Caffeic acid oligomers from Mesona chinensis and their In Vitro antiviral activities

Anti-inflammatory naphthoquinone-monoterpene adducts and neolignans from Eugenia caryophyllata

A phytochemical investigation on the buds of edible medicinal plant, Eugenia carvophyllata, led to the discovery of seven new compounds, caryophones A-G (1-7), along with two biogenetically-related known ones, 2-methoxy-7-methyl-1,4-naphthalenedione (8) and eugenol (9). Compounds 1-3 represent the first examples of C-5-C-1' connected naphthoquinone-monoterpene adducts with a new carbon skeleton. Compounds 4-7 are a class of novel neolignans with unusual linkage patterns, in which the C-9 position of one phenylpropene unit coupled with the aromatic core of another phenylpropene unit. The chemical structures of the new compounds were determined based on extensive spectroscopic analysis, X-ray diffraction crystallography, and quantum-chemical calculation. Among the isolates, compounds (-)-2, 3, 6, and 9 showed significant in vitro inhibitory activities against respiratory syncytial virus (RSV)-induced nitric oxide (NO) production in RAW264.7 cells.

Antiviral C-geranylated flavonoids from Artocarpus communis

Ten C-geranylated flavonoids, along with three known analogues, were isolated from the leaves of Artocarpus communis. The chemical structures of these compounds were unambiguously determined via comprehensive spectroscopic analysis, single-crystal X-ray diffraction experiments, and quantum chemical electronic circular dichroism calculations. Structurally, artocarones A-I (1-9) represent a group of unusual, highly modified C-geranylated flavonoids, in which the geranyl chain is cyclised with the ortho-hydroxy group of flavonoids to form various heterocyclic scaffolds. Notably, artocarones E and G-I (5 and 7-9) feature a 6H-benzo[c]chromene core that is hitherto undescribed in C-geranylated flavonoids. Artocarone J (10) is the first example of C-9-C-16 connected C-geranylated aurone. Meanwhile, the plausible biosynthetic pathways for these rare C-geranylated flavonoids were also proposed. Notably, compounds 1, 2, 4, 8, 11, and 12 exhibited promising in vitro inhibitory activities against respiratory syncytial virus and herpes simplex virus type 1.

Preparation technologies, structural features, and biological activities of polysaccharides from Mesona chinensis Benth.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Mesona chinensis Benth. (or Platostoma palustre (Blume) A. J. Paton) is an important medicinal and edible plant also known as the Hsian-tsao in China and Southeast Asian countries. It is cold in nature and sweet in taste, with the effects of clearing heat, relieving heatstroke and diuretic, and traditionally used to treat heatstroke, erysipelas, hypertension, joint pain and other diseases in folk medicine. It is also a popular supplement with the function of detoxifying and heat-clearing use in Asia. It is used to be processed into the popular tea, Bean jelly, and so on. Published studies have demonstrated that polysaccharides from M. chinensis (MCPs) are one of the principal bioactive ingredients with a variety of health-promoting effects in the prevention and treatment of diseases, including antioxidant, immunomodulation, anti-inflammatory, hepatoprotective, anti-tumor, hypoglycemic, regulation of gut microbiota, and other pharmacological properties.

AIM OF THE REVIEW

This review aims to compile the extraction and purification methods, structural characteristics, pharmacological activities including the mechanism of action of MCPs, and to further understand the applications of M. chinensis in order to lay the foundation for the development of MCPs.

MATERIALS AND METHODS

By inputting the search term "Mesona chinensis polysaccharides", relevant research information was obtained from databases such as PubMed, Google Scholar, Web of Science, and China National Knowledge Infrastructure (CNKI).

RESULTS

More than 40 polysaccharides have been extracted from M. chinensis, different extraction and purification methods have been described, as well as the structural features and pharmacological activities of MCPs have been systematically reviewed. Polysaccharides, as important components of M. chinensis, were mainly extracted by methods such as hot water dipping method, hot alkali extraction method, enzyme-assisted extraction method and ultrasonic-assisted extraction method, subsequently obtained by decolorization, deproteinization, removal of other small molecules and separation on various chromatographic columns. The chemical composition and structure of MCPs show diversity and have a variety of pharmacological activities, including antioxidant, immunomodulation, anti-inflammatory, hepatoprotective, anti-tumor, hypoglycemic, regulation of gut microbiota, and so on.

CONCLUSIONS

This article systematically reviews the research progress of MCPs in terms of extraction and purification, structural characteristics, rheological gel properties, pharmacological properties, and safety assessment. The potentials and roles of M. chinensis in the field of medicine, functional food, and materials are further highlighted to provide references and bases for the high-value processing and utilization of MCPs.

High Value-Added Application of Natural Products in Crop Protection: Discovery and Exploration of Caffeoyl and Flavonoid Derivatives from Clematis brevicaudata DC. as Novel Insecticide Candidates

Nine caffeoyl derivatives (1-9), including two new dicaffeoyl glycosides, brevicaudatosides A and B (1 and 2), and six flavonoids (10-15), were identified from overground Clematis brevicaudata DC. Compounds 1 and 13 exhibited significant oral toxicities against Acyrthosiphon pisum Harris with LC50 (half-lethal concentration) values of 0.12 and 0.28 mM, respectively. Meanwhile, compounds 1, 8, 10, 13, and 15 showed remarkable repellent effects against A. pisum with the repellent indexes valued at 1.00 under 50-200 μg/mL at 24 h. Compounds 1 and 8 also displayed moderate antifeedant activities against Plutella xylostella L. The shrunken bodies, especially for wizened cauda, and the ultrastructural damages of microvilli, mitochondrion, nucleus, and endoplasmic reticulum in midgut were toxic symptoms of A. pisum caused by 1 and 13. The inhibition of Chitinase was the main reason for their potent insecticidal activities. This study provided valuable pieces of evidence for the high value-added application of caffeoyl and flavonoid derivatives from C. brevicaudata as novel plant-origin biopesticides for crop protection.

Effect of Operational Variables on Supercritical Foaming of Caffeic Acid-Loaded Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends for the Development of Sustainable Materials

Expanded polystyrene will account for 5.3% of total global plastic production in 2021 and is widely used for food packaging due to its excellent moisture resistance and thermal insulation. However, some of these packages are often used only once before being discarded, generating large amounts of environmentally harmful plastic waste. A very attractive alternative to the conventional methods used for polymer processing is the use of supercritical carbon dioxide (scCO2) since it has mass-transfer properties adapted to the foam morphology, generating different path lengths for the diffusion of active compounds within its structure and can dissolve a wide range of organic molecules under supercritical conditions. The objective of this research was to evaluate the effect of operational variables on the process of caffeic acid (CA) impregnation and subsequent foaming of polylactic acid (PLA) as well as two PLA/poly(butylene-co-terephthalate-adipate) (PBAT) blends using scCO2. The results showed an increase in the degree of crystallinity of the CA-impregnated samples due to the nucleation effect of the active compound. On the other hand, SEM micrographs of both films and foams showed significant differences due to the presence of PBAT and its low miscibility with PLA. Finally, the results obtained in this work contribute to the knowledge of the important parameters to consider for the implementation of the impregnation and foaming process of PLA and PLA/PBAT blends with potential use in food packaging.

All natural mussel-inspired bioadhesives from soy proteins and plant derived polyphenols with marked water-resistance and favourable antibacterial profile for wound treatment applications

HYPOTHESIS

Implementation of tissue adhesives from natural sources endowed with good mechanical properties and underwater resistance still represents a challenging research goal. Inspired by the extraordinary wet adhesion properties of mussel byssus proteins resulting from interaction of catechol and amino residues, hydrogels from soy protein isolate (SPI) and selected polyphenols i.e. caffeic acid (CA), chlorogenic acid (CGA) and gallic acid (GA) under mild aerial oxidative conditions were prepared.

EXPERIMENTS

The hydrogels were subjected to chemical assays, ATR FT-IR and EPR spectroscopy, rheological and morphological SEM analysis. Mechanical tests were carried out on hydrogels prepared by inclusion of agarose. Biological tests included evaluation of the antibacterial and wound healing activity, and hemocompatibility.

FINDINGS

The decrease of free NH2 and SH groups of SPI, the EPR features, the good cohesive strength and excellent underwater resistance (15 days for SPI/GA) under conditions relevant to their use as surgical glues indicated an efficient interaction of the polyphenols with the protein in the hydrogels. The polyphenols greatly also improved the mechanical properties of the SPI/ agarose/polyphenols hydrogels. These latter proved biocompatible, hemocompatible, not harmful to skin, displayed durable adhesiveness and good water-vapour permeability. Excellent antibacterial properties and in some cases (SPI/CGA) a favourable wound healing activity on dermal fibroblasts was obtained.

Isolation of Anti-SARS-CoV-2 Natural Products Extracted from Mentha canadensis and the Semi-synthesis of Antiviral Derivatives

Traditional herbal medicine offers opportunities to discover novel therapeutics against SARS-CoV-2 mutation. The dried aerial part of mint (Mentha canadensis L.) was chosen for bioactivity-guided extraction. Seven constituents were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). Syringic acid and methyl rosmarinate were evaluated in drug combination treatment. Ten amide derivatives of methyl rosmarinate were synthesized, and the dodecyl (13) and 3-ethylphenyl (19) derivatives demonstrated significant improvement in the anti-SARS-CoV-2 plaque reduction assay, achieving IC50 of 0.77 and 2.70 μM, respectively, against Omicron BA.1 as compared to methyl rosmarinate's IC50 of 57.0 μM. Spike protein binding and 3CLpro inhibition assays were performed to explore the viral inhibition mechanism. Molecular docking of compounds 13 and 19 to 3CLpro was performed to reveal potential interaction. In summary, natural products with anti-Omicron BA.1 activity were isolated from Mentha canadensis and derivatives of methyl rosmarinate were synthesized, showing 21- to 74-fold improvement in antiviral activity against Omicron BA.1.

Docking Analysis of Some Bioactive Compounds from Traditional Plants against SARS-CoV-2 Target Proteins

COVID-19 is still a global pandemic that has not been stopped. Many traditional medicines have been demonstrated to be incredibly helpful for treating COVID-19 patients while fighting the disease worldwide. We introduced 10 bioactive compounds derived from traditional medicinal plants and assessed their potential for inhibiting viral spike protein (S-protein), Papain-like protease (PLpro), and RNA dependent RNA polymerase (RdRp) using molecular docking protocols where we simulate the inhibitors bound to target proteins in various poses and at different known binding sites using Autodock version 4.0 and Chimera 1.8.1 software. Results found that the chicoric acid, quinine, and withaferin A ligand strongly inhibited CoV-2 S -protein with a binding energy of -8.63, -7.85, and -7.85 kcal/mol, respectively. Our modeling work also suggested that curcumin, quinine, and demothoxycurcumin exhibited high binding affinity toward RdRp with a binding energy of -7.80, -7.80, and -7.64 kcal/mol, respectively. The other ligands, namely chicoric acid, demothoxycurcumin, and curcumin express high binding energy than the other tested ligands docked to PLpro with -7.62, -6.81, and -6.70 kcal/mol, respectively. Prediction of drug-likeness properties revealed that all tested ligands have no violations to Lipinski's Rule of Five except cepharanthine, chicoric acid, and theaflavin. Regarding the pharmacokinetic behavior, all ligand predicted to have high GI-absorption except chicoric acid and theaflavin. At the same way chicoric acid, withaferin A, and withanolide D predicted to be substrate for multidrug resistance protein (P-gp substrate). Caffeic acid, cepharanthine, chicoric acid, withaferin A, and withanolide D also have no inhibitory effect on any cytochrome P450 enzymes. Promisingly, chicoric acid, quinine, curcumin, and demothoxycurcumin exhibited high binding affinity on SARS-CoV-2 target proteins and expressed good drug-likeness and pharmacokinetic properties. Further research is required to investigate the potential uses of these compounds in the treatment of SARS-CoV-2.

Genome survey sequencing and characterization of simple sequence repeat (SSR) markers in Platostoma palustre (Blume) A.J.Paton (Chinese mesona)

Platostoma palustre (Blume) A.J.Paton is an annual herbaceous persistent plant of the Labiatae family. However, there is a lack of genomic data for this plant, which severely restricts its genetic improvement. In this study, we performed genome survey sequencing of P. palustre and developed simple sequence repeat (SSR) markers based on the resulting sequence. K-mer analysis revealed that the assembled genome size was approximately 1.21 Gb. A total of 15,498 SSR motifs were identified and characterized in this study; among them, dinucleotide, and hexanucleotide repeats had the highest and lowest, respectively. Among the dinucleotide repeat motifs, AT/TA repeat motifs were the most abundant, and GC/CG repeat motifs were rather rare, accounting for 44.28% and 0.63%, respectively. Genetic similarity coefficient analysis by the UPMGA methods clustered 12 clones, of P. palustre and related species into two subgroups. These results provide helpful information for further research on P. palustre resources and variety improvements.

Isolation and evaluation of virucidal activities of flavanone glycosides and rosmarinic acid derivatives from Dracocephalum spp. against feline calicivirus

Feline calicivirus is one of the surrogate viruses of human norovirus. This study aimed to identify virucidal compounds, chemical constituents of plants from the genus Dracocephalum, which are rich in flavonoids and phenylpropanoid oligomers. Four undescribed compounds, including a flavanone glucoside, two stilbenoid glycosides, and a phenylpropanoid amide glycoside, as well as 17 known compounds, were isolated from the Mongolian plants Dracocephalum fruticulosum Stephan ex Willd., and D. nutans L. belonging to the family Lamiaceae. The structures of the compounds were determined based on NMR, MS, and electronic CD spectroscopic data. In addition to these 21 compounds, 15 previously reported compounds from D. foetidum Bunge in C.F. von Ledebour were included, and a total of 36 compounds were evaluated for their virucidal activities against feline calicivirus. Some of the flavanone glycosides and phenylpropanoid oligomers showed virucidal activities, and their structural features are discussed. The findings suggest that isosakuranetin glycosides and phenylpropanoid oligomers may have the potential for norovirus inactivation.

Mechanism of Cross-Resistance to Fusion Inhibitors Conferred by the K394R Mutation in Respiratory Syncytial Virus Fusion Protein

The fusion glycoprotein (F) is essential for respiratory syncytial virus (RSV) entry and has become an attractive target for anti-RSV drug development. Despite the promising prospect of RSV F inhibitors, issues of drug resistance remain challenging. In this study, we established a dual-luciferase protocol for RSV fusion inhibitor discovery. A small-molecule inhibitor, salvianolic acid R (LF-6), was identified to inhibit virus-cell and cell-cell fusion mediated by the RSV F protein. Sequence analysis of the resultant resistant viruses identified a K394R mutation in the viral F protein. The K394R mutant virus also conferred cross-resistance to multiple RSV fusion inhibitors, including several inhibitors undergoing clinical trials. Our study further showed that K394R mutation not only increased the triggering rate of F protein in prefusion conformation but also enhanced the fusion activity of F protein, both of which were positively correlated with resistance to fusion inhibitors. Moreover, the K394R mutation also showed cooperative effects with other escape mutations to increase the fusion activity of F protein. By substitution of K394 into different amino acids, we found that K394R or K394H substitution resulted in hyperfusiogenic F proteins, whereas F variants with other substitutions exhibited less fusion activity. Both K394R and K394H in F protein exhibited cross-resistance to RSV fusion inhibitors. Collectively, these findings reveal a positive correlation between the membrane fusion activity of F protein and the resistance of corresponding inhibitors. All of the results demonstrate that K394R in F protein confers cross-resistance to fusion inhibitors through destabilizing F protein and increasing its membrane fusion activity.

IMPORTANCE Respiratory syncytial virus (RSV) causes serious respiratory tract disease in children and the elderly. Therapeutics against RSV infection are urgently needed. This study reports the discovery of a small-molecule inhibitor of RSV fusion glycoprotein by using a dual-luciferase protocol. The escape mutation (K394R) of this compound also confers cross-resistance to multiple RSV fusion inhibitors that have been reported previously, including two candidates currently in clinical development. The combination of K394R with other escape mutations can increase the resistance of F protein to these inhibitors through destabilizing F protein and enhancing the membrane fusion activity of F protein. By amino acid deletion or substitution, we found that a positively charged residue at the 394th site is crucial for the fusion ability of F protein, as well as for the cross-resistance against RSV fusion inhibitors. These results reveal the mechanism of cross-resistance conferred by the K394R mutation and the possible cross-resistance risk of RSV fusion inhibitors.

Natural product-based Radiopharmaceuticals:Focus on curcumin and its analogs, flavonoids, and marine peptides

Natural products provide a bountiful supply of pharmacologically relevant precursors for the development of various drug-related molecules, including radiopharmaceuticals. However, current knowledge regarding the importance of natural products in developing new radiopharmaceuticals remains limited. To date, several radionuclides, including gallium-68, technetium-99m, fluorine-18, iodine-131, and iodine-125, have been extensively studied for the synthesis of diagnostic and therapeutic radiopharmaceuticals. The availability of various radiolabeling methods allows the incorporation of these radionuclides into bioactive molecules in a practical and efficient manner. Of the radiolabeling methods, direct radioiodination, radiometal complexation, and halogenation are generally suitable for natural products owing to their simplicity and robustness. This review highlights the pharmacological benefits of curcumin and its analogs, flavonoids, and marine peptides in treating human pathologies and provides a perspective on the potential use of these bioactive compounds as molecular templates for the design and development of new radiopharmaceuticals. Additionally, this review provides insights into the current strategies for labeling natural products with various radionuclides using either direct or indirect methods.

•

Potential use of natural products for the development of diagnostic and therapeutic radiopharmaceuticals.

•

Profile of potential natural products as molecular templates for the synthesis of new radiopharmaceuticals: Focus on curcumin and its closely related substances, flavonoids, and marine peptides.

•

Radiolabeling strategies, challenges, and examples of natural product-based radiopharmaceuticals under investigation.

Electrochemical sensor based on magnetic nanohybrids of multiple phthalocyanine doped ferrites/CMWCNTs for detection of rosmarinic acid

Ferrites have attracted considerable attention in biosensor developments owing to their favorable electrochemical and magnetic properties. Speedy and trace analysis can be succeeded by the sensors based on magnetic nanohybrids. In this work, we reported a novel method for one-step synthesis of magnetic ferrites composed of Fe and phthalocyanine. After hybridization with carbonylated multi wall carbon nanotubes, a sensor based on Fe3O4-Pc-CMWCNTs nanocomposites was fabricated for the detection of rosmarinic acid (RA), a bioactive phytochemical. The sensor can be constructed within 30s without any complicated process. A comparison of electrochemical activity between ZnFe2O4-Pc-CMWCNTs and Fe3O4-Pc-CMWCNTs nanohybrids also has been accomplished in this work. Compared with ZnFe2O4-Pc-CMWCNTs based on commonly used ferrites, Fe3O4-Pc-CMWCNTs/MGCE exhibited a higher catalytical ability for the detection of RA. The sensor modified with Fe3O4-Pc-CMWCNTs displayed a low LOD of 0.182 μM with a wide linear range from 0.2 to 400 μM, which was 30 times more sensitive than the one based on ZnFe2O4-Pc-CMWCNTs. The obtained sensor also owned an excellent selectivity, reproducibility, repeatability, and stability, which made it achieve the measurements in plant sample and human serum.

Caffeic Acid and Its Derivatives: Antimicrobial Drugs toward Microbial Pathogens

Caffeic acid is a plant-derived compound that is classified as hydroxycinnamic acid which contains both phenolic and acrylic functional groups. Caffeic acid has been greatly employed as an alternative strategy to combat microbial pathogenesis and chronic infection induced by microbes such as bacteria, fungi, and viruses. Similarly, several derivatives of caffeic acid such as sugar esters, organic esters, glycosides, and amides have been chemically synthesized or naturally isolated as potential antimicrobial agents. To overcome the issue of water insolubility and poor stability, caffeic acid and its derivative have been utilized either in conjugation with other bioactive molecules or in nanoformulation. Besides, caffeic acid and its derivatives have also been applied in combination with antibiotics or photoirradiation to achieve a synergistic mode of action. The present review describes the antimicrobial roles of caffeic acid and its derivatives exploited either in free form or in combination or in nanoformulation to kill a diverse range of microbial pathogens along with their mode of action. The chemistry employed for the synthesis of the caffeic acid derivatives has been discussed in detail as well.