Diels-Alder reactions are among the most powerful synthetic transformations to construct complex natural products. Despite that increasing of enzymatic intramolecular Diels-Alder reactions have been discovered, natural intermolecular Diels-Alderases are rarely described. Here, we report an intermolecular hetero-Diels-Alder reaction in the biosynthesis of tropolonic sesquiterpenes and functionally characterize EupfF as the first fungal intermolecular hetero-Diels-Alderase. We demonstrate that EupfF catalyzed the dehydration of a hydroxymethyl-containing tropolone (5) to generate a reactive tropolone o-quinone methide (6) and might further *

With the widespread use of O-alkoxyresorufin dealkylation assays since the 1990’s, thousands of inhibitors of cytochrome P450 family 1 enzymes (P450s 1A1, 1A2, and 1B1) have been identified and studied. Generally, planar polycyclic molecules such as polycyclic aromatic hydrocarbons, stilbenoids, and flavonoids are considered to potentially be effective inhibitors of these enzymes. However, the details of structure-activity relationships and selectivity of these inhibitors are still ambiguous. In this review, we thoroughly discuss the selectivity of many representative P450 family 1 inhibitors reported in the past 20 years through a meta-analysis.

Orally bioavailable SERDs may offer greater systemic drug exposure, improved clinical efficacy, and more durable treatment outcome for patients with ER-positive endocrine-resistant breast cancer. We report the design and synthesis of a boronic acid modified fulvestrant (5, ZB716), which binds to ERα competitively (IC50 = 4.1 nM) and effectively downregulates ERα in both tamoxifen-sensitive and tamoxifen-resistant breast cancer cells. Furthermore, It has superior oral bioavailability (AUC = 2547.1 ng·h/mL) in mice, indicating its promising clinical utility as an oral SERD.

Summary Ceramide serves as a central mediator in sphingolipid metabolism and signaling pathways, regulating many fundamental cellular responses. It is referred to as a “tumor suppressor lipid”, since it powerfully potentiates signaling events which drive apoptosis, cell cycle arrest, and autophagic responses. In the typical cancer cell, ceramide levels and signaling are usually suppressed by over-expression of ceramide-metabolizing enzymes or down-regulation of ceramide-generating enzymes. However, chemotherapeutic drugs as well as radiotherapy increase intracellular ceramide levels while exogenously treating cancer cells with short-chain ceramides leads to anti-cancer effects. All evidence currently points to the fact that the up-regulation of ceramide level is a promising anti-cancer target. In this review, we exhibited a full scroll of anti-cancer ceramide analogs as down-stream receptor agonists and ceramide metabolizing enzyme inhibitors.

Selective inhibition of P450 enzymes is the key to block the conversion of environmental procarcinogens to their carcinogenic metabolites in both animals and humans. To discover highly potent and selective inhibitors of P450s 1A1, 1A2, and 1B1, as well as to investigate active site cavities of these enzymes, 14 novel flavone derivatives were prepared as chemical probes. Fluorimetric enzyme inhibition assays were used to determine the inhibitory activities of these probes towards P450s 1A1, 1A2, 1B1, 2A6, and 2B1. A highly selective P450 1B1 inhibitor, 5-hydroxy-4′-propargyloxyflavone (5H4′FPE) was discovered. Some tested compounds also showed selectivity between P450s 1A1 and 1A2. Alpha-naphthoflavone-like and 5-hydroxyflavone derivatives preferentially inhibited P450 1A2, while beta-naphthoflavone-like flavone derivatives showed selective inhibition of P450 1A1. On the basis of structural analysis, the active site cavity models of P450 enzymes 1A1 and 1A2 were generated, demonstrating a planar long strip cavity and a planar triangular cavity, respectively.