Design, Synthesis, and Evaluation of Glucose Transporter Inhibitor-SN38 Conjugates for Targeting Colorectal Cancer.

Irinotecan (1), a prodrug of SN38 (2) approved by the US Food and Drug Administration for treating colorectal cancer, lacks specificity and causes many side effects. To increase the selectivity and therapeutic efficacy of this drug, we designed and synthesized conjugates of SN38 and glucose transporter inhibitors (phlorizin (5) or phloretin (6)), which could be hydrolyzed by glutathione or cathepsin to release SN38 in the tumor microenvironment, as a proof of concept. These conjugates (8, 9, and 10) displayed better antitumor efficacy with lower systemic exposure to SN38 in an orthotopic colorectal cancer mouse model compared with irinotecan at the same dosage. Further, no major adverse effects of the conjugates were observed during treatment. Biodistribution studies showed that conjugate 10 could induce higher concentrations of free SN38 in tumor tissues than irinotecan at the same dosage. Thus, the developed conjugates exhibit potential for treating colorectal cancer.

Isolation of Anti-SARS-CoV-2 Natural Products Extracted from Mentha canadensis and the Semi-synthesis of Antiviral Derivatives.

Traditional herbal medicine offers opportunities to discover novel therapeutics against SARS-CoV-2 mutation. The dried aerial part of mint (Mentha canadensis L.) was chosen for bioactivity-guided extraction. Seven constituents were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). Syringic acid and methyl rosmarinate were evaluated in drug combination treatment. Ten amide derivatives of methyl rosmarinate were synthesized, and the dodecyl (13) and 3-ethylphenyl (19) derivatives demonstrated significant improvement in the anti-SARS-CoV-2 plaque reduction assay, achieving IC50 of 0.77 and 2.70 µM, respectively, against Omicron BA.1 as compared to methyl rosmarinate's IC50 of 57.0 µM. Spike protein binding and 3CLpro inhibition assays were performed to explore the viral inhibition mechanism. Molecular docking of compounds 13 and 19 to 3CLpro was performed to reveal potential interaction. In summary, natural products with anti-Omicron BA.1 activity were isolated from Mentha canadensis and derivatives of methyl rosmarinate were synthesized, showing 21- to 74-fold improvement in antiviral activity against Omicron BA.1.

Design, structure-activity relationships, and enzyme kinetic studies of tricyclic and tetracyclic coumarin-based sulfamates as steroid sulfatase inhibitors.

Inhibition of steroid sulfatase (STS) decreases estrogen production and thus, suppresses tumor proliferation. Inspired by irosustat, the first STS inhibitor in clinical trials, we explored twenty-one tricyclic and tetra-heterocyclic coumarin-based derivatives. Their STS enzyme kinetic parameters, docking models, and cytotoxicity toward breast cancer and normal cells were evaluated. Tricyclic derivative 9e and tetracyclic derivative 10c were the most promising irreversible inhibitors developed in this study, with KI of 0.05 and 0.4 nM, and kinact/KI ratios of 28.6 and 19.1 nM-1min-1 on human placenta STS, respectively.

The Design, Structure-Activity, and kinetic studies of 3-Benzyl-5-oxa-1,2,3,4-Tetrahydro-2H-chromeno-(3,4-c)pyridin-8-yl sulfamates as Steroid sulfatase inhibitors.

Steroid sulfatase inhibitors block the local production of estrogenic steroids and are attractive agents for the treatment of estrogen-dependent cancers. Inspiration of coumarin-based inhibitors, we synthesized thirty-two 5-oxa-1,2,3,4-tetrahydro-2H-chromeno-(3,4-c)pyridin-8-yl sulfamates, focusing on the substitution derivatives on the adjacent phenyl ring and evaluated their abilities to block STS from human placenta and MCF-7 cells. SAR analysis revealed that the incorporation of chlorine at either meta and/or para position of the adjacent phenyl ring of the tricyclic skeleton enhanced STS inhibition. Di-substitutions at the adjacent phenyl ring were superior to mono and tri-substitutions. Further kinetic analysis of these compounds revealed that chloride-bearing compounds, such as 19m, 19v, and 19w, had KI of 0.02 to 0.11 nM and kinact/KI ratios of 8.8-17.5 nM-1min-1, a parameter indicated for the efficiency of irreversible inhibition. We also used the docking model to illustrate the difference in STS inhibitory potency of compounds. Finally, the safety and anti-cancer activity of selected compounds 19m, 19v, and 19w were also studied, showing the results of low cytotoxicity on NHDF cell line and being more potent than irosustat on ZR-75-1 cell, which was a hormone-dependent cancer cell line with high STS expression.

Targeting Colorectal Cancer with Conjugates of a Glucose Transporter Inhibitor and 5-Fluorouracil.

Overexpression of glucose transporters (GLUTs) in colorectal cancer cells is associated with 5-fluorouracil (1, 5-FU) resistance and poor clinical outcomes. We designed and synthesized a novel GLUT-targeting drug conjugate, triggered by glutathione in the tumor microenvironment, that releases 5-FU and GLUTs inhibitor (phlorizin (2) and phloretin (3)). Using an orthotopic colorectal cancer mice model, we showed that the conjugate exhibited better antitumor efficacy than 5-FU, with much lower exposure of 5-FU during treatment and without significant side effects. Our study establishes a GLUT-targeting theranostic incorporating a disulfide linker between the targeting module and cytotoxic payload as a potential antitumor therapy.

Design and synthesis of 3-benzylaminocoumarin-7-O-sulfamate derivatives as steroid sulfatase inhibitors.

Steroid sulfatase (STS) is a sulfatase enzyme that catalyzes the conversion of sulfated steroid precursors to free steroid. The inhibition of STS could abate estrogenic steroids that stimulate the proliferation and development of breast cancer, and therefore STS is a potential target for adjuvant endocrine therapy. In this study, a series of 3-benzylaminocoumarin-7-O-sulfamate derivatives targeting STS were designed and synthesized. Structure-relationship activities (SAR) analysis revealed that attachment of a benzylamino group at the 3-position of coumarin improved inhibitory activity. Compound 3j was found to have the highest inhibition activity against human placenta isolated STS (IC50  0.13 µM) and MCF-7 cell lines (IC50 1.35 µM). Kinetic studies found compound 3j to be an irreversible inhibitor of STS, with KI and kinact value of 86.9 nM and 158.7 min-1, respectively.