Prenylated Coumarins from the Fruits of Manilkara zapota with Potential Anti-inflammatory Effects and Anti-HIV Activities

Novel coumarin linked pyrazoles, thiazoles, and thiadiazoles: synthetic strategies and in vitro antimicrobial investigation

AIM

Emerging resistance among pathogens necessitates the development of novel antimicrobial agents. As a result, we aimed to synthesize new coumarins and study their antimicrobial activity with the hope of obtaining effective drugs.

METHOD

A series of coumarins were synthesized, characterized, and assessed for antimicrobial activity using broth microdilution and agar diffusion methods against Gram-positive (Bacillus pumilis, Streptococcus faecalis), Gram-negative (Escherichia coli, Enterobacter cloacae) bacteria, and fungi (Saccharomyces cerevisiae, Candida albicans).

RESULTS

Pyrazoles 15 and 16 revealed promising activities against all bacterial strains with MIC values ranging from 1.95 to 15.6 µg/ml. Notably, pyrazole 15 with CF3 in 3-position of pyrazole ring demonstrated higher ability to inhibit Streptococcus faecalis strain with MIC value equal to penicillin G (3.91 µg/ml). It also exhibited the best bactericidal potency against Escherichia coli with MBC value of 15.6 µg/ml while, pyrazole 16 recorded the same MBC value against Enterobacter cloacae. Pyrazole 15 demonstrated the strongest antifungal activity against both fungal strains with MIC and MFC values of 15.6, 7.81, 62.5, and 31.3 µg/ml against Saccharomyces cerevisiae and Candida albicans, respectively.

CONCLUSION

These findings underscore the potential of coumarins, particularly compounds 15 and 16, as effective antimicrobial agents and provide critical insights into the design of bioactive molecules.

Coumarins as versatile therapeutic phytomolecules: A systematic review

BACKGROUND

Coumarins, abundantly distributed in a plethora of biologically active compounds, serve as a fundamental motif in numerous natural products, drugs, and therapeutic leads. Despite their small size, they exhibit a diverse range of biological activities, intriguing researchers with their immense pharmacological potential.

PURPOSE

This study consolidates the evidence regarding the essential role of coumarins in modern drug discovery, exploring their broad-spectrum pharmaceutical effects, structural versatility, and mechanisms of action across various domains.

METHODS

For literature search, we utilized PubMed, Google scholar, and SciFinder databases. Keyword and keyword combinations such as "coumarins", "natural coumarins", "specific natural coumarins for particular diseases", and "therapeutic effects" were employed to retrieve relevant studies. The search encompassed articles published between 2005 and 2023. Selection criteria included studies reporting on the pharmacological activities of natural coumarins against various diseases.

RESULTS

The results highlight the therapeutic potential of natural coumarins against various diseases, demonstrating anti-cancer, anti-oxidant, and anti-inflammatory activities. They also act as monoamine oxidase inhibitors and phosphodiesterase inhibitors, and as anti-thrombotic, anti-diabetic, and hepatoprotective agents. They also show efficacy against diabetic nephropathy, neurodegenerative diseases, microbial infections and many other diseases.

CONCLUSION

This review underscores the significant role of natural coumarins in medicinal chemistry and drug discovery. Their diverse biological activities and structural versatility make them promising therapeutic agents. This study serves as a catalyst for further research in the field, aiming to address emerging challenges and opportunities in drug development.

Discovery of Coumarins from Zanthoxylum dimorphophyllum var. spinifoliumas and Their Potential against Rheumatoid Arthritis

In the present study, a series of coumarins, including eight undescribed bis-isoprenylated ones Spinifoliumin A-H, were isolated and identified from the aerial parts of Zanthoxylum dimorphophyllum var. spinifolium (ZDS), a plant revered in traditional Chinese medicine, particularly for treating rheumatoid arthritis (RA). The structures of the compounds were elucidated using 1D and 2D NMR spectroscopy, complemented by ECD, [Rh2(OCOCF3)4]-induced ECD, Mo2(OAc)4 induced ECD, IR, and HR-ESI-MS mass spectrometry. A network pharmacology approach allowed for predicting their anti-RA mechanisms and identifying the MAPK and PI3K-Akt signaling pathways, with EGFR as a critical gene target. A CCK-8 method was used to evaluate the inhibition activities on HFLS-RA cells of these compounds. The results demonstrated that Spinifoliumin A, B, and D-H are effective at preventing the abnormal proliferation of LPS-induced HFLS-RA cells. The results showed that compounds Spinifoliumin A, D, and G can significantly suppress the levels of IL-1β, IL-6, and TNF-α. Moreover, molecular docking methods were utilized to confirm the high affinity between Spinifoliumin A, D, and G and EGFR, SRC, and JUN, which were consistent with the results of network pharmacology. This study provides basic scientific evidence to support ZDS's traditional use and potential clinical application.

Electrospray ionization tandem mass spectrometry of 4-aryl-3,4-dihydrocoumarins

We have investigated the gas-phase fragmentation reactions of 11 synthetic 4-aryl-3,4-dihydrocoumarins by electrospray ionization tandem mass spectrometry (ESI-MS/MS) on a quadrupole-time-of flight (Q-TOF) hybrid mass spectrometer. We have also estimated thermochemical data for the protonated coumarins (precursor ion A) and product ion structures by computational chemistry at a B3LYP level of theory to establish the ion structures and to rationalize the fragmentation pathways. The most abundant ions in the product ion spectra of coumarins 1-11 resulted from C8H8O2, CO2, C4H4O3, C8H10O3, C8H8O2, and CH3OH eliminations through retro-Diels-Alder (RDA) reactions, remote hydrogen rearrangements (β-eliminations), and β-lactone ring contraction. Although the investigated coumarins shared most of the fragmentation pathways, formation of a benzylic product ion and its corresponding tropylium ion was diagnostic of the substituents at ring C. The thermochemical data revealed that the nature and position of the substituents at ring C played a key role in the formation of this product ion and determined its relative intensity in the product ion spectrum. The results of this study contribute to knowledge of the gas-phase ion chemistry of this important class of organic compounds.

Natural products as potential lead compounds to develop new antiviral drugs over the past decade

Virus infection has been one of the main causes of human death since the ancient times. Even though more and more antiviral drugs have been approved in clinic, long-term use can easily lead to the emergence of drug resistance and side effects. Fortunately, there are many kinds of metabolites which were produced by plants, marine organisms and microorganisms in nature with rich structural skeletons, and they are natural treasure house for people to find antiviral active substances. Aiming at many types of viruses that had caused serious harm to human health in recent years, this review summarizes the natural products with antiviral activity that had been reported for the first time in the past ten years, we also sort out the source, chemical structure and safety indicators in order to provide potential lead compounds for the research and development of new antiviral drugs.

Amazonian medicinal plants efficiently inactivate Herpes and Chikungunya viruses

The Amazonian species investigated in this research are commonly utilized for their anti-inflammatory properties and their potential against various diseases. However, there is a lack of scientifically supported information validating their biological activities. In this study, a total of seventeen ethanolic or aqueous extracts derived from eight Amazonian medicinal plants were evaluated for their activity against Herpes Simplex type 1 (HSV-1) and Chikungunya viruses (CHIKV). Cytotoxicity was assessed using the sulforhodamine B method, and the antiviral potential was determined through a plaque number reduction assay. Virucidal tests were conducted according to EN 14476 standards for the most potent extracts. Additionally, the chemical composition of the most active extracts was investigated. Notably, the LMLE10, LMBA11, MEBE13, and VABE17 extracts exhibited significant activity against CHIKV and the non-acyclovir-resistant strain of HSV-1 (KOS) (SI > 9). The MEBE13 extract demonstrated unique inhibition against the acyclovir-resistant strain of HSV-1 (29-R). Virucidal assays indicated a higher level of virucidal activity compared to their antiviral activity. Moreover, the virucidal capacity of the most active extracts was sustained when tested in the presence of protein solutions against HSV-1 (KOS). In the application of EN 14476 against HSV-1 (KOS), the LMBA11 extract achieved a 99.9% inhibition rate, while the VABE17 extract reached a 90% inhibition rate. This study contributes to the understanding of medicinal species native to the Brazilian Amazon, revealing their potential in combating viral infections that have plagued humanity for centuries (HSV-1) or currently lack specific therapeutic interventions (CHIKV).

Design and Synthesis of Pyrimidine Amine Containing Isothiazole Coumarins for Fungal Control

Developing new fungicides is always crucial to protecting crops. A series of 4-(3,4-dichloroisothiazol-5-yl)-7-(2-((5-(5-pyrimidin-4-yl)amino)ethoxy)-8-methyl) coumarin derivatives were designed and synthesized by Williamson ether condensation and substitution reactions. Structure determinations were clarified by 1H NMR, 13C NMR, and HRMS, and compound 4h crystallized by the fusion method for further structural confirmation. The in vitro bioassay results showed that the target compounds displayed good fungicidal activity against Alternaria solani, Botrytis cinerea, Cercospora arachidicola, Fusarium graminearum, Physalospora piricola, Rhizoctonia solani, and Sclerotinia sclerotiorum. Among them, compounds 4b and 4d showed higher inhibitory activity against R. solani, with EC50 values of 11.3 and 13.7 μg/mL, respectively, and they were more active than the positive control diflumetorim with an EC50 value of 19.8 μg/mL. Molecular docking suggested that compound 4b and diflumetorim may have similar interactions with complex I NADH oxidoreductase. Density functional theory calculation and pesticide-likeness analysis studies gave a rational explanation of their fungicidal activity. These results indicated that compounds 4b and 4d deserved further optimization according to the principle of pesticide-likeness.

Novel Coumarin-furo[2,3-d]pyrimidinone hybrid derivatives as anticancer agents: Synthesis, biological evaluation and molecular docking

A series of coumarin-furo[2,3-d]pyrimidinone hybrid derivatives were synthesized, characterized by HR-MS, 1H NMR and 13C NMR. All synthesized compounds were evaluated for antiproliferative activities against hepatic carcinoma (HepG2) and cervical carcinoma (Hela) cell lines in vitro, and results shown that most of the compounds exhibited potent antitumor activity. Moreover, compound 3i, 8d and 8i were selected to induce apoptosis in HepG2 cells, and it displayed a significant concentration-dependent. Further, transwell migration assay was used to detect the most potent compound 8i, and the results revealed that 8i can significantly inhibit HepG2 cells migration and invasion. In addition, kinase activity assay showed compound 8i may be a multi-target inhibitor, which 8i has an inhibition rate of 40-20% on RON, ABL, GSK3α and so on ten different kinases at the concentration 1 μmol/L. At the same time, molecular docking studies revealed the possible binding modes of compounds 3i, 8d and 8i with kinase recepteur d'origine nantais (RON). A comparative molecular field analysis (CoMFA) model was established from 3D-QSAR study that guide us to a more bulkly and electro-positive Y group at the C-2 position of furo[2,3-d]pyrimidinone ring was preferable for the bioactivity improvement of our compounds. Our preliminary research indicated that the coumarin skeleton introducing to the furo[2,3-d]pyrimidine system had a significantly influence on the biological activities.

Xanthones with Potential Anti-Inflammatory and Anti-HIV Effects from the Stems and Leaves of Cratoxylum cochinchinense

Four new xanthones, cratocochinones A-D (1-4), together with eight known analogues (5-12), were isolated from the stems and leaves of Cratoxylum cochinchinense. The chemical structures of cratocochinones A-D (1-4) were elucidated by comprehensive spectroscopic analyses and the known compounds were identified by comparisons with the spectral data reported in the literature. All isolated compounds 1-12 were evaluated for their anti-inflammatory activities and anti-HIV-1 activities. Compounds 1-12 showed remarkable inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro, with IC50 values in the range of 0.86 ± 0.05 to 18.36 ± 0.21 µM. Meanwhile, compounds 1-12 exhibited significant anti-HIV-1 activities with EC50 which ranged from 0.22 to 11.23 µM. These findings indicate that the discoveries of these xanthones, isolated from the stems and leaves of C. cochinchinense, showing significant anti-inflammatory and anti-HIV-1 effects could be of great importance to the research and development of new natural anti-inflammatory and anti-HIV agents.

Manilkara zapota "chicozapote" as a fruit source of health-beneficial bioactive compounds and its effects on chronic degenerative and infectious diseases, a review

Manilkara zapota "chicozapote" is an autochthonous evergreen tree from the Southern regions of Mexico, Belize, and Guatemala. Currently, it is widely distributed and extensively grown in Mexico and Southeast Asia. Traditionally, different structures of the plant have been used for medical purposes; seeds have diuretic and purgative properties, aiding in digestive complications and eliminating bladder and kidney stones. Tree bark has antidiarrheal, antipyretic, antibiotic, and astringent properties. Fruits and leaves have been used to treat cold, cough, diarrhea, indigestion, fever, hemorrhages, wounds, and ulcers. Chicozapote fruit is yellow and brown, with an oval shape and rough peel, it is an excellent source of nutrients, such as sugars, proteins, amino acids, and minerals, and is rich in phytochemical components, such as flavonoids, phenolic acids, and tannins. These bioactive compounds exert several biological activities, i.e., as an antioxidant, antidiabetic, antimicrobial, anti-inflammatory, cytotoxic, and anti-arthritic agents, to name a few. These beneficial properties assist in preventing chronic and degenerative diseases, such as cancer, diabetes, neurological, infectious, and cardiovascular diseases. The use of chicozapote is still limited to its fresh form, and its non-edible structures produce a lot of waste. Therefore, an alternative valorizing and preserving strategy is to use the fruit as a raw source to design functional foods and pharmacological products. Here, the nutritional and phytochemical profiles and the current view regarding methodologies and conditions, for the extraction and characterization of its bioactive compounds, are described, and focus is placed on their multiple biological effects and specific functional mechanisms.

Synthesis and antimicrobial activity of new series of thiazoles, pyridines and pyrazoles based on coumarin moiety

Microbial infections are currently a widespread disease in hospitals and community health centres and are a major cause of death worldwide. In pursuit of searching new antimicrobial agents, coumarin linked to thiazoles, pyridines and pyrazoles have been developed and evaluated for their antimicrobial properties against two Gram + bacteria, two Gram - bacteria as well as two fungi. Some of the prepared coumarins displayed high to moderate activity against the tested microorganisms with respect to the reference drugs. However, compound 3 exhibited antimicrobial effect equal to the reference drug Ciprofloxacin for Gram - baceria Enterobacter cloacae. Compound 12 was found to be the most potent compound against Bacillus pumilis with MIC of 7.69 (µmol/ml). Compounds 3, 4 and 12 showed remarkable activity against Streptococcus faecalis with MIC of 14.34, 3.67 and 15.36 (µmol/ml), respectively. Regarding Escherichia coli, most compounds recorded high to moderate MIC values (4.73-45.46 µmol/ml). Moreover, in case of E. cloacae compound 9 was the most potent compound with MIC value of 22.76 (µmol/ml).

Plant Coumarins with Anti-HIV Activity: Isolation and Mechanisms of Action

This review summarizes and systematizes the literature on the anti-HIV activity of plant coumarins with emphasis on isolation and the mechanism of their antiviral action. This review summarizes the information on the anti-HIV properties of simple coumarins as well as annulated furano- and pyranocoumarins and shows that coumarins of plant origin can act by several mechanisms: inhibition of HIV reverse transcriptase and integrase, inhibition of cellular factors that regulate HIV-1 replication, and transmission of viral particles from infected macrophages to healthy ones. It is important to note that some pyranocoumarins are able to act through several mechanisms or bind to several sites, which ensures the resistance of these compounds to HIV mutations. Here we review the last two decades of research on the anti-HIV activity of naturally occurring coumarins.

Syzysamalactone, an Unusual 11-Carbon δ-Lactone Derivative from the Fresh Ripe Fruits of Syzygium samarangense (Wax Apple)

To study the chemical constituents from the ripe fresh fruits of Syzygium samarangense (wax apple) and their potential health effects, a phytochemical investigation was undertaken. A new δ-lactone derivative, syzysamalactone (1), along with a known biogenetically related δ-lactone derivative, 6-pentyl-α-pyrone (2), were isolated from the fresh ripe fruits of S. samarangense. Syzysamalactone (1) is an unusual 11-carbon δ-lactone derivative, and its chemical structure and absolute configuration were elucidated by spectroscopic data analysis. A plausible biogenetic pathway for 1 was also proposed. Furthermore, the potential neuroprotective effects of compounds 1 and 2 were assessed. As a result, compounds 1 and 2 displayed notable neuroprotective effects with EC₅₀ values of 0.29 ± 0.03 and 1.28 ± 0.06 μM, respectively, using the SH-SY5Y human neuroblastoma cell line. This is the first report of δ-lactone derivatives showing significant neuroprotective activities.

Recent Advances in the Discovery and Development of Anti-HIV Natural Products

Acquired immunodeficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV) infection is a serious public problem threatening global health. At present, although "cocktail therapy" has achieved significant clinical effects, HIV still cannot be completely eradicated. Furthermore, long-term antiviral treatment has caused problems such as toxic side effects, the emergence of drug-resistant viruses, and poor patient compliance. Therefore, it is highly necessary to continue to search for high-efficient, low-toxic anti-HIV drugs with new mechanisms. Natural products have the merits of diverse scaffolds, biological activities, and low toxicity that are deemed the important sources of drug discovery. Thus, finding lead compounds from natural products followed by structure optimization has become one of the important ways of modern drug discovery. Nowadays, many natural products have been found, such as berberine, gnidimacrin, betulone, and kuwanon-L, which exert effective anti-HIV activity through immune regulation, inhibition of related functional enzymes in HIV replication, and anti-oxidation. This paper reviewed these natural products, their related chemical structure optimization, and their anti-HIV mechanisms.

Anti-Inflammatory Medicinal Plants of Bangladesh—A Pharmacological Evaluation

Inflammatory diseases are considered major threats to human health worldwide. In Bangladesh, a number of medicinal plants have been used in traditional medicine from time immemorial in the treatment of diverse diseases, including inflammatory disorders. This assignment aims at providing the status of the medicinal plants of Bangladesh which are traditionally used in the management of inflammatory disorders and are investigated for their anti-inflammatory prospects using different preclinical studies and future research directions. The information of medicinal plants assembled in this review was obtained from a literature search of electronic databases such as Google Scholar, PubMed, Scopus, Web of Science and ScienceDirect up to December, 2020 from publications on plants investigated for their anti-inflammatory activities, in which the place of plant sample collection was identified as Bangladesh. Keywords for primary searches were “anti-inflammatory,” “Bangladeshi,” and “medicinal plants.” Criteria followed to include plant species were plants that showed significant anti-inflammatory activities in 1) two or more sets of experiments in a single report, 2) same or different sets of experiments in two or more reports, and, 3) plants which are traditionally used in the treatment of inflammation and inflammatory disorders. In this study, 48 species of medicinal plants have been reviewed which have been used in traditional healing practices to manage inflammatory disorders in Bangladesh. The mechanistic pathways of the in vivo and in vitro study models used for the evaluation of anti-inflammatory properties of plant samples have been discussed. Selected plants were described in further detail for their habitat, anti-inflammatory studies conducted in countries other than Bangladesh, and anti-inflammatory active constituents isolated from these plants if any. Medicinal plants of Bangladesh have immense significance for anti-inflammatory activity and have potential to contribute toward the discovery and development of novel therapeutic approaches to combat diseases associated with inflammation. However, the plants reviewed in this article had chiefly undergone preliminary screening and require substantial investigations including identification of active molecules, understanding the mechanism of action, and evaluation for safety and efficacy to be followed by the formulation of safe and effective drug products.

Pharmacological perspectives and molecular mechanisms of coumarin derivatives against virus disease

Infections caused by viruses are one of the foremost causes of morbidity and mortality in the world. Although a number of antiviral drugs are currently used for treatment of various kinds of viral infection diseases, there is still no available therapeutic agent for most of the viruses in clinical practice. Coumarin is a chemical compound which is found naturally in a variety of plants, it can also be synthetically produced possessing diverse biological effects. More recently, reports have highlighted the potential role of coumarin derivatives as antiviral agents. This review outlines the advances in coumarin-based compounds against various viruses including human immunodeficiency virus, hepatitis virus, herpes simplex virus, Chikungunya virus and Enterovirus 71, as well as the structure activity relationship and the possible mechanism of action of the most potent coumarin derivatives.

Artapilosines A and B, Unusual Phenanthrene Derivatives Related to Aporphine Alkaloids from Artabotrys pilosus

Two unusual phenanthrene derivatives related to aporphine alkaloids, artapilosines A (1) and B (2), as well as two biogenetically related known aporphine alkaloids, (-)-anonaine (3) and (-)-N-acetylanonaine (4), were separated and purified from Artabotrys pilosus. Artapilosine A (1) is the first compound representative of a new class of phenanthrene derivatives having an unprecedented carbon skeleton, in which the six-membered nitrogen-containing heterocyclic structure in a typical aporphine alkaloid was substituted with a unique five-membered carbocyclic ring. This is the first report of the formation of a carbon-carbon bond between C-5 and C-6a in 1 with the loss of the nitrogen atom N-6 in the classic aporphine alkaloid. Artapilosine B (2) is a novel phenanthrene derivative having a hydroxyethyl as a substituent on the phenanthrene ring. Their chemical structures as well as absolute configurations were determined based on analysis of spectroscopic data. Additionally, the potential anti-HIV activities of all isolates 1-4 were appraised. Artapilosines A (1) and B (2) showed notable anti-HIV reverse transcriptase affects, with EC₅₀ values of 20.93 and 125.29 nM, respectively. These results suggested that the discovery of these novel phenanthrene derivatives from A. pilosus with remarkable anti-HIV effects could be essentially important for the researching and developing of new anti-HIV agents.

Clausanisumine, a Prenylated Bicarbazole Alkaloid from the Fruits of Clausena anisum-olens and Its Potential Anti-HIV Activity

A unique prenylated bicarbazole alkaloid, clausanisumine (1), and two biogenetically related known monomer carbazole alkaloids, mukonal (2) and 3-methylcarbazole (3), were isolated from the fruits of Clausena anisum-olens. Clausanisumine (1) was an uncommon prenylated bicarbazole alkaloid, possessing an unprecedented carbon skeleton, which was composed of a simple carbazole alkaloid and a prenylated carbazole alkaloid. The chemical structure of 1 was established by a combination of comprehensive spectral methods. A plausible biosynthetic pathway of 1 was also proposed. Additionally, the potential anti-HIV activities of all isolates 1-3 in vitro were evaluated. Compound 1 exhibited remarkable anti-HIV-1 reverse transcriptase effects showing an EC₅₀ value of 18.58 nM. The discovery of the prenylated bicarbazole alkaloid from C. anisum-olens with notable anti-HIV activity would be meaningful to discovering and developing new anti-HIV drugs.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Prenylated coumarins from the fruits of Artocarpus heterophyllus with their potential anti-inflammatory and anti-HIV activities

A phytochemical investigation on the fruits of Artocarpus heterophyllus led to the isolation and characterisation of a new prenylated coumarin, artoheteronin (1), together with six known analogues (2-7). The chemical structure of 1 was elucidated using extensive spectral methods and the known compounds (2-7) were identified by comparing their spectral data with those reported in the literature. All known compounds (2-7) were isolated from the genus Artocarpus for the first time. The anti-inflammatory and anti-HIV activities of all isolated prenylated coumarins (1-7) were assessed in vitro. As a result, compounds 1-7 displayed notable inhibitory effects against nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro with the IC₅₀ values in range of 0.58 ± 0.06 to 6.29 ± 0.12 μM. Meanwhile, compounds 1-7 exhibited notable anti-HIV-1 reverse transcriptase (RT) activities possessing EC₅₀ values in the range of 0.18 to 9.12 µM.

Antiviral Activity of Isoimperatorin Against Influenza A Virus in vitro and its Inhibition of Neuraminidase

Influenza A virus (IAV) poses a severe threat to human health and is a major public health problem worldwide. As global anti-influenza virus drug resistance has increased significantly, there is an urgent need to develop new antiviral drugs, especially drugs from natural products. Isoimperatorin, an active natural furanocoumarin, exhibits a broad range of pharmacologic activities including anticoagulant, analgesic, anti-inflammatory, antibacterial, anti-tumor, and other pharmacological effects, so it has attracted more and more attention. In this study, the antiviral and mechanistic effects of isoimperatorin on influenza A virus in vitro were studied. Isoimperatorin illustrated a broad-spectrum antiviral effect, especially against the A/FM/1/47 (H1N1), A/WSN/33 (H1N1, S31N, amantadine resistant), A/Puerto Rico/8/34 (H1N1), and A/Chicken/Guangdong/1996 (H9N2) virus strains. The experimental results of different administration modes showed that isoimperatorin had the best antiviral activity under the treatment mode. Further time-of-addition experiment results indicated that when isoimperatorin was added at the later stage of the virus replication cycle (6–8 h, 8–10 h), it exhibited an effective antiviral effect, and the virus yield was reduced by 81.4 and 84.6%, respectively. In addition, isoimperatorin had no effect on the expression of the three viral RNAs (mRNA, vRNA, and cRNA). Both the neuraminidase (NA) inhibition assay and CETSA demonstrated that isoimperatorin exerts an inhibitory effect on NA-mediated progeny virus release. The molecular docking experiment simulated the direct interaction between isoimperatorin and NA protein amino acid residues. In summary, isoimperatorin can be used as a potential agent for the prevention and treatment of influenza A virus.

Structural and kinetic insights into HIV-1 reverse transcriptase inhibition by farnesiferol C

Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) is the key enzyme for the virus gene replication and the most important target for antiviral therapy. Toxicity, drug resistance and side effects have led to search for new antiviral agents. Farnesiferol C (FC) is a well-known biologically active sesquiterpene coumarin derivative from genus Ferula. The current study was designed to examine the impacts of FC on the structure and function of HIV-1 RT, using some theoretical and experimental methods. FC inhibited HIV-1RT activity via mixed inhibition mechanism (IC₅₀ = 30 μM). Spectroscopic data showed some conformational changes in the secondary as well as tertiary structure of HIV-1RT following the interaction with FC. Results showed that FC could quench the intrinsic fluorescence emission of HIV-1RT through static quenching mechanism. Thermodynamic parameters revealed that hydrogen bondings and van der Waals forces are the major forces in the binding reaction and the low equilibrium constants (K_D) value obtained from surface plasmon resonance data, confirmed the high affinity of FC for HIV-1RT. Molecular docking studies indicated that FC interacts with enzyme through hydrophobic pocket. Taken together, the outcomes of this research revealed that, sesquiterpene coumarines can be used to design natural remedies as anti-HIV agents.

Limonoids from the Fresh Young Leaves and Buds of Toona sinensis and Their Potential Neuroprotective Effects

Toona sinensis, popularly known as Chinese toon or Chinese mahogany, is a perennial deciduous arbor belonging to the genus Toona in the Meliaceae family, which is widely distributed and cultivated in eastern and southeastern Asia. Its fresh young leaves and buds have been consumed as a very popular nutritious vegetable in China and confirmed to display a wide variety of biological activities. To investigate the chemical constituents and their potential health benefits from the fresh young leaves and buds of T. sinensis, a phytochemical study on its fresh young leaves and buds was therefore undertaken. In our current investigation, 16 limonoids (1-16), including four new limonoids, toonasinenoids A-D (1-4), and a new naturally occurring limonoid, toonasinenoid E (5), were isolated and characterized from the fresh young leaves and buds of T. sinensis. The chemical structures and absolute configurations of limonoids 1-5 were elucidated by comprehensive spectroscopic data analyses. All known limonoids (6-16) were identified via comparing their experimental spectral data containing mass spectrometry data, ¹H and ¹³C nuclear magnetic resonance data, and optical rotation values to the data reported in the literature. All known limonoids (6-16) were isolated from T. sinensis for the first time. Furthermore, the neuroprotective effects of all isolated limonoids 1-16 against 6-hydroxydopamine-induced cell death in human neuroblastoma SH-SY5Y cells were assessed in vitro. Limonoids 1-16 exhibited notable neuroprotective activities, with EC₅₀ values in the range from 0.27 ± 0.03 to 17.28 ± 0.16 μM. These results suggest that regular consumption of the fresh young leaves and buds of T. sinensis might prevent the occurrence and development of Parkinson's disease (PD). Moreover, the isolation and characterization of these limonoids that exhibit notable neuroprotective activities from the fresh young leaves and buds of T. sinensis could be very significant for researching and developing new neuroprotective drugs used for the prevention and treatment of PD.

Synthesis, antiproliferative activities, and DNA binding of coumarin-3-formamido derivatives

Ten coumarin-3-formamido derivatives, N-benzyl-coumarin-3-carboxamide (2), N-fluorobenzyl-coumarin-3-carboxamide (3-5), N-methoxybenzyl-coumarin-3-carboxamide (6-8), N-((1-methyl-1H-imidazol-5-yl)methyl)-coumarin-3-carboxamide (9), N-(thiophen-2-ylmethyl)-coumarin-3-carboxamide (10), and N-(furan-2-ylmethyl)-coumarin-3-carboxamide (11), were synthesized and characterized. Compound 5 crystallizes in a monoclinic system P2₁ /c space group with four chemical formulas in a unit cell; molecules of compound 5 are self-assembled into a two-dimensional supramolecular structure by intermolecular hydrogen bonds and C⋯C π stacking. The potential anticancer effects of these compounds on HeLa (cervical carcinoma), MCF-7 (breast), A549 (lung), HepG2 (liver), and human umbilical vein (HUVEC) cells were examined. Compared with compounds 1-8 and 10-11, compound 9 exhibits potent in vitro cytotoxicity against HeLa cells and lower cytotoxicity against normal cells. Therefore, further in-depth investigations of compound 9 were performed. Absorption titration experiments and fluorescence spectroscopy studies suggested that compound 9 binds to DNA through the intercalation mode.

Protective effect of lyophilized sapodilla (Manilkara zapota) fruit extract against CCl4-induced liver damage in rats

The tropical fruit sapodilla (Manilkara zapota syn. Achras zapota) is a rich source of nutrients, minerals and a myriad of bioactive phytochemicals such as flavonoids and catechins. Pharmacologically, sapodilla has been shown to exhibit anti-bacterial, anti-parasitic, anti-fungal, antiglycative, hypocholesterolemic and anti-cancer effects. However, its influence on hepatic tissue and serum lipids remains obscure. To address this, we used an in vivo model of liver damage to elucidate the effect of lyophilized sapodilla extract (LSE) treatment in carbon tetra chloride (CCl₄) intoxicated rats. Exposure of CCl₄ resulted in elevation of serum biomarkers of liver damage (aspartate transaminase, alanine aminotransferase, γ-glutamyl transferase and alkaline phosphatase), bilirubin and dysregulation of serum lipid profile (cholesterol and triglycerides). These effects were significantly and dose-dependently reversed by LSE treatment (250 and 500 mg/kg). Administration of LSE also reduced the structural damage caused by CCl₄ in the liver. Furthermore, determination of oxidative stress parameters (malondialdehyde and non-protein sulfhydryls) revealed that LSE treatment mitigated CCl₄-triggered modulation of both molecules. LSE also showed a strong antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In conclusion, the present study discloses the hepatoprotective and lipid-lowering effects of lyophilized sapodilla extract against CCl₄-induced liver damage, an effect, at least in part, mediated by its antioxidant activity.

An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities

Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.

Structurally Diverse Flavonolignans with Immunosuppressive and Neuroprotective Activities from the Fruits of Hippophae rhamnoides L

The fruit of Hippophae rhamnoides L. has been used for centuries in Europe and Asia as a food with high nutritional and medicinal values. In this study, a bioactivity-guided phytochemical investigation of H. rhamnoides L. has resulted in four new dimethylallylated flavonolignans (1-4), four new isopropylpentenone-flavonolignan heterodimers (5-8), two new geranylated flavonolignans (9 and 10), and 14 known flavonolignan derivatives (11-24); they were elucidated by their spectrometric and spectroscopic methods, including HR-ESI-MS, NMR, IR, and UV from the fruit of H. rhamnoides L. for the first time. Among them, compounds 2, 5, 6, 20, and 21 showed potent immunosuppressive activities with IC₅₀ values from 19.42 ± 3.91 to 48.05 ± 12.56 μM. Meanwhile, compounds 1, 4, 11, 12, and 13 showed moderate neuroprotective activities, which increased the cell survival rate from 50.30 ± 4.24% for the model group to 71.63 ± 3.04%, 70.02 ± 4.13%, 61.53 ± 5.93%, 61.08 ± 3.58%, and 65.68 ± 4.88% at 10 μM, respectively. The hypothetical biogenetic pathway and preliminary structure-activity relationship were found and discussed scientifically.

Prenylated Chromones from the Fruits of Artocarpus heterophyllus and Their Potential Anti-HIV-1 Activities

Artocarpus heterophyllus (jack tree) is an evergreen fruit tree belonging to the genus Artocarpus (Moraceae), which is widely distributed in subtropical and tropical regions of Asia. Its fruits (jackfruit), well-known as the world's largest tree-borne fruit, are being consumed in our daily diets as a very popular tropical fruit throughout the world and have been confirmed to hold various health benefits. In this study, five new prenylated chromones, artocarheterones A-E (1-5), as well as seven known prenylated chromones (6-12) were purified and isolated from the ripe fruits of A. heterophyllus (jackfruit). Their chemical structures were determined through comprehensive spectroscopic methods. This is the first report on prenylated chromones isolated from A. heterophyllus. The anti-HIV-1 effects of all isolated chromones were assessed in vitro. As a result, prenylated chromones (1-12) showed remarkable anti-HIV-1 effects with EC₅₀ values ranging from 0.09 to 9.72 μM. These research results indicate that the isolation and characterization of these prenylated chromones with remarkable anti-HIV-1 activities from the ripe fruits of A. heterophyllus could be significant to the discovery and development of new anti-HIV-1 drugs.