EFFECTS OF AQUEOUS EXTRACT OF THE ROOT AND LEAF OF RED MEDICINE (Sphenocentrum jollyanum Pierre) ON WOUNDS OF DIABETIC RATS

Abstract

Red medicine (Sphenocentrum jollyanum) is a flowering plant commonly used in folklore for the treatment of chronic wounds. This study investigated the antioxidative, antihyperglycemic, antimicrobial and wound healing effects of aqueous extracts of Sphenocentrum jollyanum root and leaf in type 2 diabetic rats. The radicals (1,1-diphenyl2picrylhdrazyl {DPPH}, 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphoric acid {ABTS}, hydroxyl {OH}) scavenging ability, Fe2+ chelating ability and enzymes (α-amylase, α-glucosidase) inhibitory properties of the aqueous extract were assessed in vitro. The antimicrobial activity and the minimum inhibitory concentration of the aqueous extracts against pathogenic strains of bacteria was also considered. The effective safe doses of the extracts for oral and topical application were established. Thereafter, the effect of the oral and topical administration of root and leaf of Sphenocentrum jollyanum was evaluated on wounds created in diabetic rats induced by high fat diet with low dose of streptozotocin (35 mg/kg b.w). The co-administration of oral acarbose (25 mg/kg b.w) and topical application of Sphenocentrum jollyanum extracts in diabetic rats was further assessed in this study. The leaf extract showed a significantly (p < 0.05) higher phenol (4.57 mg/g) and flavonoid (2.20 mg/g) content than the root extract with a phenol content of 2.79 mg/g and a flavonoid content of 1.75 mg/g. The leaf had higher antioxidant activities and α-glucosidase inhibitory properties than the root extract in vitro. The aqueous extract of the root and leaf of Sphenocentrum jollyanum was active against S. aureus, P. aeruginosa and Klebsiella spp as revealed by the zone of inhibition (mm) and Minimum Inhibitory Concentration (MIC; mg/mL) with the root having higher activities than the leaf. The root extract significantly enhanced wound closure, wound healing and reduce blood glucose level than the leaf extract in diabetic rats. The extracts was able to effectively slow down the actions of carbohydrate metabolizing enzymes, prevent abnormal lipid profile, reduce the effects of pro-inflammatory cytokines, enhance growth factor secretion, reduce the microbial burden (infection) and activity of myeloperoxidase (MPO). In addition, the extracts was able to prevent oxidative stress environment by reducing lipid peroxidation and enhancing the antioxidant status of the wound. Similarly, the aqueous extracts was able to modulate genes relevant to wound healing. Vascular endothelial growth factor, and superoxide dismutase (SOD-1) were significantly (p < 0.05) expressed on the wounds of diabetic rats as revealed by their mRNA levels while MPO was significantly (p < 0.05) down-regulated. The characterization of the study plant revealed the presence of several phenolic compounds with p-Coumaric acid (7.4 mg/100g) and kaempferol (18.2 mg/100g) being the highest quantified in the root and leaf respectively. The use of Sphenocentrum jollyanum effectively enhanced wound healing and may represent a source of phytochemicals and therapeutic agent for diabetic wound management.