Sulfate-conjugated methylprednisolone: Evaluation as a colon-specific methylprednisolone prodrug and comparison with sulfate-conjugated prednisolone and dexamethasone

Glucocorticoids-based prodrug design: Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation, antitoxin, and immunosuppression, glucocorticoids (GCs) are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus, nephritis, arthritis, ulcerative colitis, asthma, keratitis, macular edema, and leukemia. However, long-term use often causes undesirable side effects, including metabolic disorders-induced Cushing's syndrome (buffalo back, full moon face, hyperglycemia, etc.), osteoporosis, aggravated infection, psychosis, glaucoma, and cataract. These notorious side effects seriously compromise patients' quality of life, especially in patients with chronic diseases. Therefore, glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention. Among them, prodrugs have the advantages of low investment, low risk, and high success rate, making them a promising strategy. In this review, we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades, including polymer-based prodrugs, dendrimer-based prodrugs, antibody-drug conjugates, peptide-drug conjugates, carbohydrate-based prodrugs, aliphatic acid-based prodrugs and so on. Besides, we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs. This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Role of Natural Stilbenes in the Prevention of Cancer

Natural stilbenes are an important group of nonflavonoid phytochemicals of polyphenolic structure characterized by the presence of a 1,2-diphenylethylene nucleus. Stilbenes have an extraordinary potential for the prevention and treatment of different diseases, including cancer, due to their antioxidant, cell death activation, and anti-inflammatory properties which associate with low toxicity under in vivo conditions. This review aims to discuss various approaches related to their mechanisms of action, pharmacological activities in animal models and humans, and potential chemoprevention in clinical studies. The biological activity of natural stilbenes is still incompletely understood. Furthermore, after administration to animals or humans, these molecules are rapidly metabolized. Thus pharmacokinetics and/or activities of the natural structures and their metabolites may be very different. Novel drug formulations have been postulated in order to improve stability and bioavailability, to minimize side effects, and to facilitate interaction with their domains in target proteins. These pharmacological improvements should lead stilbenes to become effective candidates as anticancer drugs.

Glycyrrhizin enhances therapeutic activity of a colon-specific methylprednisolone prodrug against experimental colitis

BACKGROUND

Co-administration of a reduction inhibitor and a colon-specific prodrug of a glucocorticoid susceptible to colonic reductive metabolism is suggested as a strategy to circumvent the therapeutic loss of the glucocorticoid delivered to and acting locally at the large intestine.

AIMS

We examined whether the strategy was feasible as a pharmacotherapy for treatment of inflammatory bowel disease.

METHODS

Glycyrrhizin (GCZ), a reduction inhibitor, was tested for its inhibition of the colonic metabolism of methylprednisolone (MP). Therapeutic activity against TNBS-induced rat colitis and adrenal suppression were compared after oral administration of methylprednisolone 21-sulfate sodium (MPS), a colon-specific prodrug of MP, or MPS/GCZ to colitic rats.

RESULTS

Upon incubation of MP with the cecal contents, MP disappeared, and this was delayed by addition of GCZ. In addition, more MP produced from MPS in the cecal contents accumulated in the presence of GCZ. Consistent with these results, upon oral administration of MPS/GCZ, MPS or MP, MP was detected at a greater level in the large intestine for MPS/GCZ. MPS/GCZ ameliorated TNBS-induced colitis of rats, and this therapeutic effect was superior to that of MPS and MP. Moreover, MPS/GCZ decreased the plasma levels of corticosterone and ACTH to a greater extent than MPS, but less than MP.

CONCLUSIONS

Co-administration of GCZ, a reduction inhibitor, may be a plausible strategy to reduce the therapeutic loss of MP produced from MPS in the large intestine, thus improving the therapeutic property of the prodrug against inflammatory bowel disease.

Susceptibility of glucocorticoids to colonic metabolism and pharmacologic intervention in the metabolism: implication for therapeutic activity of colon-specific glucocorticoid 21-sulfate sodium at the target site

OBJECTIVES

The systemic side effects of glucocorticoids have prevented their long-term use for treatment of inflammatory bowel disease. Colon-specific delivery of glucocorticoids has been adopted as a strategy to circumvent the toxicological trouble. Glucocorticoids delivered to the large intestine might undergo metabolisms by colonic microflora, which should affect therapeutic availability at the target site. It was investigated whether the susceptibility of glucocorticoids to the colonic metabolisms and pharmacologic intervention in the metabolism could modulate the therapeutic availability of colon-targeted glucocorticoids.

METHODS

Various glucocorticoids and their derivatives, glucocorticoid 21-sulfate sodium compounds, were incubated in the cecal contents in the presence or absence of reduction inhibitors and the change in the levels of the drugs was monitored.

KEY FINDINGS

The accumulation profiles of the corresponding glucocorticoids liberated from glucocorticoid 21-sulfate sodium compounds vary, depending on the metabolic susceptibility of glucocorticoids. Reduction inhibitors prevented the cecal metabolisms of glucocorticoids, which was most prominent for prednisolone (PD) and methylprednisolone (MP). Moreover, reduction inhibitors increased the accumulated amount of MP and PD released from PD- and MP-21-sulfate sodium in the cecal contents.

CONCLUSIONS

Our data provide information useful for selection of a glucocorticoid and a pharmacologic strategy for the design of an efficient colon-specific glucocorticoid prodrug.

trans-Resveratrol reduces precancerous colonic lesions in dimethylhydrazine-treated rats

trans-Resveratrol, a natural occurring polyphenol, has been described as an antiproliferative and proapoptotic agent in vitro. Here, we studied the effect of trans-resveratrol administered orally at a dose of 60 mg/kg for 49 days on early preneoplastic markers induced by the intraperitoneal injection of 1,2-dimethylhydrazine (20 mg/kg). We measured trans-resveratrol and its derivates by liquid-liquid extraction followed by high-performance liquid chromatography diode array detection analysis in colon contents. Dihydroresveratrol was the most abundant compound in the colon, followed by trans-resveratrol glucuronide and small amounts of trans-resveratrol and its sulfate. The administration of trans-resveratrol decreased aberrant crypt foci by 52%, and mucin depleted foci by 45% in colon. In conclusion, the correlation between the reduction of precancerous colonic lesions and the availability of trans-resveratrol in the colon provides a new insight into the therapeutical potential of this polyphenol and its metabolites.