TitlePharmacological characterization of brassinosteroids for anabolic and cosmetic applications
NameEsposito, Debora Araujo (author), Raskin, Ilya (chair), Gianfagna, Thomas (internal member), Huang, Bingru (internal member), Shapses, Sue (outside member), Cohick, Wendie (outside member), Rutgers University, Graduate School - New Brunswick,
DescriptionBrassinosteroids (BR) are plant-specific polyhydroxylated derivatives of 5α- cholestane, structurally similar to cholesterol-derived animal steroid hormones and insect ecdysteroids, with unknown function in mammals. This research project was designed to conduct a pharmacological characterization of brassinosteroids in cell culture and small animal models in order to: (1) Elucidate the putative anabolic effect of BR in mammals (2) Establish a structure-activity relationship between BR and their effects on protein synthesis and (3) Measure the effects of BR on glucose metabolism and wound healing. 28-Homobrassinolide (HB) stimulated protein synthesis and inhibited protein degradation in L6 rat skeletal muscle cells (EC50 = 4 μM) mediated in part by PI3K/Akt. Oral administration of HB to healthy rats increased food intake, body weight gain, lean body mass, and gastrocnemius muscle mass. Both oral (up to 60 mg/kg) and subcutaneous (up to 4 mg/kg) administration of HB showed low androgenic activity. Moreover, HB showed no direct binding to the androgen receptor in vitro. These findings suggest that oral application of HB triggers selective anabolic response with minimal or no androgenic side effects. Next, we synthesized a set of HB analogues and studied their anabolic efficacy in the L6 rat skeletal muscle cells. All anabolic brassinosteroids tested in this study selectively activated the PI3K/Akt signaling pathway as seen by increased Akt phosphorylation in vitro. In C57BL/6J high fat diet-induced obese mice, acute oral administration of 50- 300 mg/kg HB to obese mice resulted in a dose-dependent decrease in fasting blood glucose. Daily chronic administration of HB (50 mg/kg for 8 weeks) ameliorated hyperglycemia and improved oral glucose tolerance associated with obesity without significantly affecting body weight or body composition. Akt is also a key signaling integrator suppressed in slow healing wounds. When C57BL/6J mice were given a dermal wound, topical application of brassinosteroids significantly reduced wound size after 10 days of treatment. Our data suggest that topical brassinosteroids accelerate the wound-healing process in part by shortening the early inflammatory phase and enhancing migration and wound repair by stimulating the PI3K/Akt pathway. Targeting this specific signaling pathway with brassinosteroids may represent a promising approach to the therapy of physical performance, glucose metabolism, and delayed wound healing.
NoteIncludes bibliographical references
Noteby Debora Araujo Esposito
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.