Xanthine oxidase inhibitory properties of Czech medicinal plants

A study on the antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activity of the Artemisia vulgaris L. extract and its fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Vietnamese people use mugwort (Artemisia vulgaris L.) to treat arthritis and gout. Our previous research shows that mugwort contains flavonoids, and its extract possesses antibacterial and anti-inflammatory activities. However, no publications have been on the xanthine oxidase inhibitory activity of mugwort and acute anti-inflammatory activity in vivo.

AIM OF THE STUDY

The study aimed to verify the antioxidant, xanthine oxidase inhibitory, and anti-inflammatory capabilities of mugwort extract in vitro and in vivo, isolate phyto-compounds from potential bioactive fractions, and then evaluate their potential in inhibiting xanthine oxidase.

METHODS

According to established methods, the extract and the active flavonoids were obtained using different chromatographic techniques. DPPH, ABTS, reducing power, and H2O2 elimination were used to evaluate antioxidant activity. The model of LPS-induced RAW264.7 cells was used to measure the inhibition of NO production. The carrageenan-induced paw oedema model was used to assess acute inflammation in mice. In vitro, xanthine oxidase inhibition assay was applied to investigate the effects of extract/compounds on uric acid production. Chemical structures were identified by spectral analysis.

RESULTS

The assessment of the acute inflammatory model in mice revealed that both the 96% ethanol and the 50% ethanol extracts significantly decreased oedema in the mice's feet following carrageenan-induced inflammation. 96% ethanol extract exhibited a better reduction in oedema at the low dose. The analysis revealed that the ethyl acetate fraction had the highest levels of total polyphenols and flavonoids. Additionally, this fraction demonstrated significant antioxidant activity in various assays, such as DPPH, ABTS, reducing power, and H2O2 removal. Furthermore, it displayed the most potent inhibition of xanthine oxidase, an anti-inflammatory activity. Five phytochemicals were isolated and determined from the active fraction such as luteolin (1), rutin (2), apigenin (3), myricetin (4), and quercetin (5). Except for rutin, the other compounds demonstrated the ability to inhibit effective xanthine oxidase compared to standard (allopurinol). Moreover, quercetin (5) inhibited NO production (IC50 21.87 μM).

CONCLUSION

The results indicate that extracts from A. vulgaris effectively suppressed the activity of xanthine oxidase and exhibited antioxidant and anti-inflammatory properties, potentially leading to a reduction in the production of uric acid in the body and eliminating ROS. The study identified mugwort extract and bioactive compounds derived from Artemisia vulgaris, specifically luteolin, apigenin, and quercetin, as promising xanthine oxidase inhibitors. These findings suggest that further development of these compounds is warranted. At the same time, the above results also strengthen the use of mugwort to treat gout disease in Vietnam.

Herbal remedies in the management of hyperuricemia and gout: A review of in vitro, in vivo and clinical evidences

Gout, or hyperuricemia is a multifactorial and multi-faceted metabolic disease that is quite difficult to manage and/or treat. Conventional therapies such as non-steroidal anti-inflammatory drugs (NSAIDs) such as allopurinol, corticosteroids and colchicine amongst others, have helped in its management and treatment to some extent. This study aimed to compile and analyze the different herbal remedies used in the management of hyperuricemia and gout. A literature search was conducted from key databases (PubMed, ScienceDirect, Cochrane Library, Google Scholar) using relevant keywords via the PRISMA model. Smilax riparia A.DC. from Traditional Chinese Medicine is used in many countries for its therapeutic effect on lowering serum urate levels. No single study was able to establish the efficacy of a specific traditionally used herb via in vitro, in vivo, and clinical studies. Patients were found to use a panoply of natural remedies, mainly plants to treat hyperuricemia and gout, which have been validated to some extent by in vitro, in vivo, and clinical studies. Nonetheless, further research is needed to better understand the ethnopharmacological relationship of such herbal remedies.

Liquid chromatography-tandem mass spectrometry profile and antioxidant, antimicrobial, antiproliferative, and enzyme activities of Thymus pectinatus and Thymus convolutus: in vitro and in silico approach

BACKGROUND

The objective of this study is to investigate the antiproliferative, antioxidant, antimicrobial, and enzyme activity capacities and phytochemical compositions of Thymus pectinatus (TP), Thymus convolutus (TC), which are endemic to Türkiye. Quantitative analysis of phenolic compounds in the extracts was conducted using liquid chromatography-tandem mass spectrometry, targeting 53 phenolic compounds.

RESULTS

Rosmarinic acid, quinic acid, and cynaroside were identified as the major compounds, exhibiting quantitative variation in both extracts. The extracts had a high total phenolic content, with 113.57 ± 0.58 mg gallic acid equivalents (GAE)/g extract for TP and 130.52 ± 1.05 mg GAE/g extract for TC. Furthermore, although both extracts exhibited high total flavonoid content; the TP extract (75.12 ± 1.65 mg quercitin equivalents (QE)/g extract) displayed a higher flavonoid content than the TC extract (30.24 ± 0.74 mg QE/g extract) did. The extracts had a promising antiproliferative effect on C6, HeLa, and HT29 cancer cell lines with a less cytotoxic effect (10.5-14.2%) against normal cells. Both extracts exhibited very potent inhibitory activity against the xanthine oxidase enzyme, with half-maximal inhibitory concentration values of respectively 2.07 ± 0.03 μg mL-1 and 2.76 ± 0.06 μg mL-1 and moderate activity against tyrosinase and α-glucosidase. Docking simulations proved that rosmarinic acid and cynaroside, the major components of the extracts, were the most potent inhibitors of xanthine oxidase. According to antimicrobial activity results, the TC extract exhibited moderate activity against Staphylococcus aureus, and the TP extract had strong activity against both Enterococcus faecium and S. aureus.

CONCLUSION

These findings emphasize the beneficial effects of the two endemic Thymus species on human health and suggest their potential use as plant-derived bioactive agents. © 2024 Society of Chemical Industry.

The genus Balanophora J. R. Forst. & G. Forst. - Its use in traditional medicine, phytochemistry, and pharmacology: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Natural products, particularly medicinal plants, have been utilized in traditional medicine for millennia to treat various diseases. The genus Balanophora (Balanophoraceae) consists of 23 accepted species. These species are the most controversial flowering plants, with highly reduced morphologies and are found parasitizing on the roots of their host. They have been used in traditional medicine as a remedy for stomach pain, detumescence, uterine prolapse, wounds, syphilis, gonorrhea, treating injuries from falls, and other conditions. However, there is no review of this genus on its traditional uses, phytochemistry, and pharmacology.

AIM

The present narrative review discusses the scientific data supporting the traditional uses of Balanophora species. The available information on its botanical properties, traditional uses, chemical contents, pharmacological activities, and toxicity was summarized to help comprehend current research and offer a foundation for future research.

MATERIALS AND METHODS

The materials used in combining data on the genus Balanophora comprises online sources such as Web of Science, Google Scholar, Science Direct, and Chinese National Knowledge Infrastructure (CNKI) for Chinese-related materials. World Flora online was used in validating the scientific names of this genus while ChemBio Draw Ultra Version 22.2 software was employed in drawing the phytochemical compounds.

RESULTS

Nine Balanophora species including B. harlandii, B. japonica, B. polyandra, B. fungosa, B. fungosa subsp. indica, B. laxiflora, B. abbreviata, B. tobiracola, and B. involucrata have been documented as vital sources of traditional medicines in different parts of Asia. A total of 159 secondary metabolites have been isolated and identified from the ten species of this genus comprising tannins, flavonoids, sterols, lignans, chalcones, terpenes, and phenylpropanoids. Among these compounds, tannins, lignans, terpenoids, chalcones and phenolic acids contribute to the pharmacological activities of the species in this genus with several biological activities both in vitro and in vivo such as anti-inflammatory, anti-oxidant, hypoglycemic activity, cytotoxicity, anti-microbial, melanin synthesis etc. CONCLUSION: This review summarizes the available literature on the traditional uses, pharmacological properties, and phytoconstituents of Balanophora species indicating that they contain fascinating chemical compounds with diverse biological activities. The traditional uses of the species in this genus have been confirmed by scientific data such as antimicrobial, hemostatic effect, gastroprotective activity and others. However, many species in this genus are yet unknown in terms of their botanical uses, chemical composition and biological activities. Thus, more research into the scientific connections between traditional medicinal uses and pharmacological activities, mode of action of the isolated bioactive constituents, and toxicity of other Balanophora species is needed to determine their efficacy and therapeutic potential for safe clinical application.

P2X7-Receptor Pathway Involvement in the Anti-Inflammatory Activity of Medicinal Plants

Medicinal plants used in European folk medicine attached to Lamiales, Gentianales or Asterales orders are used to treat inflammatory disorders. Many targets have been identified but to date, implication of purinergic receptor P2X7 activation has not yet been investigated. We managed to evaluate the protective effect on P2X7 activation by plant extracts used as anti-inflammatory in European folk medicine by the YO-PRO-1 uptake dye in vitro bioassay. Results revealed that among our selected plants, species from Scrophularia and Plantago genus were able to decrease significantly P2X7 activation (>50 % at 0.1 and 1 μg/mL). UPLC/MS, dereplication and metabolomic analysis of Scrophularia extracts, allowed us to identify the cinnamoyl-iridoid harpagoside as putative inhibitor of P2X7 activation. These results open a new research field regarding the anti-inflammatory mechanism of cinnamoyl-iridoids bearing plants, which may involve the P2X7 receptor.

Microwave-Assisted Water Extraction of Aspen (Populus tremula) and Pine (Pinus sylvestris L.) Barks as a Tool for Their Valorization

The barks of aspen (Populus tremula) and pine (Pinus sylvestris) are byproducts of wood processing, characterized by their low economic value. In the present study, microwave-assisted one-cycle water extraction was explored as a tool for the valorization of this biomass as a source of biologically active compounds. The microwave extractor of the original construction equipped with a pressurized extraction chamber and a condenser section was used. The microwave-assisted extraction (MAE), specially including dynamic dielectric heating up to 70 °C followed by 30 min of isothermal heating, promoted the isolation of salicin from aspen bark, allowing for the obtention of a two-times-higher free salicin concentration in water extracts (−14% vs. 7%) reached by multi-cycle accelerated solvent extraction (ASE), which is an advanced technique used as a reference. The MAE of pine bark with dynamic heating up to 90–130 °C, avoiding the isothermal heating step, allowed for the obtention of a 1.7-times-higher concentration of proantocyanidin dimers-tetramers, a 1.3-times-higher concentration of catechin and a 1.2-times-higher concentration of quinic acid in water extracts in comparison to a more time- and solvent-consuming ASE performed at the same temperature. The biological activity of the obtained extracts was characterized in terms of their ability to inhibit xahntine oxidase enzyme, which is a validated target for the therapeutic treatment of hyperuricemia.

Metabolites of Procyanidins From Litchi Chinensis Pericarp With Xanthine Oxidase Inhibitory Effect and Antioxidant Activity

Procyanidins from litchi pericarp (LPPC) has been evidenced to possess strong antioxidant activities in vivo that is possibly correlated with their intestinal metabolites. However, the xanthine oxidase inhibitory effect of LPPC and its metabolites was less concerned. In this study, three oligomeric procyanidins and eight metabolic phenolic acids were identified in the urine of rats administrated with LPPC by high performance liquid chromatography and liquid chromatography-mass spectrometry analysis. Data indicated that all the metabolites excreted were significantly increased by the treatment of 300 mg/kg body weight of LPPC (P < 0.05), revealing considerable 1, 1-Diphenyl-2-Picrylhydrazyl (DPPH) and hydroxyl radicals activities of scavenging. Moreover, phenolic metabolites involving epicatechin, A-type dimer, A-type trimer, caffeic acid, and shikimic acid exhibited greater xanthine oxidase inhibition effects compared with other metabolites, with an inhibitory rate higher than 50% at the concentration 200 μg/ml. The IC₅₀ value of these five phenols were 58.43 ± 1.86, 68.37 ± 3.50, 74.87 ± 1.30, 95.67 ± 3.82, and 96.17 ± 1.64 μg/ml, respectively. As a whole, this work suggests that the xanthine oxidase inhibition and antioxidant activity of LPPC-derived metabolites as one of the mechanisms involved in the beneficial effects of LPPC against hyperuricemia or gout.

Antihyperuricemic, Anti-Inflammatory and Antihypertensive Effect of a Dry Extract from Solidago virgaurea L. (Asteraceae)

Solidago virgaurea L. is a perennial plant used in European traditional medicine as a diuretic or a remedy for inflammatory conditions of the urinary tract but also for gout, especially in the Balkans. The present study was focused on a preclinical, in vivo evaluation of antihyperuricemic, anti-inflammatory, and antihypertensive effects of a dry extract from S. virgaurea L. (ESV). Colorimetric and HPLC–MS techniques were used to identify the main chemical constituents of ESV. Antihyperuricemic effect of ESV was assessed in a rat model of hyperuricemia induced by the administration of potassium oxonate. Antihypertensive effect of ESV was evaluated in hyperuricemic rats by monitoring systolic blood pressure with a non-invasive blood-pressure recording system. The anti-inflammatory effect of ESV was tested using a rat model of paw edema. The main chemical constituents of ESV were rutin and phenolic acids represented by chlorogenic and caffeic acid. ESV demonstrated significant antihyperuricemic effects in rats due to an uricosuric mechanism. Additionally, ESV reduced the progression of arterial hypertension in hyperuricemic rats and also showed anti-inflammatory properties slightly inferior to diclofenac. The results suggest that ESV could be a natural remedy for the treatment of gout and protection against endothelial dysfunction caused by hyperuricemia.

Natural Products and Extracts as Xantine Oxidase Inhibitors - A Hope for Gout Disease?

Xanthine oxidase (EC 1.17.3.2) (XO) is one of the main enzymatic sources that create reactive oxygen species (ROS) in the living system. It is a dehydrogenase enzyme that performs electron transfer to nicotinamide adenine dinucleotide (NAD+), while oxidizing hypoxanthin, which is an intermediate compound in purine catabolism, first to xanthine and then to uric acid. XO turns into an oxidant enzyme that oxidizes thiol groups under certain stress conditions in the tissue. The last metabolic step, in which hypoxanthin turns into uric acid, is catalyzed by XO. Uric acid, considered a waste product, can cause kidney stones and gouty-type arthritis as it is crystallized, when present in high concentrations. Thus, XO inhibitors are one of the drug classes used against gout, a purine metabolism disease that causes urate crystal storage in the joint and its surroundings caused by hyperuricemia. Urate-lowering therapy includes XO inhibitors that reduce uric acid production as well as uricosuric drugs that increase urea excretion. Current drugs that obstruct uric acid synthesis through XO inhibition are allopurinol, febuxostat, and uricase. However, since the side effects, safety and tolerability problems of some current gout medications still exist, intensive research is ongoing to look for new, effective, and safer XO inhibitors of natural or synthetic origins for the treatment of the disease. In the present review, we aimed to assess in detail XO inhibitory capacities of pure natural compounds along with the extracts from plants and other natural sources via screening Pubmed, Web of Science (WoS), Scopus, and Google Academic. The data pointed out to the fact that natural products, particularly phenolics such as flavonoids (quercetin, apigenin, and scutellarein), tannins (agrimoniin and ellagitannin), chalcones (melanoxethin), triterpenes (ginsenoside Rd and ursolic acid), stilbenes (resveratrol and piceatannol), alkaloids (berberin and palmatin) have a great potential for new XO inhibitors capable of use against gout disease. In addition, not only plants but other biological sources such as microfungi, macrofungi, lichens, insects (silk worms, ants, etc) seem to be the promising sources of novel XO inhibitors.

Recent Advances Regarding the Phytochemical and Therapeutic Uses of Populus nigra L. Buds

Populus nigra L. (Salicaceae family) is one of the most popular trees that can be found in deciduous forests. Some particularities that characterize the Populus genus refer to the fact that it includes more than 40 species, being widespread especially in Europe and Asia. Many residues, parts of this tree can be used as a bioresource for different extracts as active ingredients in pharmaceuticals next to multiple benefits in many areas of medicine. The present review discusses the latest findings regarding the phytochemical composition and the therapeutic properties of Populus nigra L. buds. The vegetal product has been described mainly to contain phenolic compounds (phenols, phenolic acids and phenylpropanoids), terpenoids (mono and sesquiterpenoids), flavones (e.g., apigenol and crysin), flavanones (e.g., pinocembrin and pinostrombin), caffeic/ferulic acids and their derivates, and more than 48 phytocompounds in the essential oils. The resinous exudates present on the buds have been the major plant source used by bees to form propolis. Several studies depicted its antioxidant, anti-inflammatory, antibacterial, antifungal, antidiabetic, antitumor, hepatoprotective, hypouricemic properties and its effects on melanin production. All these lead to the conclusion that black poplar buds are a valuable and important source of bioactive compounds responsible for a wide range of therapeutic uses, being a promising candidate as a complementary and/or alternative source for a large number of health problems. The aim of the review is to gather the existing information and to bring an up to date regarding the phytochemical and therapeutic uses of Populus nigra L. buds.

Bryophyllum pinnatum markers: CPC isolation, simultaneous quantification by a validated UPLC-DAD method and biological evaluations

Bryophyllum pinnatum (Lam.) Oken (Crassulaceae) is widely used as leaf juice or extracts in traditional medicine all over tropical areas, especially in Brazil, to relieve inflammation-associated symptoms. Flavonol glycosides with unusual sugar moiety are among the major metabolites. Nevertheless, there are not enough quality control studies that can contribute to authentication of B. pinnatum and determination of their markers. As it is also used as medicinal plant in several countries, it is necessary to provide data related to safety, efficacy and quality. In this context, this work aims to isolate the major flavonoids from B. pinnatum hydroethanolic extract, to validate a method to quantify the content of chemical markers and to evaluate their xanthine oxidase inhibition and antioxidant activity. The extract was submitted to centrifugal partition chromatography (CPC). The solvents system CyHex-EtOAc-EtOH-H₂O, 0.5:9:3:5.5, v/v/v/v was selected by shake-flask method. Four flavonoids (quercetin 3-O-α-L-arabinopyranosyl-(1→2)-O-α-L-rhamnopyranoside (1), kaempferol 3-O-α-L-arabinopyranosyl-(1→2)-O-α-L-rhamnopyranoside (2), quercetin 3-O-α-L-rhamnopyranoside (3) and kaempferol 3-O-α-L-rhamnopyranoside (4)) were isolated in a single and fast CPC run and their structures were confirmed by NMR analysis. An UPLC-DAD quantification method was established for the first time with validation of required parameters, according to RDC 166/2017. The calibration curves were linear with correlation coefficient ranging from 0.9996 to 0.9997 while the values of LOD (0.0077-1.984 ng.mL^-1), LOQ (0.0263-6.012 ng.mL^-1), recovery (≥ 80.7 %) and inter-day (%RSD ≤ 3.581) and intra-day precision (%RSD ≤ 2.628) were satisfactory. Quantitative analysis of these compounds showed that the proportion of 1, 2 and 3 were 2.43, 0.25 and 0.33 % (24.3 mg.g^-1, 0.25 mg.g^-1 and 0.33 mg.g^-1 of extract), respectively. Moreover, in vitro xanthine oxidase (XO), DPPH and ABTS inhibition were evaluated for the extract and the major flavonoids. Compounds 2 (168 μM) and 3 (124 μM) moderately inhibited XO, while compounds 1 and 3 displayed average radical scavenging activity. In conclusion, our results suggest the flavonoid 1 as a specific marker which may be used for quality control of B. pinnatum hydroethanolic leaves extract.

Antioxidant Activity, Enzyme Inhibition Potentials, and Phytochemical Profiling of Premna serratifolia L. Leaf Extracts

Premna serratifolia, commonly known as Arogo in Tentena-Sulawesi, is a popular vegetable. As a promising herbal tea and food ingredient, further investigation is required to find the best knowledge for medicinal use of P. serratifolia leaves. This research investigated the antioxidant activity of the ethanol (EEPS) and water (WEPS) extracts of P. serratifolia leaves, based on their scavenging activities on DPPH radicals and their reducing capacities (CuPRAC, total antioxidant/phosphomolybdenum, and ferric thiocyanate reducing power assays). The DNA-protecting effect by EEPS was tested using pBR322 plasmid DNA against •OH radical-induced damage. The inhibition potentials of both extracts against several enzymes related to metabolic diseases (α-glucosidase, α-amylase, xanthine oxidase, and protease) were evaluated. The phytochemical analysis was conducted by an LC-QTOF-MS/MS technique. EEPS proved to be a better antioxidant and had higher phenolic content compared to WEPS. EEPS demonstrated a protective effect on DNA with recovery percentage linearly correlated with EEPS concentrations. Strong inhibition on α-glucosidase and α-amylase was observed for EEPS; however, EEPS and WEPS showed weak inhibitions on xanthine oxidase and protease. LC-QTOF-MS/MS analysis identified seven main components in EEPS, namely scroside E, forsythoside A and forsythoside B, lavandulifolioside, diosmin, nobilin D, campneoside I, and isoacteoside. These components may be responsible for the observed enzymes inhibitions and antioxidant properties. Premna serratifolia leaves can be an appropriate choice for the development of nutraceutical and drug preparations.

Chemotaxonomic studies on natural population of Gloriosa superba (L.) collected from Gangetic plain (India) and their invitro antigout activity for the identification of elite germplasm(s)

ETHNOPHARMACOLOGICAL RELEVANCE

Gloriosa superba L. (Colchicaceae) is used in the treatment of gout and rheumatism as a traditional medicine dates back to 1810. It has also been used as ethnobotanical and folklore medicine to induce abortion/vaginal poison.

AIM OF STUDY

The present study was carried out to identify the chemical variation existing in the major alkaloid metabolite (colchicine) in a threatened species, Gloriosa superba L. and is correlated with invitro antigout activity.

MATERIAL AND METHOD

The samples (tuber) were collected from their natural locations in Gangetic plain of India. HPLC-PDA quantification of colchicine was done on C₁₈ column at 245 nm and invitro antigout activity was analyzed by inhibition of protein denaturation, DPPH and Hydroxyl radical scavenging assay.

RESULTS

The colchicine content within the 29 samples ranges from 0.021 to 0.665% and the maximum contents was in NBG-10 from Kanth (U.P). Such high colchicine (0.665%) containing natural population of G. superba is reported for the first time in Indian population. Four chemotypes viz. NBG-10, NBG-120, NBG-126 and NBG-88 were selected on the basis of colchicine content for invitro antigout activity. NBG-10 was separated from rest of the population exhibiting the most promising activity with high colchicine content.

CONCLUSION

The outcomes will be helpful in the identification of elite chemotype for herbal product development and quality check of metabolites in raw material. The study will also support the site-specific commercial cultivation to meet out the industrial demand as well as income generation to farmers.

Anti-inflammatory and antioxidative effects of the buds from different species of Populus in human gingival fibroblast cells: Role of bioflavanones

BACKGROUND

Poplar leaf-buds (Populi gemmae) are used traditionally as anti-inflammatory agents to the treatment of skin injuries or cough. They differ in their diverse chemical composition and different types of activities, whose mechanisms are not fully recognized.

PURPOSE

Evaluation and comparison of anti-inflammatory activity of leaf-buds extracts from Populus nigra, P. × berolinensis and P. lasiocarpa and flavanones - pinocembrin and pinostrobin towards human gingival fibroblasts (HGF-1) pro-inflammatory stimulated by silver nanoparticles (AgNPs). Determination of antioxidant activity associated with anti-inflammatory properties by means of bioautographic TLC tests.

METHODS

Phytochemical analysis was performed by TLC and videodensitometry analysis. The extracts were standardized on the pinocembrin and pinostrobin content. Bioautography was performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and riboflavin-light blue tetrazolium chloride (riboflavin-light-NBT) radicals to assess the extracts and both flavanones radical scavenging properties as well as potential inhibition of xanthine oxidase (XO) activity. The protective effects of poplar buds extract and flavanones - pinocembrin and pinostrobin on HGF-1 line exposured to AgNPs were investigated by analysis of interleukin 6 (IL-6) and interleukin IL-1β (IL-1β) level measured by ELISA kit. The messenger ribonucleic acid (mRNA) of both cytokines was determined by real-time quantitative PCR. The involvement of cyclooxygenase 2 protein (COX-2) was studied using Western blot analysis.

RESULTS

The presence of several flavanones and phenolic acids, which have radical scavenging properties, was revealed in all of the bud poplar extracts analyzed. Treatment with particular flavanones or extracts from buds of P. × berolinensis and P. nigra decreased the IL-6 and IL-1β release in HGF-1 cells and down-regulation of mRNA for both cytokines was observed. The COX-2 protein expression was demonstrated for pinocembrin and P. × berolinensis buds. These effects were not observed for buds from P. lasiocarpa not containing of flavonoids.

CONCLUSION

The potential protective role of pinocembrin and pinostrobin and extracts from buds P. nigra and P. × berolinensis against AgNPs induced inflammation and cytotoxicity in HGF-1 cells is disclosed. In addition, the antioxidant properties of poplar bud extracts have been demonstrated. P. × berolinensis buds showed the highest activity in both the in vitro model and in the bioautographic tests.

Biological Activities of Extracts from Aerial Parts of Salvia pachyphylla Epling Ex Munz

The antioxidant, antimicrobial, antiproliferative, and enzyme inhibitory properties of five extracts from aerial parts of Salvia pachyphylla Epling ex Munz were examined to assess the prospective of this plant as a source of natural products with therapeutic potential. These properties were analyzed by performing a set of standard assays. The extract obtained with dichloromethane showed the most variety of components, as they yielded promising results in all completed assays. Furthermore, the extract obtained with ethyl acetate exhibited the greatest antioxidant activity, as well as the best xanthine oxidase inhibitory activity. Remarkably, both extracts obtained with n-hexane or dichloromethane revealed significant antimicrobial activity against the Gram-positive bacteria; additionally, they showed greater antiproliferative activity against three representative cell lines of the most common types of cancers in women worldwide, and against a cell line that exemplifies cancers that typically develop drug resistance. Despite that, other extracts were less active, such as the methanolic or aqueous; their results are promising for the isolation and identification of novel bioactive molecules.

Recent Advances in Electrochemical Biosensors Based on Enzyme Inhibition for Clinical and Pharmaceutical Applications

A large number of enzyme inhibitors are used as drugs to treat several diseases such as gout, diabetes, AIDS, depression, Parkinson's and Alzheimer's diseases. Electrochemical biosensors based on enzyme inhibition are useful devices for an easy, fast and environment friendly monitoring of inhibitors like drugs. In the last decades, electrochemical biosensors have shown great potentials in the detection of different drugs like neostigmine, ketoconazole, donepezil, allopurinol and many others. They attracted increasing attention due to the advantage of being high sensitive and accurate analytical tools, able to reach low detection limits and the possibility to be performed on real samples. This review will spotlight the research conducted in the past 10 years (2007-2017) on inhibition based enzymatic electrochemical biosensors for the analysis of different drugs. New assays based on novel bio-devices will be debated. Moreover, the exploration of the recent graphical approach in diagnosis of reversible and irreversible inhibition mechanism will be discussed. The accurate and the fast diagnosis of inhibition type will help researchers in further drug design improvements and the identification of new molecules that will serve as new enzyme targets.

Secondary Metabolites of Hypericum L. Species as Xanthine Oxidase Inhibitors

Nine Hypericum species (H. barbatum, H. hirsutum, H. linarioides, H. olympicum, H. perforatum, H. rochelii, H. rumeliacum, H. tetrapterum and H. umbellatum) collected in Serbia were assayed for inhibitory potential against xanthine oxidase in vitro, on the commercial enzyme, and compared with allopurinol. Seven studied Hypericum species (H. barbatum, H. rochelii, H. rumeliacum, H. umbellatum, H. perforatum, H. tetrapterum and H. olympicum) inhibit commercial xanthine oxidase with an IC50 below 100 μg/mL. H. barbatum exerted the most potent inhibitory effect (IC50 = 31.84 ± 6.64 μg/mL), followed closely by H. perforatum (IC50 = 37.12 ± 4.06 μg/mL).

Effect of Betula pendula Leaf Extract on α-Glucosidase and Glutathione Level in Glucose-Induced Oxidative Stress

B. pendula leaf is a common ingredient in traditional herbal combinations for treatment of diabetes in southeastern Europe. Present study investigated B. pendula ethanolic and aqueous extract as inhibitors of carbohydrate hydrolyzing enzymes, as well as their ability to restore glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress. Phytochemical analysis revealed presence of rutin and other quercetin derivatives, as well as chlorogenic acid. In general, ethanolic extract was richer in phenolic substances than the aqueous extract. Furthermore, a comprehensive analysis of antioxidant activity of two extracts (determined by DPPH and ABTS radical scavenging activity, total antioxidant activity, and chelating activity as well as ferric-reducing antioxidant power) has shown that ethanolic extract was better radical scavenger and metal ion reductant. In addition, ethanolic extract effectively increased cellular glutathione levels caused by hyperglycemia and inhibited α-glucosidase with the activity comparable to that of acarbose. Therefore, in vitro research using B. pendula plant extracts has confirmed their antidiabetic properties.

Practical method for the rapid screening of xanthine oxidase inhibitors in herbal extracts by high-performance liquid chromatography based on on-line precolumn enzymatic reaction

A high-performance liquid chromatography method with on-line precolumn enzymatic reaction for the screening of xanthine oxidase inhibitors in natural extracts was developed. In this method, the enzymatic reaction occurred at the capillary inlet during a predetermined waiting period, after which the reaction product, uric acid, was separated and detected by liquid chromatography using ultraviolet absorption at 295 nm. Enzyme inhibition can be read out directly from the reduced peak area of uric acid in comparison to a reference chromatogram obtained in the absence of any inhibitor. In the present study, the availability of on-line precolumn enzymatic reaction with ultraviolet detection was firstly evaluated by determining the inhibitory mechanism and IC50 values of allopurinol, a commercially available positive drug. Then, the newly developed method was applied to screening of ten natural extracts from traditional Chinese medicine and as a result, the extract of Epimedium sagittatum (Sieb. et Zucc.) Maxim was found to be most positive for xanthine oxidase inhibition. The results obtained were compared with those obtained by offline enzyme assay and the effectiveness of the present method was confirmed. A rapid, low-cost, and fully automated method for xanthine oxidase inhibitor screening was proposed.

Medicinal plants of the genus Betula--traditional uses and a phytochemical-pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Trees and shrubs of the genus Betula (Betulaceae) inhabit various ecosystems in temperate and boreal climate zones of the northern hemisphere. The healing properties of Betula bark and bark extracts have been known for a long time in traditional medicine in different parts of the world. Several species of Betula have traditionally been used for the treatment of various inflammatory diseases including arthritis. The purpose of this review is to provide updated, comprehensive and categorized information on the botany, traditional uses, phytochemistry and pharmacological and toxicological research of Betula species in order to explore their therapeutic potential and evaluate future research opportunities.

MATERIALS AND METHODS

All the available information on various species belonging to the genus Betula was collected via electronic search (using Pubmed, SciFinder, Scirus, Google Scholar, JCCC@INSTIRC and Web of Science) and a library search for articles published in peer-reviewed journals.

RESULTS

Although over a hundred Betula species are found distributed globally, about 7 different species of Betula have been documented for their traditional uses. Phytochemical research on Betula species has led to the isolation of triterpenoids, diarylheptanoids, phenylbutanoids, lignans, phenolics and flavonoids. Crude extracts, fractions and phytochemical constituents isolated from Betula showed a wide spectrum of in vitro and in vivo pharmacological activities like immunomodulatory, anti-inflammatory, antimicrobial, antiviral, antioxidant, antidiabetic, dermatological, gastroprotective and hepatoprotective. Antiarthritic and anticancer are the two major areas of research conducted on these species. The anti-carcinogenic effects of Betula bark, betulin as well as betulinic acid have been extensively studied.

CONCLUSIONS

Several species belonging to the genus Betula are widely used in traditional medicine. Betula platyphylla and Betula pendula have specifically been found to be potentially useful in the treatment of degenerative joint disease. There is convincing evidence in experimental animal models in support of their anti-carcinogenic effects. However, it would be worthwhile to investigate the biochemical and physiological mechanisms as well as detailed preclinical toxicity, bioavailability, pharmacokinetics and pharmacodynamics of the different biologically active extracts as well as molecules in sufficient detail. An integrated and holistic approach is required for tapping the full potentials of this important genus.

Xanthine Oxidase: Isolation, Assays of Activity, and Inhibition

Xanthine oxidase (XO) is an important enzyme catalyzing the hydroxylation of hypoxanthine to xanthine and xanthine to uric acid which is excreted by kidneys. Excessive production and/or inadequate excretion of uric acid results in hyperuricemia. This paper presents a detailed review of methods of isolation, determination of xanthine oxidase activity, and the effect of plant extracts and their constituents on it. Determining the content and activities of XO can be used for diagnostic purposes. Testing inhibition of XO is important for detection of potentially effective compounds or extracts that can be used to treat diseases that are caused by increased activity of XO.In vitrobioassays are used to examine test material for XO inhibition, as inhibitors of XO may be potentially useful for the treatment of gout or other XO induced diseases. Several authors reported on the XO inhibitory potential of traditionally used medicinal plants.

New steroidal saponin from Antigonon leptopus Hook. and Arn

Background:

Antigonon leptopus Hook. and Arn., Polygonaceae (cadena de amor), is a herbal remedy for pain and gout-like symptoms in the Philippines. The methanol extract of A. leptopus have shown strong inhibitory action against xanthine oxidase.

Objective:

To isolate and identify the compound responsible for the xanthine oxidase inhibitory action.

Materials and Methods:

A bioassay-guided isolation scheme using an in vitro assay for the inhibition of xanthine oxidase was employed. The structure was established using spectroscopic analysis and chemical methods.

Results:

The isolated compound was determined to be a noncompetitive inhibitor of xanthine with an IC50 of 1.79 μg/mL.

Conclusion:

The isolated compound may represent a new class of xanthine oxidase inhibitors.

Quick identification of xanthine oxidase inhibitor and antioxidant from Erycibe obtusifolia by a drug discovery platform composed of multiple mass spectrometric platforms and thin-layer chromatography bioautography

As a final step of the purine metabolism process, xanthine oxidase catalyzes the oxidation of hypoxanthine and xanthine into uric acid. Our research has demonstrated that Erycibe obtusifolia has xanthine oxidase inhibitory properties. The purpose of this paper is to describe a new strategy based on a combination of multiple mass spectrometric platforms and thin-layer chromatography bioautography for effectively screening the xanthine oxidase inhibitory and antioxidant properties of E. obtusifolia. This strategy was accomplished through the following steps. (i) Separate the extract of E. obtusifolia into fractions by an autopurification system controlled by liquid chromatography with mass spectrometry. (ii) Determine the active fractions of E. obtusifolia by thin-layer chromatography bioautography. (iii) Identify the structure of the main active compounds with the information provided by direct analysis in real time mass spectrometry. (iv) Calculate the IC50 value of each compound against xanthine oxidase using high-performance liquid chromatography. Using the caulis of E. obtusifolia as the experimental material, seven target peaks were screened out as xanthine oxidase inhibitors or antioxidants. Our screening strategy allows for rapid analysis of small molecules with almost no sample preparation and can be completed within a week, making it a useful assay to identify unstable compounds and provide the empirical foundation for E. obtusifolia as a natural remedy for gout and oxidative-stress-related diseases.

Bioactivity of Nonedible Parts of Punica granatum L.: A Potential Source of Functional Ingredients

Punica granatum L. has a long standing culinary and medicinal traditional use in Mauritius. This prompted a comparative study to determine the bioefficacy of the flower, peel, leaf, stem, and seed extracts of the Mauritian P. granatum. The flower and peel extracts resulting from organic solvent extraction exhibited strong antioxidant activities which correlated with the high levels of total phenolics, flavonoids, and proanthocyanidins. The peel extract had the most potent scavenging capacity reflected by high Trolox equivalent antioxidant capacity value (5206.01 ± 578.48 μmol/g air dry weight), very low IC₅₀ values for hypochlorous acid (0.004 ± 0.001 mg air dry weight/mL), and hydroxyl radicals scavenging (0.111 ± 0.001 mg air dry weight/mL). Peel extracts also significantly inhibited S. mutans (P < 0.001), S. mitis (P < 0.001), and L. acidophilus (P < 0.05) growth compared to ciprofloxacin. The flower extract exhibited high ferric reducing, nitric oxide scavenging, and iron (II) ions chelation and significantly inhibited microsomal lipid peroxidation. Furthermore, it showed a dose-dependent inhibition of xanthine oxidase with an IC₅₀ value of 0.058 ± 0.011 mg air dry weight/mL. This study showed that nonedible parts of cultivated pomegranates, that are generally discarded, are bioactive in multiassay systems thereby suggesting their potential use as natural prophylactics and in food applications.

The Hypouricemic Effect of Balanophora laxiflora Extracts and Derived Phytochemicals in Hyperuricemic Mice

The objective of this study is to evaluate the lowering of uric acid using Balanophora laxiflora extracts and derived phytochemicals on potassium-oxonate-(PO-) induced hyperuricemia in mice. The results revealed that ethyl acetate (EtOAc) fraction of B. laxiflora extracts exhibited strong xanthine-oxidase-(XOD-) inhibitory activity. In addition, among the 10 subfractions (EA1–10) derived from EtOAc fraction, subfraction 8 (EA8) exhibited the best XOD-inhibitory activity. Four specific phytochemicals, 1-O-(E)-caffeoyl-β-D-glucopyranose (1), 1-O-(E)-p-coumaroyl-β-D-glucopyranose (2), 1,3-di-O-galloyl-4,6-(S)-hexahydroxydiphenoyl-β-D-glucopyranose (3), and 1-O-(E)-caffeoyl-4,6-(S)-hexahydroxydiphenoyl-β-D-glucopyranose (4), were further isolated and identified from this subfraction. Compounds 3 and 4 exhibited the strongest XOD-inhibitory activity compared with other compounds, and both hydrolyzable tannins were determined to be noncompetitive inhibitors according to the Lineweaver-Burk plot. On the other hand, the in vivo hypouricemic effect in hyperuricemic mice was consistent with XOD-inhibitory activity, indicating that B. laxiflora extracts and derived phytochemicals could be potential candidates as new hypouricemic agents.

An aqueous birch leaf extract of Betula pendula inhibits the growth and cell division of inflammatory lymphocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Leaf extracts of Betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (RA) or osteoarthritis.

AIM OF THE STUDY

We investigated the anti-proliferative capacity of an aqueous leaf extract of Betula pendula (BPE) on human primary lymphocytes in vitro, because activated lymphocytes play a major role in the initiation and maintenance of RA.

MATERIALS AND METHODS

Lymphocyte proliferation and cell division was measured by the activity of mitochondrial dehydrogenases and by using the membrane-permeable dye carboxyfluorescein diacetate succinimidyl ester (CFSE), respectively. Apoptosis was analyzed by surface staining of phosphatidylserine and intracellular activation of effector caspases 3 and 7 in comparison to the drug methotrexate using flow cytometric and photometrical analysis. In addition, the impact of the extract on cell cycle distribution was investigated by propidium iodide staining of DNA. For the bioassays BPE concentrations of 10-160 μg/mL were investigated. A phytochemical analysis, using LC-MS and HPLC, was conducted to identify the polyphenolic constituents of the birch leaf extract.

RESULTS

Leaf extracts of Betula pendula inhibited the growth and cell division (CD8(+): 40 μg/mL: 45%; 80 μg/mL: 60%; 160 μg/mL: 87%) (CD4(+): 40 μg/mL: 33%; 80 μg/mL: 54%; 160 μg/mL: 79%) of activated, but not of resting T lymphocytes in a significant dose-dependent manner. The inhibition of lymphocyte proliferation due to apoptosis induction (compared to untreated control: 40 μg/mL: 163%; 80 μg/mL: 240%; 160 μg/mL: 348%) and cell cycle arrest was comparable to that of methotrexate. LC-MS analyses showed that the extract contains different quercetin-glycosides.

CONCLUSION

Our results give a rational basis for the use of Betula pendula leaf extract for the treatment of immune disorders, like rheumatoid arthritis, by diminishing proliferating inflammatory lymphocytes.

Phenolic composition and antioxidant properties of poplar bud (Populus nigra) extract: individual antioxidant contribution of phenolics and transcriptional effect on skin aging

The Populus species possess great potential for therapeutical applications, especially for their known anti-inflammatory properties. The antioxidant properties of propolis, a hive product collected by honey bees mainly from poplar bud exudates, suggest that poplar buds also possess antioxidant properties. Here is reported the characterization of the antioxidant properties of an aqueous poplar bud (Populus nigra) extract. It presented a high total phenolic content, and moderate antioxidant properties as determined by ORAC assay. The main phenolic compounds identified were phenolic acids and flavonoid aglycons. These phenolic compounds were analyzed by ORAC assay for their individual antioxidant activity, in order to determine the major contributors to the total antioxidant activity of the extract. Thanks to their high antioxidant activity, caffeic and p-coumaric acids were identified as the major antioxidant components. Representing only 3.5% of its dry weight, these compounds represented together about 50% of the total antioxidant activity of the extract. The antioxidant properties of poplar bud extract and the phenolic compounds identified were also analyzed by cellular antioxidant activity assay (CAA), which was weakly correlated with ORAC assay. The transcriptional effect of poplar bud extract on skin aging was evaluated in vitro on a replicative senescence model of normal human dermal fibroblasts, using a customized DNA macroarray specifically designed to investigate skin aging markers. Among the detected genes, poplar bud extract significantly regulated genes involved in antioxidant defenses, inflammatory response and cell renewal. The collective antioxidant properties and transcriptional effect of this extract suggest potential antiaging properties which could be utilized in cosmetic and nutraceutical formulations.

Evaluation of enzymes inhibition activities of medicinal plant from Burkina Faso

The aim of the present study was to evaluate some enzymes inhibitory effects of 11 plant species belonging to 9 families from Burkina Faso. Methanolic extracts were used for their Glutathione-s-transferase (GST), Acetylcholinesterase (AChE), Carboxylesterase (CES) and Xanthine Oxidase (XO) inhibitory activities at final concentration of 100 microg mL(-1). The total phenolics, flavonoids and tannins were also determined spectrophotometrically using Folin-Ciocalteu, AlCl3 and ammonium citrate iron reagents, respectively. Among the 11 species tested, the best inhibitory percentages were found with Euphorbia hirta, Sclerocarya birrea and Scoparia dulcis (inhibition > 40%) followed by Annona senegalensis, Annona squamosa, Polygala arenaria and Ceratotheca sesamoides (inhibition > 25%). The best total phenolic and tannin contents were found with S. birrea with 56.10 mg GAE/100 mg extract and 47.75 mg TAE/100 mg extract, respectively. E hirta presented the higher total flavonoids (9.96 mg QE/100 mg extract). It's was found that Sclerocarya birrea has inhibited all enzymes at more than 30% and this activity is correlated to total tannins contents. Contrary to S. birrea, the enzymatic activities of E. hirta and S. dulcis are correlated to total flavonoids contents. Present findings suggest that the methanolic extracts of those plant species are potential inhibitors of GST, AChE, CES and XO and confirm their traditional uses in the treatment of mental disorders, gout, painful inflammations and cardiovascular diseases.