Isolation and structures of arvenins from Anagallis arvensis L. (Primulaceae). New cucurbitacin glucosides

Recent Advances in the Application of Cucurbitacins as Anticancer Agents

Cucurbitacins are tetracyclic triterpenoid secondary metabolites, widely distributed in the Cucurbitaceae family. These bitter-tasting compounds act primarily as defense mechanisms against external injuries, and thus against herbivores, and furthermore, they have also found use in folk medicine in the treatment of various diseases. Many studies have acknowledged significant biological activities of cucurbitacins, such as antioxidant and anti-inflammatory activities, antimicrobial properties, or antitumor potential. Overall, cucurbitacins have the ability to inhibit cell proliferation and induce apoptosis in various cancer cell lines. Both in vitro and in vivo studies were performed to evaluate the anticancer activity of varied cucurbitacins. Cucurbitacins offer a promising avenue for future cancer treatment strategies, and their diverse mechanisms of action make them attractive candidates for further investigation. The aim of the present study is to shed light on the chemical diversity of this group of compounds by providing the sources of origin of selected compounds and their chemical structure, as well as insight into their anticancer potential. In addition, within this paper molecular targets for cucurbitacins and signalling pathways important for cancer cell proliferation and/or survival that are affected by the described class of compounds have been presented.

Cucurbitane triterpenes from Hemsleya chinensis tubers and their anti-inflammatory activities

Six new cucurbitane-type triterpenes, hemchinins A-F (1-6), together with thirteen known ones (7-19) were isolated from ethyl acetate extraction of Hemsleya chinensis tubers. Compounds 1-2 were a group of cucurbitane triterpenes possessing an infrequent pentacyclic framework. Their structures were established by comprehensive UV, IR, HRMS, 1D/2D NMR, and ECD analyses. Bioassay results showed that most isolated compounds exhibited anti-inflammatory actions, in which compounds 13 and 15 exhibited stronger activities at 6.25 μM, with NO inhibition rates of 49.00 ± 0.05% and 48.40 ± 0.10%, respectively.

Anti-Diabetic Effects of Cucurbitacins from Ibervillea lindheimeri on Induced Mouse Diabetes

Mexico has a great tradition of using medicinal plants against diabetes. For example, species from the genus Ibervillea traditionally known as “wereque” in Mexican popular medicine have a long ethnobotanical history as anti-diabetic agents. Previous studies by our group indicated that ethyl acetate extract from Ibervillea lindheimeri (I. lindheimeri) roots reduced glucose in mice with chemically induced diabetes. In this work, the primary metabolites of the ethyl acetate extract of I. lindheimeri; 23,24-dihydrocucurbitacin D (1); 2-O-β glucopyranosyl-23,24-dihydrocucurbitacin D (2), and acetylated compounds (3) and (4) obtained from 1 and 2, respectively, were evaluated as anti-hyperglycemic agents in a murine model of chemically induced diabetes. Our results showed that cucurbitacins 1, 2, and 4 reduced glycemia in diabetic CD1 mice compared to the control diabetic group. In addition, the results suggest that compounds 1, 2, and 4 promote glucose transporter type 4 (Glut4) translocation to the plasma membrane (PM) mainly in epididymal adipose tissue (EAT), AMP-activated protein kinase (AMPK) activation in soleus muscle (SM) or dual activation of AMPK, and protein kinase B (AKT) in EAT in an insulin-independent manner when compared to controls. All results together indicate that the isolated cucurbitacins are responsible for the anti-diabetic properties of I. lindheimeri acting predominantly on adipose tissue and call attention to this species as a new source of anti-diabetic compounds.

Ethnopharmacological basis for folkloric claims of Anagallis arvensis Linn. (Scarlet Pimpernel) as prokinetic, spasmolytic and hypotensive in province of Punjab, Pakistan

ETHNOPHARMACOLOGICAL RELEVANCE

The conventional naturopaths of Punjab Province (Pakistan) have trivial usage of Anagallis arvensis Linn.(Primulaceae) for cure of diarrhea, constipation, asthma as well as hypertension.

AIM

Present research was focused to discover comprehensive mechanism of spasmogenic, spasmolytic, bronchorelaxant and hypotensive folkloric usage of Anagallis arvensis Linn..

METHODOLOGY

The crude extract of Anagallis arvensis Linn. (Aa.Cr) & its (aqueous & organic) portions tested in-vitro on isolated jejunum, ileum, trachea, aorta, paired atria preparations as well as in-vivo in mice & normotensive anaesthetized rats. The responses have been noted by transducers (isotonic & isometric) coupled to Power Lab.

RESULT

Anagallis arvensis Linn. (Aa.Cr; crude aqueous-alcoholic extract) produced contractile action at low concentrations but relaxant action was observed by increasing concentrations on spontaneous contractions of isolated jejunum of rabbit. But, pre-treatment of tissue with atropine prior extract caused suppression of contractile effect indicating presence of cholinergic muscarinic response of Aa.Cr. It also triggered relaxation of high Potassium -stimulated contractions of jejunum with subsequent non-parallel right move in Ca++ CRCs. Moreover, Aa.Cr relaxed carbachol - & high Potassium - stimulated contractions in trachea of rabbit but observed relaxant effect was powerful against CCh (1 μM)- stimulated contractions with rightside parallel move of CCh-curves succeeded by non-parallel move, like Dicyclomine, having dual activities. The Aa.Cr also showed relaxant result on Phenylephrine and High Potassium -prompted contractions in endothelium intact aorta. The fractionation revealed segregations of contractile & relaxant effects in relevant aqueous & organic portions. The Intravenous administration of Aa.Cr to ketamine-diazepam anaesthetized normo-tensive albino rats resulted in decreased MABP, SBP & DBP. The Aa.Cr applied negative (-) inotropic & chronotropic action on paired atria. The Aa.Cr also exhibited anti-diarrheal action in mice against castor oil prompted diarrhea and also mitigated distance covered by charcoal meal in gastrointestinal tract in a manner comparable with loperamide.

CONCLUSION

These results revealed presence of CCB and selective muscarinic agonist activity in Aa.Cr, hence validating folkloric practice of Anagallis arvensis Linn. in diarrhea, constipation, asthma & hypertension.

Lipid-Lowering Activities of Cucurbitacins Isolated from Trichosanthes cucumeroides and Their Synthetic Derivatives

In the ongoing efforts to discover natural cholesterol-lowering compounds, dihydrocucurbitacin B, isolated from Trichosanthes cucumeroides roots, was found to promote LDL uptake by upregulating LDLR protein in a PCSK9-dependent process. In this study, an in-depth investigation of T. cucumeroides roots afforded 27 cucurbitacins (1-27), including seven new cucurbitacins (1-7), and their structures were elucidated by spectroscopic data analyses. In order to gain insight into their structure-activity relationship, cucurbitacin derivatives (B1-11 and DB1-11) were synthesized. Evaluation of lipid-lowering activities of these cucurbitacins by an LDL uptake assay in HepG2 cells revealed that most of the compounds improved the LDL uptake rate, among which hexanorisocucurbitacin D (6) and isocucurbitacin D (21) exhibited the highest activities (rates of 2.53 and 2.47, respectively), which were comparable to that of the positive control, nagilactone B (rate of 2.07). According to a mechanistic study by Western blot analysis, compounds 6 and 21 dose-dependently increased LDLR protein levels and reduced PCSK9 protein levels, representing promising new lipid-lowering drug candidates.

Anagallis arvensis Induces Apoptosis in HL-60 Cells Through ROS-Mediated Mitochondrial Pathway

The present study was taken up to evaluate the apoptosis inducing ability of alcoholic extract of whole plant of Anagallis arvensis (AAE) in HL-60 cells. We observed time and concentration dependent decrease in cell viability after treatment with AAE. Fluorescent staining and scanning electron micrographs of treated HL-60 cells demonstrated chromatin condensation, nuclear fragmentation and formation of apoptotic blebs. There was a marked increase in hypodiploid population of cells as observed by cell cycle analysis. Annexin V-FITC/PI also depicted the presence of apoptotic cells. Anti-apoptotic protein Bcl-2 was observed to be decreased by 62% at 20 µg/ml concentration and a significant increase in ROS production up to 6.9-fold was observed in time dependent manner. In addition, alteration in mitochondrial membrane potential was observed, which was followed by cytochrome c release to cytoplasm. Activated levels of mitochondrial downstream pathway protein namely Caspase-3 and 9, were detected in treated HL-60 cells by colorimetric analysis. DNA ladder formation, a biochemical hallmark of apoptosis was also observed in treated HL-60 cells. The results of the present study support the apoptotic potential of AAE and probability of its promising role in development as effective anticancer agent against leukemia cells.

Lanostane-Type Saponins from Vitaliana primuliflora

The phytochemistry of the genera Androsace, Cortusa, Soldanella, and Vitaliana, belonging to the Primulaceae family is not well studied so far. Hence, in this paper, we present the results of UHPLC-MS/MS analysis of several primrose family members as well as isolation and structure determination of two new saponins from Vitaliana primuliflora subsp. praetutiana. These two nor-triterpenoid saponins were characterized as (23S)-17α,23-epoxy-29-hydroxy-3β-[(O-β-d-glucopyranosyl-(1→2)-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-α-l-arabinopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]-27-nor-lanost-8-en-25-one and (23S)-17α,23-epoxy-29-hydroxy-3β-[(O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-α-l-arabinopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]-27-nor-lanost-8-en-25-one, respectively. Their structures were determined by high resolution mass spectrometry (HRMS), tandem mass spectrometry (MS/MS), one- and two-dimensional nuclear magnetic resonance spectroscopy (1D-, and 2D-NMR) analyses. So far, the 27-nor-lanostane monodesmosides were rarely found in dicotyledon plants. Therefore their presence in Vitaliana and also in Androsace species belonging to the Aretia section is unique and reported here for the first time. Additionally, eleven other saponins were determined by HRMS and MS/MS spectra. The isolated lanostane saponins can be considered as chemotaxonomic markers of the family Primulaceae.

Trichosanhemiketal A and B: Two 13,14-seco-13,14-epoxyporiferastanes from the root of Trichosanthes kirilowii Maxim

Of the 32 Trichosanthes species in China, T. kirilowii Maxim. is the most renowned species used in traditional Chinese medicine and has diverse pharmacological properties. However, most of the phytochemical studies of T. kirilowii have focused on the fruits and seeds. In our investigation of the chemical constituents of T. kirilowii roots, two previously undescribed sterols [trichosanhemiketal A and B (1 and 2)], together with 13 known compounds, were isolated and their structures were elucidated. To the best of our knowledge, this represents the first isolation of compounds with a 13,14-seco-13,14-epoxyporiferastane (1-2) skeleton from the Cucurbitaceae family. The anti-inflammatory activity of the isolated compounds was determined through an analysis of their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in macrophage RAW264.7 cells. Of the compounds, 4, 5, 6, and 8 showed significant inhibitory activities, with IC₅₀ values of 8.5, 15.1, 25.4, and 28.5 µM, respectively. In addition, compound 4 inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expression in a concentration-dependent manner.

Colocynthenins A-D, Ring-A seco-Cucurbitane Triterpenoids from the Fruits of Citrullus colocynthis

Four ring-A seco-cucurbitane triterpenoids, colocynthenins A-D (1-4), together with seven known cucurbitane triterpenoids (5-11), were isolated from the fruits of Citrullus colocynthis. Their structures and absolute configurations were elucidated based on spectroscopic analysis and quantum chemical ECD calculations. Compound 1 possesses an unprecedented 2,11-lactone moiety, while compound 2 is the first reported cucurbitane triterpenoid with an unusual cyano group. Compounds 1 and 3 showed acetylcholinesterase inhibitory activities in a standard in vitro assay, with IC₅₀ values of 2.6 and 3.1 μM, respectively.

Cucurbitacin glucosides fromCitrullus colocynthis

A new cucurbitacin glucoside 2-O-beta-D-glucopyranosyl-16alpha-20R-dihydroxy-cucurbita-1,5,23E,25(26)-tetraen-3,11,22-trione (1) has been isolated from the methanolic extract of the fruits of Citrulluscolocynthis. The structure has been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. In addition 2-O-beta-D-glucopyranosyl-cucurbitacin B (arvenin I) (2) and 2,25-di-O-beta-D-glucopyranosyl-cucurbitacin L (3) are reported for the first time from this species.

Cucurbitacin B 2-Sulfate and Cucurbitacin Glucosides from the Root Bark of Helicteres angustifolia

A new sulfated cucurbitacin, cucurbitacin B 2-sulfate (1) and a new cucurbitacin glucoside, cucurbitacin G 2-O-beta-D-glucopyranoside (2) together with two known cucurbitacin glucosides, arvenin I and arvenin III were isolated from the root bark of Helicteres angustifolia. The structures of these compounds were established on the basis of spectroscopic and chemical evidence. These four compounds taste of strong bitterness. Compound 1 is a first sulfated cucurbitacin found in plants.

Two New Cucurbitacin Glucosides, Opercurins A and B, from the Brazilian Folk Medicine "Buchinha" (Luffa operculata)

The structures of two new cucurbitacin glucosides designated opercurins A (1) and B (2), isolated from the fruit of Luffa operculata, have been confirmed by extensive spectroscopic investigation.

Antifungal activity of plant extracts against dermatophytes

The aqueous extracts (15 micrograms ml-1 medium) of 22 plants used in folkloric medicine in Palestine were investigated for their antifungal activity and minimum inhibitory concentrations (MICs) against nine isolates of Microsporum canis, Trichophyton mentagrophytes and Trichophyton violaceum. The extract of the different plant species reduced colony growth of the three dermatophytes by 36 to 100% compared with the control treatment. Antimycotic activity of the extract against the three dermatophytes varied significantly (P < 0.05) between test plants. Extracts of Capparis spinosa and Juglans regia completely prevented growth of M. canis and T. violaceum. The most active extracts (90-100% inhibition) were those of Anagallis arvensis, C. spinosa, J. regia, Pistacia lentiscus and Ruta chalapensis against M. canis; Inula viscosa, J. regia and P. lentiscus against T. mentagrophytes; and Asphodelus luteus, A. arvensis, C. spinosa, Clematis cirrhosa, I. viscosa, J. regia, P. lentiscus, Plumbago europea, Ruscus aculeatus, Retema raetam and Salvia fruticosa against T. violaceum. The MICs of these most active plants ranged from 0.6 to 40 micrograms ml-1. The three dermatophytes differed significantly with regard to their susceptibility to plant extracts. Trichophyton violaceum was the most susceptible being completely inhibited by 50% of the extracts followed by M. canis and T. mentagrophytes which were completely inhibited by only 23 and 14% of the extracts, respectively.