Polyozellin, a new inhibitor of prolyl endopeptidase from Polyozellus multiplex

Biosynthesis of p-Terphenyls in Aspergillus ustus Implies Enzymatic Reductive Dehydration and Spontaneous Dibenzofuran Formation

p-Terphenyls contain a central benzene ring substituted with two phenyl residues at its para positions. Heterologous expression of a biosynthetic gene cluster from Aspergillus ustus led to the formation of four new p-terphenyl derivatives. Gene deletion experiments proved the formation and reductive dehydration of the terphenylquinone atromentin, followed by O-methylation and prenylation. Spontaneous dibenzofuran formation led to the final products. These results provide new insights into the biosynthesis of p-terphenyls in fungi and dibenzofuran formation in the biosynthesis of numerous natural products.

Structural diversity and biological activity of natural p-terphenyls

p-Terphenyls are aromatic compounds consisting of a central benzene ring substituted with two phenyl groups, and they are mainly isolated from terrestrial and marine organisms. The central ring of p-Terphenyls is usually modified into more oxidized forms, e.g., para quinone and phenols. In some cases, additional ring systems were observed on the terphenyl-type core structure or between two benzene moieties. p-Terphenyls have been reported to have cytotoxic, antimicrobial, antioxidant and α-glucosidase inhibitory effects. In this review, we will mainly summarize the structural diversity and biological activity of naturally occurring p-Terphenyls referring to the research works published before.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00117-8.

Polyozellus vs. Pseudotomentella: generic delimitation with a multi-gene dataset

Polyozellus and Pseudotomentella are two genera of closely related, ectomycorrhizal fungi in the order Thelephorales; the former stipitate and the latter corticioid. Both are widespread in the Northern Hemisphere and many species from both genera seem to be restricted to old growth forest. This study aimed to: a) identify genetic regions useful in inferring the phylogenetic relationship between Polyozellus and Pseudotomentella, b) infer this relationship with the regions identified and c) make any taxonomic changes warranted by the result. RPB2, mtSSU and nearly full-length portions of nrLSU and nrSSU were found to be comparatively easy to sequence and provide a strong phylogenetic signal. A STACEY species tree of these three regions revealed that Polyozellus makes Pseudotomentella paraphyletic. As a result, nearly all species currently placed in Pseudotomentella were recombined to Polyozellus. Pseudotomentella larsenii was found to be closer to Tomentellopsis than Polyozellus, but its placement needs further study and it was hence not recombined.

Bioactive Phytochemical Constituents of Wild Edible Mushrooms from Southeast Asia

Mushrooms have a long history of uses for their medicinal and nutritional properties. They have been consumed by people for thousands of years. Edible mushrooms are collected in the wild or cultivated worldwide. Recently, mushroom extracts and their secondary metabolites have acquired considerable attention due to their biological effects, which include antioxidant, antimicrobial, anti-cancer, anti-inflammatory, anti-obesity, and immunomodulatory activities. Thus, in addition to phytochemists, nutritionists and consumers are now deeply interested in the phytochemical constituents of mushrooms, which provide beneficial effects to humans in terms of health promotion and reduction of disease-related risks. In recent years, scientific reports on the nutritional, phytochemical and pharmacological properties of mushroom have been overwhelming. However, the bioactive compounds and biological properties of wild edible mushrooms growing in Southeast Asian countries have been rarely described. In this review, the bioactive compounds isolated from 25 selected wild edible mushrooms growing in Southeast Asia have been reviewed, together with their biological activities. Phytoconstituents with antioxidant and antimicrobial activities have been highlighted. Several evidences indicate that mushrooms are good sources for natural antioxidants and antimicrobial agents.

Polyozellin alleviates atopic dermatitis-like inflammatory and pruritic responses in activated keratinocytes and mast cells

Polyozellus multiplex is an edible mushroom that offers beneficial pharmacological effects against intestinal inflammation and cancer. Previous studies have demonstrated that polyozellin, a major component of P. multiplex, has therapeutic activities against inflammation, cancer, and oxidative stress-related disorders. This study aimed to determine the pharmacological effects of polyozellin on inflammatory and pruritic responses, the major symptoms of atopic dermatitis (AD), and to define its underlying mechanism of action. Our results showed that polyozellin inhibited the expression of inflammatory cytokines and chemokines through blockade of signal transducer and activator of transcription 1 and nuclear factor-κB in activated keratinocytes, the major cells involved in AD progression. Based on the histological and immunological analyses, oral treatment with polyozellin attenuated the Dermatophagoides farinae extract (DFE)/2,4-dinitrochlorobenzene (DNCB)-induced atopic inflammatory symptoms in the skin. Pruritus is an unpleasant sensation for AD patients that causes scratching behavior and ultimately exacerbates the severity of AD. To find a possible explanation for the anti-pruritic effects of polyozellin, we investigated its effects on mast cells and mast cell-derived histamines. Oral treatment with polyozellin reduced the DFE/DNCB-induced tissue infiltration of mast cells, the serum histamine levels, and the histaminergic scratching behaviors. Additionally, polyozellin decreased the immunoglobulin E-stimulated degranulation of mast cells. Taken together, the findings of this study provide us with novel insights into the potential pharmacological targets of polyozellin for treating AD by inhibiting the inflammatory and pruritic responses.

Synthesis of polyozellin, a prolyl oligopeptidase inhibitor, and its structural revision

Polyozellin is a p-terphenyl compound which was isolated from Polyozellus multiplex, and exhibits an inhibitory activity against prolyl oligopeptidase (POP). Its structure was assigned as 1 having a p-terphenyl skeleton including a p-substituted dibenzofuran moiety by spectroscopic analyses and chemical means. This paper describes the total syntheses of the proposed structure 1 for polyozellin and its o-isomer 2, revising the structure of polyozellin to the latter. These syntheses involved a double Suzuki-Miyaura coupling using chlorophenylboronic acid as a common key building block, and Cu mediated Ullmann cyclization as key steps. The inhibitory activities of synthetic compounds against POP and cancer cells were also evaluated.

β-Secretase (BACE1) inhibitory and neuroprotective effects of p-terphenyls from Polyozellus multiplex

Polyozellin, thelephoric acid, and polyozellic acid might be useful in the development of lead compounds for the prevention of neurodegenerative disorders, especially Alzheimer's disease (AD).

Suppressive effects of polyozellin on TGFBIp-mediated septic responses in human endothelial cells and mice

Polyozellus multiplex (Thelephoraceae) is a wild mushroom in Korea and Japan and is usually harvested in early autumn for food. Polyozellin, a major constituent of the edible mushroom P multiplex, has been known to exhibit biological activities such as antioxidative and anti-inflammatory effects. Transforming growth factor β-induced protein (TGFBIp) is an extracellular matrix protein whose expression in several cell types is greatly increased by TGF-β. TGFBIp is released by human umbilical vein endothelial cells and functions as a mediator of experimental sepsis. We hypothesized that polyozellin could reduce TGFBIp-mediated severe inflammatory responses in human endothelial cells and mice. Here, we investigated the antiseptic effects and underlying mechanisms of polyozellin against TGFBIp-mediated septic responses. Polyozellin effectively inhibited lipopolysaccharide-induced release of TGFBIp and suppressed TGFBIp-mediated septic responses. In addition, polyozellin suppressed cecal ligation and puncture-induced sepsis lethality and pulmonary injury. In conclusion, polyozellin suppressed TGFBIp-mediated and cecal ligation and puncture-induced septic responses. Therefore, polyozellin could be a potential therapeutic agent for treatment of various severe vascular inflammatory diseases via inhibition of the TGFBIp signaling pathway.

Inhibitory effect of polyozellin on secretory group IIA phospholipase A2

The expression of secretory group IIA phospholipase A2 (sPLA2-IIA) is enhanced by development of inflammatory disorders. In this study, sPLA2-IIA expression was induced in the lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells and mice to evaluate the effect of polyozellin. Polyozellin, a major constituent of a Korea edible mushroom Polyozellus multiplex, has been known to exhibit the biological activities such as anti-oxidative and anti-inflammatory effects. Polyozellin remarkably suppressed the LPS-mediated protein expression and activity of sPLA2-IIA via inhibition of phosphorylation of cytosolic phospholipase A2 and extracellular signal-regulated kinase 1/2. These results demonstrated that polyozellin might play an important role in the modulation of sPLA2-IIA expression and activity in response to the inflammatory diseases.

Polyozellin, a key constituent of the edible mushroom Polyozellus multiplex, attenuates glutamate-induced mouse hippocampal neuronal HT22 cell death

Polyozellus multiplex (PM), a Korean edible mushroom, has biological activities such as chemoprevention of stomach cancer, inhibition of lipid peroxidation, and reduction of prolyl endopeptidase activity. However, there are little reports on the protective effects of PM or its constituents against glutamate-induced mouse hippocampal neuronal cell (HT22) death. In this study, polyozellin (PZ), a key constituent of PM, was applied to glutamate-treated HT22 cells to evaluate its neuroprotective mechanisms. PZ (25 μM) dramatically increased the HT22 cell viability when the cell death was induced by 5 mM glutamate for 12 h, which was mediated by inhibition of Ca(2+) influx, intracellular reactive oxygen species (ROS) production, and lipid peroxidation. PZ also regulated expression of Bid, Bcl-2, and apoptosis-inducing factor (AIF), as well as phosphorylation of mitogen-activated protein kinases (MAPKs). These data suggest that PM and its constituent PZ might be useful for prevention and treatment of neurodegenerative disorders.

Suppressive effects of polyozellin on endothelial protein C receptor shedding via inhibiting TACE activity and MAP kinases

Beyond its role in the activation of protein C, the endothelial cell protein C receptor (EPCR) plays an important role in the cytoprotective pathway. EPCR can be shed from the cell surface, which is mediated by tumor necrosis factor-α converting enzyme (TACE). Polyozellin, a major constituent of a Korea edible mushroom Polyozellus multiplex, has been known to exhibit the biological activities such as anti-oxidative and anti-inflammatory effects. However, little is known about the effects of polyozellin on EPCR shedding. We investigated this issue by monitoring the effects of polyozellin on phorbol-12-myristate 13-acetate (PMA)-, tumor necrosis factor (TNF)-α-, interleukin (IL)-1β-induced EPCR shedding in human umbilical vein endothelial cells (HUVECs), and cecal ligation and puncture (CLP)-mediated EPCR shedding in mice and underlying mechanism. Data demonstrate that polyozellin induced potent inhibition of PMA-, TNF-α-, IL-1β- (in HUVECs), and CLP-induced EPCR shedding (in mice) via inhibition of phosphorylation of mitogen-activated protein kinases (MAPKs) such as p38, janus kinase (JNK), and extracellular signal-regulated kinase (ERK) 1/2. Polyozellin also inhibited the expression and activity of PMA-induced TACE in HUVECs suggesting that p38, ERK1/2, and JNK could be the molecular targets of POZ. These results demonstrate the potential of polyozellin as an anti-EPCR shedding reagent against PMA-mediated and CLP-mediated EPCR shedding.

Inhibitory effects of polyozellin from Polyozellus multiplex on HMGB1-mediated septic responses

AIM AND OBJECTIVE

The ubiquitous nuclear protein, high-mobility group box 1 (HMGB1), is released by activated macrophages and human umbilical vein endothelial cells (HUVECs) and functions as a late mediator of experimental sepsis. Polyozellin, which has been reported to have a variety of biological activities including antioxidant and anticancer activity, is the major active compound found in edible mushroom (Polyozellus multiplex). In this study, we investigated the antiseptic effects and underlying mechanisms of polyozellin against HMGB1-mediated septic responses in HUVECs and mice.

METHODS

The anti-inflammatory activities of polyozellin were determined by measuring permeability, human neutrophil adhesion and migration, and activation of proinflammatory proteins in HMGB1-activated HUVECs and mice.

RESULTS

According to the results, polyozellin effectively inhibited lipopolysaccharide (LPS)-induced release of HMGB1, and suppressed HMGB1-mediated septic responses, such as hyperpermeability, adhesion and migration of leukocytes, and expression of cell adhesion molecules. In addition, polyozellin suppressed the production of tumor necrosis factor-α and interleukin (IL)-6, and the activation of nuclear factor-κB and extracellular signal-regulated kinases 1/2 by HMGB1.

CONCLUSION

Collectively, these results indicate that P. multiplex containing polyozellin could be commercialized as functional food for preventing and treatment of various severe vascular inflammatory diseases via inhibition of the HMGB1 signaling pathway.

Potential anti-angiogenesis effects of p-terphenyl compounds from Polyozellus multiplex

One novel p-terphenyl compound, polyozellic acid (1), and its acetone adduct (3), along with a known p-terphenyl compound, thelephoric acid (2), were isolated from the mushroom Polyozellus multiplex. Their molecular structures were determined by spectroscopic analysis, X-ray crystallographic analysis, and chemical modification. In some assays related to angiogenesis, compounds 1 and 2 in particular showed inhibitory effects on proliferation, tubule formation, and invasion of human umbilical vein endothelial cells. The quinone moiety within these molecules possibly contributes to their antiangiogenesis activity.

A Comparison of the In Vitro Inhibitory Effects of Thelephoric Acid and SKF-525A on Human Cytochrome P450 Activity

Thelephoric acid is an antioxidant produced by the hydrolysis of polyozellin, which is isolated from Polyozellus multiplex. In the present study, the inhibitory effects of polyozellin and thelephoric acid on 9 cytochrome P450 (CYP) family members (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) were examined in pooled human liver microsomes (HLMs) using a cocktail probe assay. Polyozellin exhibited weak inhibitory effects on the activities of all 9 CYPs examined, whereas thelephoric acid exhibited dose- and time-dependent inhibition of all 9 CYP isoforms (IC50 values, 3.2-33.7 μM). Dixon plots of CYP inhibition indicated that thelephoric acid was a competitive inhibitor of CYP1A2 and CYP3A4. In contrast, thelephoric acid was a noncompetitive inhibitor of CYP2D6. Our findings indicate that thelephoric acid may be a novel, non-specific CYP inhibitor, suggesting that it could replace SKF-525A in inhibitory studies designed to investigate the effects of CYP enzymes on the metabolism of given compounds.

New bioactive compounds from korean native mushrooms

Mushrooms are ubiquitous in nature and have high nutritional attributes. They have demonstrated diverse biological effects and therefore have been used in treatments of various diseases, including cancer, diabetes, bacterial and viral infections, and ulcer. In particular, polysaccharides, including β-glucan, are considered as the major constituents responsible for the biological activity of mushrooms. Although an overwhelming number of reports have been published on the importance of polysaccharides as immunomodulating agents, not all of the healing properties found in these mushrooms could be fully accounted for. Recently, many research groups have begun investigations on biologically active small-molecular weight compounds in wild mushrooms. In this mini-review, both structural diversity and biological activities of novel bioactive substances from Korean native mushrooms are described.

Atromentin and Leucomelone, the First Inhibitors Specific to Enoyl-ACP Reductase (FabK) of Streptococcus pneumoniae

Two potent inhibitors of FabK, the enoyl-acyl carrier protein (ACP) reductase of Streptococcus pneumoniae, were isolated from the solid state fermentation of an unidentified fungus F010248. Their structures were identified to be atromentin and leucomelone by various spectral analysis. Atromentin and leucomelone inhibited the FabK with IC50 values of 0.24 and 1.57 microM, respectively, while did not inhibit FabI, the enoyl-ACP reductase of either Escherichia coli or Staphylococcus aureus, even at 200 microM. Atromentin and leucomelone are the first inhibitors specific to the enoyl-ACP reductase (FabK) of Streptococcus pneumoniae.

A prolyl endopeptidase-inhibiting antioxidant from Phyllanthus ussurensis

A prolyl endopeptidase inhibitor was isolated from the ethyl acetate soluble fraction of Phyllanthus ussurensis. The active compound was identified as an ellagitannin, corilagin. It was shown to non-competitively inhibit prolyl endopeptidase (PEP) with the IC50 value of 1.17x10(-6) microM. The Ki value was 6.70x10(-7) M. Corilagin was less inhibitory to other serine proteases such as chymotrypsin, trypsin, and elastase, indicating that it was relatively a specific inhibitor of PEP. Corilagin also effectively inhibited reactive oxygen species such as hydroxide and superoxide anion radical, hydrogen peroxide, and DPPH. Especially, corilagin showed potent scavenging activity on the superoxide anion radical in the ESR method (IC50 = 3.79x10(-6) M) as well as xanthine oxidase system.

Polyozellus multiplex, a Korean wild mushroom, as a potent chemopreventive agent against stomach cancer

Polyozellus multiplex, a Korean wild mushroom, was extracted using methanol, and the extract was further fractionated with water and ethylacetate. Assay of each fraction with MTT revealed significant tumoristatic effects of the water fraction of Polyozellus multiplex against human gastric and other cancer cells but not normal human lymphocytes. Modifying effects of the water fraction on glandular stomach mucosa were investigated in male Wistar rats treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The dietary 0.5% or 1% water fraction of Polyozellus multiplex significantly increased glutathione S-transferase (GST) and superoxide dismutase (SOD) activities, and showed a tendency for increase in glutathione (GSH) levels, compared to the MNNG alone group. It also caused a significant reduction in proliferating cell nuclear antigen (PCNA)-labeling index of the glandular stomach epithelium, along with increase in p53 tumor suppressor gene expression. These results suggest that Polyozellus multiplex is a candidate for chemoprevention against gastric cancer.

Prolyl endopeptidase inhibitors from green tea

Three prolyl endopeptidase (PEP) inhibitors were isolated from the methanolic extract of green tea leaves. They were identified as (-)-epigallocatechin gallate, (-)-epicatechin gallate, and (+)-gallocatechin gallate with the IC50 values of 1.42 x 10(-4) mM, 1.02 x 10(-2) mM, and 1.09 x 10(-4) mM, respectively. They were non-competitive with a substrate in Dixon plots and did not show any significant effects against other serine proteases such as elastase, trypsin, and chymotrypsin, suggesting that they were relatively specific inhibitors against PEP. The isolated compounds are expected to be useful for preventing and curing of Alzheimer's disease.

Prolyl endopeptidase inhibitors from caryophylli flos

Three prolyl endopeptidase inhibitors were isolated and identified as luteolin, quercetin and beta-sitosterol-3-O-beta-D-glucopyranoside with IC50 of 0.17, 0.19 and 27.5 ppm, respectively. The inhibition of two flavonoids were non-competitive with substrate. Twenty authentic flavonoids were tested in order to investigate structure-activity relationship. No significant relationship was found in them, however, catechol moiety of B-ring and 7-OH group in flavonoid skeleton were seemed to be responsible for the stronger activity.