New isocoumarins and alkaloid from Chinese insect medicine, Eupolyphaga sinensis Walker

Organocatalytic enantioselective synthesis of Csp2-N atropisomers via formal Csp2-O bond amination

Compared with well-developed construction of Csp2-Csp2 atropisomers, the synthesis of Csp2-N atropisomers remains in its infancy, which is recognized as both appealing and challenging. Herein, we achieved the first organocatalyzed asymmetric synthesis of Csp2-N atropisomers by formal Csp2-O amination. With the aid of a suitable acid, 3-alkynyl-3-hydroxyisoindolinones reacted smoothly with 1-methylnaphthalen-2-ols to afford a wide range of atropisomers by selective formation of the Csp2-N axis. Particularly, both the kinetic (Z)-products and the thermodynamic (E)-products could be selectively formed. Furthermore, the rarely used combination of two chiral Brønsted acid catalysts achieved excellent enantiocontrol, which is intriguing and unusual in organocatalysis. Based on control experiments and DFT calculations, a cascade dehydration/addition/rearrangement process was proposed. More importantly, this work provided a new plat-form for direct atroposelective construction of the chiral Csp2-N axis.

Antidiabetic Potential of a Trimeric Anthranilic Acid Peptide Isolated from Malbranchea flocciformis

Compound 3, a trimeric anthranilic acid peptide, and another three metabolites were isolated from an organic extract from the culture medium of Malbranchea flocciformis ATCC 34530. The chemical structure proposed previously for 3 was unequivocally assigned via synthesis and X-ray diffraction analysis. Tripeptide 3 showed insulinotropic properties by decreasing the postprandial peak in healthy and hyperglycemic mice. It also increased glucose-induced insulin secretion in INS-1E at 5 μM, specifically at higher glucose concentrations. These results revealed that 3 might act as an insulin sensitizer and a non-classical insulin secretagogue. Altogether, these findings are in harmony with the in vivo oral glucose tolerance test and acute oral hypoglycemic assay. Finally, the chemical composition of the extract was established by the Global Natural Products Social Molecular Network platform. Phylogenetic analysis using the internal transcribed spacer region revealed that M. flocciformis ATCC 34530 is related to the Malbrancheaceae.

N-acetyldopamine oligomers from Periplaneta americana with anti-inflammatory and vasorelaxant effects and their spatial distribution visualized by mass spectrometry imaging

ETHNOPHARMACOLOGICAL RELEVANCE

Periplaneta americana is a medicinal insect that has been applied to promote blood circulation and remove blood stasis based on traditional Chinese medicine (TCM) for a long time. Its modern preparation, Xinmailong injection, was adopted for the treatment of congestive heart failure (CHF). The bioactive constituents of P. americana and their correlation with its traditional uses need further investigation.

AIM OF THE STUDY

This study aimed to elucidate the N-acetyldopamine (NADA) oligomers from P. american, determine their spatial distribution, and investigate their anti-inflammatory and vasorelaxant effects to provide scientific evidence supporting the clinical use of this medicinal insect.

MATERIAL AND METHODS

NADA oligomers were isolated from the CH2Cl2: CH3OH (2:1) extract of P. americana, through sequential chromatographic methods including silica gel, Sephadex LH-20, preparative HPLC, and chiral-phase separation. Their structures were determined by HRESIMS, 1D and 2D NMR spectroscopic analysis, chiral resolution, and calculated electronic circular dichroism analysis. With the aid of atmospheric pressure scanning matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI), the isolated compounds in a spatial profile within P. americana were identified. NO production was measured to assess anti-inflammatory activity. Vasorelaxant activity assessments were performed on the norepinephrine-precontracted 3rd-order mesenteric arteries.

RESULTS

Seven new NADA trimers, peridopamines A-G (1-7), two new NADA dimers, peridopamines H and I (8 and 9), and six known NADA derivatives (10-15), were obtained from P. americana. The trimers and dimers were detected and showed similar pattern of distribution with accumulation in peripheral and rigid parts of P. americana, based on quasimolecular ion AP-SMALDI MS images of sections from the whole body and dissected areas of the insect. Furthermore, the anti-inflammatory and vasorelaxant effects of isolated compounds were investigated. Compounds 8 and 9 presented significant and moderate anti-inflammatory potentials, respectively. Compounds 8, 10, 12 and 15 possess significant vasorelaxant potentials at concentrations correlated with EC50 values of 6.7-23.7 μM.

CONCLUSION

Fifteen NADA oligomers were isolated from P. americana. The distribution of these compounds was visualized by AP-SMALDI imaging experiments and NADA oligomers were mainly observed in peripheral parts. Bioassays showed that the tested compounds had anti-inflammatory and vasorelaxant activities, which indicated that NADA oligomers are active ingredients of this insect-based TCM and have potential for the treatment of cardiovascular disease.

Asymmetric Allylic Substitution-Isomerization for the Modular Synthesis of Axially Chiral N-Vinylquinazolinones

Axially chiral N-substituted quinazolinones are important bioactive molecules, which are presented in many synthetic drugs. However, most strategies toward their atroposelective synthesis are mainly limited to the axially chiral arylquinazolinone frameworks. The development of modular synthetic methods to access diverse quinazolinone-based atropisomers remains scarce and challenging. Herein, we report the regio- and atroposelective synthesis of axially chiral N-vinylquinazolinones via the strategy of asymmetric allylic substitution-isomerization. The catalysis system utilized both asymmetric transition-metal catalysis and organocatalysis to efficiently afford trisubstituted and tetrasubstituted N-vinylquinazolinone atropisomers, respectively. With the meticulous design of β-substituted allylic substrates, both Z- and E-tetrasubstituted axially chiral N-vinylquinazolinones were obtained in good yields and high enantioselectivities.

Tubiechong：A review on ethnomedicinal uses, bioactive chemical constituents and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Tubiechong comprises mainly Eupolyphaga and Steleophaga is widely distributed in China. It has been used in the traditional medicine systems in Asian countries specially in China，Japan and Singapore for thousand years.

AIM OF THE REVIEW

The aim of this work is to review the scientific work about Tubiechong regarding their ethnomedicinal uses, bioactive chemical constituents and pharmacological activities.

MATERIALS AND METHODS

Relevant literature of Tubiechong was collected for its traditional uses, pharmacological activities, and bioactive compounds released from inception until May 2022. The online databases such as Web of Science, PubMed, Google Scholar, Science Direct, Scopus, SciFinder Scholar, Springer Link, China National Knowledge Infrastructure (CNKI), Wanfang Data, and VIP database were used as electronic search engines for articles with the various specific keywords. Additionally, references from ancient texts and local information such as PhD and MSc theses, books, and Chinese journals were also included.

RESULTS

The clinical researches have revealed that Tubiechong alone has been successfully used to treat bone disease, ache, sprain, herpes zoster, paronychia and so on. Tubichong's main clinical application is to form formulations with other herbs. The most widely used 34 kinds of Chinese patent medicine containing Tubiechong were included in Chinese Pharmacopoeia (2020 Edition) for the treatment of traumatic injury, low back pain, cardiovascular disease, tumors or mass and nodule, cervical spondylopathy, osteoarthritis and psoriasis. Its other derived formulas have been used in the clinical treatment of various diseases, such as blood stasis, hepatic cirrhosis, cyclomastopathy, chronic active hepatitis, nephropathy, gynaecopathia, cancer diseases. To date, the bioactive substances reported are limited to protein and peptides, fatty acids, polysaccharides and alkaloids from Eupolyphaga sinensis Walker. So far, the pharmacological activities of Tubiechong and its various extracts have been evaluated, including anticoagulant and antithrombotic, anticancer, bone repair, immunomodulation, analgesia, antioxidant, antihyperlipidemic, antimicrobial and protective and repair functions for damage to the liver, heart, brain and skin. As an edible insect, its safety has also been confirmed by acute toxicity tests and 30-day feeding trials.

CONCLUSION

Tubiechong is an important insect medicine with the effect of promoting blood circulation and removing blood stasis, which has been used in traditional Chinese medicine for thousands of years for the treatment of trauma and abdominal lumps, and has now been clinically extended to the treatment of a variety of diseases. Its multiple pharmacological activities indicate that it has great potential for development and application. However, its chemical constituents with pharmacological activity require further excavation and detailed study. In addition, the in-depth molecular pharmacological mechanisms deserve further explanation.

Scoping review of the medicinal effects of Eupolyphaga sinensis Walker and the underlying mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Eupolyphaga sinensis Walker (ES) is an insect widely used in traditional East Asian medicine known to exhibit clinical effects on various pathological conditions. Overall, ES is a useful medicinal insect that can treat various diseases, including cancer and immune diseases. However, further mechanistic studies based on its therapeutic effects in clinical settings are required.

AIM OF THE STUDY

We aimed to evaluate the current research landscape and diseases associated with ES to synthesize the clinical value of ES based on the associated diseases and underlying therapeutic mechanisms.

MATERIALS AND METHODS

Embase and PubMed databases were searched for experimental studies that evaluated the therapeutic efficacy or underlying mechanisms of ES until May 2021. The evidence for each study was summarized using a narrative synthesis approach. Studies on extracted or dried whole ES and ES-derived compounds were quantitatively analyzed by year and disease type. Meanwhile, the overall research trend was confirmed for studies on ES-containing prescriptions by visualizing the disease type analysis.

RESULTS

A total of 151 studies were identified, of which 51 were included in our review. There were 14 studies on extracted or dried whole ES, 15 on ES-derived compounds, and 22 on ES-containing prescriptions. ES was most commonly used for cancer-related diseases, followed by those related to endocrine function and immunity. ES regulates the cell cycle, tumor suppressor genes and proteins, immune-related biomarkers, and antioxidant molecules.

CONCLUSIONS

Overall, ES is a beneficial medicinal insect that can treat various diseases, including cancer and immune diseases. However, further mechanistic studies based on its therapeutic effects in clinical settings are required.

A periodic review of chemical and pharmacological profiles of Tubiechong as insect Chinese medicine

Tubiechong, in Chinese medicine, denotes the dried female insects of Eupolyphaga sinensis Walker (ESW) or Polyphaga plancyi Bolivar (PPB). As a traditional insect-type, in medicine, it has been historically utilized to treat bruises, fractures, amenorrhea, postpartum blood stasis, lumps and relieving pain. We herein have performed a systematic survey involving the chemical and biological studies in the past decades to reveal the value of such insect resources for their development and clinical utilization. Chemical studies indicated that Tubiechong generated many active compounds, including proteins, amino acids, peptides, fatty acids, alkaloids, nucleosides, polysaccharides, fat-soluble vitamins and mineral elements. Tubiechong or its extract has a wide range of activities including anticoagulation and anti-thrombosis, anti-tumor, antioxidant, immune regulation, blood lipid regulation and hepatoprotection. Finally, a periodic mini-review was conducted to summarize such chemical and pharmacological profiles of Tubiechong medicine. The active peptides in Tubiechong are majorly focused in this review and introduced as one important aspect since there is much literature and huge investigative interest in it. Traditional medical use of the insect was also stressed in this review associating with its disease-eliminating actions by promoting blood circulation or eliminating tissue-swelling pains, which might play important roles in anticancer practices or investigation. In accordance with the modern pharmacological progress, Tubiechong and its extracts indeed exerted antitumor actions through multiple pathways, such as interfering with tumor biological behaviors (growth, apoptosis, invasion, metastasis and angiogenesis), and regulating host immune function. To some extent, this knowledge would provide a basis for further research and application of Tubiechong medicine.

Recent applications of asymmetric organocatalytic annulation reactions in natural product synthesis

The past two decades have witnessed remarkable growth of asymmetric organocatalysis, which is now a firmly established synthetic tool, serving as a powerful platform for the production of chiral molecules. Ring structures are ubiquitous in organic compounds, and, in the context of natural product synthesis, strategic construction of ring motifs is often crucial, fundamentally impacting the eventual fate of the whole synthetic plan. In this review, we provide a comprehensive and updated summary of asymmetric organocatalytic annulation reactions; in particular, the application of these annulation strategies in natural product synthesis will be highlighted.

Asymmetric organocatalysis: an enabling technology for medicinal chemistry

The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.

Enantioselective Construction of C-C Axially Chiral Quinazolinones via Chirality Exchange and Phase-Transfer Catalysis

A family of axially chiral quinazolinone-based heterobiaryls were constructed with high levels of enantiocontrol (up to 94% ee). Convergently, three different synthetic methods have been realized to prepare these valuable compounds including central-to-axial chirality transfer, dynamic kinetic resolution, and phase-transfer catalysis. Importantly, novel P,N-ligands with a π-π stacking can be derived from heterobiaryls by chirality exchange strategy or synthesized directly from complementary phase-transfer catalysis by using the inexpensive chiral quaternary ammonium salt.

Continuous Electrochemical Synthesis of Iso-Coumarin Derivatives from o-(1-Alkynyl) Benzoates under Metal- and Oxidant-Free

A non-oxidant and metal-free strategy for synthesizing iso-coumarin by using a continuous electrochemical microreactor to initiate an oxidative cyclization reaction of o-(1-alkynyl) benzoate and radicals. This efficient and clean continuous electrosynthesis method not only avoids the complicated gas protection operation and production of by-products in the batch processes, but also help to overcome the difficulty that batch metal catalysis and electrocatalysis are difficult to scale up, and has the potential for pilot-scale experiment.

Beneficial role of insect-derived bioactive components against inflammation and its associated complications (colitis and arthritis) and cancer

Insect-based bioactive components are emerging as novel sources of drugs, effective against various diseases. Inflammation is considered to be an innate immune response developed by different organisms against foreign pathogens and cellular stress. However, repetitive elevated inflammation is considered to be responsible for development of many other diseases including colitis and arthritis. Due to the limited activities and side effects of non-steroidal anti-inflammatory drugs, researchers are continuously looking for alternative sources of drug molecules to alleviate the inflammatory related complications. Recently, insect-based bioactive components, such as venoms, haemocytes, cecropin A, papiliocin, N-acetyldopamine dimers, cecropin-TY1 peptide, cop A3 peptide, glycosaminoglycan, coprisin peptide, silk fibroin microparticles, and silk fibroin nanoparticles have been found to be active against different inflammatory mechanisms and associated diseases. Cancers, are some of the deadliest diseases, which are mainly treated by chemotherapy, radiation therapy and surgery. However, such treatments, mainly chemotherapy, is associated with enormous side effects. Therefore, as an alternative, less hazardous option, compounds from insects with anti-cancerous activity are being explored. Insect-derived compounds, such as cantharidin, norcantharidin, isocoumarin, plancyols A, plancypyrazine A, pancratistatin, narciclasine, and ungeremine, show potential anti-cancerous activity. In this review, we will be discussing the role of different potential drug molecules of insect origin with special emphasis on anti-inflammation and their association with health disorders and cancer.

Insects: an underrepresented resource for the discovery of biologically active natural products

Nature has been the source of life-changing and -saving medications for centuries. Aspirin, penicillin and morphine are prime examples of Nature׳s gifts to medicine. These discoveries catalyzed the field of natural product drug discovery which has mostly focused on plants. However, insects have more than twice the number of species and entomotherapy has been in practice for as long as and often in conjunction with medicinal plants and is an important alternative to modern medicine in many parts of the world. Herein, an overview of current traditional medicinal applications of insects and characterization of isolated biologically active molecules starting from approximately 2010 is presented. Insect natural products reviewed were isolated from ants, bees, wasps, beetles, cockroaches, termites, flies, true bugs, moths and more. Biological activities of these natural products from insects include antimicrobial, antifungal, antiviral, anticancer, antioxidant, anti-inflammatory and immunomodulatory effects.

Brønsted acid-catalysed enantioselective construction of axially chiral arylquinazolinones

The axially chiral arylquinazolinone acts as a privileged structural scaffold, which is present in a large number of natural products and biologically active compounds as well as in chiral ligands. However, a direct catalytic enantioselective approach to access optically pure arylquinazolinones has been underexplored. Here we show a general and efficient approach to access enantiomerically pure arylquinazolinones in one-pot fashion catalysed by chiral phosphoric acids. A variety of axially chiral arylquinazolinones were obtained in high yields with good to excellent enantioselectivities under mild condition. Furthermore, we disclosed a method for atroposelective synthesis of alkyl-substituted arylquinazolinones involving Brønsted acid-catalysed carbon–carbon bond cleavage strategy. Finally, the asymmetric total synthesis of eupolyphagin bearing a cyclic arylquinazolinone skeleton was accomplished with an overall yield of 32% in six steps by utilizing the aforementioned methodology.

Axially chiral arylquinazolinones are structural motifs in several natural products and can also act as chiral ligands. Here, the authors show a chiral phosphoric acid-catalysed strategy to access enantiomerically pure arylquinazolinones by efficient transfer of central chirality into axial chirality.

Metabolic Profile Changes of CCl₄-Liver Fibrosis and Inhibitory Effects of Jiaqi Ganxian Granule

Jiaqi Ganxian Granule (JGG) is a famous traditional Chinese medicine, which has been long used in clinical practice for treating liver fibrosis. However, the mechanism underlying its anti-hepatic fibrosis is still not clear. In this study, an Ultra-Performance Liquid Chromatography-Time-Of-Flight Mass Spectrometry (UPLC-TOF-MS)-based metabolomics strategy was used to profile the metabolic characteristic of serum obtained from a carbon tetrachloride (CCl₄)-induced hepatic fibrosis model in Sprague-Dawley (SD) rats with JGG treatment. Through Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS-DA), it was shown that metabolic perturbations induced by CCl₄ were inhibited after treatment of JGG, for 17 different metabolites related to CCl₄. Among these compounds, the change tendency of eight potential drug targets was restored after the intervention with JGG. The current study indicates that JGG has a significant anti-fibrosis effect on CCl₄-induced liver fibrosis in rats, which might be by regulating the dysfunction of sphingolipid metabolism, glycerophospholipid metabolism, N-acylethanolamine biosynthesis, fat digestion and absorption, while glycerophospholipid metabolism played vital roles in the inhibitory effects of JGG on hepatic fibrosis according to Metabolic Pathway Analysis (MetPA). Our findings indicated that the metabolomics approach may provide a useful tool for exploring potential biomarkers involved in hepatic fibrosis and elucidate the mechanisms underlying the action of therapies used in traditional Chinese medicine.

Isocoumarins, miraculous natural products blessed with diverse pharmacological activities

Isocoumarins are lactonic natural products abundant in microbes and higher plants. These are considered an amazing scaffold consecrated with more or less all types of pharmacological applications. This review is complementary to the earlier reviews and aims to focus the overlooked aspects of their fascinating chemistry with special emphasis on their classification and diverse biological activities with some SAR conclusions. The most recent available literature on the structural diversity and biological activity of these natural products has been reviewed.

An unusual dihydrobenzofuroisocoumarin and ent-kaurane diterpenoids from Pteris multifida

An unusual 5-C-methylated-dihydrobenzofuroisocoumarin, named multifidarin A (1), and two new ent-kaurane diterpenoids, named multikauranes A (2) and B (3), together with three known ent-kaurane diterpenoids, were isolated from the whole plants of Pteris multifida. The structures of 1-3 were elucidated by spectroscopic methods. The cytotoxic activities of all new compounds were evaluated against five human tumor cell lines. A possible biosynthetic process for the formation of 1 is proposed.

Biosynthetically Distinct Cytotoxic Polyketides from Setophoma terrestris

Sixteen polyketides belonging to diverse structural classes, including monomeric/dimeric tetrahydroxanthones and resorcylic acid lactones, were isolated from an organic extract of a fungal culture Setophoma terrestris (MSX45109) using bioactivity-directed fractionation as part of a search for anticancer leads from filamentous fungi. Of these, six were new: penicillixanthone B (5), blennolide H (6), 11-deoxy blennolide D (7), blennolide I (9), blennolide J (10), and pyrenomycin (16). The known compounds were: secalonic acid A (1), secalonic acid E (2), secalonic acid G (3), penicillixanthone A (4), paecilin B (8), aigialomycin A (11), hypothemycin (12), dihydrohypothemycin (13), pyrenochaetic acid C (14), and nidulalin B (15). The structures were elucidated using a set of spectroscopic and spectrometric techniques; the absolute configurations of compounds 1-10 were determined using ECD spectroscopy combined with time-dependent density functional theory (TDDFT) calculations, while a modified Mosher's ester method was used for compound 16. The cytotoxic activities of compounds (1-15) were evaluated using the MDA-MB-435 (melanoma) and SW-620 (colon) cancer cell lines. Compounds 1, 4, and 12 were the most potent with IC50 values ranging from 0.16 to 2.14 μM. When tested against a panel of bacteria and fungi, compounds 3 and 5 showed promising activity against the Gram-positive bacterium Micrococcus luteus with MIC values of 5 and 15 μg/mL, respectively.

Isocoumarins from American cockroach (Periplaneta americana) and their cytotoxic activities

Four new isocoumarins (1-4), along with three known ones (5-7), were isolated from the 70% ethanol extract of the whole body of the traditional Chinese insect medicine, American cockroach (Periplaneta americana). The structures with absolute configurations of new compounds were elucidated by extensive spectroscopic methods in combination with X-ray diffraction experiment and CD analyses. Compounds 3-5 showed significant cytotoxic activities in HepG2 and MCF-7 cells with IC50 values in the ranges 6.41-23.91 μM and 6.67-39.07 μM, respectively.

Characterization and comparative profiling of MicroRNAs in a sexual dimorphism insect, Eupolyphaga sinensis Walker

BACKGROUND

MicroRNAs are now recognized as key post-transcriptional regulators in animal ontogenesis and phenotypic diversity. Eupolyphaga sinensis Walker (Blattaria) is a sexually dimorphic insect, which is also an important source of material used in traditional Chinese medicine. The male E. sinensis have shorter lifecycles and go through fewer instars than the female. Furthermore, the males have forewings, while the females are totally wingless.

RESULTS

We used the Illumina/Solexa deep sequencing technology to sequence small RNA libraries prepared from the fourth-instar larvae of male and female E. sinensis. 19,097,799 raw reads were yielded in total: 7,817,445 reads from the female library and 11,280,354 from the male, respectively. As a result, we identified 168 known miRNAs belonging to 55 families as well as 204 novel miRNAs. Moreover, 45 miRNAs showed significantly different expression between the female and the male fourth-instar larvae, and we validated 10 of them by Stem-loop qRT-PCR. Some of these differentially expressed miRNAs are related to metamorphosis, development and phenotypic diversity.

CONCLUSIONS/SIGNIFICANCE

This is the first comprehensive description of miRNAs in E. sinensis. The results provide a useful resource for further in-depth study on molecular regulation and evolution of miRNAs. These findings not only enrich miRNAs for hemimetabolans but also lay the foundation for the study of post-transcriptional regulation on the phenomena of sexual dimorphism.