Discovery of a novel water-soluble, rapid-release triptolide prodrug with improved drug-like properties and high efficacy in human acute myeloid leukemia

In this work, a series of water-soluble triptolide prodrugs were synthesized, and their triptolide release rate, pharmacokinetic characteristics and anti-tumor effect were measured. We found that inserting glycolic acid as a linker between triptolide and the cyclic amino acid accelerated the release of triptolide from prodrugs into the plasma while preserving its safety. Among them, prodrug TP-P1 was significantly better than Minnelide (the only water-soluble triptolide prodrug in clinical trials) in terms of release rate in plasma and synthetic yield. In mouse models of human acute myeloid leukemia (AML), TP-P1 was effective in reducing xenograft tumors at dose levels as low as 25 μg/kg, and eliminating tumors at dose 100 μg/kg. Furthermore, TP-P1 could significantly enhance the efficacy of FLT3 inhibitors in the treatment of AML. These experimental results showed the potential of TP-P1 as water-soluble prodrugs of triptolide.

Scalable Total Synthesis of (-)-Triptonide: Serendipitous Discovery of a Visible-Light-Promoted Olefin Coupling Initiated by Metal-Catalyzed Hydrogen Atom Transfer (MHAT)

An efficient and scalable total synthesis of (-)-triptonide is accomplished based on a metal-catalyzed hydrogen atom transfer (MHAT)-initiated radical cyclization. During the optimization of the key step, we discovered that blue LEDs significantly promoted the efficiency of reaction initiated by Co(TPP)-catalyzed MHAT. Further exploration and optimization of this catalytic system led to development of a dehydrogenative MHAT-initiated Giese reaction.

Ninhydrins inhibit carbonic anhydrases directly binding to the metal ion

Ninhydrins show extensive application in organic chemistry and agriculture whereas they have been poorly investigated as bioactive molecules for medicinal chemistry purposes. A series of ninhydrin derivatives was here investigated for the inhibition of human carbonic anhydrases (CAs, EC 4.2.1.1), based on earlier evidence that gem diols are able to coordinate the metal ion from the CA active site. Ninhydrins demonstrated a micromolar inhibitory action against CA I and IX (K_Is in the range 0.57-68.2 μM) and up to a nanomolar efficacy against CA II and VII (K_Is in the range 0.025-78.2 μM), validated isoforms as targets in several CNS-related diseases. CA IV was instead weakly or poorly inhibited. A computational protocol based on docking, MM-GBSA and metadynamics calculations was used to elucidate the putative binding mode of this type of inhibitors to CA II and CA VII. The findings of this study testify that such pharmacologically underestimated ligands may represent interesting lead compounds for the development of CA inhibitors possessing an innovative mechanism of action, i.e., mono- or bis-coordination to the zinc ion through the diol moiety.

A review of the total syntheses of triptolide

Triptolide is a complex triepoxide diterpene natural product that has attracted considerable interest in the organic chemistry and medicinal chemistry societies due to its intriguing structural features and multiple promising biological activities. In this review, progress in the total syntheses of triptolide are systematically summarized. We hope to gain a better understanding of the field and provide constructive suggestions for future studies of triptolide.

Abietane Diterpenoids from the Roots of Clerodendrum trichotomum and Their Nitric Oxide Inhibitory Activities

Twelve new abietane diterpenoids (1-12) and 31 known analogues (13-43) were isolated from a medicinal Chinese herb, Clerodendrum trichotomum Thunberg. The absolute configurations of 1-3 were established on the basis of ECD and X-ray crystallography data, whereas that of 4 was elucidated by comparison of experimental and calculated ECD data. Eight diterpenoids, 15,16-dehydroteuvincenone G (1), trichotomin A (4), 2α-hydrocaryopincaolide F (7), villosin C (20), 15-dehydro-17-hydroxycyrtophyllone A (22), demethylcryptojaponol (38), 6β-hydroxydemethylcryptojaponol (39), and trichotomone (43), exerted inhibitory effects against NO production with IC₅₀ values of 5.6-16.1 μM. The structure-activity relationships of the isolated diterpenoids are also estimated.

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

The Robinson annulation is a reaction that has been useful for numerous syntheses since its discovery in 1935, especially in the field of steroid synthesis. The products are usually obtained after three consecutive steps: the formation of an enolate (or derivative), a conjugate addition, and an aldol reaction. Over the years, several methodological improvements have been made for each individual step or alternative routes have been devised to access the Robinson annulation products. The first part of this Review outlines the most relevant developments towards the formation of monocarbonyl-derived Robinson annulation products (MRA products, MRAPs) and activated monocarbonyl-derived Robinson annulation products (AMRA products, AMRAPs). The following sections are then devoted to the diastereoselective and enantioselective synthesis of these products, while the last section describes the enantiomeric resolution of racemic mixtures.

Catalytic Asymmetric Formal Total Synthesis of (-)-Triptophenolide and (+)-Triptolide

Catalytic asymmetric formal synthesis of (-)-Triptophenolide and (+)-Triptolide have been achieved. Key reaction involves Palladium catalyzed asymmetric conjugate addition of aryl boronic acid to 3-methyl cyclohexe-1-none to form quaternary carbon. Claisen rearrangement and subsequent aldol reaction furnished trans-decaline key intermediate, which assured a formal total synthesis of (-)-Triptophenolide and (+)-Triptolide.

Divergent total synthesis of triptolide, triptonide, tripdiolide, 16-hydroxytriptolide, and their analogues

A divergent route was developed for the formal total synthesis of triptolide, triptonide, and tripdiolide, as well as a total synthesis of 16-hydroxytriptolide and their analogues in an enantioselective form. Common advanced intermediate 5 was concisely assembled by employing an indium(III)-catalyzed cationic polycyclization reaction and a palladium-catalyzed carbonylation-lactone formation reaction as key steps. This advanced intermediate was readily converted to the above natural products by using palladium-catalyzed cross-coupling or the Claisen rearrangement reaction as key steps. Additionally, preliminary structure-cytotoxic activity relationship studies of C13 suggested that it might be a new modification site that could still retain the cytotoxicity.