Spiroarborin, an ent-Clerodane Homodimer from Callicarpa arborea as an Inhibitor of the Eleven-Nineteen Leukemia (ENL) Protein by Targeting the YEATS Domain.

A spiro ent-clerodane homodimer with a rare 6/6/6/6/6-fused pentacyclic scaffold, spiroarborin (1), together with four new monomeric analogues (2-5), were isolated from Callicarpa arborea. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum-chemical calculations, and X-ray diffraction. A plausible biosynthetic pathway of 1 was proposed, and a biomimetic synthesis of its derivative was accomplished. Compound 1 showed a potent inhibitory effect by directly binding to the YEATS domain of the 11-19 leukemia (ENL) protein with an IC50 value of 7.3 µM. This gave a KD value of 5.0 µM, as recorded by a surface plasmon resonance binding assay.

Synthesis of nigranoic acid and manwuweizic acid derivatives as HDAC inhibitors and anti-inflammatory agents.

As a successful anti-tumor drug target, the family of histone deacetylases (HDACs) is also a critical player in immune response, making the research of anti-inflammatory HDAC inhibitors an attractive new focus. In this report, triterpenoids nigranoic acid (NA) and manwuweizic acid (MA) were identified as HDAC inhibitors through docking-based virtual screening and enzymatic activity assay. A series of derivatives of NA and MA were synthesized and assessed for their biological effects. As a result, hydroxamic acid derivatives of NA and MA showed moderately increased activity for HDAC1/2/4/6 inhibition (the lowest IC50 against HDAC1 is 1.14 µM), with no activity against HDAC8. In J774A.1 macrophage, compound 1-3, 13 and 17-19 demonstrated inhibitory activity against lactate dehydrogenase (LDH) and IL-1ß production, without affecting cell viability. Compound 19 increased the histone acetylation level in J774A.1 cells, as well as inhibited IL-1ß maturation and caspase-1 cleavage. These results indicated that compound 19 blocks the activation of NLRP3 inflammasome, probably related to HDAC inhibition. This work provided a natural scaffold for developing low-cytotoxic and anti-inflammatory HDAC inhibitors, as well as a class of tool molecules for studying the relationship between HDACs and NLRP3 activation.

Design, synthesis and anti-HIV evaluation of 5-alkyl- 6-(benzo[d][1,3]dioxol-5-alkyl)-2-mercaptopyrimidin-4(3H)-ones as potent HIV-1 NNRTIs.

In order to discover and develop the new HIV-1 NNRTIs, a series of 5-alkyl-6-(benzo[d][1,3]dioxol-5-ylalkyl)-2-mercaptopyrimidin-4(3H)-ones was synthesized and screened for their in vitro cytotoxicity against HIV-1. Most of the compounds we synthetized showed high activity against wild-type HIV-1 strain (IIIB) while IC50 values are in the range of 0.06-12.95 µM. Among them, the most active HIV-1 inhibitor was compound 6-(benzo[d][1,3]dioxol-5-ylmethyl)-5-ethyl-2-((2-(4-hydroxyphenyl)-2-oxoethyl)thio)pyrimidin-4(3H)-one (5b), which exhibited similar HIV-1 inhibitory potency (IC50 = 0.06 µM, CC50 = 96.23 µM) compared with nevirapine (IC50 = 0.04 µM, CC50 >200 µM) and most of compounds exhibited submicromolar IC50 values indicating they were specific RT inhibitors. The compounds 5b, 6-(benzo[d] [1,3]dioxol-5-yl)-5-ethyl-2-((2-(4-hydroxyphenyl)-2-oxoethyl)thio)pyrimidin-4(3H)-one (5c) and 4-(2-((4-(benzo[d][1,3]dioxol-5-ylmethyl)-5-ethyl-6-oxo-1,6-dihydropyrimidin-2-yl)thio)acetyl)phenylbenzo[d][1,3]dioxole-5-carboxylate (5r) were selected for further study. It was found that all of them had little toxicity to peripheral blood mononuclear cell (PBMC), and had a good inhibitory effect on the replication of HIV-1 protease inhibitor resistant strains, fusion inhibitor resistant strains and nucleosides reverse transcriptase inhibitor resistant strains, as well as on clinical isolates. Besides, compound 5b and 5c showed inhibition of HIV-1 RT RNA-dependent DNA polymerization activity and DNA-dependent DNA polymerization activity, while compound 5r only showed inhibition of HIV DNA-dependent DNA polymerization activity, which was different from classical reverse transcriptase inhibitors. Our study which offered the preliminary structure-activity relationships and modeling studies of these new compounds has provided the valuable avenues for future molecular optimization.

Nudifloids A-N, structurally diverse 3,4-seco-labdane diterpenoids from Callicarpa nudiflora with inflammatory inhibitory activity.

Fourteen undescribed seco-type diterpenoids, named nudifloids A-N, together with ten known analogs, were isolated from the leaves of Callicarpa nudiflora. Nudifloids A-N had a characteristic 3,4-seco-labdane-type diterpenoid skeleton, whereas nudifloids A-C and K-N were 3,4-seco-norditerpenoids. Nudifloid A was the first example of a 3,4-seco-12,13,14,15,16-quartnor-labdane diterpenoid, with a seven-membered lactone ring formed through esterification between C-3 and C-11. Nudifloids B and C were a pair of highly modified 3,4-seco-labdane nor-diterpenoid epimers, of which C-2 and C-18 were cyclized together to form a cyclohexene fragment. The structures of these undescribed diterpenoids were established by spectroscopic analysis and reference data. The anti-inflammatory activity of diterpenoids in rich yield was evaluated by analyzing the inhibition of lipopolysaccharide plus nigericin-induced pyroptosis in J774A.1 cells. Nudifloids D and E exhibited prominent anti-NLRP3 inflammasome activity, with IC50 values of 1.80 and 1.59 µM, respectively. Cell permeability assays revealed that nudifloid D inhibited pyroptosis, which could ameliorate inflammation by blocking the activation of the NLRP3 inflammasome.