactivity of extracts within this widespread species. In addition, extracts of bark are significantly more active than foliar extracts. Foliar extracts significantly deter neonate larvae, but nutritional analyses of fourth instar larvae fed artificial diets laced with A. odorata extracts indicate that both diet consumption and dietary utilizatin are impaired. These results are similar to that obtained with pure (−)-rocaglamide, an insecticidal principle isolated from A. odorata. This species should provide a useful starting point for the development of a botanical insecticide.

Proanthocyanidin (PA) polymers (condensed tannins) were extracted from sainfoin leaves at different stages of plant development. Analysis of the phloroglucinol degradation products by HPLC showed that catechin, epicatechin, gallocatechin, and epigallocatechin were present as terminal units at all stages, while gallocatechun and epigallocatechun were the predominant extension units with lesser amounts of epicatechin incorporated at early stages. Catechin was not incorporated as an extension unit. The number-average molecular weight and degree of polymerization increased with leaf development

A soluble proanthocyanidin polymer (PAP; condensed tannin) has been histologically localized in the pallisade layer of the alfalfa seedcoat, purified, and characterized by spectroscopic, chemical, and biochemical procedures. The polymer consists principally (91-93%) of 4 leads to 8 linked (-)-epicatechin units with a mean degree of polymerization of 5. (+)-Catechin is the predominant terminal unit. Only traces of prodelphinidin units were detected. No significant quantities of low molecular weight flavanols 3-could be detected in ethyl acetate fractions of seed extracts, but analysis of seed leachate indicated the presence of (+)-catechin, (-)-epicatechin, and higher molecular weight oligomeric flavanols. Time course studies indicated that PAPs were leached at rates similar to that of monomeric flavonoids. Comparison of binding of PAPs from alfalfa seed and sainfoin leaf with bovine serum albumin at pH 2.5 and 6 indicated no significant differences between the tannins; however, there was a significant pH effect at higher tannin concentrations with protein binding greater at pH 6.0 than at pH 2.5.

The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosagedependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered.

Summary UV-irradiation caused significant changes in the digestion of cell walls from dark-grown barley ( Hordeum vulgare cv. Conquest) coleoptiles by a partially purified xylanase from culture filtrates of Aspergillus niger grown on lignocellulose. Irradiation resulted in reduced rate and extent of solubilization of pentoses and changes in their neutral sugar composition and molecular weight distribution. GC-MS analysis of irradiated cell walls indicated the presence of significant quantities of the esterified cis -isomer of ferulic acid but no measurable quantities of the cyclobutane dimers of hydroxycinnamic acids.

In an ethnopharmacological screening of medicinal plants used in Yunnan province of China, ethanol extracts from 31 plant species were assayed for inhibition of murine cytomegalovirus and Sindbis virus infections. Parallel assays were carried out with and without exposure to UVA radiation to test for photo-mediation of activity. Antiviral activity was observed with 16 of the plant extracts. Eight plant extracts have been selected for further studies, with the objective of characterizing the antiviral constituents.

The polycyclic compound hypericin, a known photodynamic agent, was investigated for antiviral activity in the presence and absence of light. The three viruses tested: murine cytomegalovirus; Sindbis virus; and human immunodeficiency virus type 1, were all susceptible to hypericin; but these antiviral activities were considerably enhanced, in a dose-dependent manner, by exposure to light.

Hypericin, a photodynamic plant quinone, readily inactivated murine cytomegalovirus (MCMV), Sindbis virus, and human immunodeficiency virus type 1 (HIV-1), especially on exposure to fluorescent light. Sindbis virus was significantly more sensitive than MCMV. The inactivated MCMV, when used to infect cells, was incapable of synthesizing early or late viral antigens. In addition to this direct virucidal effect, when hypericin was added to cells infected with viable MCMV, inhibition was also observed, particularly when the compound was added in the first two hours of infection. Again the antiviral effect was augmented by visible light. At effective antiviral concentrations, there were no discernible adverse effects on cultured cells. Thus hypericin appears to have two modes of antiviral activity: one directed at the virions, possibly on membrane components (although other virion targets cannot be ruled out), and the other directed at virus-infected cells. Both activities are substantially enhanced by light. Other recent studies on the antiviral activities of hypericin have not considered the role of light, and it is conceivable that apparent discrepancies between their results may have reflected different conditions of light exposure.

GC-MS analyses of Agrobacterium signal compound mixtures from species belonging to a variety of flowering plant families revealed that the occurrence of virulence-inducing acetophenones may be restricted to members of the Solanaceae. Following wounding, species of Atropa, Datura, Hyoscyamus, Lycopersicon, Nicotiana, Scopolia and Solanum , produced a set of active C 6 C 2 compounds, whereas genera belonging to other families commonly produced sets of virulence-inducing C 6 C 1 and C 6 C 3 acids, esters and/or benzaldehydes. Prior to wounding there exists a small pool of acetophenone and C 6 C 1 acid glucosides in leaves of the Nicotiana species. After wounding, some of the acetophenones are generated by hydrolysis of the glucosides. Experiments with cycloheximide indicate that de novo biosynthesis also occurs. The enzyme systems required for the production of the acetophenones from phenylpropanoid precursors appear to be restricted in distribution amongst plant families.

The toxicity of the fungal phytotoxin dothistromin (l) to microorganisms, its lysis of human red blood corpuscles and beetroot tissue, and its unexpectedly selective inhibition of radicle elongation for Trigonella foenum-graecum were strongly light-dependent. Dothistromin was also toxic to Artemia salina but without requiring light activation. It was not active as a wilt or necrosis toxin, possible because of its ready adsorption onto external plant tissue.

Two host-plant-derived phenolic compounds (acetosyringone and α-hydroxyacetosyringone), which act as chemical signals for wide host range strains of Agrobacterium tumefaciens , have remained the only virulence ( vir ) gene inducing compounds identified from host plant tissues. Here we report the isolation of a vir -inducing phenolic compound from a number of Vitis cultivars, including a known host for limited host range A. tumefaciens , and its identification as syringic acid methyl ester (3,5-dimethoxy-4-hydroxybenzoic acid methyl ester). The presence of this compound in wound exudates does not provide a simple explanation for host range limitation of grapevine strains as it induces vir gene expression in both limited and wide host range strains of Agrobacterium .

The antibacterial activity of methanol extracts of ten moss species and fractions prepared from 80% methanol extract of Hylocomium splendens were evaluated by disk diffusion method. Nine moss species showed antibacterial activity against Gram (+) bacteria, in particular H. splendens and its ethyl acetate fractions showed stronger activity. Enhancement of antibacterial activity against Staphylococci by UV-A light irradiation was demonstrated in the extracts of Bartramia pomiformis, Ceratodon purpureus and Neckera douglasii.

Hypocrellin, a photodynamic perylene quinonoid isolated from the Chinese medicinal fungus Hypocrella bambuase, was evaluated for antiviral activity against the human immunodeficiency virus (HIV-1). Hypocrellin was phototoxic to HIV-1, almost as good as the structurally similar plant pigment hypericin, and like hypericin its activity required visible light. In contrast peroxyhypocrellin had little or no effect on the virus.

Bioactivity-directed fractionation of a root extract ofDuroia hirsuta (Rubiaceae), a toxic and potentially allelopathic understory tree from the western Amazon, has led to the isolation of the tetracyclic iridoid lactone, plumericin (1). Bioassays showing plumericin strongly inhibited lettuce radicle elongation at a concentration (IC50) of 35.8 μm/ml (123 μM). The isolation of a highly potent inhibitor of plant growth fromDuroia hirsuta supports the hypothesis that the lack of vegetation surrounding this tree is the result of allelopathy.

Activity-guided fractionation of the 95% ethanol extract from the stem bark of Iryanthera megistophylla led to the isolation of two new compounds, named megislignan [2,3-dimethyl-4-(4-methoxyphenyl)-6-hydroxynaphthalene] (1) and megislactone [(2R,3R,4R)-3-hydroxy-4-methyl-2-(hexacos-17-enyl)butanolide] (2), along with seven known compounds, grandinolide (3), iryantherin K (4), iryantherin L (5), cinchonain I b (6), cinchonain I a (7), procyanidin B-2 (8), and cinchonain IIa (9). The structures of the new compounds were elucidated by spectral data interpretation. Isolates were evaluated for their antibacterial, antifungal, antiviral, and antiacetylcholinesterase activities.

In the first step of the phenylpropanoid metabolic pathway, L-phenylalanine (L-Phe) is deaminated to form E-cinnamate, in a conversion catalyzed by phenylalanine ammonia-lyase (PAL; EC 4.3.1.5). The metabolic fate of the ammonium ion (NH4+) produced in this reaction was investigated in sweet potato (Ipomoea batatas) tuber discs. [15N]-Labeled substrates including L-Phe, in the presence or absence of specific enzyme inhibitors, were administered to sweet potato discs in light under aseptic conditions. 15N-Nuclear magnetic resonance spectroscopic analyses revealed that the 15NH4+ liberated during the PAL reaction is first incorporated into the amide nitrogen of L-glutamine (L-Gln) and then into L-glutamate (L-Glu). These results extend our previous observations in pine and potato that PAL-generated NH4+ is assimilated by the glutamine synthetase (GS; EC 6.3.1.2)/glutamate synthase (GOGAT; EC 1.4.1.13) pathway, with the NH4+ so formed ultimately being recycled back to L-Phe via L-Glu as aminoreceptor and donor.

Wood and bark extracts of 14 eastern North American hardwood tree species which were used traditionally as medicine by First Nation's people were screened for antimicrobial activities with eight strains of bacteria and six strains of fungi. Eighty-six percent of the bark extracts were active against methicillin sensitive Staphylococcus aureus; 71% against Bacillus subtilus and 79% against Mycobacterium phlei. The bark extract of Juglans cinerea was active against Pseudomonas aeruginosa 187, Salmonella typhiumurium, and Klebsiella pneumoniae. The wood extracts were less active: 72% were active against S. aureus (methicillin-sensitive), 36% against B. subtilus and 43% against M. phlei. Results from antifungal tests indicated that 36% of the extracts were active against at least one fungal strain and that bark extracts were more active than wood extracts. The bark extract from Juglans cinerea had the broadest spectrum of activities against Candida albicans, Saccharomyces cerevisiae, Cryptococcus neoformans, Trichophyton mentagrophytes, Microsporum gypseum, and Aspergillus fumigatus. In general, the extracts were more active against gram positive bacteria than gram negative bacteria and against filamentous fungi than yeast-like fungi. The study also demonstrated a correlation between frequency of traditional medicinal use by the First Nations people and antimicrobial activity of extracts indicating that the traditional knowledge encompasses an understanding of aspects of chemical ecology.

The structure of a piscicidal triterpenoid saponin (saponin A) isolated from the leaves of Maesa ramentacea has been shown to be 3-O-{[(α- l -rhamnopyranosyl(1 → 2)-α- l -rhamnopyranosyl(1 → 2)-β- d -galactopyranosyl(1 → 3)]-[β- d - glucopyranosyl(1 → 2)]-β- d -glucuronopyranosyl}barringtogenol C21, 22- O -diangeloate. Extensive use was made of homo- and heteronuclear 2D NMR techniques.

In a screening of plants used traditionally in Nepal to treat diseases that could be caused by viruses, methanol extracts from 21 species were assayed for activity against three mammalian viruses: herpes simplex virus, Sindbis virus and poliovirus. Assays were performed in UV-A or visible light, as well as dark. Individual species of Hypericum, Lygodium, and Maesa exhibited impressive antiviral activities, although their selective effects on the three viruses suggested that the antiviral ingredients were different in each extract. In addition, many of the other extracts showed partial inactivation of one or more test viruses.

The Carrier, an Athapaskan-speaking people of northcentral British Columbia, occupy the sub-boreal spruce forests of the central interior. This report, which is based on field study, documents some traditional and contemporary knowledge of the medicinal use of plants by the Carrier people. Important medicinal plants include: Abies lasiocarpa, Alnus incana, Arctostaphylos uva-ursi, Artemisia frigida, Fragaria virginiana, Juniperus communis, Picea glauca, Pinus contorta, Populus tremuloides, Rubus idaeus and Shepherdia canadensis.

Balsamorhiza sagittata, a species of ethnopharmacological interest in British Columbia, is reported to have antibacterial and antifungal properties. An antibacterial compound isolated from this species was identified as 7,10-epithio-7,9-tridecadiene-3,5,11-triyne-1,2-diol based on the HMQC and HMBC experiments.

A study of the antimicrobial compounds from Moneses uniflora resulted in the isolation of a novel compound, 8-chloro-2,7-dimethyl-1,4-naphthoquinone (8-chlorochimaphilin) (1), together with chimaphilin (2) and 3-hydroxychimaphilin (3) as the antimicrobial components. 2,7-Dimethyl-1,3-dihydroxynaphthyl 4-O-alpha-L-rhamnopyranoside (4) and 2,7-dimethoxy-1,4,8-trihydroxynaphthalene (6) were also isolated and identified.