Wound healing activity of the hydro-ethanol extract of the rhizomes of cochlospermum tinctorium (cochlospermaceae)

Abstract

Wound is an injury to a living tissue, caused by a cut or an impact, typically one which the integrity of the skin is broken. The breach in skin structure impairs proper skin function and exposes underlining tissues to further damage. Skin wounds are associated with significant morbidity and mortality especially if infected. An excellent wound healing agent is able to promote the natural phases (hemostasis, inflammation, re-epithelization and formation of scar tissue) of wound healing and prevent acute wounds from becoming chronic. Medicinal plants present an enormous resource to develop such wound healing agents. The aim of the present study is to evaluate the wound healing activity of the hydro-ethanol extract of the rhizomes of Cochlospermum tinctorium used traditionally for the treatment of infections and burns. The dried powdered rhizomes of C. tinctorium was soxhlet extracted with 70% ethanol and incorporated in an aqueous cream at 1, 2 and 4% concentrations and tested for wound healing activity using the excision wound model. The wound tissues were harvested after 14 days to study the progress of healing at the tissue level. The antioxidant activities of the hydro-ethanol extract and various fractions were evaluated using the DPPH radical scavenging assay and the total antioxidant capacity determined by phosphate molybdate method with gallic acid as the standard drug (concentrations of 500-7.81 µg/mL). Using the agar well diffusion method the extract and fractions (concentration of 100 mg/mL, 50 mg/mL and 25 mg/mL) and the creams (1%, 2%, 4%, blank cream and silver sulphadiazine) were screened for their potential antimicrobial activity. The MICs of the hydro-ethanol extract and the fractions (pet ether, chloroform and methanol) were determined by the High-Throughput Spot growth inhibition (HT-SPOTi) method. Also pharmacognostic standardization of the rhizomes was carried out by looking at the macroscopic, microscopic, organoleptic features of the rhizome and physicochemical analysis of the powdered rhizome. By day fourteen (14), all the test creams and the reference drug showed a gradual reduction in the surface wound area. The lowest concentration of the creams (1%) and the reference drug showed statistically significant (** P<0.01) progressive reduction of wound area as compared to the blank cream. The histopathology of sections revealed that the epithelium was yet to form in most cases except for silver sulphadiazine. However, there was less amount of lymphocytes present in the group treated with the1 % of cream compared to moderate to silver sulphadiazine, 2 %, 4 % and untreatediv group. There was heavy deposition of collagen and formation of new vessels in group treated with 1 % of formulated cream compared to mild to moderate deposition of collagen in the other groups. Betulinic acid was isolated from the rhizomes as one of its constituents. The powdered rhizomes of C. tinctorium contain abundant starch grains, fibres and prismatic calcium oxalate crystals and can serve as reference for the identification of the powder. This study validates the traditional use of Cochlospermum tinctorium rhizome in the treatment of wounds (burns) and infections. The ethanol extract of the rhizomes of Cochlospermum tinctorium has wound healing activity by enhancing wound contraction and stimulation of fibroblast production.