NDGA enhances the physicochemical and anti-biodegradation performance of dentin collagen.

OBJECTIVES: Collagen fibrils from carious dentin matrix are prone to enzymatic degradation. This study investigates the feasibility and mechanism of nordihydroguaiaretic acid (NDGA), as a collagen crosslinker, to bio-modify the demineralized dentin matrix. METHODS: The physicochemical properties of the crosslinked dentin matrix were characterized by swelling ratio, ninhydrin assay, Fourier Transform Infrared spectroscopy, and atomic force microscopy. The collagenase degradation resistance was evaluated by measuring loss of dry mass, hydroproline release, loss of elasticity, and micro-nano structure integrity. The cytotoxicity of NDGA-crosslinked dentin collagen was evaluated by flow cytometry. RESULTS: NDGA crosslinked dentin matrix without destroying the integrity of collagen. Mechanistically, NDGA formed bisquinone bond between two adjacent o-quinone groups, resulting in NDGA polymeric matrix in which collagen fibrils were embedded. NDGA modification could significantly enhance the stiffness of dentin matrix at macro-nano scale. The NDGA-crosslinked dentin matrix exhibited remarkably low collagen degradation and sustained bulk elasticity after collagenase challenge, which were attributed to decreased water content, physical masking of collagenase bind sites on collagen, and improved stiffness of collagen fibrils. Notably, NDGA-crosslinked dentin matrix exhibited excellent biocompatibility. CONCLUSION: NDGA, as a biocompatible collagen crosslinker, improves the mechanical properties and biodegradation resistance of demineralized dentin matrix.

Chemical and biological properties of nordihydroguaiaretic acid

Nordihydroguaiaretic acid (NDGA) is a natural product obtained by the alkaline extraction of dried plants of Larrea tridentata species. Due to the biological properties presented, such as antioxidant, anti-inflammatory, antiviral and cytotoxic capacity, this compound is being increasingly studied. In this review, it was evaluated the benefits of NDGA against different animal models. Besides that, it was found that this compound has antitumor activity similar to its synthetic derivative terameprocol in prostate tumors. The hypoglycemic effect may be evidenced by the inhibition of sugar uptake by NDGA; in obesity, studies have observed that NDGA presented a positive regulatory effect for Peroxisome proliferator-activated receptors (PPAR-α) involved in the oxidation of hepatic fatty acids and reduced the expression of lipogenic genes. Regarding its antioxidant potential, its mechanism is related to the ability to in vitro scavenging reactive substances. Although there are several studies demonstrating the benefits of using NDGA, there are also reports of its toxicity, mainly of liver damage and nephrotoxicity

Stability of an Aqueous Extract of Larrea divaricata Cav. during a Simulated Digestion Process.

Larrea divaricata Cav. (Zygophyllaceae) is a South American plant widely distributed in Argentina that is used in folk medicine to treat inflammatory diseases. The aqueous extract is known to have well-documented biological activities such as antitumour, immunomodulatory, antimicrobial, antiinflammatory and antioxidant. However, its stability in gastrointestinal fluids is unknown. The latter is an important factor to assure the bioavailability of plant extracts intended to be administered via the oral route. The aim of this work was to study the stability of a lyophilized aqueous extract of L. divaricata compressed as a pill. To this end, the main polyphenol compound found in the extract, that is, the nordihydroguaiaretic acid, the total polyphenols and flavonoids content and the antioxidant activity such as diphenylpicrylhydrazyl scavenger activity and reducing power were assayed after subjecting the extract to different incubation times in simulated digestive fluids. The HPLC and spectroscopic methods were employed. Although the levels of polyphenols and flavonoids decreased upon incubation in gastric and intestinal fluids, the extract maintained its antioxidant activity related to the presence of nordihydroguaiaretic acid. These results are promising and encourage the potential use of the extract by the oral route as a supplement or phytomedicine with antioxidant activity. Copyright © 2017 John Wiley & Sons, Ltd.

Reactive oxygen species and lipoxygenases regulate the oncogenicity of NPM-ALK-positive anaplastic large cell lymphomas.

The chimera nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), the tyrosine kinase activity of which is constitutively upregulated, is the causative agent of 75% of the anaplastic large-cell lymphomas (ALCLs). We have demonstrated that NPM-ALK induces the production of reactive oxygen species (ROS) by a pathway involving the arachidonic acid-metabolizing enzymes of the lipoxygenase (LOX) family. The use of the LOX inhibitor nordihydroguaiaretic acid (NDGA) and of the anti-oxidant N-acetylcysteine (NAC) demonstrated that ROS are important in maintaining the ALK kinase active. Consistent with this, NDGA treatment resulted in the inhibition of key pathways, such as Akt, signal transducer and activator of transcription factor 3 (STAT3) and extracellular signal-regulated kinase (ERK), which are involved in NPM-ALK antiapoptotic and pro-mitogenic functions. Conversely, the stress-activated kinase p38, described in some instances as a mediator of apoptosis, was activated. Interestingly, 5-LOX, an isoform involved in many cancers, was found to be activated in NPM-ALK(+) cells. Functional studies have shown that transforming properties, namely proliferation and resistance to apoptosis, were abrogated by treatment with either NDGA or the 5-LOX inhibitor (N-(3-phenoxycinnamyl)-acetohydroxamic acid) (BW A4C). Together, these data point to the ROS/LOX pathway as a potential new target for therapy in NPM-ALK-positive tumors.

Single-laboratory validated method for determination of nordihydroguaiaretic acid in chaparral-containing dietary supplements.

Nordihydroguaiaretic acid (NDGA) occurs naturally in chaparral (Larrea tridentate Coville), a plant which commonly grows in the Southwest United States and has been used for medicinal purposes by Native Americans indigenous to that region. In addition to its traditional use as a tea, manufacturers of dietary supplements have marketed chaparral-containing products in a variety of formulations. Because of the hepatotoxicity of NDGA, and its occurrence in regulated products, we have developed a method for the determination of NDGA in dietary supplements and have tested this method in several dietary supplement formulations. Products were extracted with 80% methanol, filtered, and analyzed by high-performance liquid chromatography. NDGA was detected and determined with both a diode array detector and negative-ion electrospray. Fragmentation in the triple-quadrupole mass spectrometer was obtained by collisional activation of the [M-H](-) ion. Collisional activation produced sufficient fragmentation to provide unambiguous identification. Lack of a stable isotope labeled internal standard has led us to compare quantitations based on UV detection with quantitations based on tandem mass spectrometry (MS/MS). Presence of NDGA was confirmed in several dietary supplement products. Quantitative results from the 2 detection methods were comparable for most products. The limit of quantitation using MS/MS was lower and fewer interferences were observed, although UV detection provided better linearity.

Activation and apoptosis of mouse peritoneal macrophages by extracts of Larrea divaricata Cav. (jarilla).

Two aqueous extracts, decoction and infusion from Larrea divaricata Cav. (Zygophyllaceae) were investigated for immunomodulating activity on peritoneal macrophages (MPhi). Both extracts reduced significantly the cell viability assessed with the MTT assay at 1 and 4 mg/ml (decoction) and 0.8-4 mg/ml (infusion). Apoptotic morphology showed that at 1 and 4 mg/ml both infusion and decoction triggered an increment of the apoptosis. Pretreatment of MPhi with decoction increased significantly the phagocytosis of zymosan and Candida albicans. The production of NO was estimated as nitrite using the Griess reagent. A slight but significant increase in NO release was observed after the incubation of both extracts (0.2 mg/ml) with LPS during 48 h. As shown in western blot data MPhi cultured with infusion and LPS exhibited the stronger expression of iNOS compared with untreated cells. Both extracts (0.2 mg/ml) increased the binding of LPS-FITC to cells compared with untreated ones. The addition of Staphylococcus aureus blocked completely the binding of LPS-FITC to cells. L. divaricata stimulated the MPhi activation at 0.2 mg/ml whereas it showed a clear pro-apoptotic activity at higher concentrations. The dual effects of L. divaricata are relevant considering the use of this plant to activate the immune system.

Determination and confirmation of five phenolic antioxidants in foods by LC/MS and GC/MS.

Identification and determination of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), nordihydroguaiaretic acid (NDGA), propyl gallate (PG) and tert-butylhydroquinone (TBHQ) by means of LC/MS and GC/MS were examined. These five phenolic antioxidants were detected as their pseudo-molecular ions [M-H]- by LC/MS using a Shim-pack FC-ODS column with drying gas. Moreover, BHA, BHT and TBHQ were detected based on their mass fragment ions by GC/MS. Decomposition of TBHQ, NDGA and PG during analysis could be prevented by the addition of L-ascorbic acid (AsA) to the extraction solvent. All five antioxidants were extracted from nikuman, olive oils, peanut butter, pasta sauce and chewing gum with a mixture of acetonitrile-2-propanol-ethanol (2:1:1) containing 0.1% AsA (AsA mixture), which had been cooled in a freezer and filtered. One part filtrate and 5 parts water were mixed and placed on a Mega-Bond Elut C18 cartridge, except in the case of chewing gum. Lipids in foods were removed on a C18 cartridge by washing with 5 mL of 5% acetic acid, and antioxidants were eluted with 5 mL of AsA mixture. The antioxidants spiked into nikuman, olive oil, peanut butter, pasta sauce and chewing gum were successfully identified and their concentrations determined by LC/MS, and GC/MS with good recoveries.

[Simultaneous determination of five antioxidants in food by HPLC with fluorescence detection].

An HPLC method with fluorescence detection was developed for the determination of propyl gallate, nordihydroguaiaretic acid, butylated hydroxyanisole (2- and 3-tert-butyl-4-hydroxyanisole), tert-butylhydroquinone and octyl gallate in edible oils and foods. The antioxidants in edible oil were isolated directly with acetonitrile saturated with n-hexane. The antioxidants in food were extracted with ethyl acetate and the extract was concentrated under vacuum. They were isolated from the residue with acetonitrile saturated with n-hexane. The acetonitrile layer was centrifuged at 5,000 rpm for 10 min. The HPLC separation was performed on a Symmetry C18 column (3.5 microns, 4.6 mm i.d. x 150 mm) using a mixture of 5% acetic acid-acetonitrile-methanol (4:3:3, v/v/v) as the mobile phase and monitored by using a fluorescence detector with time programming. Sample peaks were identified by comparison of the fluorescence spectra with those of antioxidant standards. Average recoveries of fortified antioxidants at 100 micrograms/g were 72.1-99.6%. Coefficients of variation were 0.7-7.2%.