A curcumin-diglutaric acid conjugated prodrug with improved water solubility and antinociceptive properties compared to curcumin.

In this work, a curcumin-diglutaric acid (CurDG) prodrug was synthesized by conjugation of curcumin with glutaric acid via an ester linkage. The water solubility, partition coefficient, release characteristics, and antinociceptive activity of CurDG were compared to those of curcumin. The aqueous solubility of CurDG (7.48 µg/mL) is significantly greater than that of curcumin (0.068 µg/mL). A study in human plasma showed that the CurDG completely releases curcumin within 2 h, suggesting the ability of CurDG to serve as a prodrug of curcumin. A hot plate test in mice showed the highest antinociceptive effect dose of curcumin at 200 mg/kg p.o., whereas CurDG showed the same effect at an effective dose of 100 mg/kg p.o., indicating that CurDG significantly enhanced the antinociceptive effect compared to curcumin. The enhanced antinociceptive effect of CurDG may be due to improved water solubility and increased oral bioavailability compared to curcumin.

A Novel Curcumin-Mycophenolic Acid Conjugate Inhibited Hyperproliferation of Tumor Necrosis Factor-Alpha-Induced Human Keratinocyte Cells.

Curcumin (CUR) has been used as adjuvant therapy for therapeutic application in the treatment of psoriasis through several mechanisms of action. Due to the poor oral bioavailability of CUR, several approaches have been developed to overcome the limitations of CUR, including the prodrug strategy. In this study, CUR was esterified with mycophenolic acid (MPA) as a novel conjugate prodrug. The MPA-CUR conjugate was structurally elucidated using FT-IR, 1H-NMR, 13C-NMR, and MS techniques. Bioavailable fractions (BFs) across Caco-2 cells of CUR, MPA, and MPA-CUR were collected for further biological activity evaluation representing an in vitro cellular transport model for oral administration. The antipsoriatic effect of the BFs was determined using antiproliferation and anti-inflammation assays against hyperproliferation of tumor necrosis factor-alpha (TNF-α)-induced human keratinocytes (HaCaT). The BF of MPA-CUR provided better antiproliferation than that of CUR (p < 0.001). The enhanced hyperproliferation suppression of the BF of MPA-CUR resulted from the reduction of several inflammatory cytokines, including IL-6, IL-8, and IL-1ß. The molecular mechanisms of anti-inflammatory activity were mediated by an attenuated signaling cascade of MAPKs protein, i.e., p38, ERK, and JNK. Our results present evidence for the MPA-CUR conjugate as a promising therapeutic agent for treating psoriasis by antiproliferative and anti-inflammatory actions.

In Vitro Hepatic Metabolism of Curcumin Diethyl Disuccinate by Liver S9 from Different Animal Species.

Liver S9 (LS9) is a nearly complete collection of all hepatic drug-metabolizing enzymes. It is a low-cost model for predicting drug metabolic activity. This study aimed to identify the suitability of using LS9 of different animal sources in drug metabolism profiling with respect to the possible translation of the in vitro outcomes to clinical studies. The in vitro hepatic metabolism of curcumin diethyl disuccinate (CDD) in LS9 of rats, dogs, monkeys, and humans was evaluated. The identity of CDD metabolites and the metabolism kinetic parameters, including degradation rate constant, in vitro/in vivo intrinsic clearance, and half-life, were determined. CDD was rapidly metabolized into monoethylsuccinyl curcumin and curcumin in LS9 of all tested species mainly by carboxylesterases (CESs), including CES1 and CES2, and butyrylcholinesterase. The in vitro intrinsic clearance of CDD was in the order of human > dog > monkey > rat, whereas that of monoethylsuccinyl curcumin in the order of dog > monkey > human > rat; this parameter was not correlated with their respective in vivo clearance, which followed the order of dog > monkey > rat > human. Therefore, in vitro drug metabolism data inferred from LS9 of nonhuman origin, especially from monkeys and dogs, cannot be used as preclinical data for human trials, as humans have a smaller liver-to-body weight ratio than monkeys, dogs, and rats. The in vivo drug metabolism is dictated by the anatomical factors of the test subject.

Enhanced Antipsoriatic Activity of Mycophenolic Acid Against the TNF-α-Induced HaCaT Cell Proliferation by Conjugated Poloxamer Micelles.

Mycophenolic acid (MPA), an immunosuppressant drug, possesses antimicrobial, anticancer, and antipsoriatic activities. However, the use of MPA in therapeutic applications is limited to its poor oral bioavailability, low aqueous solubility, and undesired gastrointestinal side effects. Polymeric micelles are a drug delivery system that has been used to enhance the water solubility of pharmaceuticals. In this work, poloxamer 407 (P407) and MPA were conjugated via an ester linkage resulting in a P407-MPA conjugate. The P407-MPA conjugate was investigated for micellization, particle size, size distribution, MPA release in phosphate buffer (pH 7.4) and human plasma, and antipsoriatic activity. 1H-nuclear magnetic resonance suggested that polymeric micelles formed from the P407-MPA conjugate exposed its polyethylene oxide chain to the aqueous environment while restricting the conjugated MPA within the inner core. The P407-MPA conjugate has an improved micellization property with the over 12-fold lower critical micelle concentration compared to P407. The conjugate exhibited an enzyme-dependent sustained-release property in human plasma. Finally, the conjugate exhibited an improved antiproliferation activity in tumor necrosis factor-α-induced HaCaT cells, which is an in vitro psoriasis model. Therefore, the prepared P407-MPA conjugate, with an improved aqueous solubility and biological activity of MPA, has the potential to be further developed for psoriasis treatment.

Curcumin diethyl disuccinate, a prodrug of curcumin, enhances anti-proliferative effect of curcumin against HepG2 cells via apoptosis induction.

Curcumin (Cur) has been reported to have anti-hepatocellular carcinoma activity but its poor oral bioavailability limits its further development as a chemotherapeutic agent. We synthesized previously a succinate ester prodrug of Cur, curcumin diethyl disuccinate (CurDD) with better chemical stability in a buffer solution pH 7.4. Here, we further investigated and compared the cellular transport and anti-proliferative activity against HepG2 cells of CurDD and Cur. Transport of CurDD across the Caco-2 monolayers provided a significantly higher amount of the bioavailable fraction (BF) of Cur with better cytotoxicity against HepG2 cells compared to that of Cur (p < 0.05). Flow cytometric analysis showed that the BF of CurDD shifted the cell fate to early and late apoptosis to a higher extent than that of Cur. The Western blot analysis revealed that CurDD increased Bax protein expression, downregulated Bcl-2 protein, activated caspase-3 and -9 and increased LC3-II protein level in HepG2 cells. Flow cytometric and immunoblotting results suggest that CurDD can induce HepG2 cell death via an apoptotic pathway. We suggest that CurDD can overcome the limitations of Cur in terms of cellular transport with a potential for further extensive in vitro and in vivo studies of anti-hepatocellular carcinoma effects.