Two new stereoisomeric antioxidant triterpenes from Potentilla fulgens

Antiproliferative effect of Potentilla fulgens on glioblastoma cancer cells through downregulation of Akt/mTOR signaling pathway

BACKGROUND

Glioblastoma multiforme (GBM) is the most aggressive brain tumor that is common among adults. This aggression is due to increased invasion, migration, proliferation, angiogenesis, and decreased apoptosis. Plant-based compounds have a high potential to be used as an anticancer agent due to their various mechanisms and less undesirable side effects. Potentilla fulgens is a medicinal plant, and methanolic root extract of P. fulgens (PRE) has anti-inflammatory and anticancer properties.

OBJECTIVE

In this study, we aimed to investigate antiproliferative effect of PRE on U118 and T98G glioblastoma cancer cells and to reveal which molecular signaling pathways regulate this mechanism of action.

MATERIALS AND METHODS

The effect of PRE on cell viability of GBM cells was investigated by MTT assay. Involvement of PRE with cell growth and survival signaling pathways, phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR and c-Src/signal transducer and activator of transcription 3 (STAT3), was examined using Western Blot.

RESULTS

PRE reduced cell viability of GBM and human dermal fibroblast (HDF) cells in a dose-and time-independent manner. PI3K expression/phosphorylation level remained unchanged in both GBM and HDF cells after PRE treatment, but Akt/mTOR signaling pathway was downregulated in PRE-treated cells. PRE treatment did not affect c-Src expression/phosphorylation level in GBM cells; however, expression of c-Src was suppressed in HDF cells. Similar results were observed for STAT3 expression and phosphorylation status.

CONCLUSION

PRE has the ability to suppress cell viability in GBM cells, by targeting the Akt/mTOR signaling pathway.

Mitigation of X-ray induced DNA damages and expression of DNA-repair genes by antioxidative Potentilla fulgens root extract and its ethyl-acetate fraction in mammalian cells

Potentilla fulgens is a medicinal plant in North-East India whose root is reported to have anti-diabetic, anticarcinogenic and antioxidant properties. The potential of hydro-alcoholic extract of P. fulgens root (PRE) for providing protection to mammalian cells exposed to ionising radiation was investigated in this study. The methanolic extract of PRE shows an enhanced radical scavenging ability in a concentration dependent manner. PRE-pre-treatment to stimulated human blood lymphocytes (HBLs) reduced the frequency of deletion and exchange aberrations induced by X-irradiation. Similar protection of chromosome aberrations was also observed in mouse bone marrow cells (BMCs) where mice were given PRE extract (1 mg extract/day/mice) ad libitum in the drinking water for 45 days before whole-body X-irradiation. Of the various extracts prepared by partitioning of the methanol extract, the ethyl-acetate (EA) fraction was found to possess better antioxidant, radical scavenging and DNA-damage reduction activities. PRE-pre-treatment also reduced the radiation-induced cell-cycle delay effectively in HBL. In HEK-293 cells, PRE reduced radiation-induced G2-block in cell kinetics. Interestingly, PRE-treatment alone increased the concentration of endogenous glutathione (GSH) in mouse BMC and in stimulated HBL along with the elevated expression of γ-glutamyl-cysteine synthetase heavy/catalytic subunit, a key determinant of GSH synthesis. Studies on expression of two DNA-repair genes revealed that there was a marked increase in the expression of GADD45 and H2AX genes after X-irradiation in stimulated HBL, and such expression was reduced significantly if PRE-treatment was given prior to radiation. The present findings show the ability of PRE to reduce radiation-induced DNA damages probably by free radical scavenging whereas modulation of expression of DNA-repair genes' and endogenous GSH-increment emerge as effective strategies. The present study is the first report on the selected medicinal plant species that suggests it to be a potential natural radioprotector when used as root extract or its EA fraction for mitigating radiation toxicity.

Recent phytochemical and pharmacological advances in the genus Potentilla L. sensu lato - An update covering the period from 2009 to 2020

ETHNOPHARMACOLOGICAL RELEVANCE

Potentilla plants are still common herbal medicines used in folk medicine. This review provides an update of research undertaken on Potentilla from 2009 until 2020.

AIM OF THE STUDY

This comprehensive review considers biological updates, recent advances in phytochemical and pharmacological research, and toxicological reports on Potentilla sensu lato based on available data since 2009.

METHODS

A literature search was conducted using available databases including ScienceDirect, PubMed, Scopus, Web of Science, China National Knowledge Infrastructure and Google Scholar.

RESULTS

Until now, more than 210 new and known compounds, including flavonoids, tannins, triterpenes and phenolic compounds, have been confirmed and elucidated for numerous Potentilla species, i.e., in the underground and aerial parts of this genus. Modern pharmacology studies have revealed that those structures are responsible for a broad spectrum of pharmacological activities, such as anti-neoplastic, antihyperglycemic, anti-inflammatory, antioxidant, hepatoprotective, neuroprotective, antibacterial and anti-yeast effects.

CONCLUSIONS

However, in vitro studies must be re-considered due to the discovery of urolithins and their origins, including microbiota, which can lead to different results when applying Potentilla species and their extracts to in vivo conditions. Thus, future research should focus more on in vivo and particularly clinical studies to confirm the validity and safety of traditional uses. Particularly, the use of Potentilla alba extracts in the treatment of thyroid gland disorders should be further explored to confirm the underlying mechanism of their action, efficacy and safety. In addition, more clinical studies should focus on Potentilla erecta rhizome extracts for application as herbal remedies against dysentery, diarrhoea and inflammation of the skin.

Pentacyclic triterpenes with nitric oxide inhibitory activity from Potentilla chinensis

Three new ursane-type triterpenes (1-3) and twenty-one known triterpenoids (4-24) were isolated from the methanolic extract of the whole plants of Potentilla chinensis. Their structures were elucidated by extensive spectroscopic analysis of 1D and 2D NMR (HSQC, HMBC, COSY and ROESY) and HRESIMS data. The bioassay screening revealed the inhibitory effects on nitric oxide production of compounds 2, 5, 7, 9, 10, and 13-24 in LPS-induced RAW264.7 macrophages.

Biotransformation of Oleanane and Ursane Triterpenic Acids

Oleanane and ursane pentacyclic triterpenoids are secondary metabolites of plants found in various climatic zones and regions. This group of compounds is highly attractive due to their diverse biological properties and possible use as intermediates in the synthesis of new pharmacologically promising substances. By now, their antiviral, anti-inflammatory, antimicrobial, antitumor, and other activities have been confirmed. In the last decade, methods of microbial synthesis of these compounds and their further biotransformation using microorganisms are gaining much popularity. The present review provides clear evidence that industrial microbiology can be a promising way to obtain valuable pharmacologically active compounds in environmentally friendly conditions without processing huge amounts of plant biomass and using hazardous and expensive chemicals. This review summarizes data on distribution, microbial synthesis, and biological activities of native oleanane and ursane triterpenoids. Much emphasis is put on the processes of microbial transformation of selected oleanane and ursane pentacyclic triterpenoids and on the bioactivity assessment of the obtained derivatives.

Ursane-type triterpenoids from the roots of Rosa multiflora with their anti-inflammatory activity

Nine ursane-type triterpenoids including three new ones 2α, 19α-dihydroxyurs-3-O-acetyltormentic acid (1), 1α, 2α, 3α, 20β-tetrahydroxyurs -13(18)-en-28-oic acid (2), and 2α, 3α, 20β, 24-tetrahydroxyurs-13(18)-en-28-oic acid (3) were isolated from the roots of Rosa multiflora. Their structures were elucidated by extensive spectroscopic methods, including NMR, MS, and IR spectroscopic analyses data. All the isolates were evaluated for their anti-inflammatory activity in vitro and the results showed that compounds 1-9 displayed moderate inhibitory activity with IC₅₀ values ranging from 24.7 to 86.2 μM compared with the postitive control Amino guanidine (IC₅₀ 4.3 μM).[Formula: see text].

Methanolic extract of Potentilla fulgens root and its ethyl-acetate fraction delays the process of carcinogenesis in mice

People of north-eastern states of India consume raw areca-nut (RAN) and lime which could lead to oral, esophageal and gastric cancers. However, the incidence of these cancers are significantly lesser in those who consume pieces of Potentilla fulgens root along with RAN. Since evaluation of anticancer role, if any, of P. fulgens on RAN-mediated genetic alterations in human is difficult because of other compounding factors, this study was undertaken in mice to focus on gastric carcinogenesis since ad libitum administration of RAN extract with lime in drinking water induced stomach cancer due to greater exposure of its lining. A total of 160 mice were used at different time points and either methanol extract of P. fulgens roots (PRE) or mixture of four compounds of ethyl-acetate fraction (EA-mixture) was mixed with mice feed. Histological studies revealed that RAN + lime induced cancer in all the mice and interestingly only 20% developed cancer when PRE/EA-mixture was provided along with RAN + lime. Higher frequency of precocious anaphase and over expression of p53 and Securin genes were significantly reduced by PRE/EA-mixture. Thus PRE/EA-mixture mitigates the RAN-induced tumor-initiating process in stomach by maintaining expression of tumor suppressor and check-point genes under control.

Multidirectional insights into the biochemical and toxicological properties of Bougainvillea glabra (Choisy.) aerial parts: A functional approach for bioactive compounds

The current research work was conducted in order to probe into the biochemical and toxicological characterisation of methanol and dichloromethane (DCM) extracts of Bougainvillea glabra (Choisy.) aerial parts. Biological fingerprints were assessed for in vitro antioxidant, key enzyme inhibitory and cytotoxicity potential. Total bioactive contents were determined spectrophotometrically and the secondary metabolite components of methanol extract was assessed by UHPLC mass spectrometric analysis. The antioxidant capabilities were evaluated via six different in vitro antioxidant assays namely DPPH, ABTS (free radical scavenging), FRAP, CUPRAC (reducing antioxidant power), phosphomolybdenum (total antioxidant capacity) and ferrous chelating activity. Inhibition potential against key enzymes urease, α-glucosidase and cholinesterases were also determined. Methanol extract exhibited higher phenolic (24.01 mg GAE/g extract) as well as flavonoid (41.51 mg QE/g extract) contents. Phytochemical profiling of methanol extract identified a total of twenty secondary metabolites and the major compounds belonged to flavonoids, phenolics and alkaloid derivatives. The findings of antioxidant assays revealed the methanol extract to exhibit stronger antioxidant (except phosphomolybdenum) activities. Similarly, the methanol extract showed highest butyrylcholinesterase and urease inhibition. The DCM extract was most active for phosphomolybdenum and α-glucosidase inhibition assays. Moreover, both extracts exhibited significant cytotoxic potential against five (MCF-7, MDA-MB-231, CaSki, DU-145, and SW-480) human carcinoma cell lines with half maximal inhibitory concentration values of 22.09 to 257.2 μg/mL. Results from the present study highlighted the potential of B. glabra aerial extracts to be further explored in an endeavour to discover novel phytotherapeutics as well as functional ingredients.

Triterpenoids

Covering: 2013. Previous review: Nat. Prod. Rep., 2015, 29, 1028-1065This review covers the isolation and structure determination of triterpenoids reported during 2013 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 350 references are cited.

Cytotoxic and Enzyme Inhibitory Potential of Two Potentilla species (P. speciosa L. and P. reptans Willd.) and Their Chemical Composition

In this work, the biological and chemical fingerprints of three extracts (ethyl acetate, methanol, and water) from two Potentilla species (Potentilla reptans and P. speciosa) were investigated. Antioxidant, enzyme inhibitory, and cytotoxic activities were performed for the biological fingerprint. For the chemical characterization, total bioactive components, and individual phenolic components were determined using photometric and HPLC methods, respectively. The main identified phenolic compounds in these extracts were rutin and catechin. Methanol and water extracts contained the highest total phenolic and flavonoid content. The results of antioxidant assays showed that methanol and water extracts displayed higher antioxidant activity compared to the ethyl acetate extract. Generally, methanol and water extracts exhibited higher biological activities correlated with higher levels the bioactive components. For P. speciosa, the methanol extract exhibited the highest enzyme inhibitory activity (except BChE inhibitory activity). P. reptans exhibited also high antiproliferative activity against MCF-7 cells whilst P. speciosa had weak to moderate activity against both of A549 and MCF-7 cell lines. The results suggest that Potentilla species could be potential candidates for developing new phyto-pharmaceuticals and functional ingredients.

Amelioration of age-dependent increase in oxidative stress markers in male mice by extract of Potentilla fulgens

OBJECTIVE

To investigate the effect of Potentilla fulgens extract on lipid peroxidation and antioxidant status in male mice as a function of age.

METHODS

Eighteen-month-old Swiss albino male mice were administered the dichloromethane-methanol extract of P. fulgens (250 mg/kg b.w.) on alternate days via intraperitoneal route for a period of 14 days. Lipid peroxidation and activities of catalase (CAT) and glutathione peroxidase (GPx1) in liver and kidney were measured and serum oxygen radical absorbance capacity (ORAC) assay was estimated. Phytochemical analysis of P. fulgens extract using high performance thin layer chromatography (HPTLC) was carried out with gallic acid, quercetin, catechin, and epicatechin as markers.

RESULTS

Significant increase in level of thiobarbituric acid-reactive substances (TBARS), decreased GPx1, and CAT activities as well as reduction in ORAC were observed in 18-month-old mice as compared to that of 2-month-old mice. Treatment with P. fulgens extract significantly lowered TBARS level, ameliorated CAT, and GPx1 activities in liver and kidney and improved serum ORAC in aging mice. HPTLC studies revealed well resolved bands of P. fulgens extract containing epicatechin and catechin.

DISCUSSION

This study showed that P. fulgens is a potent antioxidative agent, which can emerge as a promising candidate in alleviating the age-associated oxidative stress and related diseases.

The Scavenging of DPPH, Galvinoxyl and ABTS Radicals by Imine Analogs of Resveratrol

Resveratrol (3,5,4′-trihydroxystilbene) is a phytoalexin produced by plants. Resveratrol is known for its anti-cancer, antiviral and antioxidant properties. We prepared imine analogs of resveratrol ((hydroxyphenyliminomethyl)phenols) and tested their antioxidant activity. All prepared resveratrol analogs were able to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR) and 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The antioxidant activity efficiency correlated with the number and position of hydroxyl groups. The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules. These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs.

Induction of Apoptosis and Reduction of Endogenous Glutathione Level by the Ethyl-Acetate Soluble Fraction of the Methanol Extract of the Roots of Potentilla fulgens in Cancer Cells

Potentilla fulgens root traditionally used as a folk remedy in Meghalaya, India. However, systematic evaluation of its anticancer efficacy was limited. We investigated the anticancer potentials of the various extracts prepared by partitioning of the methanol extract of the root with the aim to discover major contributing factors from the most effective fractions. Methanol extract of P. fulgens roots (PRE) was prepared by maceration which was subsequently fractionated into hexane, ethyl-acetate (EA) and n-butanol soluble fractions. Various assays (clonogenic assay, Flow cytometry analysis, western blot, semiquantitative RT-PCR and the level of endogenous glutathione) were used to evaluate different parameters, such as Cell survivability, PARP-1 proteolysis, expression pattern of anti-apoptotic and γ-glutamyl-cysteine synthetase heavy subunit (GCSC) genes in both MCF-7 and U87 cancer cell lines. Since the EA-fraction showed most efficient growth inhibitory effect, it was further purified and a total of nine compounds and some monomeric and dimeric flavan-3-ols were identified and characterized. Three compounds viz., epicatechin (EC), gallic acid (GA) and ursolic acid (UA) were taken on the basis of their higher yield and 10 μg/ml of each was mixed together. The concentration used in this study for PRE, EA- and Hex-fraction was 100 μg/ml, which was higher than the IC₅₀ value. Apoptotic cell death in the PRE, EA-fraction and EC+GA+UA treated cancer cell cultures was significantly greater than in normal cells due to suppression of anti-apoptotic protein Bcl2 following treatment. Depletion of glutathione by downregulating GCSC was also observed. Induction of apoptosis and lowering the level of glutathione are considered to be positive activity for an anticancer agent. Therefore, modulation of GSH concentration in tumor cells by PRE and its EA-fraction opened up the possibility of a new therapeutic approach because these plant products are not harmful to normal cells and may regulate the tumor cellular response to different anticancer treatments. Thus, it would be interesting to examine efficacy of these plant products or EA-fraction in human cancer treatment.

Bio-synthesis of silver nanoparticles using Potentilla fulgens Wall. ex Hook. and its therapeutic evaluation as anticancer and antimicrobial agent

The present study aims to develop an easy and eco-friendly method for the synthesis of silver nanoparticles using extracts from the medicinal plant, Potentilla fulgens and evaluation of its anticancer and antimicrobial properties. The various parts of P. fulgens were screened and the root extract was found to have the highest potential for the synthesis of nanoparticles. The root extracts were able to quickly reduce Ag(+) to Ag(0) and stabilized the nanoparticles. The synthesis of nanoparticles was confirmed by UV-Visible spectrophotometry and further characterized using Zeta sizer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electron microscopic study showed that the size of the nanoparticle was in the range of 10 to 15 nm and spherical in shape. The studies of phytochemical analysis of nanoparticles indicated that the adsorbed components on the surface of nanoparticles were mainly flavonoid in nature. Furthermore, nanoparticles were evaluated as cytotoxic against various cancer cell lines and 0.2 to 12 μg/mL nanoparticles showed good toxicity. The IC50 value of nanoparticles was found to be 4.91 and 8.23 μg/mL against MCF-7 and U-87 cell lines, respectively. Additionally, the apoptotic effect of synthesized nanoparticles on normal and cancer cells was studied using trypan blue assay and flow-cytometric analysis. The results indicate the synthesized nanoparticle ability to kill cancer cells compared to normal cells. The nanoparticles also exhibited comparable antimicrobial activity against both Gram-positive and Gram-negative bacteria.

Qualitative and quantitative analysis of Potentilla fulgens roots by NMR, matrix-assisted laser desorption/ionisation with time-of-flight MS, electrospray ionisation MS/MS and HPLC/UV

INTRODUCTION

Potentilla fulgens is a commonly used folk medicine by natives of northeast India, Nepal and Bhutan and is rich in polyphenolic and triterpene constituents.

OBJECTIVE

To identify chemomarkers in the roots of P. fulgens by an interplay of (13)C-NMR, matrix-assisted laser desorption/ionisation with time-of-flight (MALDI/TOF) MS, electrospray ionisation (ESI) MS/MS and HPLC/UV.

MATERIAL AND METHODS

The (13)C-NMR spectrum of crude methanolic extract was recorded in deuterated dimethyl sulphoxide. For MALDI/TOF/MS analysis, 2,5-dihydroxybenzoic acid was used as the matrix. For determination of chemical constituents, two independent simple isocratic HPLC/UV methods for monomeric/oligomeric flavanols and triterpene acids were developed and validated.

RESULTS

The (13)C-NMR spectrum of the methanolic extract indicated the presence of B-type oligomeric polyphenolics containing mainly epicatechin/catechin (epicat/cat) and epiafzelechin/afzelechin (epiafz/afz) as the monomeric units. Several isobaric monomeric and oligomeric flavanols and triterpenoids were tentatively identified by MALDI/TOF/MS and ESI/MS/MS. Fourteen compounds (four monomeric and five dimeric flavanols and five triterpene acids) were isolated using repeated column chromatography and semi-preparative HPLC, and were quantitated using HPLC/UV.

CONCLUSION

It is evident from these analyses that roots of P. fulgens contain flavans, including oligomeric flavanols, as major constituents followed by triterpene acids. The methods described can be applied to other Potentilla species to identify their constituents.

Antimicrobial activity of oleanolic and ursolic acids: an update

Triterpenoids are the most representative group of phytochemicals, as they comprise more than 20,000 recognized molecules. These compounds are biosynthesized in plants via squalene cyclization, a C30 hydrocarbon that is considered to be the precursor of all steroids. Due to their low hydrophilicity, triterpenes were considered to be inactive for a long period of time; however, evidence regarding their wide range of pharmacological activities is emerging, and elegant studies have highlighted these activities. Several triterpenic skeletons have been described, including some that have presented with pentacyclic features, such as oleanolic and ursolic acids. These compounds have displayed incontestable biological activity, such as antibacterial, antiviral, and antiprotozoal effects, which were not included in a single review until now. Thus, the present review investigates the potential use of these triterpenes against human pathogens, including their mechanisms of action, via in vivo studies, and the future perspectives about the use of compounds for human or even animal health are also discussed.

Antihypertensive potential of the aqueous extract which combine leaf of Persea americana Mill. (Lauraceae), stems and leaf of Cymbopogon citratus (D.C) Stapf. (Poaceae), fruits of Citrus medical L. (Rutaceae) as well as honey in ethanol and sucrose experimental model

BACKGROUND

The present study was designed to evaluate the effects of the aqueous extract obtained from the mixture of fresh leaf of Persea americana, stems and fresh leaf of Cymbopogon citratus, fruits of Citrus medica and honey on ethanol and sucrose induced hypertension in rats.

METHODS

Rats were divided into eight groups of 6 rats each and daily treated for 5 weeks. The control group received distilled water (1 mL/kg) while rats of groups 2, 3 and 4 received ethanol 40 degrees (3 g/kg/day), 10% sucrose as drinking water and the two substances respectively. The remaining groups received in addition to sucrose and ethanol, the aqueous extract (50, 100 and 150 mg/kg) or nifedipine (10 mg/kg) respectively. Many parameters including hemodynamic, biochemical and histopathological were assessed at the end of the study.

RESULTS

The concomitant consumption of ethanol and sucrose significantly (p < 0.001) increased the blood pressure and the heart rate compared to distilled water treated-rats. The levels of total cholesterol, LDL-cholesterol, triglycerides, atherogenic index, glucose, proteins, AST, ALT, creatinin, potassium, sodium and albumin increased while the HDL-cholesterol decreased under ethanol and sucrose feeding. Chronic ethanol and sucrose intake significantly decreased the activities of superoxide dismutase (SOD) and catalase (CAT) as well as the contents of reduced glutathione (GSH) and nitrites whereas elevated the malondialdehyde (MDA) levels. Histological analysis revealed among other vascular congestion, inflammation, tubular clarification and thickening of the vessel wall in rats treated with alcohol and sucrose. Administration of the aqueous extract or nifedipine prevented the hemodynamic, biochemical, oxidative and histological impairments induced chronic ethanol and sucrose consumption.

CONCLUSION

Current results suggest that the aqueous extract used in this study possess antihypertensive activity against ethanol and sucrose induced hypertension in rats by the improvement of biochemical and oxidative status, and by protecting liver, kidney and vascular endothelium against damages induced by chronic consumption of ethanol and sucrose.