RESUMEN
Enzymatic browning is a biological process that can have significant consequences for fresh produce, such as quality reduction in fruit and vegetables. It is primarily initiated by polyphenol oxidase (PPO) (EC 1.14.18.1 and EC 1.10.3.1) which catalyses the oxidation of phenolic compounds. It is thought that subsequent non-enzymatic reactions result in these compounds polymerising into dark pigments called melanins. Most work to date has investigated the kinetics of PPO with anti-browning techniques focussed on inhibition of the enzyme. However, there is substantially less knowledge on how the subsequent non-enzymatic reactions contribute to enzymatic browning. This review considers the current knowledge and recent advances in non-enzymatic reactions occurring after phenolic oxidation, in particular the role of non-PPO substrates. Enzymatic browning reaction models are compared, and a generalised redox cycling mechanism is proposed. The review identifies future areas for mechanistic research which may inform the development of new anti-browning processes.
RESUMEN
Pickled radish is a general source of natural bioactive compounds that include phenols. Here, we used molecular docking, fluorescence quenching, circular dichroism spectroscopy and molecular dynamics simulations to identify potential inhibitors against xanthine oxidase from a library of pickled radish compounds. The most effective compounds were selected for validation through in vitro experiments including enzyme activity inhibition tests, and cell-based assays. Molecular docking results revealed that 2,6-Dihydroxyacetophenone, 4-Hydroxyphenethyl alcohol, and 4-Hydroxybenzaldehyde exhibited significant effects on xanthine oxidase inhibition. Three phenols have varying degrees of inhibition on xanthine oxidase, which is driven by hydrophobic interactions and hydrogen bonds and affects the secondary structure and hydrophobic homeostasis of xanthine oxidase. The stability of xanthine oxidase inhibition by three phenols was analyzed by molecular dynamics simulation. Finally, cellular experiments confirmed that three phenols reduced uric acid levels by inhibiting the xanthine oxidase enzyme activity of BRL 3A cells.
RESUMEN
Nerium oleander L., commonly known as oleander, is a toxic shrub and also a medicinal plant. All parts of oleander are rich in cardiac glycosides that inhibits Na+/K+-ATPase and induce inotropic effect on the cardiomyocytes. Several pre-clinical and clinical reports indicate acute toxicity due to intentional, accidental and suicidal oleander consumption. Contrarily, oleander is used for the treatment of diverse ailments in traditional medicinal practices around the globe and several evidence-based pre-clinical studies indicated metabolic and immunological health benefits of polyphenol-rich oleander extracts. Thus, the current review aims to address this pharmaco-toxicological conundrum of oleander by addressing the possible role of gut microflora in the differential oleander toxicity. Additionally, a comprehensive account of ethnopharmacological usage, metabolic and immunological health benefits has been documented that supplement the conflicting arguments of pharmaco-toxicological properties of oleander. Finally, by addressing the gap of knowledge of ethnomedicinal, pharmacological and toxicological reports of oleander, the current review is expected to pave the way to address the differential pharmaco-toxicological effects of oleander.
Asunto(s)
Bacterias/metabolismo , Intestinos/microbiología , Nerium , Extractos Vegetales/farmacología , Animales , Biotransformación , Etnofarmacología , Microbioma Gastrointestinal , Humanos , Nerium/química , Nerium/toxicidad , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/metabolismo , Extractos Vegetales/toxicidad , Plantas Medicinales , Medición de RiesgoRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Patrinia heterophylla Bunge, known as "Mu-Tou-Hui" in China, is distributed in most provinces and regions of China. As a traditional medicinal plant, which was first found in
Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Apoptosis/efectos de los fármacos , Patrinia/química , Extractos Vegetales/farmacología , Raíces de Plantas/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Concentración 50 Inhibidora , Estructura Molecular , Extractos Vegetales/aislamiento & purificación , Rizoma/químicaRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Acacia nilotica (L.) Delile is used as a traditional anti-diabetic remedy in Bangladesh, Pakistan, Egypt, Nigeria and is mentioned in Ayurveda as well. AIM: The objective of the study was to evaluate the ethnomedicinal claim of A. nilotica leaf (ANL) extract for its efficiency in ameliorating diabetic complications. MATERIALS AND METHODS: ANL was orally administrated (50 and 200mg/kg) to alloxanized mice (blood glucose > 200mg/dL) for 20d. Parameters of glucose metabolism, hepatotoxicity, hyperlipidemia and nephrotoxicity were measured with emphasis on elevated oxidative stress. ANL was chemically characterized using GC-MS. Further, docking studies were employed to predict molecular interactions. RESULTS: ANL lowered (65%, P< 0.001) systemic glucose load in diabetic mice, which was otherwise 398% higher than control. ANL lowered (35%) insulin resistance, without any significant effect on insulin sensitivity (P> 0.05). Anti-hyperglycemic properties of ANL was further supported by lowering of HbA1c (34%; P< 0.001) and improved glucose utilization (OGTT). Overall diabetic complications were mitigated as reflected by lowered hepatic (ALT, AST) and renal (creatinine, BUN) injury markers and normalization of dyslipidemia. Elevated systemic oxidative stress was lowered by increased catalase and peroxidase activities in liver, kidney and skeletal muscle, resulting in 32% decrease of serum MDA levels. Apart from high phenolic and flavonoid content, tocopherol, catechol and ß-sitosterol, identified in ANL, demonstrated substantial binding affinity with Nrf2 protein (5FNQ) reflecting possible crosstalk with intracellular antioxidant defense pathways. CONCLUSION: The present study revealed the potentials of A. nilotica to alleviate diabetes-related systemic complications by limiting oxidative stress which justified the ethnopharmacological antidiabetic claim.
Asunto(s)
Acacia/química , Diabetes Mellitus Experimental/tratamiento farmacológico , Resistencia a la Insulina , Extractos Vegetales/farmacología , Administración Oral , Animales , Antioxidantes/metabolismo , Glucemia/efectos de los fármacos , Diabetes Mellitus Experimental/complicaciones , Relación Dosis-Respuesta a Droga , Cromatografía de Gases y Espectrometría de Masas , Hemoglobina Glucada/metabolismo , Hiperglucemia/tratamiento farmacológico , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/farmacología , Masculino , Medicina Tradicional , Ratones , Simulación del Acoplamiento Molecular , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/administración & dosificación , Hojas de la PlantaRESUMEN
The adsorption and desorption characteristics of seven macroporous resins on the antioxidants in soy sauce were investigated. SP-207 and SP-825 resins possessing good adsorption and desorption capacities were studied further. The pseudo-second-order kinetics and Langmuir isotherm models were demonstrated to be appropriate to describe the whole exothermic and physical adsorption processes of antioxidants onto resins. The 60% ethanol eluted fraction from soy sauce purified by SP-825 resin column possessed the strongest antioxidant activity. The antioxidant activities and contents of typical soy isoflavones, furanones, pyranones, and phenolic acids in soy sauce were determined. These compounds contributed to 50.02% of the total antioxidant activity of the SP-60% fraction. The key small molecule antioxidant compounds in soy sauce were identified as 4-ethylguaiacol, catechol, daidzein, and 4-ethylphenol by the antioxidants omission experiments. Additionally, the purified active fraction with high contents of antioxidants from soy sauce could be applied as bioactive ingredient in food industry.
Asunto(s)
Alimentos de Soja , Antioxidantes , Catecoles , Guayacol/análogos & derivados , Isoflavonas , FenolesRESUMEN
This study confirmed the inhibitory effects of clove essential oil (CEO) and eugenol (EUG) on the browning and relevant enzymes of fresh-cut lettuce, and examined associated mechanisms by inhibition kinetics and computational docking analysis. Fresh-cut lettuce was treated with 0.05% CEO and 0.05% EUG solutions, resulting in inhibition of the deterioration of texture quality and browning of the lettuce surface and interior. Compared with the controls, CEO and EUG significantly inhibited the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD, all p<0.05). EUG suppressed PAL, PPO, and POD in vitro in a dose-dependent manner, with IC50 values of 5.4±0.9, 29.5±3.5, and 61.9±6.7mM, respectively. The binding and inhibition effects of EUG on PAL, PPO, and POD, determined by inhibition kinetics and computational docking analysis, established EUG as a competitive inhibitor of these browning-relevant enzymes.
Asunto(s)
Aceite de Clavo/farmacología , Eugenol/farmacología , Conservación de Alimentos/métodos , Lactuca/efectos de los fármacos , Reacción de Maillard/efectos de los fármacos , Aceites Volátiles/farmacología , Aceite de Clavo/química , Aceite de Clavo/metabolismo , Relación Dosis-Respuesta a Droga , Eugenol/química , Eugenol/metabolismo , Lactuca/metabolismo , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Syzygium/metabolismoRESUMEN
Polyphenol oxidase (PPO) was purified from peach pulp by a three-step column chromatographic procedure. The kinetics properties of the PPO fractions obtained from different purification steps were compared. All the fractions showed high affinities for (+)-catechin and (-)-epicatechin. The optimum pHs and optimum temperatures for all the fractions were the same. However, the fraction that contained pectin was more sensitive to the change of pH, and it had a lower affinity for the substrates and a higher thermostability than the fractions without pectin. In addition, the protein impurities in PPO fractions might have no effect on the properties of PPO. l-Cysteine and glutathione were effective for the inhibition of all the PPO fractions, while NaF inhibited moderately. However, the pectin could reduce the inhibition effects of those inhibitors.
Asunto(s)
Catecol Oxidasa/química , Pectinas/metabolismo , Proteínas de Plantas/química , Prunus persica/enzimología , Catequina/metabolismo , Catecol Oxidasa/metabolismo , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , Cinética , Pectinas/química , Proteínas de Plantas/metabolismo , Prunus persica/química , Especificidad por Sustrato , TemperaturaRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Lithraea molleoides (Vell.) Engl. (Anacardiaceae) is a medicinal plant traditionally used in South America to treat various ailments, including diseases of the digestive system. AIM OF THE STUDY: To evaluate the in vivo antiulcer and antimicrobial activities against Helicobacter pylori of L. molleoides and its isolated compounds. MATERIALS AND METHODS: Methanolic extract 250 and 500 mg/kg, (LmE 250 and LmE 500, respectively) and infusions, 10 g and 20 g en 100mL (LmI 10 and LmI 20, respectively) of L. molleoides was evaluated for antiulcer activity against 0.6N HCl, 0.2N NaOH, 200mg/kg acetilsalicilic acid and absolute ethanol-induced gastric ulcers in rats. The degree of erosion in the glandular part of the stomach was assessed from a scoring system. Acute toxicity in mice was also evaluated. The antiulcer effect of the isolated compounds (catechol, mannitol, rutin, gallic acid, ferulic acid and caffeic acid, 100mg/kg) was evaluated against absolute ethanol-induced gastric ulcers in rats. The anti-Helicobacter pylori activity of L. molleoides and isolated compounds was performed using broth dilution methods. RESULTS: The LmE 250, LmE 500, LmI 10 and LmI 20 produced significant inhibition on the ulcer index in 0.6N HCl, 0.2N NaOH, 200mg/kg acetilsalicilic acid and absolute ethanol- induced gastric ulcers in rats. The isolated compounds, catechol, mannitol, rutin, ferulic acid and caffeic acid were active in absolute ethanol- induced gastric ulcers in rats. L. molleoides and different compounds showed antimicrobial activity in all strains tested. The lowest MIC value (0. 5 µg/mL) was obtained with catechol in six of eleven strains assayed. No signs of toxicity were observed with doses up to 2g/kg in an acute toxicity assay. CONCLUSION: These findings indicate that L. molleoides displays potential antiulcerogenic and antimicrobial activities and the identification of active principles could support the use of this plant for the treatment of digestive affections.
Asunto(s)
Anacardiaceae , Antibacterianos , Helicobacter pylori/efectos de los fármacos , Extractos Vegetales , Sustancias Protectoras , Úlcera Gástrica/tratamiento farmacológico , Animales , Antibacterianos/química , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Antibacterianos/toxicidad , Etanol , Femenino , Helicobacter pylori/crecimiento & desarrollo , Masculino , Ratones , Pruebas de Sensibilidad Microbiana , Fitoquímicos/análisis , Fitoquímicos/farmacología , Fitoquímicos/uso terapéutico , Fitoquímicos/toxicidad , Fitoterapia , Extractos Vegetales/química , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Extractos Vegetales/toxicidad , Sustancias Protectoras/química , Sustancias Protectoras/farmacología , Sustancias Protectoras/uso terapéutico , Sustancias Protectoras/toxicidad , Ratas Wistar , Úlcera Gástrica/inducido químicamente , Pruebas de Toxicidad AgudaRESUMEN
This investigation reveals that hydroxytyrosol (HT) could compete with lysine, arginine and histidine to bind methylglyoxal (MGO) and reducing the formation of advanced glycation end products. Kinetic of the degradation of HT in presence/absence of MGO under simulated physiological conditions is monitored by HPLC coupled to a QTOF spectrometer. HT should previously be oxidized to DOPAC (3,4-dihydroxyphenylacetic acid) which reacts with MGO by electrophilic aromatic substitution of the ortho-diphenyl ring. DOPAC was detected as the major degradation product of HT under simulated physiological conditions. Ortho-hydroxyl groups are necessary to promote the nucleophilic addition of MGO by HT and related compounds. The formation of four adducts were described by mass spectrometry, but monoDOPAC-monoMGO adduct (C11H12O6) was predominant. Results suggest that HT and its degradation product DOPAC could have a relevant role in preventing the formation of advanced glycation end products and therefore potentially mitigate the diabetic complications.
Asunto(s)
Alcohol Feniletílico/análogos & derivados , Piruvaldehído/química , Cromatografía Líquida de Alta Presión/métodos , Productos Finales de Glicación Avanzada/química , Espectrometría de Masas/métodos , Alcohol Feniletílico/químicaRESUMEN
We investigated a potential molecular target for anti-colitic effects of esculetin, 6,7-dihydroxycoumarin. Esculetin administered rectally effectively ameliorated TNBS-induced rat colitis and attenuated the expression of pro-inflammatory mediators in the inflamed colon. In human colon carcinoma HCT116 cells, esculetin induced hypoxia-inducible factor-1α (HIF-1α), leading to secretion of vascular endothelial growth factor, a HIF-1 target gene product involved in ulcer healing of the gastrointestinal mucosa. Esculetin directly inhibited HIF prolyl hydroxylase-2 (HPH-2), an enzyme playing a major role in negatively regulating HIF-1α protein stability. Esculetin inhibition of HPH and consequent induction of HIF-1α were attenuated by escalating dose of either ascorbate or 2-ketoglutarate, the required factors of the enzyme. Structurally, the catechol moiety in esculetin was required for HPH inhibition. Collectively, HPH may be a molecular target for esculetin-mediated anti-colitic effects and the catechol moiety in esculetin is the pharmacophore for HPH inhibition.