Organocatalyzed [2+2] Cycloaddition Reactions between Quinone Imine Ketals and Allenoates

A new cycloaddition reaction of quinone imine ketals (QIKs), which could be utilized to the construction of functionalized azaspirocyclics under mild conditions, is described. This transformation involved a [2+2] cycloaddition reaction between QIKs and allenoates catalyzed by DABCO, and then treatment with 1 N HCl in one-pot. The strategy could provide a practical route to access azetidine-fused spirohexadienones in good to excellent yields and with high E-selectivity.

Biological Activity of Halogen-Containing Derivatives of N-Substituted Quinone Imines

The different halogen-containing derivatives of N-substituted quinone imines have been synthesized by the halogenation and hydrohalogenation of the corresponding quinone imines. N,N'-(Cyclohexa-2-en-1,4-diylidene)-diarylsulfonamides are good insecticides. They cause 89–97% of the insects to die. Compared with quinone imine, compounds having 4-oxocyclohexa-2,5-en-1-ylidene structure show higher fungicidal activity. N-(3,5-Dichloro-4-oxocyclohexa-2,5-dien-1-ylidene)-4-methylbenzene-1-sulfonamide and 4-chloro-N-[2,3,5,5,6,6-hexachloro-4-oxocyclohexa-2-en-1-ylidene]benzene-1-sulfonamide inhibit the growth and development of Phytophthora infestans by 82 and 81%, respectively. N-[2,3,5,5,6,6-Hexachloro-4-oxocyclohexa-2-en-1-ylidene]-4-methylbenzene-1-sulfonamide has a high herbicidal activity. The compounds with the largest number of chlorine atoms have the highest insecticidal, fungicidal, and herbicidal activity.

Comparison of the in vitro activity of novel and established nitrification inhibitors applied in agriculture: challenging the effectiveness of the currently available compounds

ABSTRACTNitrification inhibitors (NIs) applied to soil reduce nitrogen fertilizer losses from agricultural ecosystems. Currently available NIs appear to selectively inhibit ammonia-oxidizing bacteria (AOB), while their impact on other groups of nitrifiers is limited. Ethoxyquin (EQ), a preservative shown to inhibit ammonia-oxidizers (AO) in soil, is rapidly transformed to 2,6-dihydro-2,2,4-trimethyl-6-quinone imine (QI) and 2,4-dimethyl-6-ethoxy-quinoline (EQNL). We compared the inhibitory potential of EQ and its derivatives in vitro with other established NIs that have been applied in an agricultural setting (dicyandiamide (DCD), nitrapyrin (NP), 3,4-dimethylpyrazole phosphate (DMPP)) by evaluating their impact on the activity and growth of five soil-derived strains (two AOB (Nitrosomonas europaea, Nitrosospira multiformis), two ammonia-oxidizing archaea (AOA) (“Candidatus Nitrosocosmicus franklandus”, “Candidatus Nitrosotalea sinensis”), and one nitrite-oxidizing bacterium (NOB) (Nitrobacter sp.)). NIs degradation was also determined. AOA were more sensitive than AOB or NOB to EQ and its derivatives. Despite its transient character, QI was primarily responsible for AO inhibition by EQ, and the most potent NI against AOA. For AOB, QI was more potent than DCD but less than nitrapyrin and DMPP. AOA and NOB showed higher tolerance to the persistent compounds DCD and DMPP. Our findings benchmark the activity range of known and novel NIs with practical implications for their use, and the development of novel NIs with broad or complementary activity against all AO.

Synthesis of quinone imine and sulphur-containing compounds with antitumor and trypanocidal activities: redox and biological implications

New quinoidal compounds were prepared and evaluated against T. cruzi and cancer cell lines for the identification of new bioactive agents.

Management of acetaminophen toxicity, a review

Acetaminophen (APAP) is a widely used drug in our environment with few adverse effects. Because of this, several patients affected by APAP hepatotoxicity unknown that the APAP dose-intake was excessive. This damage is mainly produced via one of APAP metabolites: N-acetyl-para-benzo-quinone imine (NAPQI), which is very toxic. The drug’s ingested doses as well as the length of time from APAP ingestion to N-acetylcysteine (NAC) therapy are the most essential determining factors in both the development and severity of APAP hepatotoxicity. However, there are other factors related, including alcohol intake, herbs and medications, age and genetic factors, nutritional status, and chronic liver disease. The ingestion of a toxic dose of APAP causes different clinical manifestations that depend fundamentally on the time elapsed since the intake. The diagnosis process depends on the intake (acute single overdose of after repeated overdoses). The Rumack-Matthew nomogram is acceptable after an acute single overdose, being the “possible hepatic toxicity” point 200 μg/mL at 4 hours and 25 μg/mL at 16 hours). This normogram is no applicable in after repeated overdoses. NAC is the antidote for APAP intoxication, and could be administered orally or intravenous. Finally, a multidisciplinary approach with the support of Psychiatry, Intensive Care Unit as well as Gastroenterology and Digestive Department will be necessary, especially in the case of attempted autolysis and severe liver failure.