Oxalate is a divalent organic anion that affects many biological and commercial processes. It is derived from plant sources, such as spinach, rhubarb, tea, cacao, nuts, and beans, and therefore is commonly found in raw or processed food products. Oxalate can also be made endogenously by humans and other mammals as a byproduct of hepatic enzymatic reactions. It is theorized that plants use oxalate to store calcium and protect against herbivory. Clinically, oxalate is best known to be a major component of kidney stones, which commonly contain calcium oxalate crystals. Oxalate can induce an inflammatory response that decreases the immune system’s ability to remove renal crystals. When formulated with platinum as oxaliplatin (an anticancer drug), oxalate has been proposed to cause neurotoxicity and nerve pain. There are many sectors of industry that are hampered by oxalate, and others that depend on it. For example, calcium oxalate is troublesome in the pulp industry and the alumina industry as it deposits on machinery. On the other hand, oxalate is a common active component of rust removal and cleaning products. Due to its ubiquity, there is interest in developing efficient methods to quantify oxalate. Over the past four decades, many diverse methods have been reported. These approaches include electrochemical detection, liquid chromatography or gas chromatography coupled with mass spectrometry, enzymatic degradation of oxalate with oxalate oxidase and detection of hydrogen peroxide produced, and indicator displacement-based methods employing fluorescent or UV light-absorbing compounds. Enhancements in sensitivity have been reported for both electrochemical and mass-spectrometry-based methods as recently as this year. Indicator-based methods have realized a surge in interest that continues to date. The diversity of these approaches, in terms of instrumentation, sample preparation, and sensitivity, has made it clear that no single method will work best for every purpose. This review describes the strengths and limitations of each method, and may serve as a reference for investigators to decide which approach is most suitable for their work.

The conjugate N-adducts of thio-1,3,4-diazole and 2-thiazoline with levoglucosenone were synthesized via a stereoselective, base-catalyzed conjugate N-Michael addition to levoglucosenone at C-4. Structural assignments were established using 1H and 13C NMR analysis, and X-ray single-crystal analysis for one of the compounds. The biological properties of the novel compounds were tested on a cell model. Cytotoxicity was analyzed via colorimetric assay. Two distinct types of cell death, apoptosis and necrosis, were analyzed by determining the phosphatidylserine levels from the outer leaflet of the plasma membrane, caspase activation, and lactate dehydrogenase release. We also evaluated DNA damage using an alkaline comet assay. The level of oxidative stress was measured with a modified comet assay and an H2DCFDA probe. The thio-1,3,4-diazole adduct (FCP23) and the 2-thiazoline adduct (FCP26) exhibit similar cytotoxicity values for cancer cells (ovarian (A2780), breast (MCF-7), cervix (HeLa), colon (LoVo), and brain (MO59J and MO59K)), but their mechanism of action is drastically different. While FCP23 induces oxidative stress, DNA damage, and necrosis, FCP26 induces apoptosis through caspase activation.

Heterocyclic sulfur and nitrogen containing compounds capable of forming an equilibrium: thiol/imine = thione/amine (N=C-S-H ⇌ H-N-C=S) were reacted with levoglucosenone (LG) in the presence of triethylamine. Unexpectedly, the only isolated products were the result of the aza-Michael addition. No S-adducts were detected. All products were crystalline with good to excellent yields. The structure of products was determined using NMR, MS, and single-crystal X-ray analysis.

A continuation of our studies of dihydrolevoglucosenone (DHL) reaction products with heterocyclic aromatic aldehyde^1,2 are presented. Base catalyzed Michael addition of thiols to these products at the 3-exo-cyclic bond is investigated. 1-thioglucose 17 was selected as a convenient nucleophile. The products resulting from anhydrous potassium carbonate catalyzed

The reaction of dihydrolevoglucosenone 1 (DHLG) Cyrene^R with aromatic aldehydes in the presence of a base produces exo-cyclic enone^[1-2] as a main (and usually only) product. However, when DHGL 1 (2 moles) was reacted with 1,4-diacetyl-2,5-dihydroxybenzene 2, we noticed a formation of an entirely different product 3 in a good 58 %