Novel spirocyclic trichothecanes, spirotenuipesine A and B, isolated from entomopathogenic fungus, Paecilomyces tenuipes

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Pathogenesis and defense mechanism while Beauveria bassiana JEF-410 infects poultry red mite, Dermanyssus gallinae

The poultry red mite, Dermanyssus gallinae (Mesostigmata: Dermanyssidae), is a major pest that causes great damage to chicken egg production. In one of our previous studies, the management of red mites using entomopathogenic fungi was evaluated, and the acaricidal fungus Beauveria bassiana JEF-410 was selected for further research. In this study, we tried to elucidate the pathogenesis of B. bassiana JEF-410 and the defense mechanisms of red mites at a transcriptome level. Red mites collected from a chicken farm were treated with B. bassiana JEF-410. When the mortality of infected red mites reached 50%, transcriptome analyses were performed to determine the interaction between B. bassiana JEF-410 and red mites. Uninfected red mites and non-infecting fungus served as controls. In B. bassiana JEF-410, up-regulated gene expression was observed in tryptophan metabolism and secondary metabolite biosynthesis pathways. Genes related to acetyl-CoA synthesis were up-regulated in tryptophan metabolism, suggesting that energy metabolism and stress management were strongly activated. Secondary metabolites associated with fungal up-regulated DEGs were related to the production of substances toxic to insects such as beauvericin and beauveriolide, efflux pump of metabolites, energy production, and resistance to stress. In red mites, physical and immune responses that strengthen the cuticle against fungal infection were highly up-regulated. From these gene expression analyses, we identified essential factors for fungal infection and subsequent defenses of red mites. These results will serve as a strong platform for explaining the interaction between B. bassiana JEF-410 and red mites in the stage of active infection.

Brief overview of recently reported misassigned natural products and their in silico revisions enabled by DU8ML, a machine learning-augmented DFT computational NMR method

Mostly covering 2018 to 2022This Highlight article describes a personal selection of recent misassigned structures of natural products and their revision with the aid of DU8ML, a machine learning-augmented DFT computational method for fast and accurate calculations of solution NMR chemical shifts and spin-spin coupling constants.

Fungal Toxins and Host Immune Responses

Fungi are ubiquitous organisms that thrive in diverse natural environments including soils, plants, animals, and the human body. In response to warmth, humidity, and moisture, certain fungi which grow on crops and harvested foodstuffs can produce mycotoxins; secondary metabolites which when ingested have a deleterious impact on health. Ongoing research indicates that some mycotoxins and, more recently, peptide toxins are also produced during active fungal infection in humans and experimental models. A combination of innate and adaptive immune recognition allows the host to eliminate invading pathogens from the body. However, imbalances in immune homeostasis often facilitate microbial infection. Despite the wide-ranging effects of fungal toxins on health, our understanding of toxin-mediated modulation of immune responses is incomplete. This review will explore the current understanding of fungal toxins and how they contribute to the modulation of host immunity.

Synthetic Strategies to Access Heteroatomic Spirocentres Embedded in Natural Products

The spirocyclic motif is abundant in natural products and provides an ideal three-dimensional template to interact with biological targets. With significant attention historically expended on the synthesis of flat-heterocyclic compound libraries, methods to access the less-explored three-dimensional medicinal-chemical space will continue to increase in demand. Herein, we highlight by reaction class the common strategies used to construct the spirocyclic centres embedded in a series of well-studied natural products.

1 Introduction

2 Cycloadditions

3 Palladium-Catalysed Coupling Reactions

4 Conjugate Additions

5 Imines, Aminals, and Hemiaminal Ethers

6 Mannich-Type Reactions

7 Oxidative Dearomatisation

8 Alkylation

9 Organometallic Additions

10 Conclusions

Secondary Metabolites and Their Bioactivities Produced by Paecilomyces

Paecilomyces, a common saprobic filamentous fungus, not only plays an important role in biological control, but also has applications in medicine, food, and environmental protection. In this paper, 223 secondary metabolites and their bioactivities from 13 known species and various unidentified strains of Paecilomyces are reviewed. Their structures can be described as polyketide, terpenoid, peptide, alkaloid, quinone, pyrone, sterol, and fatty acid. They have been demonstrated varying biological activities, including antimicrobial, antitumor, insecticidal, antiplasmodial, antimalarial, nematicidal, herbicidal, and enzyme-inhibiting. This review provides a comprehensive overview of secondary metabolites and their biological activities from strains of Paecilomyces.

A Systematic Review on Secondary Metabolites of Paecilomyces Species: Chemical Diversity and Biological Activity

Fungi are well known for their ability to synthesize secondary metabolites, which have proven to be a rich resource for exploring lead compounds with medicinal and/or agricultural importance. The genera Aspergillus, Penicillium, and Talaromyces are the most widely studied fungal groups, from which a plethora of bioactive metabolites have been characterized. However, relatively little attention has been paid to the genus Paecilomyces, which has been reported to possess great potential for its application as a biocontrol agent. Meanwhile, a wide structural array of metabolites with attractive bioactivities has been reported from this genus. This review attempts to provide a comprehensive overview of Paecilomyces species, with emphasis on the chemical diversity and relevant biological activities of these metabolic products. Herein, a total of 148 compounds and 80 references are cited in this review, which is expected to be beneficial for the development of medicines and agrochemicals in the near future.

Genetic bases for variation in structure and biological activity of trichothecene toxins produced by diverse fungi

Trichothecenes are sesquiterpene toxins produced by diverse but relatively few fungal species in at least three classes of Ascomycetes: Dothideomycetes, Eurotiomycetes, and Sordariomycetes. Approximately 200 structurally distinct trichothecene analogs have been described, but a given fungal species typically produces only a small subset of analogs. All trichothecenes share a core structure consisting of a four-ring nucleus known as 12,13-epoxytrichothec-9-ene. This structure can be substituted at various positions with hydroxyl, acyl, or keto groups to give rise to the diversity of trichothecene structures that has been described. Over the last 30 years, the genetic and biochemical pathways required for trichothecene biosynthesis in several species of the fungi Fusarium and Trichoderma have been elucidated. In addition, phylogenetic and functional analyses of trichothecene biosynthetic (TRI) genes from fungi in multiple genera have provided insights into how acquisition, loss, and changes in functions of TRI genes have given rise to the diversity of trichothecene structures. These analyses also suggest both divergence and convergence of TRI gene function during the evolutionary history of trichothecene biosynthesis. What has driven trichothecene structural diversification remains an unanswered question. However, insight into the role of trichothecenes in plant pathogenesis of Fusarium species and into plant glucosyltransferases that detoxify the toxins by glycosylating them point to a possible driver. Because the glucosyltransferases can have substrate specificity, changes in trichothecene structures produced by a fungus could allow it to evade detoxification by the plant enzymes. Thus, it is possible that advantages conferred by evading detoxification have contributed to trichothecene structural diversification. KEY POINTS : • TRI genes have evolved by diverse processes: loss, acquisition and changes in function. • Some TRI genes have acquired the same function by convergent evolution. • Some other TRI genes have evolved divergently to have different functions. • Some TRI genes were acquired or resulted from diversification in function of other genes. • Substrate specificity of plant glucosyltransferases could drive trichothecene diversity.

New entry to the enantioselective formation of substituted cyclohexenes bearing an all-carbon quaternary stereogenic center

Enantioselective formation of cyclohexene derivatives bearing an all-carbon quaternary stereogenic center is described. The racemic cyclohexenes are readily transformed to chiral substituted cyclohexenes in good yield with excellent enantioselectivity and diastereoselectivity by a palladium-mediated deracemization. The resulting products are promising synthetic intermediates of biologically active natural products. This protocol provides us with a new entry to the concise and scalable synthesis of multifunctionalized compounds.

Secondary metabolites (SMs) of Isaria cicadae and Isaria tenuipes

Both Isaria cicadae and Isaria tenuipes are important entomopathogenic fungi used in health foods and traditional herbal medicines in East Asia. However, the safety concerns for both fungal species have been attracting significant attention. Thus, surveying their secondary metabolites (SMs) will be beneficial to improving the safety of their fungal products. In the case of I. cicadae, its SMs mainly include nucleosides, amino acids, beauvericins, myriocin, and oosporein. In contrast, trichothecene derivatives, isariotins, cyclopenta benzopyrans and PKs, are found in the case of I. tenuipes. Among them, beauvericins, myriocin, oosporein and many trichothecene derivatives are toxic compounds. The toxicity and side effects of the fungal products may be related to these SMs. Thus, to ensure the safety of fungal products, the residues standards of SMs need to be reported. Furthermore, methods for the detection of their SMs and biological identification of their strains must be considered. This review gives new insight into the secondary metabolites of medical and edible fungi.

Effect of deletion of a trichothecene toxin regulatory gene on the secondary metabolism transcriptome of the saprotrophic fungus Trichoderma arundinaceum

Trichothecenes are terpenoid toxins produced by multiple fungal species with diverse lifestyles. In these fungi, the trichothecene biosynthetic gene (tri) cluster includes a gene encoding a Cys₂His₂ Zn-finger protein (TRI6). Analyses of plant pathogenic Fusarium species indicate that tri6 regulates tri gene expression. Here, we analyzed TRI6 function in the saprotrophic fungus Trichoderma arundinaceum, which produces the antimicrobial trichothecene harzianum A (HA). Deletion of the TRI6-encoding gene, tri6, blocked HA production and reduced expression of tri genes, and mevalonate biosynthetic genes required for synthesis of farnesyl diphosphate (FPP), the primary metabolite that feeds into trichothecene biosynthesis. In contrast, tri6 deletion did not affect expression of ergosterol biosynthetic genes required for synthesis of ergosterol from FPP, but did increase ergosterol production, perhaps because increased levels of FPP were available for ergosterol synthesis in the absence of trichothecene production. RNA-seq analyses indicated that genes in 10 of 49 secondary metabolite (SM) biosynthetic gene clusters in T. arundinaceum exhibited increased expression and five exhibited reduced expression in a tri6 deletion mutant (Δtri6). Despite the metabolic and transcriptional changes, Δtri6 mutants were not reduced in their ability to inhibit growth of fungal plant pathogens. Our results indicate that T. arundinaceum TRI6 regulates expression of both tri and mevalonate pathway genes. It remains to be determined whether the effects of tri6 deletion on expression of other SM clusters resulted because TRI6 can bind to promoter regions of cluster genes or because trichothecene production affects other SM pathways.

Evolution of structural diversity of trichothecenes, a family of toxins produced by plant pathogenic and entomopathogenic fungi

Trichothecenes are a family of terpenoid toxins produced by multiple genera of fungi, including plant and insect pathogens. Some trichothecenes produced by the fungus Fusarium are among the mycotoxins of greatest concern to food and feed safety because of their toxicity and frequent occurrence in cereal crops, and trichothecene production contributes to pathogenesis of some Fusarium species on plants. Collectively, fungi produce over 150 trichothecene analogs: i.e., molecules that share the same core structure but differ in patterns of substituents attached to the core structure. Here, we carried out genomic, phylogenetic, gene-function, and analytical chemistry studies of strains from nine fungal genera to identify genetic variation responsible for trichothecene structural diversity and to gain insight into evolutionary processes that have contributed to the variation. The results indicate that structural diversity has resulted from gain, loss, and functional changes of trichothecene biosynthetic (TRI) genes. The results also indicate that the presence of some substituents has arisen independently in different fungi by gain of different genes with the same function. Variation in TRI gene duplication and number of TRI loci was also observed among the fungi examined, but there was no evidence that such genetic differences have contributed to trichothecene structural variation. We also inferred ancestral states of the TRI cluster and trichothecene biosynthetic pathway, and proposed scenarios for changes in trichothecene structures during divergence of TRI cluster homologs. Together, our findings provide insight into evolutionary processes responsible for structural diversification of toxins produced by pathogenic fungi.

Toxins produced by pathogens can contribute to infection and/or colonization of hosts. Some toxins consist of a family of metabolites with similar but distinct chemical structures. This structural variation can affect biological activity, which in turn likely contributes to adaptation to different environments, including to different hosts. Trichothecene toxins consist of over 150 structurally distinct molecules produced by certain fungi, including some plant and insect pathogens. In multiple systems that have been examined, trichothecenes contribute to pathogenesis on plants. To elucidate the evolutionary processes that have given rise to trichothecene structural variation, we conducted comparative analyses of nine fungal genera, most of which produce different trichothecene structures. Using genomic, molecular biology, phylogenetic, and analytical chemistry approaches, we obtained evidence that trichothecene structural variation has arisen primarily from gain, loss, and functional changes of trichothecene biosynthetic genes. Our results also indicate that some structural changes have arisen independently in different fungi. Our findings provide insight into genetic and biochemical changes that can occur in toxin biosynthetic pathways as fungi with the pathways adapt to different environmental conditions.

Metabolic Conservation and Diversification of Metarhizium Species Correlate with Fungal Host-Specificity

The ascomycete genus Metarhizium contains several species of insect pathogenic fungi ranging from specialists with narrow host ranges to generalists that can infect diverse invertebrates. Genetic and metabolic conservations and diversifications of Metarhizium species are not well understood. In this study, using the genome information of seven Metarhizium species, we performed a comparative analysis of gene clusters involved in secondary metabolisms (SMs) in these species. The results revealed that the generalist species contain more SM gene clusters than the specialists, and that both conserved and divergent evolutions may have occurred in SM genes during fungal speciation. In particular, the loss/gain events, as well as gene mutagenesis, are evident for the gene cluster responsible for the biosynthesis of non-ribosomal cyclopeptide destruxins. The presence of conserved SM gene clusters in Metarhizium and other divergently evolved insect pathogenic fungi implies their link to fungal entomopathogenicity. Mass spectrometry based metabolomic analyses were also conducted to investigate the chemical diversities of seven Metarhizium species. Consistent with the evolutionary relationships of SM genes among the seven species, significant differences are observed in fungal metabolic profiles, whether the same or different metabolites are produced in different species. Clustering analysis based on the metabolome data revealed that Metarhizium species could be grouped based on their association to fungal host specificity. Our metabolomics-based methods also facilitate the identification of bioactive metabolites that have not been reported previously in Metarhizium. The results of this study will benefit future investigations of the chemical biology of insect-fungal interactions.

Oxirapentyns F-K from the marine-sediment-derived fungus Isaria felina KMM 4639

Six new highly oxygenated chromene derivatives, oxirapentyns F-K (2-7), one new polyketide (8), one new benzofurane (9), and two known cyclodepsipeptides, isoisariin B and isaridin E, were isolated from the lipophilic extract of the marine-derived fungus Isaria felina KMM 4639. The structures of compounds 2-9 were determined using spectroscopic methods. The relative configurations of compounds 2-7 were established through a combination of NOE data and spin coupling constants, and these results were confirmed by X-ray crystallographic analysis of 4. The absolute structures of all oxirapentyns were assumed based on their biogenetic relationship and confirmed using the modified Mosher's method on 2 and 7. Isariketide (8) showed moderate cytotoxicity toward HL-60 cells.

Neurotrophic natural products: chemistry and biology

Neurodegenerative diseases and spinal cord injury affect approximately 50 million people worldwide, bringing the total healthcare cost to over 600 billion dollars per year. Nervous system growth factors, that is, neurotrophins, are a potential solution to these disorders, since they could promote nerve regeneration. An average of 500 publications per year attests to the significance of neurotrophins in biomedical sciences and underlines their potential for therapeutic applications. Nonetheless, the poor pharmacokinetic profile of neurotrophins severely restricts their clinical use. On the other hand, small molecules that modulate neurotrophic activity offer a promising therapeutic approach against neurological disorders. Nature has provided an impressive array of natural products that have potent neurotrophic activities. This Review highlights the current synthetic strategies toward these compounds and summarizes their ability to induce neuronal growth and rehabilitation. It is anticipated that neurotrophic natural products could be used not only as starting points in drug design but also as tools to study the next frontier in biomedical sciences: the brain activity map project.

Beauvericin production by the Lepidoptera pathogenic fungus Isaria tenuipes: Analysis of natural specimens, synnemata from cultivation, and mycelia from liquid-media fermentation

Beauvericin was analyzed in three forms of the Lepidoptra pathogenic fungus Isaria tenuipes (4 isolates): (a) natural specimen, (b) cultivated synnemata on rice media, and (c) mycelia from fermentation in liquid media. Beauvericin was detected in very low amounts in all tested natural specimens. Synnemata on rice contained much higher concentrations of beauvericin than the corresponding natural materials, although the concentrations were lower than mycelia from liquid fermentation. The results casted a caution that beauvericin concentration should be carefully checked, as a possible toxic constituent, upon mass production of a selected strain of Isaria tenuipes for health food purposes.

N-hydroxypyridones, phenylhydrazones, and a quinazolinone from Isaria farinosa

New N-hydroxypyridones, militarinones E (1) and F (2), phenylhydrazones, farylhydrazones A (3) and B (4), a quinazolinone, 2-(4-hydroxybenzyl)quinazolin-4(3H)-one (5), and the known militarinones A (6) and B (7) were isolated from cultures of the Cordyceps-colonizing fungus Isaria farinosa. The structures of 1-5 were elucidated by spectroscopic methods, and 3 was confirmed by X-ray crystallography. The absolute configuration of the C-4' secondary alcohol in 1 was deduced via the circular dichroism data of the in situ formed [Rh(2)(OCOCF(3))(4)] complex. Compounds 1 and 6 showed significant cytotoxicity against A549 cells, whereas 7 was active against Staphylococcus aureus, Streptococcus pneumoniae, and Candida albicans.

Isariotins E and F, spirocyclic and bicyclic hemiacetals from the entomopathogenic fungus Isaria tenuipes BCC 12625

New spirocyclic and bicyclic hemiacetals, isariotins E (1) and F (2), together with TK-57-164A (3) were isolated from the entomopathogenic fungus Isaria tenuipes BCC 12625. The absolute configuration of 3 was addressed by application of the modified Mosher's method. Isariotin F (2) exhibited activity against the malaria parasite Plasmodium falciparum K1 with an IC(50) value of 5.1 microM and cytotoxic activities against cancer cell lines (KB, BC, and NCI-H187) and nonmalignant (Vero) cells with respective IC(50) values of 15.8, 2.4, 1.6, and 2.9 microM.

Total synthesis of spirotenuipesines A and B

Spirotenuipesines A and B, isolated from the entomopathogenic fungus Paecilomyces tenuipes by Oshima and co-workers, have been synthesized. The synthesis features the highly stereoselective construction of two vicinal all-carbon quaternary centers (C(5) and C(6)) via an intramolecular cyclopropanation/radical initiated fragmentation sequence and a diastereoselective intermolecular Diels-Alder reaction between alpha-methylenelactone dienophile 20 and synergistic diene 6a. Installation of the C(9) tertiary alcohol occurred via nucleophilic methylation. An RCM reaction to produce a tetrasubstituted double bond in the presence of free allylic alcohol and homoallylic oxygenated functional group is also described. This route shortened the synthesis of 11 from 9 steps to 3 steps. We have further developed a strategy to gain access to optically active spirotenuipesines A and B through the synthesis of enantioenriched 10 from commercially available R-(-)-epichlorohydrin.

Identification of fredericamycin E from Streptomyces griseus: Insights into fredericamycin A biosynthesis highlighting carbaspirocycle formation

Fredericamycin (FDM) A ( 1), a pentadecaketide featuring two sets of peri-hydroxy tricyclic aromatic moieties connected through a unique asymmetric carbaspiro center, exhibits potent cytotoxicity and represents a novel anticancer drug lead. We have localized previously the fdm gene cluster to a 33 kb DNA segment of Streptomyces griseus ATCC49344, the involvement of which in the biosynthesis of 1 was confirmed by gene inactivation, complementation, and heterologous expression experiments. We now report the isolation and characterization of FDM E ( 5), a heretofore undetected intermediate for 1 biosynthesis from S. griseus, shedding new insight into the mechanism of carbaspirocycle formation. The structure of 5 was elucidated through the combination of spectroscopic methods and isotope-labeling experiments. The core spiro[4.5]decane scaffold of 5 is characterized by a unique cyclohexa-1,2,4-triketone moiety. Transformation of the spiro[4.5]decane 5 into the spiro[4.4]nonane 1 can be rationalized by a biosynthetic benzilic acid-like rearrangement. This unusual rearrangement can be mimicked in vitro by proceeding under aerobic conditions in the absence of enzyme. FDM E displays cytotoxic activity on par with 1 against a selected set of cancer cells, a finding that further supports the unique molecular topology, resulting from the unprecedented carbaspirocycle as exemplified by 1 and 5, as a novel pharmacophore for this family of anticancer agents.

Isariotins A-D, alkaloids from the insect pathogenic fungus Isaria tenuipes BCC 7831

Isariotins A-D (1- 4), alkaloids possessing a unique bicyclo[3.3.1]nonane ring, were isolated from the insect pathogenic fungus Isaria tenuipes BCC 7831. The structures of these compounds were elucidated primarily by NMR and mass spectroscopic analyses.

Pattern Recognition in Retrosynthetic Analysis: Snapshots in Total Synthesis

In this Perspective, the value of small molecule natural products (SMNPs) in the discovery of active biological agents is discussed. The usefulness of the natural products-based method of potential pharma discovery is much augmented by the capacities of chemical synthesis. The great advances in synthetic methodology allow for major editing of the natural product in the hopes of optimizing potency and therapeutic index. As a consequence of the enormous increase in the power of multistep chemical synthesis, one can now approach structures of previously impractical complexity. In constructing a plan for a multistep synthesis, two complementary thought styles are often encountered. One is the traditional and extremely powerful concept of prioritized strategic bond disconnections. The other, which we term "pattern recognition," involves the identification of moieties within the target, which are associated with reliable chemistry, and can serve to facilitate progress to the target. Recognition of such targets may require substantial recasting of the target structure to connect it to well-established types of transformations. Some of our older ventures, where ideas about pattern recognition were first being fashioned and used productively, are revisited. In addition, we provide snapshots of recently achieved total syntheses of SMNPs of novel biological potential. These vignettes serve to harmonize insights occasioned by pattern recognition, in concert with transformations enabled by the enormous growth in the power of synthesis.

Paecilodepsipeptide A, an antimalarial and antitumor Cyclohexadepsipeptide from the insect pathogenic fungus Paecilomyces cinnamomeus BCC 9616

Paecilodepsipeptide A (1), a new cyclohexadepsipeptide possessing three d-amino acid residues, together with its linear analogues paecilodepsipeptides B (2) and C (3), was isolated from the insect pathogenic fungus Paecilomyces cinnamomeus BCC 9616. Structures of these compounds were elucidated primarily by NMR and mass spectroscopic analyses. The absolute configurations of the amino acid and hydroxy acid residues of 1 were addressed by HPLC analysis of its acid hydrolyzate using a chiral column and Marfey's method. Paecilodepsipeptide A (1) showed activity against the malarial parasite Plasmodium falciparum K1 with an IC50 value of 4.9 microM. This compound also showed cytotoxicity to two cancer cell lines, KB (IC50 5.9 microM) and BC (IC50 6.6 microM); however, it was inactive against noncancerous Vero cells up to 67 microM (50 microg/mL).

Effects of Paecilomyces tenuipes Cultivated in Egg Yolk on Lipid Metabolism in Rats on a High Fat-Cholesterol Diet

We investigated the effects of the fruiting bodies of cultivated Paecilomyces tenuipes grown on egg yolk (PTE) on lipid and antioxidant metabolisms. Forty 8-week-old male Sprague-Dawley rats were fed a high fat/high cholesterol diet (control) or a high fat/high cholesterol diet with 1%, 3%, or 5% PTE for 5 weeks. PTE was found to significantly lower plasma total lipid, total cholesterol, low-density lipoprotein cholesterol, and the atherogenic index, compared with the control. Hepatic total lipid and total cholesterol were also significantly lower than in the control group. The hypolipidemic activity of PTE was increased with increasing concentrations, and plasma lipid peroxidation was significantly lower in the 3% and 5% PTE groups than in the control or 1% PTE group. Plasma total radical trapping antioxidant potential, erythrocytic antioxidant enzyme, and leukocytic DNA damage were not significantly different among the groups. Our results indicate that P. tenuipes cultivated on egg yolk can improve lipid profiles and lipid peroxidation in rats fed a high fat/high cholesterol diet.

Inhibition of sodium glucose cotransporter-1 expressed inXenopus laevisoocytes by 4-acetoxyscirpendiol from Cordyceps takaomantana (anamorph = Paecilomyces tenuipes)

Cordyceps contains many health-promoting constituents. Recent studies revealed that the fruiting body of cordyceps significantly alleviates hyperglycemia which usually accompanies diabetes mellitus. The mechanism of the anti-hyperglycemic effect by cordyceps, however, is not fully understood. In this study, methanolic extracts were prepared from fruiting bodies of Paecilomyces tenuipes, and 4-beta acetoxyscirpendiol (ASD) was eventually purified from the extracts. The Na+/ glucose transporter-1 (SGLT-1) was expressed in Xenopus oocytes, and the effect of ASD on it was analyzed using voltage clamp and 2-deoxy-D-glucose (2-DOG) uptake studies. Fluorescence microscopy was performed to monitor the effect of ASD on glucose uptake using HEK293 cells expressing recombinant SGLT-1. ASD inhibited SGLT-1 activity, and its two derivatives (2-acetoxyscirpenol and 15-acetoxyscirpendiol), were also effective; 15-acetoxyscirepenol was as inhibitory as ASD while diacetoxyscirpenol had less effect. Thus, the ASD in P. tenuipes may play an important role in lowering blood sugar in the circulatory system along with its derivatives as specific inhibitors of SGLT-1.

Bioactive substances from insect pathogenic fungi

Insect pathogenic fungi have opened up a relatively untapped area of natural product research which, unfortunately, has not received much attention to date. Found in wild abundance in wet tropical Thailand, the insect fungi are shown to contribute not only as controllers of insect populations but also as rich sources of structurally novel biologically active substances.

4-Acetoxyscirpendiol of Paecilomyces tenuipes Inhibits Na+/D-Glucose Cotransporter Expressed in Xenopus laevis Oocytes

Cordyceps, an entomopathogenic fungus, contains many health-promoting ingredients. Recent reports indicate that the consumption of cordyceps helps reduce blood-sugar content in diabetics. However, the mechanism underlying this reduction in circulatory sugar content is not fully understood. Methanolic extracts were prepared from the fruiting bodies of Paecilomyces tenuipes, and 4-beta acetoxyscirpendiol (4-ASD) was eventually isolated and purified. Na(+)/Glucose transporter-1 (SGLT-1) was expressed in Xenopus oocytes, and the effect of 4-ASD on SGLT-1 was analyzed utilizing a voltage clamp and by performing 2-deoxy-D-glucose (2-DOG) uptake studies. 4-ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose-dependent manner. In the presence of the derivatives of 4-ASD (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited in an 4-ASD-like manner. Of these derivatives, 15-acetoxyscirepenol inhibited SGLT-1 as well as 4-ASD, whereas diacetoxyscirpenol was slightly less effective. Taken together, these results strongly indicate that 4-ASD in P. tenuipes may lower blood sugar levels in the circulatory system. We conclude that 4-ASD and its derivatives are effective SGLT-1 inhibitors.

A Novel Carbon Skeletal Trichothecane, Tenuipesine A, Isolated from an Entomopathogenic Fungus, Paecilomyces tenuipes

Tenuipesine A (1), a novel trichothecane with an unprecedented carbon-migrated skeleton that embodies of a cyclopropane ring, was isolated from cultivated fruiting bodies of Paecilomyces tenuipes (Isaria japonica), a popular entomopathogenic fungi employed in folk medicine and health foods in China, Korea, and Japan. The structure was determined on the basis of two-dimensional NMR data. Its stereochemistry was elucidated by spectroscopic data and the chemical transformation of the coexisting trichothecene, 4beta-acetoxy-12,13-epoxytrichothec-9-ene-3alpha,15-diol (2). [structure: see text]