Acacetin, an important ingredient of acacia honey and a component of several medicinal plants, exhibits therapeutic effects such as antioxidative, anticancer, anti-inflammatory, and anti-plasmodial activities. However, to date, studies reporting a systematic investigation of the in vivo fate of orally administered acacetin are limited. Moreover, the in vitro physicochemical and biopharmaceutical properties of acacetin in the gastrointestinal (GI) tract and their pharmacokinetic impacts remain unclear. Therefore, in this study, we aimed to systematically investigate the oral absorption and disposition of acacetin using relevant rat models. Acacetin exhibited poor solubility (≤119 ng/mL) and relatively low stability (27.5–62.0% remaining after 24 h) in pH 7 phosphate buffer and simulated GI fluids. A major portion (97.1%) of the initially injected acacetin dose remained unabsorbed in the jejunal segments, and the oral bioavailability of acacetin was very low at 2.34%. The systemic metabolism of acacetin occurred ubiquitously in various tissues (particularly in the liver, where it occurred most extensively), resulting in very high total plasma clearance of 199 ± 36 mL/min/kg. Collectively, the poor oral bioavailability of acacetin could be attributed mainly to its poor solubility and low GI luminal stability.

Neuroinflammation is associated with neurodegenerative diseases, including Alzheimer’s disease (AD). Thus, modulating the neuroinflammatory response represents a potential therapeutic strategy for treating neurodegenerative diseases. Several recent studies have shown that dopamine (DA) and its receptors are expressed in immune cells and are involved in the neuroinflammatory response. Thus, we recently developed and synthesized a non-self-polymerizing analog of DA (CA140) and examined the effect of CA140 on neuroinflammation. To determine the effects of CA140 on the neuroinflammatory response, BV2 microglial cells were pretreated with lipopolysaccharide (LPS, 1 μg/mL), followed by treatment with CA140 (10 μM) and analysis by reverse transcription-polymerase chain reaction (RT-PCR). To examine whether CA140 alters the neuroinflammatory response in vivo, wild-type mice were injected with both LPS (10 mg/kg, intraperitoneally (i.p.)) and CA140 (30 mg/kg, i.p.), and immunohistochemistry was performed. In addition, familial AD (5xFAD) mice were injected with CA140 or vehicle daily for 2 weeks and examined for microglial and astrocyte activation. Pre- or post-treatment with CA140 differentially regulated proinflammatory responses in LPS-stimulated microglia and astrocytes. Interestingly, CA140 regulated D1R levels to alter LPS-induced proinflammatory responses. CA140 significantly downregulated LPS-induced phosphorylation of ERK and STAT3 in BV2 microglia cells. In addition, CA140-injected wild-type mice exhibited significantly decreased LPS-induced microglial and astrocyte activation. Moreover, CA140-injected 5xFAD mice exhibited significantly reduced microglial and astrocyte activation. CA140 may be beneficial for preventing and treating neuroinflammatory-related diseases, including AD.

GSK5182 (4) is currently one of the lead compounds for the development of estrogen-related receptor gamma (ERRγ) inverse agonists. Here, we report the design, synthesis, pharmacological and in vitro absorption, distribution, metabolism, excretion, toxicity (ADMET) properties of a series of compounds related to 4. Starting from 4, a series of analogs were structurally modified and their ERRγ inverse agonist activity was measured. A key pharmacophore feature of this novel class of ligands is the introduction of a heterocyclic group for A-ring substitution in the core scaffold. Among the tested compounds, several of them are potent ERRγ inverse agonists as determined by binding and functional assays. The most promising compound, 15g, had excellent binding selectivity over related subtypes (IC₅₀ = 0.44, >10, >10, and 10 μM at the ERRγ, ERRα, ERRβ, and ERα subtypes, respectively). Compound 15g also resulted in 95% transcriptional repression at a concentration of 10 μM, while still maintaining an acceptable in vitro ADMET profile. This novel class of ERRγ inverse agonists shows promise in the development of drugs targeting ERRγ-related diseases.

Honokiol (2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol) and magnolol (4-Allyl-2-(5-allyl-2-hydroxy-phenyl)phenol) are the major active polyphenol constituents of Magnolia officinalis (Magnoliaceae) bark, which has been widely used in traditional Chinese medicine (Houpu Tang) for the treatment of various diseases, including anxiety, stress, gastrointestinal disorders, infection, and asthma. The aim of this study was to investigate the direct effects of honokiol and magnolol on hepatic CYP1A and 2C-mediated metabolism in vitro using rat liver microsomes and in vivo using the Sprague-Dawley rat model. Honokiol and magnolol inhibited in vitro CYP1A activity (probe substrate: phenacetin) more potently than CYP2C activity (probe substrate: diclofenac): The mean IC₅₀ values of honokiol for the metabolism of phenacetin and diclofenac were 8.59 μM and 44.7 μM, while those of magnolol were 19.0 μM and 47.3 μM, respectively. Notably, the systemic exposure (AUC and C_max) of phenacetin, but not of diclofenac, was markedly enhanced by the concurrent administration of intravenous honokiol or magnolol. The differential effects of the two phytochemicals on phenacetin and diclofenac in vivo pharmacokinetics could at least be partly attributed to their lower IC₅₀ values for the inhibition of phenacetin metabolism than for diclofenac metabolism. In addition, the systemic exposure, CL, and V_ss of honokiol and magnolol tended to be similar between the rat groups receiving phenacetin and diclofenac. These findings improve our understanding of CYP-mediated drug interactions with M. officinalis and its active constituents.

PF-543, the most potent sphingosine kinase (SK) inhibitor, does not demonstrate effective anticancer activity in some cancer cells, unlike other known SK1 inhibitors. PF-543 has a non-lipid structure with a unique toluene backbone; however, the importance of this structure remains unclear. Therefore, the purpose of this study was to investigate changes in SK inhibitory and anticancer activities and to explore the role of the tolyl group structure of PF-543 through various modifications. We transformed the methyl group of PF-543 into hydrogen, fluorine, and hydroxy. PF-543 derivatives in which the methyl group was substituted by hydrogen and fluorine (compound 5) demonstrated SK1 inhibitory and anticancer activities similar to PF-543. Moreover, we performed molecular modeling studies of PF-543 and compound 5. To assess the metabolic stability of PF-543 and compound 5, we determined their degree of degradation using the liver microsomes of four different animal species (human, dog, rat, and mouse). However, both PF-543 and compound 5 showed poor microsomal stability. Therefore, for the medical applications of PF-543, the structural modifications of its other parts may be necessary. Our results provide important information for the design of additional PF-543 analogs.

Sphingosine kinase (SK) enzyme, a central player of sphingolipid rheostat, catalyzes the phosphorylation of sphingosine to the bioactive lipid mediator sphingosine 1 phosphate (S1P), which regulates cancer cell proliferation, migration, differentiation, and angiogenesis through its extracellular five G protein-coupled S1P receptors (S1PR_1–5). Recently, several research studies on SK inhibitors have taken place in order use them for the development of novel anticancer-targeted therapy. In this study, we designed and synthesized analog derivatives of known SK1 inhibitors, namely RB005 and PF-543, by introducing heteroatoms at their tail structure, as well as investigated their anticancer activities and pharmacokinetic parameters in vitro. Compounds 1–20 of RB005 and PF-543 derivatives containing an aliphatic chain or a tail structure of benzenesulfonyl were synthesized. All compounds of set 1 (1–10) effectively reduced cell viability in both HT29 and HCT116 cells, whereas set 2 derivatives (11–20) showed poor anticancer effect. Compound 10, having the highest cytotoxic effect (48 h, HT29 IC₅₀ = 6.223 µM, HCT116 IC₅₀ = 8.694 µM), induced HT29 and HCT116 cell death in a concentration-dependent manner through the mitochondrial apoptotic pathway, which was demonstrated by increased annexin V-FITC level, and increased apoptotic marker cleaved caspase-3 and cleaved PARP. Compound 10 inhibited SK1 by 20%, and, thus, the S1P level decreased by 42%. Unlike the apoptosis efficacy, the SK1 inhibitory effect and selectivity of the PF-543 derivative were superior to that of the RB005 analog. As a result, compounds with an aliphatic chain tail exhibited stronger apoptotic effects. However, this ability was not proportional to the degree of SK inhibition. Compound 10 increased the protein phosphatase 2A (PP2A) activity (1.73 fold) similar to FTY720 (1.65 fold) and RB005 (1.59 fold), whereas compounds 11 and 13 had no effect on PP2A activation. Since the PP2A activity increased in compounds with an aliphatic chain tail, it can be suggested that PP2A activation has an important effect on anticancer and SK inhibitory activities.