New lupane triterpenoids from Solidago canadensis that inhibit the lyase activity of DNA polymerase β

Allelopathic Activity of Canadian Goldenrod (Solidago canadensis L.) Extracts on Seed Germination and Growth of Lettuce (Lactuca sativa L.) and Garden Pepper Cress (Lepidium sativum L.)

Native to N. America, Canadian goldenrod (Solidago canadensis L.) was introduced to Europe as an ornamental plant and quickly spread here and in other parts of the world. The rapid spread of the plant is due to several reasons: phenotypic plasticity, broad climatic tolerance, propagation via underground rhizomes and seeds that mature in large numbers, etc. Additionally, the success of Canadian goldenrod's invasion is determined by its allelochemicals that affect seed germination, root formation and whole growth of nearby plants. Allelopathy of various extracts and essential oils (EOs) of S. canadensis on seed germination and growth of lettuce (Lactuca sativa L.) and garden pepper cress (Lepidium sativum L.) was evaluated and compared with other Solidago species (S. virgaurea, S. × niederederi) collected from the same growing locality in Lithuania. Soil characteristics (conductivity, pH and major elements) of the collecting site were determined. Aqueous flower extracts of all studied Solidago species showed the highest inhibitory effect on model plants. Canadian goldenrod leaf water/diethyl ether extract showed highest inhibitory effect in all relative concentrations (1.0; 0.1; 0.01) suppressing growth of L. sativa (from 0 to 2.3 mm compared with 22.7 mm for control samples) and L. sativum (from 0.5 to 16.8 mm compared with 35.3 mm in control). It was noticed that garden pepper cress was more susceptible to Solidago spp. inhibitory effects than lettuce. S. canadensis root EOs comprised mainly of limonene (35.0%) and β-pinene (26.2%) and inflorescence oils containing α-pinene (21.6%), germacrene D (15.1%), limonene (10.2%) and lupenyl acetate (9.8%) exhibited the highest inhibitory effect on lettuce and garden pepper cress growth. Relative germination and vigor index of model plants was conducted. Chemical composition of extracts and EOs was determined by HPLC/DAD/TOF and GC/MS techniques.

Selected aspects of invasive Solidago canadensis with an emphasis on its allelopathic abilities: a review

Solidago canadensis L., native to North America, is now an invasive plant worldwide. Its abundant seeds, rapid vegetative reproduction ability, and allelopathy to other plants are the main reasons for its successful invasion. It has negative impacts on the ecological environment of the invaded area and causes a reduction in local biodiversity and economic losses of agriculture and stock farming. Each part of the plant contains a variety of allelochemicals (terpenoids, phenolics, and flavonoids), including a large number of essential oil components. These allelochemicals can be released in various ways to inhibit the growth of adjacent plants and promote their invasion; they can also affect soil properties and soil microorganisms. This paper summarizes the allelopathic effects of S. canadensis on other plant species and the interaction mechanism between it and the ecosystem.

Lupeol-induced nitric oxide elicits apoptosis-like death within Escherichia coli in a DNA fragmentation-independent manner

Lupeol is known to be plentiful in fruits or plant barks and has an antimicrobial effect, however, its mode of action(s) has yet to be determined. To elucidate lupeol generates nitric oxide (NO), which is recognized for possessing an antimicrobial activity, intracellular NO was measured in Escherichia coli using DAF-FM. Using the properties of NO passing through plasma membrane easily, increased malondialdehyde levels have shown that lupeol causes lipid peroxidation, and the resulting membrane depolarization was confirmed by DiBAC4(3). These data indicated that lupeol-induced NO is related to the destruction of bacterial membrane. Further study was performed to examine whether NO, known as a cell proliferation inhibitor, affects bacterial cell division. As a result, DAPI staining verified that lupeol promotes cell division arrest, and followed by early apoptosis is observed in Annexin V/PI double staining. Even though these apoptotic hallmarks appeared, the endonuclease failed to perform properly with supporting data of decreased intracellular Mg2+ and Ca2+ levels without DNA fragmentation, which is confirmed using a TUNEL assay. These findings indicated that lupeol-induced NO occurs DNA fragmentation-independent bacterial apoptosis-like death (ALD). Additionally, lupeol triggers DNA filamentation and morphological changes in response to DNA repair system called SOS system. In accordance with the fact that ALD deems to SOS response, and that the RecA is considered as a caspase-like protein, increase in caspase-like protein activation occurred in E. coli wild-type, and no ΔRecA mutant. In conclusion, these results demonstrated that the antibacterial mode of action(s) of lupeol is an ALD while generating NO.

An assay for DNA polymerase β lyase inhibitors that engage the catalytic nucleophile for binding

DNA polymerase β (Pol β) repairs cellular DNA damage. When such damage is inflicted upon the DNA in tumor cells treated with DNA targeted antitumor agents, Pol β thus diminishes their efficacy. Accordingly, this enzyme has long been a target for antitumor therapy. Although numerous inhibitors of the lyase activity of the enzyme have been reported, none has yet proven adequate for development as a therapeutic agent. In the present study, we developed a new strategy to identify lyase inhibitors that critically engage the lyase active site primary nucleophile Lys72 as part of the binding interface. This involves a parallel evaluation of the effect of the inhibitors on the wild-type DNA polymerase β (Pol β) and Pol β modified with a lysine analogue at position 72. A model panel of five structurally diverse lyase inhibitors identified in our previous studies (only one of which has been published) with unknown modes of binding were used for testing, and one compound, cis-9,10-epoxyoctadecanoic acid, was found to have the desired characteristics. This finding was further corroborated by in silico docking, demonstrating that the predominant mode of binding of the inhibitor involves an important electrostatic interaction between the oxygen atom of the epoxy group and N^ε of the main catalytic nucleophile, Lys72. The strategy, which is designed to identify compounds that engage certain structural elements of the target enzyme, could find broader application for identification of ligands with predetermined sites of binding.

Volatile Compositions and Antifungal Activities of Native American Medicinal Plants: Focus on the Asteraceae

In the past, Native Americans of North America had an abundant traditional herbal legacy for treating illnesses, disorders, and wounds. Unfortunately, much of the ethnopharmacological knowledge of North American Indians has been lost due to population destruction and displacement from their native lands by European-based settlers. However, there are some sources of Native American ethnobotany remaining. In this work, we have consulted the ethnobotanical literature for members of the Asteraceae used in Cherokee and other Native American traditional medicines that are native to the southeastern United States. The aerial parts of Eupatorium serotinum, Eurybia macrophylla, Eutrochium purpureum, Polymnia canadensis, Rudbeckia laciniata, Silphium integrifolium, Smallanthus uvedalia, Solidago altissima, and Xanthium strumarium were collected from wild-growing plants in north Alabama. The plants were hydrodistilled to obtain the essential oils and the chemical compositions of the essential oils were determined by gas chromatography-mass spectrometry. The essential oils were tested for in-vitro antifungal activity against Aspergillus niger, Candida albicans, and Cryptococcus neoformans. The essential oil of E. serotinum showed noteworthy activity against C. neoformans with a minimum inhibitory concentration (MIC) value of 78 μg/mL, which can be attributed to the high concentration of cyclocolorenone in the essential oil.

quareticctivity of S olidago canadensiscultivated ingypt and etermination of theostioactiveraction

Despite the traditional use of Solidago canadensis L. (Asteraceae) as a diuretic drug, there is a scarcity in scientific data concerning the activity of its different extracts and fractions as well as the class of constituents responsible for this diuretic action. A comparative study was carried out for the diuretic activities of the different standardized extracts and fractions of the flowering aerial parts of S. canadensis, as well as isolation of compounds from the most biologically active fraction. The ethanol extract and its ethyl acetate fraction (EA) showed the highest aquaretic activities (91 and 58% at a dose of 400 mg/Kg b.wt., respectively) compared to 100% of furosemide at 20 mg/Kg b.wt.. Their activities were higher than Cystinol® and spironolactone reference standards (74% and 59% of furosemide, respectively). EA showed the highest total phenolic and flavonoid contents among the tested fractions of the ethanol and aqueous extracts (9.38 ± 0.004 g GAE and 39.75 ± 0.005 g RE/100 g dried extract, respectively). Eight flavonoids, 2 phenolic acids and 1 nucleoside were isolated from EA. This is the first report of a comparative study between the aquaretic activities of the different extracts, fractions and essential oil of S. canadensis, as well as isolation of thyimidine (1), isorhamnetin-3-O-β-ᴅ-glucopyranoside (2), kaempferol-3-O-(6”-O-acetyl)-β-ᴅ-glucopyranoside (4), quercetin-3-O-(6”-O-acetyl)-β-ᴅ-glucopyranoside (5), and kaempferol-3-O-β-ᴅ-apiofuranoside (7) from genus Solidago.

Solidago graminifolia L. Salisb. (Asteraceae) as a Valuable Source of Bioactive Polyphenols: HPLC Profile, In Vitro Antioxidant and Antimicrobial Potential

Solidago species are often used in traditional medicine as anti-inflammatory, diuretic, wound-healing and antimicrobial agents. Still, the bioactive compounds and biological activities of some species have not been studied. The present work aimed to investigate the polyphenolic profile and the biological properties of Solidago graminifolia L. Salisb., a poorly explored medicinal plant. The hydroalcoholic extracts from aerial parts were evaluated for total phenolic content (TPC), total flavonoid content (TFC) and the polyphenolic compounds were investigated by HPLC-MS. The antioxidant potential in vitro was determined using DPPH and FRAP assays. Antibacterial and antifungal effects were evaluated by dilution assays and MIC, MBC and MFC were calculated. The results showed that Solidago graminifolia aerial parts contain an important amount of total phenolics (192.69 mg GAE/g) and flavonoids (151.41 mg RE/g), with chlorogenic acid and quercitrin as major constituents. The hydroalcoholic extracts showed promising antioxidant and antimicrobial potential, with potent antibacterial activity against Staphylococcus aureus and important antifungal effect against Candida albicans and C. parapsilosis. The obtained results indicated that the aerial parts of Solidago graminifolia could be used as novel resource of phytochemicals in herbal preparations with antioxidant and antimicrobial activities.

Regulation of the levels of health promoting compounds: lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit: a review

There is a demand for feasible methodologies that can increase/maintain the levels of health-promoting phytochemicals in horticultural produce, due to strong evidence that these compounds can reduce risk of chronic diseases. Mango (Mangifera indica L.), ranks fifth among the most cultivated fruit crops in the world, is naturally rich in phytochemicals such as lupeol, mangiferin and phenolic acids (e.g. gallic acid, chlorogenic acid and vanillic acid). Yet, there is still much scope for up-regulating the levels of these compounds in mango fruit through manipulation of different preharvest and postharvest practices that affect their biosynthesis and degradation. The process of ripening, harvest maturity, physical and chemical elicitor treatments such as low temperature stress, methyl jasmonate (MeJA), salicylic acid (SA) and nitric oxide (NO) and the availability of enzyme cofactors (Mg²⁺ , Mn²⁺ and Fe²⁺ ) required in terpenoid biosynthesis were identified as potential determinants of the concentration of health-promoting compounds in mango fruit. The effectiveness of these preharvest and postharvest approaches in regulating the levels of lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit will be discussed. In general spray application of 0.2% iron(II) sulphate (FeSO₄ ) 30 days before harvest, harvest at sprung stage, storage of mature green fruit at 5 °C for 12 days prior to ripening, fumigation of mature green fruit with 10^-5  mol L^-1 and/or 10^-4  mol L^-1 MeJA for 24 h or 20 and/or 40 µL L^-1 NO for 2 h upregulate the levels of lupeol, mangiferin and phenolic acids in pulp and peel of ripe mango fruit. © 2019 Society of Chemical Industry.

3-O-(3′-Hydroxytetradecanoyl)lupeol from Sorocea trophoides Inhibits Cruzain

The crude chloroform extract from the stem bark of Sorocea trophoides (Moraceae) showed in-vitro inhibition of the cysteine protease cruzain. Activity-directed fractionation led to isolation of the novel 3- O-(3′-hydroxytetradecanoyl)lupeol as the inhibitory agent. The structure was elucidated by analysis of NMR spectra.

Comparison of Polyphenol Profile and Antimutagenic and Antioxidant Activities in Two Species Used as Source of Solidaginis herba - Goldenrod

European Pharmacopoeia accepts two equivalent species Solidago canadensis L. and S. gigantea Aiton as goldenrod (Solidaginis herba). We compared phytochemical profile of both species from invasive populations in Poland. Further, we compared in vitro antimutagenic and antioxidant activities of solvent extracts from aerial (AP) and underground parts (UP). In S. gigantea, flavonoid profile was dominated by quercetin glycosides, with quercitrin as the major compound. In S. canadensis, quercetin and kaempferol rutinosides were two major constituents. Caffeoylquinic acids (CQAs) were less diverse with 5-CQA as a main compound. In UP, over 20 putative diterpenoids were detected, mostly unidentified. Several CQAs were present in higher amounts than in AP. Antioxidant and antimutagenic activities were different between species and organs, with the strongest inhibition of lipid peroxidation by Et₂ O and AcOEt fractions from AP of both species (IC₅₀ 13.33 - 16.89 μg/mL) and BuOH fraction from S. gigantea UP (IC₅₀  = 13.32 μg/mL). Chemical mutagenesis was completely inhibited by non-polar fractions, but oxidative mutagenesis was inhibited up to 35% only by S. canadensis. No clear relationship was found between chemical profiles and antimutagenic activity. In conclusion, both species have diverse activity and their phytochemical profiles should be considered in quality evaluation. UP of these weeds can also provide potential chemopreventive substances for further studies.

Honokiol Inhibits DNA Polymerases β and λ and Increases Bleomycin Sensitivity of Human Cancer Cells

A major concept to sensitize cancer cells to DNA damaging agents is by inhibiting proteins in the DNA repair pathways. X-family DNA polymerases play critical roles in both base excision repair (BER) and nonhomologous end joining (NHEJ). In this study, we examined the effectiveness of honokiol to inhibit human DNA polymerase β (pol β), which is involved in BER, and DNA polymerase λ (pol λ), which is involved in NHEJ. Kinetic analysis with purified polymerases showed that honokiol inhibited DNA polymerase activity. The inhibition mode for the polymerases was a mixed-function noncompetitive inhibition with respect to the substrate, dCTP. The X-family polymerases, pol β and pol λ, were slightly more sensitive to inhibition by honokiol based on the Ki value of 4.0 μM for pol β, and 8.3 μM for pol λ, while the Ki values for pol η and Kf were 20 and 26 μM, respectively. Next we extended our studies to determine the effect of honokiol on the cytotoxicity of bleomycin and temozolomide in human cancer cell lines A549, MCF7, PANC-1, UACC903, and normal blood lymphocytes (GM12878). Bleomycin causes both single strand DNA damage that is repaired by BER and double strand breaks that are repaired by NHEJ, while temozolomide causes methylation damage repaired by BER and O6-alkylguanine-DNA alkyltransferase. The greatest effects were found with the honokiol and bleomycin combination in MCF7, PANC-1, and UACC903 cells, in which the EC50 values were decreased 10-fold. The temozolomide and honokiol combination was less effective; the EC50 values decreased three-fold due to the combination. It is hypothesized that the greater effect of honokiol on bleomycin is due to inhibition of the repair of the single strand and double strand damage. The synergistic activity shown by the combination of bleomycin and honokiol suggests that they can be used as combination therapy for treatment of cancer, which will decrease the therapeutic dosage and side effects of bleomycin.

DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair

DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell's genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy.

Molecular mechanism of adenomatous polyposis coli-induced blockade of base excision repair pathway in colorectal carcinogenesis

Colorectal cancer (CRC) is the third leading cause of death in both men and women in North America. Despite chemotherapeutic efforts, CRC is associated with a high degree of morbidity and mortality. Thus, to develop effective treatment strategies for CRC, one needs knowledge of the pathogenesis of cancer development and cancer resistance. It is suggested that colonic tumors or cell lines harbor truncated adenomatous polyposis coli (APC) without DNA repair inhibitory (DRI)-domain. It is also thought that the product of the APC gene can modulate base excision repair (BER) pathway through an interaction with DNA polymerase β (Pol-β) and flap endonuclease 1 (Fen-1) to mediate CRC cell apoptosis. The proposed therapy with temozolomide (TMZ) exploits this particular pathway; however, a high percentage of colorectal tumors continue to develop resistance to chemotherapy due to mismatch repair (MMR)-deficiency. In the present communication, we have comprehensively reviewed a critical issue that has not been addressed previously: a novel mechanism by which APC-induced blockage of single nucleotide (SN)- and long-patch (LP)-BER play role in DNA-alkylation damage-induced colorectal carcinogenesis.

Chemical constituents from Solidago canadensis with hypolipidemic effects in HFD-fed hamsters

Two new compounds, 8-dehydroxymethylvisanol (1) and 9-O-[3-O-acetyl-β-d-glucopyranosyl]-4-hydroxy-cinnamic acid (4), together with two known lignans, visanol (2) and 9-aldehydevibsanol (3), were isolated from the 80% EtOH extract of Solidago canadensis. The structures of the two new compounds were elucidated on the basis of 1D, 2D NMR, and mass spectral analysis. All the lignans exhibited moderate hypolipidemic activity in high-fat diet-fed hamsters.

DNA polymerase beta (pol β) inhibitors: a comprehensive overview

Base excision repair (BER) is the fundamental pathway responsible for the elimination of damaged DNA bases and repair of DNA single-strand breaks generated spontaneously or produced by DNA-damaging agents. Among the essential enzymes that are required to achieve the BER reaction is DNA polymerase beta (pol β), which has been regarded as a potential therapeutic target. More than 60 pol β-inhibitors have been identified so far; however, most of them are either not potent or not specific enough to become a drug. In this article we compile an essential knowledge base regarding the structures, the modes of inhibition and the activities of these pharmacologically interesting molecules.

Inhibitory effects of Solidago chilensis Meyen hydroalcoholic extract on acute inflammation

AIM OF THE STUDY

Alcoholic or hydroalcoholic preparations of the plant Solidago chilensis Meyen (Asteraceae) are employed in popular medicines to treat inflammation. The anti-inflammatory effects of the hydroalcoholic extract of aerial parts of the plant (93% ethanol) were investigated and the main components of the extract were identified.

MATERIALS AND METHODS

Ear oedema was induced in male Wistar rats by topical application of the chloroform fraction of latex-extract from Euphorbia milii. Leukocyte mobilisation was quantified after air-pouch inflammation evoked by oyster glycogen. Leukocyte-endothelial interactions and mast cell degranulation were quantified by intravital microscopy. The extract itself was characterised via HPLC-DAD-MS and HPLC-MS/MS.

RESULTS

Topical (12.5-50mg/kg) or intraperitoneal (25 or 50mg/kg) administrations of the extract reduced ear oedema formation (>25% reduction). Intraperitoneal applications of 25mg/kg of extract inhibited the migration of polymorphonuclear cells into the inflamed cavity (about 50%). In addition, the rolling behaviour and adherence of circulating leukocytes to postcapillary venules of the mesentery network was diminished (50%), but the mast cell degranulation in the perivascular area was not affected. The major components of the extract were identified as caffeoylquinic acid derivatives and the flavonoid rutin.

CONCLUSIONS

The data presented herein show local and systemic anti-inflammatory effects of the hydroalcoholic extract of aerial parts of Solidago chilensis, and implicate the inhibition of leukocyte-endothelial interactions as an important mechanism of the extract's action.

Inhibitors of DNA polymerase beta: activity and mechanism

Bioassay-guided fractionation of extracts prepared from Couepia polyandra and Edgeworthia gardneri resulted in the isolation of the DNA polymerase beta (pol beta) inhibitors oleanolic acid (1), edgeworin (2), betulinic acid (3), and stigmasterol (4). Study of these pol beta inhibitors revealed that three of them inhibited both the lyase and polymerase activities of DNA polymerase beta, while stigmasterol inhibited only the lyase activity. Further investigation indicated that the four inhibitors had substantially different effects on the DNA-pol beta binary complex that is believed to be an obligatory intermediate in the lyase reaction. It was found that the inhibitors potentiated the inhibitory action of the anticancer drug bleomycin in cultured A549 cells, without any influence on the expression of pol beta in the cells. The results of the unscheduled DNA synthesis assay support the thesis that the potentiation of bleomycin cytotoxicity by DNA pol beta inhibitors was a result of an inhibition of DNA repair synthesis.

A new phenolic glycoside from the aerial parts of Solidago canadensis

A new phenolic glycoside, 2'-hydroxy-4',6'-di-O-beta-D-glucopyranosyl-butyrrophenone (1), was isolated from the aerial parts of Solidago canadensis. The structure was elucidated on the basis of spectroscopic methods.

Chemical Composition and Antibacterial Activity of the Essential Oils of Blainvillea Rhomboidea (Asteraceae)

The essential oils of Blainvellea rhomboidea (Asteraceae) were obtained by hydrodistillation and analyzed by GC/MS and GC/FID. Initially, the essential oil from the aerial parts was investigated. From the 18 identified components, 5-indanol (14.5%) followed by p-cymen-8-ol (10.1%), β-caryophyllene (9.6%), caryophyllene oxide (9.6%), limonene (8.6%), terpinolene (7.8%), and spathulenol (7.7%) were the major constituents. The oil was tested against seven bacterial strains and the results showed significant antimicrobial activity. As a consequence, the essential oils from leaves and from flowers were analyzed separately. The major constituents of the leaf oil were terpinolene (21.2%), β-caryophyllene (19.2%), spathulenol (9.1%), caryophyllene oxide (7.4%), and bicyclogermacrene (7.1%), while the oil of the flowers contained terpinolene (28.1%), 5-indanol (16.3%), p-cymen-8-ol (15.3%) and limonene (14.7%) as prevalent compounds. The oils were tested against the same bacterial strains and the flower oil was the more active. These results indicated that the components of the essential oil from flowers seem to be responsible for the activity.