Click strategy using disodium salts of amino acids improves the water solubility of plinabulin and KPU-300

A self-activating nanoized vascular disrupting agent for selective anti-tumor therapy

Vascular disrupting agents (VDAs) have great potential in antitumor therapy, while the efficiency is limited by cardiovascular toxicity. In this study, a self-activating nanoized plinabulin (poly (_l-glutamic acid) grafted Azo-Plinabulin, AzoP-NP) was constructed. The AzoP-NPs can selectively be activated to an amino derivative of plinabulin (AmP) by intrinsic tumor hypoxia, disrupting tumor vessels and amplifying hypoxia, whilst be activated by self-amplified tumor hypoxia, then selectively inhibit tumor growth. In 4T1 tumor model, the AzoP-NPs had a selective biodistribution in tumor, as the free AmP in tumors at 24 h after AzoP-NPs treatment was 18.6 fold of that after AmP treatment and significantly higher than that in other tissues. Accordingly, AzoP-NPs resulted in no obvious acute cardiovascular toxicity (plasma von Willebrand factor in PBS, AzoP-NPs and AmP group: 143.1, 184.0 and 477.6 ng/mL) and a significantly stronger tumor inhibition than AmP. And the sustained release of drug in AzoP-NPs led to a higher maximum tolerated dose (MTD) (MTD of AzoP-NPs and AmP: > 80 vs 20 mg/kg). In addition, AzoP-NPs amplified tumor hypoxic, and synergized the anti-tumor effect of Tirapazamine (TPZ), a hypoxia-activated drug in clinical trials, with an inhibition rate of 97.7% and Q value of 1.89. Therefore, our findings provide new insights into next generation VDAs and their application in tumor therapy.

From the North Sea to Drug Repurposing, the Antiseizure Activity of Halimide and Plinabulin

PharmaSea performed large-scale in vivo screening of marine natural product (MNP) extracts, using zebrafish embryos and larvae, to identify compounds with the potential to treat epilepsy. In this study, we report the discovery of two new antiseizure compounds, the 2,5-diketopiperazine halimide and its semi-synthetic analogue, plinabulin. Interestingly, these are both known microtubule destabilizing agents, and plinabulin could have the potential for drug repurposing, as it is already in clinical trials for the prevention of chemotherapy-induced neutropenia and treatment of non-small cell lung cancer. Both halimide and plinabulin were found to have antiseizure activity in the larval zebrafish pentylenetetrazole (PTZ) seizure model via automated locomotor analysis and non-invasive local field potential recordings. The efficacy of plinabulin was further characterized in animal models of drug-resistant seizures, i.e., the larval zebrafish ethyl ketopentenoate (EKP) seizure model and the mouse 6 Hz psychomotor seizure model. Plinabulin was observed to be highly effective against EKP-induced seizures, on the behavioral and electrophysiological level, and showed activity in the mouse model. These data suggest that plinabulin could be of interest for the treatment of drug-resistant seizures. Finally, the investigation of two functional analogues, colchicine and indibulin, which were observed to be inactive against EKP-induced seizures, suggests that microtubule depolymerization does not underpin plinabulin’s antiseizure action.

Synthesis and Cytotoxic Activity of Several Novel N-Alkyl-Plinabulin Derivatives With Aryl Group Moieties

Seven novel N-alkyl-plinabulin derivatives with aryl groups moieties (nitroquinoline, 1,4-dihydroquinoline, 4-methoxybenzene, and 4-chlorobenzene) have been synthesized via aldol condensation and alkylation in one-pot, and tested for their cytotoxicity against 4 cancer cell lines (KB, HepG2, Lu, and MCF7). Compounds ( Z)−3-((6,8-dimethyl-4-oxo-1,4-dihydroquinolin-2-yl)methylene)−6-(( Z)−4-methoxybenzylidene)−1-(prop-2-yn-1-yl)piperazine-2,5-dione (5a), ( Z)−6-(( Z)−4-methoxybenzylidene)−1-(prop-2-yn-1-yl)−3-((1,6,8-trimethyl-4-oxo-1,4-dihydroquinolin-2-yl)methylene)piperazine-2,5-dione (5b), and ( Z)−3-(( Z)−4-chlorobenzylidene)−1,4-dimethyl-6-((8-methyl-4-nitroquinolin-2-yl)methylene)piperazine-2,5-dione (8) showed strong cytotoxicity against 3 of the cancer cells lines (KB, HepG2 and Lu) with IC50 values ranging from 3.04 to 10.62 µM. The quinoline-derived compounds had higher cytotoxic activity than the benzaldehyde derivatives. The successful synthesis of these derivatives offers useful information for the development of more potent vascular disrupting agents based on plinabulin.

Design, synthesis and biological evaluation of anti-pancreatic cancer activity of plinabulin derivatives based on the co-crystal structure

Based on the co-crystal structures of tubulin with plinabulin and Compound 1 (a derivative of plinabulin), a total of 18 novel plinabulin derivatives were designed and synthesized. Their biological activities were evaluated against human pancreatic cancer BxPC-3 cell lines. Two novel Compounds 13d and 13e exhibited potent activities with IC₅₀ at 1.56 and 1.72 nM, respectively. The tubulin polymerization assay indicated that these derivatives could inhibit microtubule polymerization. Furthermore, the interaction between tubulin and these compounds were elucidated by molecular docking. The binding modes of Compounds 13d and 13e were similar to the co-crystal structure of Compound 1. H-π interaction was observed between the aromatic hydrogen of thiophene moiety with Phe20, which could enhance their binding affinities.