Techniques for the analysis of pentacyclic triterpenoids in medicinal plants

Triterpenes are a major class of chemical compounds found in natural plants and can be categorized into acyclic triterpenoids, monocyclic triterpenoids, tricyclic triterpenoids, tetracyclic triterpenoids, and pentacyclic triterpenoids. Among them, pentacyclic triterpenoids have gained more extensive attention due to their biological activities, including anti‐inflammation, antibacterial, antioxidation, antitumor, anti‐HIV, hepatoprotection, and immunological adjuvant properties. In this review, we summarize the extraction and analytical methods for pentacyclic triterpenoids, where more than 56 triterpenes from 49 kinds of plants were involved. The analysis methods include gas chromatography, liquid chromatography, capillary electrophoresis, thin‐layer chromatography, supercritical fluid chromatography, NMR spectroscopy, and X‐ray spectroscopy. This review provides valuable reference for the determination of pentacyclic triterpenoids in medicinal plants.     

Pentacyclic Triterpenoids from Sabia discolor Dunn and Their α-Glycosidase Inhibitory Activities

Four new pentacyclic triterpenoids named Sabiadiscolor A–D (1 and 7–9) together with eleven known ones were isolated by repeated column chromatography. Their structures were identified and characterized by NMR and MS spectral data as 6 oleanane-type pentacyclic triterpenoids (1–6), 7 ursane-type ones (7–13), and 2 lupanane-type ones (14–15). Except for compound 15, all other compounds were isolated from Sabia discolor Dunn for the first time. Their α-glycosidase inhibitory activities were evaluated, which showed that compounds 1, 3, 8, 9, 13, and 15 implied remarkable activities with IC₅₀ values ranging from 0.09 to 0.27 μM, and the preliminary structure–activity relationship was discussed.     

Natural Formulations Based on Olea europaea L. Fruit Extract for the Topical Treatment of HSV-1 Infections

In the present study, a hydroxytyrosol-rich Olea europaea L. fruit extract (OFE) was added to three thoroughly green formulations—hydrogel, oleogel, and cream—in order to evaluate their antiviral activity against HSV-1. The extract was characterized by different analytical techniques, i.e., FT-IR, XPS, and TGA. HPLC analyses were carried out to monitor the content and release of hydroxytyrosol in the prepared formulations. The total polyphenol content and antioxidant activity were investigated through Folin–Ciocâlteu’s reagent, DPPH, and ABTS assays. The ability of the three formulations to convey active principles to the skin was evaluated using a Franz cell, showing that the number of permeated polyphenols in the hydrogel (272.1 ± 1.8 GAE/g) was significantly higher than those in the oleogel and cream (174 ± 10 and 179.6 ± 2 GAE/g, respectively), even if a negligible amount of hydroxytyrosol crossed the membrane for all the formulations. The cell viability assay indicated that the OFE and the three formulations were not toxic to cultured Vero cells. The antiviral activity tests highlighted that the OFE had a strong inhibitory effect against HSV-1 with a 50% inhibitory concentration (IC50) at 25 µg/mL, interfering directly with the viral particles. Among the three formulations, the hydrogel exhibited the highest antiviral activity also against the acyclovir-resistant strain.     

Antiviral Activity of a Cyclic Pro-Pro-β3-HoPhe-Phe Tetrapeptide against HSV-1 and HAdV-5

The core of Cyclolinopeptide A (CLA, cyclo(LIILVPPFF)), responsible for its high immunosuppressive activity, contains a Pro-Pro-Phe-Phe sequence. A newly synthesized cyclic tetrapeptide, cyclo(Pro-Pro-β³-HoPhe-Phe) (denoted as 4B8M) bearing the active sequence of CLA, was recently shown to exhibit a wide array of anti-inflammatory properties in mouse models. In this investigation, we demonstrate that the peptide significantly inhibits the replication of human adenovirus C serotype 5 (HAdV-5) and Herpes simplex virus type-1 (HSV-1) in epithelial lung cell line A-549, applying Cidofovir and Acyclovir as reference drugs. Based on a previously established mechanism of its action, we propose that the peptide may inhibit virus replication by the induction of PGE2 acting via EP2/EP4 receptors in epithelial cells. In summary, we reveal a new, antiviral property of this anti-inflammatory peptide.     

Complete assignment of 1H and 13C NMR spectra of new pentacyclic triterpene acid benzyl esters

Complete assignments of ¹H and ¹³C NMR chemical shifts for newly synthesized benzyl esters of oleanolic, ursolic and crataegolic acid based on DEPT, HSQC, HMBC, COSY, TOCSY, NOE and ROESY experiments are reported. Copyright © 2002 John Wiley & Sons, Ltd.     

Antiviral Effect of Nonfunctionalized Gold Nanoparticles against Herpes Simplex Virus Type-1 (HSV-1) and Possible Contribution of Near-Field Interaction Mechanism

The antiviral activity of nonfunctionalized gold nanoparticles (AuNPs) against herpes simplex virus type-1 (HSV-1) in vitro was revealed in this study. We found that AuNPs are capable of reducing the cytopathic effect (CPE) of HSV-1 in Vero cells in a dose- and time-dependent manner when used in pretreatment mode. The demonstrated antiviral activity was within the nontoxic concentration range of AuNPs. Interestingly, we noted that nanoparticles with smaller sizes reduced the CPE of HSV-1 more effectively than larger ones. The observed phenomenon can be tentatively explained by the near-field action of nanoparticles at the virus envelope. These results show that AuNPs can be considered as potential candidates for the treatment of HSV-1 infections.     

Structural determination of seven new triterpenoids from Kadsura heteroclita by NMR techniques

Seven new triterpenoids, namely heteroclitalactones G-M (1-7), were isolated from the ethanol extract of the stems of Kadsura heteroclita. Structures of these compounds were characterized by extensive 1D and 2D NMR spectroscopic analyses.     

The in vitro antiherpes activity of some selected antitumor organotin compounds

A number of antitumor-active octahedral organotin complexes of the type R₂SnX₂L₂, where R=ethyl or phenyl, X = chloride or bromide, and L₂ = o- phenanthroline or 2-(2-pyridyl)benzimidazole, have been shown to exhibit in vitro antiherpes activity towards both herpes simplex virus types 1 and 2 (HSV-1 and HSV-2). In addition, a series of mono-, di-, and tri-organotin halides (alkyl and phenyl) demonstrated weak antiherpes activity in the same viral assay system. Selectivity indexes for the tin compounds were calculated and compared with those available in the literature for a number of well-characterized and commercially important antivirals, e.g. adenine-9-β-D-arabinofuranoside (ara-A), cytosine-β-D-arabinofuranoside (ara-C), 5-iodo-2′-deoxyuridine (IDU) and 9-(2-hydroxyethoxymethyl)guanine (acyclovir, ACY). Although the organotin complexes are less effective in vitro than either ACY or IDU, as determined by their selectivity indexes, they are comparable in activity with both ara-A and ara-C in this particular assay. With few exceptions, most notably (C₂H₅)₂SnBr₂(o-phen), the organotin compounds examined in this study are more active against HSV-1 (F strain) than HSV-2 (MS strain). The results presented here represent the first study of the potential antiviral properties of organotin compounds.     

单纯疱疹二型病毒和口蹄疫病毒感染过程能量代谢的微量热研究

本论文采用LKB－2277生物活性检测器研究HeLa细胞在单纯疱疹Ⅱ型病毒感染和BHK－21细胞在口蹄疫病毒感染下的能量代谢过程，以及热疗及抗病毒药物干扰素对这一过程的能量代谢的影响。结果表明病毒感染细胞的代谢热功率大于未被感染的细胞并且被不同类型病毒感染的细胞之间代谢产热功率存在显著的差别；病毒感染是一个温度敏感的过程；干扰素对病毒感染过程有抑制作用。通过对不同贮存时间口蹄疫病毒感染BHK－21细胞的能量代谢产热曲线的分析表明长时间保存对病毒的毒力和感染能力产生了较明显的影响。这些结果都表明微量热法是研究病毒感染过程的一种有效方法。     

The Antiviral Effects of Jasminin via Endogenous TNF-α and the Underlying TNF-α-Inducing Action

Previous studies have reported that recombinant tumor necrosis factor (TNF)-α has powerful antiviral activity but severe systematic side effects. Jasminin is a common bioactive component found in Chinese herbal medicine beverage “Jasmine Tea”. Here, we report that jasminin-induced endogenous TNF-α showed antiviral activity in vitro. The underlying TNF-α-inducing action of jasminin was also investigated in RAW264.7 cells. The level of endogenous TNF-α stimulated by jasminin was first analyzed by an enzyme-linked immunosorbent assay (ELISA) from the cell culture supernatant of RAW264.7 cells. The supernatants were then collected to investigate the potential antiviral effect against herpes simplex virus 1 (HSV-1). The antiviral effects of jasminin alone or its supernatants were evaluated by a plaque reduction assay. The potential activation of the PI3K–Akt pathway, three main mitogen-activated protein kinases (MAPKs), and nuclear factor (NF)–κB signaling pathways that induce TNF-α production were also investigated. Jasminin induces TNF-α protein expression in RAW264.7 cells without additional stimuli 10-fold more than the control. No significant up-expression of type I, II, and III interferons; interleukins 2 and 10; nor TNF-β were observed by the jasminin stimuli. The supernatants, containing jasminin-induced-TNF-α, showed antiviral activity against HSV-1. The jasminin-stimulated cells caused the simultaneous activation of the Akt, MAPKs, and NF–κB signal pathways. Furthermore, the pretreatment of the cells with the Akt, MAPKs, and NF–κB inhibitors effectively suppressed jasminin-induced TNF-α production. Our research provides evidence that endogenous TNF-α can be used as a strategy to encounter viral infections. Additionally, the Akt, MAPKs, and NF–κB signaling pathways are involved in the TNF-α synthesis that induced by jasminin.     

1H and 13C NMR spectral assignments of four dammarane triterpenoids from carnauba wax

The phytochemical investigation of carnauba wax led to the isolation of three new dammarane triterpenoids 1, 2 and 4, together with the known triterpene 3. The structures of the new compounds were determined by 1D and 2D NMR spectroscopy and by comparison with published data for closely related compounds.     

Isolation and structural determination of sorbinols A and B, new triterpenes from Sorbus cashmariana, by 1D and 2D NMR spectroscopy

Two new pentacyclic triterpenes, sorbinols A (1) and B (2) have been isolated from the ethyl acetate fraction of Sorbus cashmariana and their structures assigned from (1)H and (13)C NMR spectra, DEPT and by 2D COSY, NOE, HMQC and HMBC experiments. Both 1 and 2 showed moderate inhibitory potential against the enzyme lipoxygenase.     

Activity of Propolis Nanoparticles against HSV-2: Promising Approach to Inhibiting Infection and Replication

Herpes simplex type 2 (HSV-2) infection causes a significant life-long disease. Long-term side effects of antiviral drugs can lead to the emergence of drug resistance. Thus, propolis, a natural product derived from beehives, has been proposed to prevent or treat HSV-2 infections. Unfortunately, therapeutic applications of propolis are still limited due its poor solubility. To overcome this, a nanoparticle-based drug delivery system was employed. An ethanolic extract of propolis (EEP) was encapsulated in nanoparticles composed of poly(lactic-co-glycolic acid) and chitosan using a modified oil-in-water single emulsion by using the solvent evaporation method. The produced nanoparticles (EEP-NPs) had a spherical shape with a size of ~450 nm and presented satisfactory physicochemical properties, including positively charged surface (38.05 ± 7.65 mV), high entrapment efficiency (79.89 ± 13.92%), and sustained release profile. Moreover, EEP-NPs were less cytotoxic on Vero cells and exhibited anti-HSV-2 activity. EEP-NPs had a direct effect on the inactivation of viral particles, and also disrupted the virion entry and release from the host cells. A significant decrease in the expression levels of the HSV-2 replication-related genes (ICP4, ICP27, and gB) was also observed. Our study suggests that EEP-NPs provide a strong anti-HSV-2 activity and serve as a promising platform for the treatment of HSV-2 infections.     

Structural determination of silymins A and B, new pentacyclic triterpenes from Silybum marianum, by 1D and 2D NMR spectroscopy

Silymins A (1) and B (2), the new pentacyclic triterpenes, have been isolated from ethyl acetate fraction of Silybum marianum and their structures assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOE and HMBC experiments.     

Capturing a Pentacyclic Fragment-Based Library Derived from Perophoramidine: Their Design,Synthesis and Evaluation as Anticancer Compounds by DNA Double-Strand Breaks (DSB) and PARP-1 Inhibition

Herein we have reported the discovery of a pentacyclic building block comprised of fused indole-quinoline and piperidinone from the natural product perophoramidine as a formidable anticancer agent. The compounds were synthesized in six steps where the key steps involved a blue LED mediated intramolecular cyclopropanation of the indole intermediates and concomitant reduction of the associated aryl nitro moiety to nitroso in the molecule. Cytotoxicity screening of the compounds against an array of cancer cells that is, MCF7, HCT116 and A549 demonstrated 0.6 to 9 μM IC₅₀s by few of the compounds. γH2AX immunofluorescence assay of the two most potent molecules from the phenotypic screening with anti-γ-H2AX Alexa Fluor 488 antibody revealed extensive DNA damage of the A549 cells which indicated probable PARP inhibition (similar to Perophoramidine). Through molecular docking and molecular dynamic (MD) simulation studies the binding efficiency of our compounds with poly(ADP-ribose)polymerase 1 (PARP 1) enzyme was determined. Chemiluminescent PARP Assay with Histone-coated strips indicated that the most active compounds from the phenotypic screening induced PARP-1 inhibition with IC₅₀s of 1.3→1.5 μM.     

Structural determination of two new triterpenoids from Potentilla discolor Bunge by NMR techniques

Two new pentacyclic triterpenoids, 3alpha, 30-dihydroxylup-20(29)-en-27-oic acid (1) and (20S)-3alpha, 29-dihydroxylupan-27-oic acid (2) were isolated from the whole herbs of Potentilla discolor Bunge. The structures of these two new compounds were elucidated, and complete assignments of the (1)H and (13)C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, (1)H-(1)HCOSY and ROESY).     

Antidepressant-like effect of triterpenoids extracts from Poria cocos on the CUMS rats by 16S rRNA gene sequencing and LC–MS metabolomics

Abstract

Poria cocos is an edible medicinal mushroom with the effects of inducing diuresis, excreting dampness, invigorating the spleen and tranquilizing the mind. The triterpenoids of Poria cocos as the main active ingredients have shown health benefits of the central nervous system of the human body. Accordingly, this study aimed at further understanding the antidepressant-like effect and a potential mechanism of the triterpenoids extracts from Poria cocos (TPC). As a result, the TPC significantly ameliorated depression-like behaviors on chronic unpredictable mild stress (CUMS) rats, and restored the levels of brain-derived neurotrophic factor and nerve growth factor in the hippocampus of rats. Gut microiota analysis revealed that TPC could increase the biodiversity and markedly regulate the relative abundance of [Prevotella], Allobaculum and Ochrobactrum of CUMS rats. The cecal contents metabolomics pointed to thirteen biomarkers associated with TPC antidepressant effect, which involved in primary bile acid biosynthesis, taurine and hypotaurine metabolism, arginine and proline metabolism. Correlation analysis further showed that there was a strong correlation relationship between the gut microbiota and the cecal contents metabolites, especially compounds involved in energy metabolism, inflammation and immunity. In conclusion, TPC showed a potential antidepressant effect, which was possibly mediated the gut microbiota and cecal contents metabolism.     

Anti-SARS-CoV-2 Inhibitory Profile of New Quinoline Compounds in Cell Culture-Based Infection Models

The presently ongoing pandemic of human SARS-CoV-2 infections (COVID-19) presents an enormous challenge in surveillance, vaccine and antiviral drug development. Here we report the synthesis of new bioactive quinoline-morpholine hybrid compounds and their virological evaluation, which proves pronounced cell culture-based inhibitory profile against SARS-CoV-2. Thus, selected quinoline compounds may suggest specific hit-to-lead development.     

A concise synthesis of 2-benzoyl-1-indanones and 1-indanones from 2-aryl-1-tetralones

Abstract

Methyl-2-(3-oxo-3-aryl) benzoates derived from acid catalyzed air oxidative fragmentation of 2-aryl-1-tetralones were efficiently undergone intramolecular-Claisen condensation in the presence of potassium tertiary butoxide. The resulting 2-benzoyl-1-indanones formed in two-step ring contractions were further subjected to indium triflate mediated retro-Claisen condensation to get 1-indanones.     

Synthesis,Anti-Influenza H1N1 and Anti-Dengue Activity of A-Ring Modified Oleanonic Acid Polyamine Derivatives

A series of sixteen A-ring modified (2,3-indolo-, 2-benzylidene) oleanonic acid derivatives, holding some cyclic amines, linear polyamines and benzylaminocarboxamides at C28, has been synthesized and screened for antiviral activity against influenza A/PuertoRico/8/34 (H1N1) and Dengue virus serotypes of DENV-1, -2, -3, -4. It was found that 28-homopiperazine 2 and 3-N-phthalyl 22 amides of oleanonic acid demonstrated high potency with selectivity index SI 27 (IC₅₀ 21 μM) and 42 (IC₅₀ 12 μM). Oleanonic acid aminoethylpiperazine amide 6 and C-azepano-erythrodiol 23 appeared to be the most effective compounds against DENV-1 (IC_50′s 67 and 107 μM) and -2 (IC_50′s 86 and 68 μM correspondingly) serotypes.