Bioactive metabolites from the fungus Nectria galligena, the main apple canker agent in Chile

Ilicicolin C suppresses the progression of prostate cancer by inhibiting PI3K/AKT/mTOR pathway

Aberrant activation of the PI3K/AKT pathway is a driving factor in the development of prostate cancer. Therefore, inhibiting the function of the PI3K/AKT signaling pathway is a strategy for the treatment of prostate cancer. Ilicicolin C is an ascochlorin derivative isolated from the coral-derived fungus Acremonium sclerotigenum GXIMD 02501. Which has anti-inflammatory activity, but its activity against prostate cancer has not yet been elucidated. MTT assay, plate clone-formation assay, flow cytometry and real-time cell analysis technology were used to detect the effects of ilicicolin C on cell viability, proliferation, apoptosis and migration of prostate cancer cells. Molecular docking software and surface plasmon resonance technology were used to analyze the interaction between ilicicolin C and PI3K/AKT proteins. Western blot assay was performed to examine the changes in protein expression. Finally, QikProp software was used to simulate the process of ilicicolin C in vivo, and a zebrafish xenograft model was used to further verify the anti-prostate cancer activity of ilicicolin C in vivo. Ilicicolin C showed cytotoxic effects on prostate cancer cells, with the most significant effect on PC-3 cells. Ilicicolin C inhibited proliferation and migration of PC-3 cells. It could also block the cell cycle and induce apoptosis in PC-3 cells. In addition, ilicicolin C could bind to PI3K/AKT proteins. Furthermore, ilicicolin C inhibited the expression of PI3K, AKT and mTOR proteins and could also regulate the expression of downstream proteins in the PI3K/AKT/mTOR signaling pathway. Moreover, the calculations speculated that ilicicolin C was well absorbed orally, and the zebrafish xenograft model confirmed the in vivo anti-prostate cancer effect of ilicicolin C. Ilicicolin C emerges as a promising marine compound capable of inducing apoptosis of prostate cancer cells by counteracting the aberrant activation of PI3K/AKT/mTOR, suggesting that ilicicolin C may be a viable candidate for anti-prostate cancer drug development. These findings highlight the potential of ilicicolin C against prostate cancer and shed light on its mechanism of action.

The Discovery of Acremochlorins O-R from an Acremonium sp. through Integrated Genomic and Molecular Networking

The fermentation of a soil-derived fungus Acremonium sp. led to the isolation of thirteen ascochlorin congeners through integrated genomic and Global Natural Product Social (GNPS) molecular networking. Among the isolated compounds, we identified two unusual bicyclic types, acremochlorins O (1) and P (2), as well as two linear types, acremochlorin Q (3) and R (4). Compounds 1 and 2 contain an unusual benzopyran moiety and are diastereoisomers of each other, the first reported for the ascochlorins. Additionally, we elucidated the structure of 5, a 4-chloro-5-methylbenzene-1,3-diol with a linear farnesyl side chain, and confirmed the presence of eight known ascochlorin analogs (6-13). The structures were determined by the detailed interpretation of 1D and 2D NMR spectroscopy, MS, and ECD calculations. Compounds 3 and 9 showed potent antibacterial activity against Staphylococcus aureus and Bacillus cereus, with MIC values ranging from 2 to 16 μg/mL.

Filamentous Fungi-Derived Orsellinic Acid-Sesquiterpene Meroterpenoids: Fungal Sources, Chemical Structures, Bioactivities, and Biosynthesis

Fungi-derived polyketide-terpenoid hybrids are important meroterpenoid natural products that possess diverse structure scaffolds with a broad spectrum of bioactivities. Herein, we focus on an ever-increasing group of meroterpenoids, orsellinic acid-sesquiterpene hybrids comprised of biosynthetic start unit orsellinic acid coupling to a farnesyl group or/and its modified cyclic products. The review entails the search of China National Knowledge Infrastructure (CNKI), Web of Science, Science Direct, Google Scholar, and PubMed databases up to June 2022. The key terms include "orsellinic acid", "sesquiterpene", "ascochlorin", "ascofuranone", and "Ascochyta viciae", which are combined with the structures of "ascochlorin" and "ascofuranone" drawn by the Reaxys and Scifinder databases. In our search, these orsellinic acid-sesquiterpene hybrids are mainly produced by filamentous fungi. Ascochlorin was the first compound reported in 1968 and isolated from filamentous fungus Ascochyta viciae (synonym: Acremonium egyptiacum; Acremonium sclerotigenum); to date, 71 molecules are discovered from various filamentous fungi inhabiting in a variety of ecological niches. As typical representatives of the hybrid molecules, the biosynthetic pathway of ascofuranone and ascochlorin are discussed. The group of meroterpenoid hybrids exhibits a broad arrange of bioactivities, as highlighted by targeting hDHODH (human dihydroorotate dehydrogenase) inhibition, antitrypanosomal, and antimicrobial activities. This review summarizes the findings related to the structures, fungal sources, bioactivities, and their biosynthesis from 1968 to June 2022.

Effects of Phytotoxic Nonenolides, Stagonolide A and Herbarumin I, on Physiological and Biochemical Processes in Leaves and Roots of Sensitive Plants

Phytotoxic macrolides attract attention as prototypes of new herbicides. However, their mechanisms of action (MOA) on plants have not yet been elucidated. This study addresses the effects of two ten-membered lactones, stagonolide A (STA) and herbarumin I (HBI) produced by the fungus Stagonospora cirsii, on Cirsium arvense, Arabidopsis thaliana and Allium cepa. Bioassay of STA and HBI on punctured leaf discs of C. arvense and A. thaliana was conducted at a concentration of 2 mg/mL to evaluate phenotypic responses, the content of pigments, electrolyte leakage from leaf discs, the level of reactive oxygen species, Hill reaction rate, and the relative rise in chlorophyll a fluorescence. The toxin treatments resulted in necrotic and bleached leaf lesions in the dark and in the light, respectively. In the light, HBI treatment caused the drop of carotenoids content in leaves on both plants. The electrolyte leakage caused by HBI was light-dependent, in contrast with that caused by STA. Both compounds induced light-independent peroxide generation in leaf cells but did not affect photosynthesis 6 h after treatment. STA (10 µg/mL) caused strong disorders in root cells of A. thaliana leading to the complete dissipation of the mitochondrial membrane potential one hour post treatment, as well as DNA fragmentation and disappearance of acidic vesicles in the division zone after 8 h; the effects of HBI (50 µg/mL) were much milder. Furthermore, STA was found to inhibit mitosis but did not affect the cytoskeleton in cells of root tips of A. cepa and C. arvense, respectively. Finally, STA was supposed to inhibit the intracellular vesicular traffic from the endoplasmic reticulum to the Golgi apparatus, thus interfering with mitosis. HBI is likely to have another main MOA, probably inhibiting the biosynthesis of carotenoids.

Untargeted metabolomics screening reveals unique secondary metabolite production from Alternaria section Alternaria

Alternaria section Alternaria is comprised of many species that infect a broad diversity of important crop plants and cause post-harvest spoilage. Alternaria section Alternaria species, such as A. alternata and A. arborescens, are prolific producers of secondary metabolites that act as virulence factors of disease and are mycotoxins that accumulate in infected tissues-metabolites that can vary in their spectrum of production between individuals from the same fungal species. Untargeted metabolomics profiling of secondary metabolite production using mass spectrometry is an effective means to detect phenotypic anomalies in secondary metabolism within a species. Secondary metabolite phenotypes from 36 Alternaria section Alternaria isolates were constructed to observe frequency of production patterns. A clear and unique mass feature pattern was observed for three of the strains that were linked with the production of the dehydrocurvularin family of toxins and associated detoxification products. Examination of corresponding genomes revealed the presence of the dehydrocurvularin biosynthesis gene cluster associated with a sub-telomeric accessory region. A comparison of sequence similarity and occurrences of the dehydrocurvularin biosynthetic gene cluster within Pleosporalean fungi is presented and discussed.

Terpenoids and Meroterpenoids from Cultures of Two Grass-Associated Species of Amylosporus (Basidiomycota)

An investigation of the chemical components of the fermentation extract of two cultures of Amylosporus cf. graminicola and Amylosporus cf. campbelii from Cuba and Zimbabwe, respectively, led to the isolation of seven previously undescribed secondary metabolites for which we proposed the trivial names amylosporanes A-G (1-7) along with the known compounds orsellinic acid (11), colletorin D acid (12), colletorin B (13), colletochlorin B (14), and the β-lactam cyclo-(S-Pro-R-Leu) (15). Three additional compounds (8-10) previously unknown from a fungal source were also characterized for the first time, and two of them were assigned the trivial names amylosporanes H-I (8-9) while the other was identified as cannabigerorcinic acid (10). The structures of the isolated compounds were determined based on their high-resolution electrospray ionization mass spectrometry (HR-ESIMS) spectra and an extensive analysis of their 1D and 2D NMR spectroscopic data. Based on literature searches, we hypothesized that a majority of the isolated metabolites have orsellinic acid (11) as a biosynthetic precursor following a combined route of mevalonate-associated and orsellinic acid-associated pathways. Colletochlorin B (14), the only compound possessing chlorine in its structure, exhibited significant activity against Bacillus subtilis (minimum inhibitory concentration, 2 μg/mL), stronger than that of oxytetracycline, and significant cytotoxicity against A431 cells with an IC₅₀ value of 4.6 μM.

Variations in the Community Structure of Fungal Microbiota Associated with Apple Fruit Shaped by Fruit Bagging-Based Practice

The various fungal communities that adhere to apple fruit are influenced by agricultural practices. However, the effects of fruit bagging-based management practice on the fungal microbiota are still unknown, and little is known about the fungal communities of bagged apple fruit. We conducted a study using apple fruit grown in a conventionally managed orchard where pesticide use is an indispensable practice. Fungal communities were collected from the calyx-end and peel tissues of bagged and unbagged fruit and characterized using barcode-type next-generation sequencing. Fruit bagging had a stronger effect on fungal richness, abundance, and diversity of the fungal microbiota in comparison to non-bagging. In addition, bagging also impacted the compositional variation of the fungal communities inhabiting each fruit part. We observed that fruit bagging had a tendency to maintain ecological equilibrium since Ascomycota and Basidiomycota were more distributed in bagged fruit than in unbagged fruit. These fungal communities consist of beneficial fungi rather than potentially harmful fungi. Approximately 50 dominant taxa were detected in bagged fruit, for example, beneficial genera such as Articulospora, Bullera, Cryptococcus, Dioszegia, Erythrobasidium, and Sporobolomyces, as well as pathogenic genera such as Aureobasidium and Taphrina. These results suggested that fruit bagging could significantly increase fungal richness and promote healthy fungal communities, especially the harmless fungal communities, which might be helpful for protecting fruit from the effects of pathogens. This study provides a foundation for understanding the impacts of bagging-based practice on the associated fungal microbiota.

Review of 10,11-Dehydrocurvularin: Synthesis, Structural Diversity, Bioactivities and Mechanisms

10,11-Dehydrocurvularin is a natural benzenediol lactone (BDL) with a 12-membered macrolide fused to resorcinol ring produced as secondary metabolite by many fungi. In this review, we summarized literatures regarding the biosynthesis, chemical synthesis, biological activities and assumed work mechanisms of 10,11-dehydrocurvularin, which presented potential for agricultural and pharmaceutical uses.

Phytotoxic Secondary Metabolites from Fungi

Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit a high level of diversity in their properties, such as structures, phytotoxic activities, and modes of toxicity. They are mainly isolated from phytopathogenic fungal species in the genera of Alternaria, Botrytis, Colletotrichum, Fusarium, Helminthosporium, and Phoma. Phytotoxins are either host specific or non-host specific phytotoxins. Up to now, at least 545 fungal phytotoxic secondary metabolites, including 207 polyketides, 46 phenols and phenolic acids, 135 terpenoids, 146 nitrogen-containing metabolites, and 11 others, have been reported. Among them, aromatic polyketides and sesquiterpenoids are the main phytotoxic compounds. This review summarizes their chemical structures, sources, and phytotoxic activities. We also discuss their phytotoxic mechanisms and structure-activity relationships to lay the foundation for the future development and application of these promising metabolites as herbicides.

Bioactive Ascochlorin Analogues from the Marine-Derived Fungus Stilbella fimetaria

The marine-derived fungus Stilbella fimetaria is a chemically talented fungus producing several classes of bioactive metabolites, including meroterpenoids of the ascochlorin family. The targeted dereplication of fungal extracts by UHPLC-DAD-QTOF-MS revealed the presence of several new along with multiple known ascochlorin analogues (19–22). Their structures and relative configuration were characterized by 1D and 2D NMR. Further targeted dereplication based on a novel 1,4-benzoquinone sesquiterpene derivative, fimetarin A (22), resulted in the identification of three additional fimetarin analogues, fimetarins B–D (23–25), with their tentative structures proposed from detailed MS/HRMS analysis. In total, four new and eight known ascochlorin/fimetarin analogues were tested for their antimicrobial activity, identifying the analogues with a 5-chloroorcylaldehyde moiety to be more active than the benzoquinone analogue. Additionally, the presence of two conjugated double bonds at C-2′/C-3′ and C-4′/C-5′ were found to be essential for the observed antifungal activity, whereas the single, untailored bonds at C-4′/C-5′ and C-8′/C-9′ were suggested to be necessary for the observed antibacterial activity.

Metabolites from Clonostachys Fungi and Their Biological Activities

Clonostachys (teleomorph: Bionectria) fungi are well known to produce a variety of secondary metabolites with various biological activities to show their pharmaceutical and agrochemical applications. Up to now, at least 229 secondary metabolites, mainly including 84 nitrogen-containing metabolites, 85 polyketides, 40 terpenoids, and 20 other metabolites, have been reported. Many of these compounds exhibit biological activities, such as cytotoxic, antimicrobial, antileishmanial, antimalarial activities. This mini-review aims to summarize the diversity of the secondary metabolites as well as their occurrences in Clonostachys fungi and biological activities.

Fungal benzene carbaldehydes: occurrence, structural diversity, activities and biosynthesis

Covering: up to April 2020Fungal benzene carbaldehydes with salicylaldehydes as predominant representatives carry usually hydroxyl groups, prenyl moieties and alkyl side chains. They are found in both basidiomycetes and ascomycetes as key intermediates or end products of various biosynthetic pathways and exhibit diverse biological and pharmacological activities. The skeletons of the benzene carbaldehydes are usually derived from polyketide pathways catalysed by iterative fungal polyketide synthases. The aldehyde groups are formed by direct PKS releasing, reduction of benzoic acids or oxidation of benzyl alcohols.

Bioactive metabolites from the Arctic fungus Nectria sp. B-13

Two new cyclohexanone derivatives, nectriatones A-B (1-2), and one new natural product, nectriatone C (3), together with three known phenolic sesquiterpene derivatives (4-6), were isolated from the culture of Nectria sp. B-13 obtained from high-latitude soil of the Arctic. The structures of all compounds were unambiguously elucidated by extensive spectroscopic analysis, as well as by comparison with the literature. These compounds were evaluated in cytotoxic and antibacterial activities. Compounds 1-6 showed cytotoxicities against SW1990, HCT-116, MCF-7, and K562 cells, with IC₅₀ values in the range of 0.43 to 42.64 μM. Only compound 4 exhibited antibacterial activity against Escherichisa coli, Bacillus subtilis, and Staphylococcus aureus (MIC 4.0, 2.0, and 4.0 μg/ml, respectively).

Synthesis of Pyrazolo-Fused 4-Azafluorenones in an Ionic Liquid. Mechanistic Insights by Joint Studies Using DFT Analysis and Mass Spectrometry

A series of pyrazolo-fused 4-azafluorenones (indeno[1,2-b]pyrazolo[4,3-e]pyridines, IPP) were synthesized via the three-component reaction between arylaldehydes, 3-methyl-1H-pyrazol-5-amine and 1,3-indanedione in an ionic liquid as a catalyst at room temperature. The applied synthetic route has the advantages of easy work-up under mild reaction conditions presenting moderate yields and an environmentally benign procedure. A theoretical study based on conceptual-density functional theory has been done, bond reactivity indices have been calculated and an electrophilic and nucleophilic character of localized orbitals has been determined to analyze the possible electronic mechanisms.

Deleting a Chromatin Remodeling Gene Increases the Diversity of Secondary Metabolites Produced by Colletotrichum higginsianum

Colletotrichum higginsianum is the causal agent of crucifer anthracnose disease, responsible for important economic losses in Brassica crops. A mutant lacking the CclA subunit of the COMPASS complex was expected to undergo chromatin decondensation and the activation of cryptic secondary metabolite biosynthetic gene clusters. Liquid-state fermentation of the Δ cclA mutant coupled with in situ solid-phase extraction led to the production of three families of compounds, namely, colletorin and colletochlorin derivatives with two new representatives, colletorin D (1) and colletorin D acid (2), the diterpenoid α-pyrone higginsianin family with two new analogues, higginsianin C (3) and 13- epi-higginsianin C (4), and sclerosporide (5) coupling a sclerosporin moiety with dimethoxy inositol.

Ilicicolinic acids and ilicicolinal derivatives from the fungus Neonectria discophora SNB-CN63 isolated from the nest of the termite Nasutitermes corniger found in French Guiana show antimicrobial activity

The fungus Neonectria discophora SNB-CN63 has been isolated from the nest of the termite Nasutitermes corniger found in French Guiana. From the ethyl acetate extract of fungal culture, bioassay guided fractionation led to the isolation of fourteen ilicicolinic acids and ilicicolinal derivatives. Their structures were elucidated by analyses of 1D and 2D NMR and MS spectroscopic data. All metabolites were tested against several microbial pathogens and six displayed antimicrobial activities with MIC <16 μg/mL on T. rubrum, Staphylococcus aureus and methicillin-resistant S. aureus. Based on their structural similarities, a common biosynthetic pathway is proposed for all isolated metabolites.

Differentiated surface fungal communities at point of harvest on apple fruits from rural and peri-urban orchards

The diverse fungal communities that colonize fruit surfaces are closely associated with fruit development, preservation and quality control. However, the overall fungi adhering to the fruit surface and the inference of environmental factors are still unknown. Here, we characterized the fungal signatures on apple surfaces by sequencing internal transcribed spacer 1 (ITS1) region. We collected the surface fungal communities from apple fruits cultivated in rural and peri-urban orchards. A total of 111 fungal genera belonging to 4 phyla were identified, showing remarkable fungal diversity on the apple surface. Comparative analysis of rural samples harboured higher fungal diversity than those from peri-urban orchards. In addition, fungal composition varied significantly across apple samples. At the genus level, the protective genera Coniothyrium, Paraphaeosphaeria and Periconia were enriched in rural samples. The pathogenic genera Acremonium, Aspergillus, Penicillium and Tilletiposis were enriched in peri-urban samples. Our findings indicate that rural samples maintained more diverse fungal communities on apple surfaces, whereas peri-urban-planted apple carried potential pathogenic risks. This study sheds light on ways to improve fruit cultivation and disease prevention practices.

Chlorinated Dehydrocurvularins and Alterperylenepoxide A from Alternaria sp. AST0039, a Fungal Endophyte of Astragalus lentiginosus

Investigation of Alternaria sp. AST0039, an endophytic fungus obtained from the leaf tissue of Astragalus lentiginosus, led to the isolation of (-)-(10E,15S)-4,6-dichloro-10(11)-dehydrocurvularin (1), (-)-(10E,15S)-6-chloro-10(11)-dehydrocurvularin (2), (-)-(10E,15S)-10(11)-dehydrocurvularin (3), and alterperylenepoxide A (4) together with scytalone and α-acetylorcinol. Structures of 1 and 4 were established from their spectroscopic data, and the relative configuration of 4 was determined with the help of nuclear Overhauser effect difference data. All metabolites were evaluated for their cytotoxic activity and ability to induce heat-shock and unfolded protein responses. Compounds 2 and 3 exhibited cytotoxicity to all five cancer cell lines tested and increased the level of the pro-apoptotic transcription factor CHOP, but only 3 induced the heat-shock response and caused a strong unfolded protein response.

Total Synthesis of Grifolin, Grifolic Acid, LL-Z1272α, LL-Z1272β, and Ilicicolinic Acid A

A novel synthetic approach for the synthesis of bioactive phenolic natural products is reported. This strategy highlights the power of halogenative aromatization reactions recently developed in our group for preparing densely functionalized arenes in a controlled fashion. Five natural products related by an aromatic core and a farnesyl side chain are synthesized. In contrast to prior methods, this synthesis features high efficiency and generality that permits preparation of targets in gram-scale quantities.

Polyketides from the Mangrove-Derived Endophytic Fungus Nectria sp. HN001 and Their α-Glucosidase Inhibitory Activity

Four new polyketides: nectriacids A-C (1-3) and 12-epicitreoisocoumarinol (4), together with three known compounds: citreoisocoumarinol (5), citreoisocoumarin (6), and macrocarpon C (7) were isolated from the culture of the endophytic fungus Nectria sp. HN001, which was isolated from a fresh branch of the mangrove plant Sonneratia ovata collected from the South China Sea. Their structures were determined by the detailed analysis of NMR and mass spectroscopic data. The absolute configuration of the stereogenic carbons for compound 4 was further assigned by Mosher's ester method. All of the isolated compounds were tested for their α-glucosidase inhibitory activity by UV absorbance at 405 nm, and new compounds 2 and 3 exhibited potent inhibitory activity with IC50 values of 23.5 and 42.3 μM, respectively, which were more potent than positive control (acarbose, IC50, 815.3 μM).

Recent progress regarding the bioactivities, biosynthesis and synthesis of naturally occurring resorcinolic macrolides

Macrolides, which comprise a family of lactones with different ring sizes, belong to the polyketide class of natural products. Resorcinolic macrolides, an important subgroup, possess interesting structures and exhibit a wide variety of bioactivities, such as anti-tumor, anti-bacteria, and anti-malaria activities, etc. This review summarizes progress in isolation, bioactivity studies, biosynthesis, and representative chemical syntheses of this group of macrolides in recent decades, encompassing 63 naturally occurring macrolides published in 120 articles.

New Diterpenes from Azorella spinosa

Two new diterpenes,2-acetoxy-13-hydroxy-mulin-11-ene and 2-acetoxy-mulin-11, 13-diene, have been isolated from the aerial parts of Azorella spinosa and their structures determined by spectroscopic and conventional chemical methods. Furthermore, 2, 13-dihydroxy-mulin-11-ene was obtained using a basic hydrolysis of the first compound. Two diterpenes reported for other Azorella species have also been found, namely mulinolic acid and 13β-hydroxyazorellane, as well as the triterpene lactone of ursolic acid, quercetin, and 7-hydroxycoumarin. The compounds were evaluated using antibacterial, antioxidant and enzymatic assays; no significant activity was detected.

Isoxazoles: synthesis, evaluation and bioinformatic design as acetylcholinesterase inhibitors

OBJECTIVES

Inhibition of acetylcholinesterase (AChE) is a common treatment for early stages of Alzheimer's disease. In this study, nine isoxazoles derivatives were tested for their in-vitro AChE activity. The molecular docking showed the interaction of the compounds with the active site.

METHODS

The isoxazoles were synthesized using 1,3-dipolar cycloaddition in the presence of sodium hypochlorite. They were also isolated and characterized by spectroscopic methods. The in-vitro activity was measured by an adapted version of Ellman's assay.

KEY FINDINGS

The isoxazoles are described as inhibitors of AChE. The most potent compound in the series exhibited a moderate inhibitory activity (50% inhibitory concentration = 134.87 μm). The design of new compounds was created by using the RACHEL module of the SYBYL software.

CONCLUSIONS

Our research provided enough evidence of the efficacy of isoxazoles as AChE inhibitors. The isoxazoles were synthesized and evaluated as inhibitors of AChE. The docking study based on a novel series of complexes isoxazole with AChE from Electroporus electricus has demonstrated that the ligand bind is similar to the compounds used as reference. To find new candidates with the isoxazole core that act as inhibitors of AChE, part of the structure of the compound 9 was used for de-novo design. Molecular docking models of the ligand-AChE complexes suggest that the compound 10 is located on the periphery of the AChE active site.

Metabolite profiling and biological activities of bioactive compounds produced by Chrysosporium lobatum strain BK-3 isolated from Kaziranga National Park, Assam, India

In an ongoing survey for bioactive potential of microorganisms from different biosphere zones of India, a new Chrysosporium lobatum strain BK-3 was isolated from soil sample collected from a biodiversity hotspot, Kaziranga National Park, Assam, India. Bioactivity-guided purification resulted in the isolation of two bioactive compounds whose chemical structures were elucidated by ¹H and ¹³C Nuclear Magnetic Resonance (NMR), 2D-NMR, Fourier Transform Infra-red (FT-IR) and mass spectroscopic techniques, and were identified as α, β-dehydrocurvularin and curvularin. Only curvularin exhibited 80% acetylcholinesterase (AChE) inhibitory activity. Detailed ligand receptor binding interactions were studied for curvularin by molecular docking studies. Further, both curvularin and α, β-dehydrocurvularin had similar level of cytotoxicity against different human tumour cell lines like A549, HeLa, MDA-MB-231 and MCF-7, while α, β-dehydrocurvularin was active against COLO 205 with a IC₅₀ of 7.9 μM, but curvularin was inactive. α, β-Dehydrocurvularin also showed good superoxide anion scavenging activity with an EC₅₀ value of 16.71 μg ml^-1. Hence, both these compounds exhibited differences in bioactive profiles and this was probably associated with their minor structural differences. This is a first report on bioactive compounds exhibiting AChE inhibitory, cytotoxicity and antioxidant activities from Chrysosporium lobatum strain BK-3.

Biological Activity of Isoflavonoids from Azorella madreporica

Four isoflavones, isolated from the whole plant of Azorella madreporica, were identified as angustone C (1), alpinumisoflavone (2), licoisoflavone A (3) and isolupalbigenin (4) by spectroscopic studies. The compounds were evaluated for antibacterial and gastroprotective activities. This is the first time that isoflavonoids have been reported in this genus.

Phomentrioloxin: A phytotoxic pentasubstituted geranylcyclohexentriol produced by Phomopsis sp., a potential mycoherbicide for Carthamus lanatus Biocontrol

A new phytotoxic geranylcyclohexenetriol, named phomentrioloxin, was isolated from the liquid culture of Phomopsis sp., a fungal pathogen proposed for the biological control of Carthamus lanatus, a widespread and troublesome thistle weed belonging to the Asteraceae family causing severe crop and pastures losses in Australia. The structure of phomentrioloxin was established by spectroscopic, X-ray, and chemical methods as (1S,2S,3S,4S)-3-methoxy-6-(7-methyl-3-methylene-oct-6-en-1-ynyl)cyclohex-5-ene-1,2,4-triol. At a concentration of 6.85 mM, the toxin causes the appearance of necrotic spots when applied to leaves of both host and nonhost plants. It also causes growth and chlorophyll content reduction of fronds of Lemna minor and inhibition of tomato rootlet elongation. Finally, in preliminary bioassays, phomentrioloxin did not show any antibacterial, fungicidal, or zootoxic activities.

Chemical and Functional Diversity of Natural Products from Plant Associated Endophytic Fungi

This review describes examples of naturally occurring bioactive compounds obtained from fungal endophytes from various host plants. The main topics addressed are sources, identification, biological activity, biosynthesis, and ecological and chemosystematic significance of those bioactive compounds whose sources were well defined.

Cylindrocyclin A, a new cytotoxic cyclopeptide from Cylindrocarpon sp

In the course of a screening of fungal extracts for new metabolites with cytotoxic activities cylindrocyclin A (1) was isolated. The producing strain was identified as Cylindrocarpon sp. by microscopy and ITS rDNA sequence analysis. 1 is a novel compound that exhibits cytotoxic acticity against six different cell lines with IC50 values ranging from 11 to 53 microM. 1 has no antibacterial or antifungal activity. The compound is a cyclic nonapeptide comprising three alanines, five leucines and one isoleucine. Four amino acids are N-methylated. Its structure was elucidated by spectroscopic methods.

Natural products from plant-associated microorganisms: distribution, structural diversity, bioactivity, and implications of their occurrence

A growing body of evidence suggests that plant-associated microorganisms, especially endophytic and rhizosphere bacteria and fungi, represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological relevance. A diverse array of bioactive small molecule natural products has been encountered in these microorganisms. The structures of over 230 metabolites isolated and characterized from over 70 plant-associated microbial strains during the past four years are presented with information on their hosts, culture conditions, and biological activities. Some significant biological and ecological implications of their occurrence are also reviewed.

Natural sesquiterpenoids

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. The literature from January to December 2005 is reviewed,and 386 references are cited.

Acetylcholinesterase inhibitors from plants and fungi

This review describes 183 compounds obtained from plants and fungi which have been shown to inhibit acetylcholinesterase. The mechanism of action of cholinesterase, together with the binding sites, and, where this is known, the mode of action of inhibitors is described. The relative activities of the different compounds are recorded. The strongest inhibitors are generally alkaloids although some meroterpenoids from fungi have also been found to be active and display better selectivity.