Glycosylated flavonoid kaempferitrin: Electroanalytical detection and the proposal of an oxidation mechanism supported by quantum chemical calculations.

In this work, the electrochemical behavior of the glycosylated flavonoid kaempferitrin was studied, and an electroanalytical methodology was developed for its determination in infusions of Bauhinia forficata using a boron-doped diamond electrode (BDD). The electrochemical behavior of the flavonoid was studied by cyclic voltammetry, and two irreversible oxidation peaks at 0.80 and 1.0 V vs Ag/AgCl were observed. The influence of the pH on the voltammograms was examined, and higher sensitivity was found at pH 7.0. The electrochemical process corresponding to peak 1 at 0.80 V is predominantly diffusion-controlled, as the study shows at varying scan rates. An analytical plot was obtained by square wave voltammetry at optimized experimental conditions (frequency = 100 s-1, amplitude = 90 mV, and step potential = 8 mV) in the concentration range from 3.4 µmol L-1 to 58 µmol L-1, with a linearity of 0.99. The limit of detection and limit of quantification values were 1.0 µmol L-1 and 3.4 µmol L-1, respectively. Three samples of Bauhinia forficata infusions (2 g of sample in 100 mL of water) were analyzed, and the KF values found were 5.0 × 10-4 mol L-1, 3.0 × 10-4 mol L-1, and 7.0 × 10-4 mol L-1, with recovery percentages of 98 %, 106 % and 94 %, respectively. Finally, experiments were performed with two other flavonoids (chrysin and apeginin) to compare and propose an electrochemical oxidation mechanism for kaempferitrin, which was supported by quantum chemical calculations.

Potential of Kalanchoe pinnata as a Cancer Treatment Adjuvant and an Epigenetic Regulator.

Cancer is a global public health problem that is related to different environmental and lifestyle factors. Although the combination of screening, prevention, and treatment of cancer has resulted in increased patient survival, conventional treatments sometimes have therapeutic limitations such as resistance to drugs or severe side effects. Oriental culture includes herbal medicine as a complementary therapy in combination with chemotherapy or radiotherapy. This study aimed to identify the bioactive ingredients in Kalanchoe pinnata, a succulent herb with ethnomedical applications for several diseases, including cancer, and reveal its anticancer mechanisms through a molecular approach. The herb contains gallic acid, caffeic acid, coumaric acid, quercetin, quercitrin, isorhamnetin, kaempferol, bersaldegenin, bryophyllin a, bryophyllin c, bryophynol, bryophyllol and bryophollone, stigmasterol, campesterol, and other elements. Its phytochemicals participate in the regulation of proliferation, apoptosis, cell migration, angiogenesis, metastasis, oxidative stress, and autophagy. They have the potential to act as epigenetic drugs by reverting the acquired epigenetic changes associated with tumor resistance to therapy-such as the promoter methylation of suppressor genes, inhibition of DNMT1 and DNMT3b activity, and HDAC regulation-through methylation, thereby regulating the expression of genes involved in the PI3K/Akt/mTOR, Nrf2/Keap1, MEK/ERK, and Wnt/ß-catenin pathways. All of the data support the use of K. pinnata as an adjuvant in cancer treatment.

In silico and in vivo protective effect of Morus nigra leaves on oxidative damage induced by iron overload.

Morus nigra L. is a plant popularly known as 'amoreira preta', very used in folk medicine. Iron overload (hemochromatosis) is a clinical condition that causes damage to various tissues due to oxidative stress. Therapy to control iron overload is still unsatisfactory. The protective effect on oxidative stress induced by iron overload was verified. Phytochemical characterization was evaluated by UHPLC-MS/MS. The in silico toxicity predictions of the main phytochemicals were performed via computer simulation. To induce iron overload, the animals received iron dextran (50 mg/kg/day). The test groups received doses of 500 and 1000 mg/kg of M. nigra extract for six weeks. Body weight, organosomatic index, serum iron, hepatic markers, cytokines, interfering factors in iron metabolism, enzymatic and histopathological evaluations were analyzed. Vanillic acid, caffeic acid, 6-hydroxycoumarin, p-coumaric acid, ferulic acid, rutin, quercitrin, resveratrol, apigenin and kaempferol were identified in the extract. In addition, in silico toxic predictions showed that the main compounds presented a low probability of toxic risk. The extract of M. nigra showed to control the mediators of inflammation and to reduce iron overload in several tissues. Our findings illustrate a novel therapeutic action of M. nigra leaves on hemochromatosis caused by iron overload.

Six months under uncontrolled relative humidity and room temperature changes technological characteristics and maintains the physicochemical and functional properties of carioca beans (Phaseolus vulgaris L.).

Carioca beans contribute to health maintenance around the world, and the evaluation of commercial postharvest storage (CPS) ensures their quality. This study aimed to evaluate the effect of CPS on technological, physicochemical and functional properties of carioca beans. Two genotypes (Pontal-PO and Madreperola-MP beans) were stored under CPS or controlled conditions and were evaluated after harvest and after three- and six-months storage. PO and MP hardened with time, but the cooking time did not differ. PO is darker than MP and both darkened over time. Storage time affected pH and acidity of the beans and MP presented better physicochemical properties than PO, with lower activity of peroxidase (p = 0.004) and polyphenoloxidase (p = 0.001) enzymes. Glycosylated kaempferol was suggested as a possible chemical marker to differentiate the aging of PO and MP beans. In conclusion, besides the technological differences, the storage was able to prevent physicochemical and functional alterations of beans.

Chemical composition and bioactive properties of the wild edible plant Raphanus raphanistrum L.

Recently, there has been an interest regarding the consumption of wild edible plants in modern diets. However, there is still scarce information about several wild vegetables traditionally consumed. Therefore, this work aims on documenting the nutritional and chemical composition of wild radish (Raphanus raphanistrum L.), as well as its bioactive potential. Results showed that wild radish is a potential source of beneficial compounds, including vitamin E, polyunsaturated fatty acid (particularly α-linolenic acid) and different phenolic compounds, in which fourteen phenolics were identified, with kaempferol-3,7-O-di-rhamnoside being the most abundant. The bioactive potential was exploited using hydroethanolic and decoction extracts. Both proved to inhibit several Gram-positive and Gram-negative bacteria and revealed antioxidant activity, while cytotoxicity against non-tumor cell was not observed. In general, results evidence the interest in recovering the use of this wild vegetable as part of a varied diet, which can bring several health benefits.

Analysis of flavonoid glycosides with potential medicinal properties on Bauhinia uruguayensis and Bauhinia forficata subspecies pruinosa.

Several Bauhinia species are widely used in Southern South America in the treatment of infections, pain and several diseases including diabetes. Flavonoid compounds based on quercetin and kaempferol glycoside derivatives are believed to be responsible for their therapeutic properties. To investigate this, we have studied two native species from Argentina: B. uruguayensis (BU) and B. forficata subsp. pruinosa (BF). We have analyzed the major polyphenol components in hydro-methanolic extracts of leaves, by high performance liquid chromatography tandem mass spectrometry. Chromatographic analysis yielded five main compounds in BF, corresponding to rutinosides and rhamnosides derivatives of kaempferol and quercetin, which are considered chemotaxonomic markers and responsible for antioxidant activity. The presence of kaempferitrin, an antidiabetic agent, has been confirmed. In extracts of BU, four major compounds were identified as rhamnosides and galloyl derivates from quercetin and kaempferol. One of these compounds, quercitrin-3-rhamnoside may confer anti-inflammatory and analgesic properties to BU extracts.

Occurrence of isoflavonoids in Brazilian common bean germplasm (Phaseolus vulgaris L.).

Common bean (Phaseolus vulgaris) is present in the daily diet of various countries and, as for other legumes, has been investigated for its nutraceutical potential. Thus, 16 genotypes from different gene pools, representing seven types of seed coats and different responses to pathogens and pests, were selected to verify their isoflavone contents. The isoflavonoids daidzein and genistein and the flavonols kaempferol, myricetin, and quercetin were found. Grains of the black type showed the highest concentrations of isoflavonoids and were the only ones to exhibit daidzein. IAC Formoso, with high protein content and source of resistance to anthracnose, showed the greatest concentration of genistein, representing around 11% of the content present in soybean, as well as high levels of kaempferol. Arc 1, Raz 55, and IAC Una genotypes showed high content of coumestrol. The results suggest the use of IAC Formoso to increase the nutraceutical characteristics in common bean.

Effect of thermal processing and maceration on the antioxidant activity of white beans.

Phenolic compounds, which naturally occur in beans, are known to have antioxidant activity, which may be partially lost during the processing of this legume. This study evaluated the effect of thermal processing and maceration on the phenolic acid and flavonoids profile and content and on the antioxidant activity of white beans. According to the results obtained from the 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method, there were no significant differences among treatment groups analysed. When was using 1,1-diphenyl-2-pycrylhydrazyl method (DPPH), beans cooked without maceration present the higher antioxidant activity, and raw beans the lower. The phenolic acids found in greater amounts were gallic acid and chlorogenic acid. Kaempferol was only detected in the soaked and cooked samples; catechin and kaempferol-3-rutinoside were found in the highest concentrations. Quercetin and kaempferol-3-glucoside were not affected by the cooking process, either with or without maceration. In general, the heat treatment increased the antioxidant activity.

Anti-inflammatory and antioxidative effects of the methanolic extract of the aerial parts of Mitracarpus frigidus in established animal models.

OBJECTIVES: This study reports the in vivo anti-inflammatory and antioxidative effects of the methanolic extract of the aerial parts of Mitracarpus frigidus (MFM) and its chemical fingerprint. METHODS: The acute anti-inflammatory activity was performed using the carrageenan-induced paw oedema and peritonitis, ear oedema induced by croton oil and ethyl phenylpropiolate methods. Total COX, COX-1 and COX-2 expression was also evaluated. Chronic activity was determined by cotton pellet granuloma model. The antioxidative activity was assessed using liver tissue malondialdehyde, catalase and myeloperoxidase activities. KEY FINDINGS: M. frigidus showed an intense acute anti-inflammatory action (100 and 300 mg/kg) in a nondose-dependent manner with selective inhibition of COX-2 expression. This activity may be also related to the strong antioxidative effect observed. By the other side, the chronic anti-inflammatory activity of MFM was not expressive. Kaempferol, kaempferol-O-rutenoside, rutin, ursolic acid and psychorubrin were identified in MFM. CONCLUSIONS: The anti-inflammatory activity of MFM was probably due to inhibition of COX expression in a selective manner for COX-2. Other mechanisms, such as inhibition of inflammatory mediators and of the oxidative stress were possibly involved in the effects observed. To the best of our knowledge, it is the first time those activities are reported for M. frigidus.

HPLC-DAD-ESI/MS identification and quantification of phenolic compounds in Ilex paraguariensis beverages and on-line evaluation of individual antioxidant activity.

"Chimarrão" and "tererê" are maté (dried, toasted and milled Ilex paraguariensis leaves and stemlets) beverages widely consumed in South America. This paper describes the application of HPLC-DAD-ESI/MS method for the identification and quantification of caffeoylquinic acids (CQA), flavonol glycosides and purine alkaloids in these beverages. The beverage samples were prepared from commercial lots of maté from Southern Brazil. The caffeoylquinic acids, 4,5-diCQA, 3-CQA, 5-CQA, and 4-CQA were the major compounds, having 238-289, 153-242, 183-263, and 123-188 µg/mL, respectively, for chimarrão and 206-265, 122-218, 164-209, 103-169 µg/mL, respectively, for tererê. Caffeine also had high amounts while glycosides of quercetin and kaempferol were found at much lower levels. The individual antioxidant activity was also determined by an on-line system that measured their ABTS•+ radical scavenging activity, showing that the antioxidant capacity was not proportional to the concentrations of the phenolic compounds. 3-CQA, quercetina-3-O-ramnosylglucoside, and quercetina-3-O-glucoside were the major contributors to the antioxidant capacity, although the quercetin glycosides had concentrations less than 10 times that of 3-CQA.

The flavonoid content and antiproliferative, hypoglycaemic, anti-inflammatory and free radical scavenging activities of Annona dioica St. Hill.

BACKGROUND: Annona dioica St. Hill (Annonacaeae) is a Brazilian plant used in folk medicine for the treatment of several types of rheumatisms and diarrhoea. The focus of this work was to evaluate the in vitro antiproliferative and antioxidant activity and the in vivo hypoglycaemic and anti-inflammatory activity of A. dioica and identify the principal constituents of this plant. METHODS: The crude methanol extract (EAD) and hexane (HF), chloroform (CF), ethyl acetate (EAF) and hydromethanol fractions (HMF) were evaluated for free radical scavenging activity using the DPPH assay. The EAD and EAF were assayed for hypoglycaemic activity in rats. The EAD was tested in an antiproliferation assay and for anti-inflammatory effects in paw oedema, in addition to myeloperoxidase activity induced by carrageenan (Cg) in mice. The EAF was assayed using chromatographic methods. RESULTS: The fractionation of the EAF through chromatographic methods identified derivatives of the flavonoids quercetin and kaempferol. Among all the tested fractions, the ethyl acetate and hydromethanol fractions were the most potent, exhibiting an IC50 of 8.53 and 10.57 µg/mL, respectively, which is comparable to that of the commercial antioxidant butylated hydroxytoluene (BHT). The oral administration of the EAD (100 mg/kg) and EAF (15 mg/kg) inhibited the increase of glucose levels, resulting in a hypoglycaemic effect. The EAD (30 to 300 mg/kg) exhibited an anti-oedematogenic effect in Cg-induced paw oedema in a time- and dose-dependent manner. The results showed a reduction of MPO activity by A. dioica 6 h after the induction of paw oedema at all doses tested with maximal inhibition at 300 mg/kg. CONCLUSIONS: Our results reveal for the first time that compounds contained in the A. dioica leaves exert anti-inflammatory, hypoglycaemic, antiproliferative, and antioxidant effects. The antioxidant activity may be associated with the presence of flavonoids.

In vitro antimycobacterial activity and HPLC-DAD screening of phenolics from Ficus benjamina L. and Ficus luschnathiana (Miq.) Miq. leaves.

The total phenolic content (Folin-Ciocalteu) of the leaves of Ficus benjamina and Ficus luschnathiana was evaluated and screened by HPLC-DAD. Ficus luschnathiana crude extract (CE) presented phenolic content higher than that of F. benjamina (149.92 ± 3.65 versus 122.63 ± 2.79 mg of GAE). Kaempferol (1.63 ± 0.16 mg g(-1) dry weight of CE) and chlorogenic acid (17.77 ± 0.57 mg g(-1) of butanolic fraction) were identified and quantified in F. benjamina, whereas rutin (1.39 ± 0.20 mg g(-1)), caffeic (1.14 ± 0.13 mg g(-1)) and chlorogenic (3.73 ± 0.29 mg g(-1)) acids were quantified in the CE of F. luschnathiana. Additionaly, rutin (15.55 ± 1.92 mg g(-1)) and quercetin (3.53 ± 0.12 mg g(-1)) were quantified in ethyl acetate and butanolic fractions, respectively. Antimycobacterial activity of CEs and fractions was evaluated against Mycobacterium smegmatis by broth microdilution method. Ethyl acetate fraction from F. benjamina and n-butanol fraction from F. luschnathiana displayed the highest inhibitory activity (MIC = 312.50 µg mL(-1) and 156.25 µg mL(-1), respectively). Further studies are required to identify the compounds directly related to antimycobacterial activity.

Behavior of flavonols and carotenoids of minimally processed kale leaves during storage in passive modified atmosphere packaging.

Minimally processed kale leaves were packed in passive modified atmosphere and stored at 3 conditions: 1 °C in the dark and 11 °C with or without light exposure. The products were evaluated during storage in terms of headspace gas composition, sensory attributes, flavonol, and carotenoid contents. The sensory quality decreased slightly during 17 d at 1 °C in the dark. At 11 °C, the vegetable shelf life was predicted to be 6 d in the dark and 3 d with light. Quercetin and kaempferol were stable during storage for 15 d at 1 °C in the absence of light. At 11 °C in the dark, quercetin was stable during 10 d, increasing slightly on the 8th day. Kaempferol decreased up to the 5th day but increased on the 8th day, decreasing again on the 10th day. After 5 d at 11 °C under light, the flavonol levels were significantly higher than those of the initial values. Neoxanthin and violaxanthin did not change significantly after 15 d at 1 °C in the dark. Lutein and ß-carotene, however, decreased 7.1% and 11.3%, respectively. At 11 °C in the dark, neoxanthin, violaxanthin, lutein, and ß-carotene decreased 16.1%, 13.2%, 24.1%, and 23.7% after 10 d, respectively. At 11 °C under light, neoxanthin and lutein had a slight increase while violaxanthin and ß-carotene decreased 23.1% and 16.5% after 5 d. Practical Application: Passive modified atmosphere packaging together with refrigeration can extend the shelf life of minimally processed kale, retaining the health-promoting compounds, flavonols and carotenoids. Quercetin, kaempferol, neoxanthin, and violaxanthin are stable and lutein and ß-carotene slightly reduced.

HPLC/MS analysis and anxiolytic-like effect of quercetin and kaempferol flavonoids from Tilia americana var. mexicana.

AIM OF THE STUDY: Around the world, Tilia species have been used in traditional medicine for their properties as tranquilizer. Furthermore, Mexican species of Tilia have been grouped as Tilia americana var. mexicana, but their specific content in flavonoids is poorly described. In this study, inflorescences of Mexican Tilia were collected in three different regions of Mexico to compare their flavonoid content and anxiolytic-like response. MATERIALS AND METHODS: Flavonoid content was analyzed by using an HPLC-MS technique. For anxiolytic-like response, Tilia inflorescences extracts (from 10 to 300 mg/kg, i.p.) were tested in experimental models (open-field, hole-board and plus-maze tests, as well as sodium pentobarbital-induced hypnosis) in mice. RESULTS: HPLC-MS analysis revealed specific peaks of flavonoid composition demonstrating some differences in these compounds in flowers and bracts depending on the region of collection. No differences in the neuropharmacological activity among these samples of Tilia were found. Moreover, their effects were associated with quercetin and kaempferol glycosides. CONCLUSIONS: Dissimilarities in the flavonoid composition of Mexican Tilias might imply that these species must be re-classified in more than one species, not as a unique Tilia americana var. mexicana. Since quercetin and kaempferol aglycons demonstrated anxiolytic-like response and that no difference in the pharmacological evaluation was observed between these three Mexican Tilias, we suggest that this pharmacological effect of Tilia inflorescences involves these flavonoids occurrence independently of the kind of glycosides present in the samples reinforcing their use in traditional medicine in several regions of Mexico.

Effects of acute administration of the hydroalcoholic extract of mate tea leaves (Ilex paraguariensis) in animal models of learning and memory.

AIM OF THE STUDY: Ilex paraguariensis St. Hilaire (Aquifoliaceae) is a plant widely cultivated in South America that is used to prepare a tea-like beverage with a reputation to improve cognitive function, a response that has been attributed to the constituents of the leaves, especially caffeine. Our previous study indicated that the hydroalcoholic extract of Ilex paraguariensis presents an antiparkinsonian profile in reserpine- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-treated rodents. MATERIALS AND METHODS: In the present study, the effects of the hydroalcoholic extract of Ilex paraguariensis on the short- and long-term learning and memory of rats were assessed with the social recognition, Morris water maze, and step-down inhibitory avoidance tasks. RESULTS: A preliminary HPLC fingerprint of the plant extract confirmed the presence of caffeine (the major compound), rutin and kaemperol, and revealed the absence of detectable concentrations of caffeic acid, quercetin and ursolic acid. Acute pre-training intraperitoneal (i.p.) or oral administration of the extract of Ilex paraguariensis improved the short-term social memory in a specific manner as well as facilitated the step-down inhibitory avoidance short-term memory evaluated 1.5h after training. Moreover, a synergistic response was observed following the co-administration of 'non-effective' doses of caffeine and Ilex paraguariensis in the social memory. In contrast, pre-training administration of hydroalcoholic extract of Ilex paraguariensis did not alter the step-down inhibitory avoidance long-term memory evaluated 24h after training, while the highest dose tested (250 mg/kg, i.p.) disrupted the animals' performance in a cued version of the Morris water maze. CONCLUSION: These results partly substantiate the traditional use of mate tea for improvement of cognition indicating that acute administration of hydroalcoholic extract of Ilex paraguariensis differentially modulates short- and long-term learning and memory in rats probably through its antagonist's action on adenosine receptors.

Radioresistance of Salmonella species and Listeria monocytogenes on minimally processed arugula (Eruca sativa Mill.): effect of irradiation on flavonoid content and acceptability of irradiated produce.

This work studied the radiation resistance of Listeria monocytogenes and Salmonella species and the effect of irradiation on leaf flavonoid content and sensory acceptability of minimally processed arugula. Immersion in ozone-treated water reduced the analyzed microorganisms by 1 log. L. monocytogenes and Salmonella were not isolated from samples. Samples of this vegetable were inoculated with a cocktail of Salmonella spp. and L. monocytogenes and exposed to gamma irradiation. D10 values for Salmonella ranged from 0.16 to 0.19 kGy and for L. monocytogenes from 0.37 to 0.48 kGy. Kaempferol glycoside levels were 4 and ca. 3 times higher in samples exposed to 1 and 2 kGy, respectively, than in control samples. An increase in quercetin glycoside was also observed mainly in samples exposed to 1 kGy. In sensory evaluation, arugula had good acceptability, even after exposure to 2 and 4 kGy. These results indicate that irradiation has potential as a practical processing step to improve the safety of arugula.

Comparative assessment of kaempferitrin from medicinal extracts of Bauhinia forficata link.

The leaves of the pantropical genus Bauhinia (Fabaceae) are popularly known as cow's-paw or cow's hoof due to their unique characteristic bilobed aspect. The species Bauhinia forficata (Brazilian Orchid-tree) is widely used in folk medicine as an antidiabetic. This article deals with the quantitative analysis of kaempferitrin from B. forficata medicinal extract (aqueous and hydro alcoholic) using the LC method, and the comparison of kaempferitrin content in leaves collected from two different regions in the south Brazil. The total flavonoid content assessed by LC was also compared with the classical spectrophotometric determination. Kaempferitrin was found in different amounts, in samples from two geographical areas (Telêmaco Borba/PR and Itajaí/SC), for aqueous (368.68 and 77.91 microg/mL) and hydro alcoholic extracts (1952.59 and 211.61 microg/mL), respectively. The method was subjected to recovery assay, to determine its accuracy. A marked difference in total flavonoid concentration was observed in relation to kaempferitrin content: 2759.95 and 2188.20 microg/mL for the fluidextract and 863.35 and 856.77 microg/mL for the aqueous extract (Telêmaco Borba/PR and Itajaí/SC). The spectrophotometric assay overestimated the total flavonoid content (3620 microg/mL) in relation to the LC assay.

Chromatographic and electrochemical determination of quercetin and kaempferol in phytopharmaceuticals.

An NP-HPLC method both with diode-array (DAD) and electrochemical detection (ED) was developed and validated for the determination of quercetin and kaempferol, the principal active constituents in phytopharmaceuticals of Ginkgo Biloba. Calculated retention of the two flavonoids was contrasted with experimental values in five different reversed phase columns for methanol-water, acetonitrile-water, THF-water and dioxane-hexane binary mixtures as mobile phases. The capacity factor k, selectivity alpha and asymmetry factor F were evaluated and compared in DAD-RP-HPLC, DAD-NP-HPLC, ED-RP-HPLC and ED-NP-HPLC. The methods were used for the quantitative analysis of acid hydrolyzed extracts of tablet phytopharmaceuticals. Calibration curves were linear within the range 10 and 40 microg ml(-1) for the DAD and 10-270 microg ml(-1) for the ED, whereby limits of detection ranged from 0.5 microg ml(-1) (quercetin) to 0.1 microg ml(-1) (kaempferol). The electrochemical method based on differential pulse voltammetry (DPV) with a C-PVC electrode resolved the quercetin and kaempferol peaks and exhibited a two orders higher sensitivity in comparison with a carbon fiber electrode. DPV calibration curves were linear within the range 96-300 microg ml(-1) for quercetin and 68-960 microg ml(-1) for kaempferol. The respective oxidation peaks appeared at 462 and 518+/-2 mV and were used in the direct determination of quercetin in extracts of commercial phytopharmaceuticals.