The effective delivery of menahydroquinone-4 (MKH), an active form of menaquinone-4 (MK-4, vitamin K₂₍₂₀₎), to the skin is beneficial in the treatment of various skin pathologies. However, its delivery through the application of MK-4 to the skin is hampered due to the photoinstability and phototoxicity of MK-4. This study aimed to evaluate the potential of ester prodrugs of MKH for its delivery into the skin to avoid the abovementioned issues. The ester prodrugs, MKH 1,4-bis-N,N-dimethylglycinate hydrochloride (MKH-DMG) and MKH 1,4-bis-hemisuccinate (MKH-SUC), were prepared using our previously reported methods. Photostability was determined under artificial sunlight and multi-wavelength light irradiation, phototoxicity was determined by intracellular ROS formation and cell viability of UVA-irradiated human epidermal keratinocyte cells (HaCaT), and delivery of MKH into HaCaT cells was assessed by measuring menaquinone-4 epoxide (MKO) levels. MKH prodrugs showed higher photostability than MK-4. Although MK-4 induced cellular ROS and reduced cell viability after UVA irradiation, MKH prodrugs did not affect either ROS generation or cell viability. MKH prodrugs enhanced intracellular MKO, indicating effective delivery of MKH and subsequent carboxylation activity. In conclusion, these MKH prodrugs show potential for the delivery of MKH into the skin without photoinstability and phototoxicity.

Schizophrenia is a severe, chronic mental illness characterized by delusions, hallucinations, negative symptoms, and cognitive dysfunction. Recently, several studies have demonstrated that the pathogenesis of schizophrenia involves mitochondrial dysfunction and oxidative stress. However, the effect of antipsychotic drugs for these events has been poorly investigated. In the present study, we evaluated the neuroprotective effect of an atypical antipsychotic drug, ziprasidone (ZPD), on rotenone (ROT)-induced neurotoxicity involving oxidative stress in PC12 cells. Our data showed that ZPD treatment promoted the translocation of NF-E2-related factor-2 (Nrf2) from cytoplasm to nucleus and activated the expression of its target genes NAD(P)H quinone oxidoreductase (NQO-1), catalase (CAT), and heme oxygenase (HO-1). Additionally, ZPD prevented ROT-induced cell death and intracellular reactive oxygen species production. Interestingly, the use of serotonin 5-HT_1A receptor antagonist 1-(2-methoxyphenyl)-4 (4-(2-phtalimido) butyl) piperazine (NAN-190) completely blocked the protective effect of ZPD against ROT-induced cell death. Our results demonstrate the neuroprotective effect of ZPD against ROT-induced neurotoxicity and suggest that ZPD may be a potential candidate for the prevention of mitochondrial dysfunction and oxidative stress in schizophrenia.

The intestinal absorption of hydrophobic compounds is severely influenced by their transportation rate through the unstirred water layer in the intestinal lumen. A member of the vitamin E family, α-Tocotrienol (α-T3) has remarkable pharmacological effects, but its intestinal absorption is hampered due to its hydrophobicity. Here, we prepared three ester derivatives of 2R-α-T3, and we selected a suitable prodrug compound using rat plasma and liver microsomes. The micellization profile of the selected compound in the presence of taurocholic acid (TCA) was evaluated. After gastrostomy administration of the prodrug candidate or α-T3 solution containing TCA, AUC values were determined for α-T3 in plasma obtained from bile duct-ligated rats. Among the three types in the efficiency of the reconversion to the parent drug, α-T3 N,N-dimethylglycinate (α-T3DMG) was the best prodrug; α-T3DMG formed mixed micelles via ion pairs with anionic TCA. The solubility of α-T3DMG in n-octanol/water depended on its ratio to TCA. The AUC after α-T3DMG administration to ligated rats was 2-fold higher than that after α-T3 administration, suggesting a smooth interaction with intrinsic bile acids. In conclusion, utilization of the prodrug synthesized using N,N-dimethylglycine ester may be a beneficial approach to promote intestinal absorption of α-T3 via self-micellization with intrinsic bile acid.

Hepatocellular carcinoma (HCC) shows poor prognosis owing to its very frequent recurrence even after curative treatment. Thus, an effective and safe long-term chemopreventive agent is strongly in demand. Menahydroquinone-4 (MKH) is an active form of menaquinone-4 (MK-4, vitamin K₂) that is involved in the synthesis of vitamin K-dependent proteins in the liver. We hypothesized that efficient delivery of MKH might be critical to regulate HCC proliferation. The discovery of a suitable prodrug targeting HCC in terms of delivery and activation could reduce the clinical dose of MK-4 and maximize efficacy and safety. We previously showed that MKH dimethylglycinate (MKH-DMG) enables effective delivery of MKH into HCC cells and exhibits strong antitumor effects compared with MK-4. In this study, we prepared anionic MKH hemi-succinate (MKH-SUC) and non-ionic MKH acetate (MKH-ACT), in addition to cationic MKH-DMG, and evaluated MKH delivery profiles and antitumor effects in vitro. MKH-SUC showed the highest uptake and the most efficient release of MKH among the examined compounds and exhibited rapid and strong antitumor effects. These results indicate that MKH-SUC might have a good potential as an MKH delivery system for HCC that overcomes the limitations of MK-4 as a clinical chemopreventive agent.

The aim of this study was to develop a prodrug of ubiquinol-10 (UqH-10), the active form of ubiquinone-10 (Uq-10), for oral delivery. Bioavailability of UqH-10 is hampered by its high susceptibility to oxidation and water-insolubility. We prepared three novel N,N-dimethylglycine ester derivatives of UqH-10, including a 1-monoester (UqH-1-DMG), 4-monoester (UqH-4-DMG), and 1,4-bis-ester (UqH-DMG), and assessed their physicochemical properties in vitro and in vivo. UqH-DMG spontaneously formed an aqueous micelle solution comprising 20 nm particles at 36.5 °C. Cationic UqH-DMG formed nano-sized (5 nm) mixed-micelles with taurocholic acid. Reconversion of the derivatives to UqH-10 was accelerated in human liver microsomes. The oral bioavailability of UqH-10 after administration of UqH-derivatives or Uq-10 was determined in fasted and postprandial rats secreting normal and high levels of bile, respectively. In fasted rats, plasma UqH-10 after UqH-derivatives administration reached C_max at 2–3 h and after Uq-10 administration, it remained low. The AUC_0-24h of UqH-10 after UqH-derivatives administration was 2–3-fold higher than that after Uq-10 administration. In postprandial rats, the T_max of UqH-10 after UqH-derivatives administration was an hour earlier than after Uq-10 administration. In conclusion, cationic UqH-derivatives are convenient prodrugs that enhance UqH-10 bioavailability by forming nanosized mixed-micelles with intestinal bile acids.