Evaluation of Dermal Toxicity and Wound Healing Activity of Cnestis ferruginea Vahl ex DC

Cnestisferruginea is a tropical plant, which is traditionally used in the treatment and management of various conditions including skin infections and wounds. The aim of this study was to investigate the dermal toxicity and wound healing potential of C. ferruginea. Ten millimeter full-thickness mucosal wounds were created on the dorsal midportion of the Sprague Dawley rats. Wounds were treated with 10, 5, and 2.5% w/w aqueous creams, prepared from the methanol extract of the root bark of C. ferruginea (CFM). The wound tissues were harvested on day 21 for histology studies. Compared with the untreated group, 10, 5, and 2.5% w/w CFM-treated wounds significantly reduced the wound size over the study period (). Tissue histology revealed a healed wound with well-regenerated collagen and skin appendages with no pus cells. A skin irritation test was conducted on CFM, as well as the dermal toxicity of CFM was determined in the repeated dose and acute dermal toxicity bioassays. These tests revealed that CFM showed no toxic effect on the skin and showed that CFM was not a skin irritant. C. ferruginea exhibited wound healing activity, which gives credence to its folkloric use.

1. Introduction
Every year around the world, many people get wounded as they are often inevitable occurrences[1]. Apart from the morbidity, disability, and reduced quality of life it imposes on patients, it also creates an economic challenge to the individual and the country at large [2]. Wounds are created when there are interruptions in the integrity of the skin and muscles, as well as bones [3]. It may be attributed to causes such as burns, gunshots, falls, surgical procedures, deleterious skin infection, or by other basal conditions [4]. Wounds appear to be the third most frequent nosocomial infection and unfortunately for developing and resource-constrained countries such as Ghana and others, traumatic and surgical site infections cause high morbidity and death rates [5].

When wounds occur, the body naturally regenerates the skin tissues through the wound healing process [6]. The process of wound healing includes different overlapping events and is categorized into four phases namely homeostasis, inflammation, proliferation, and remodeling phases [7]. Medicinal plants are used in managing acute and chronic wounds in many traditional medicine practice areas in the world, and this practice is a common one [8]. Undoubtedly, these plants have become a great source of wound healing agents to tap into [9].

Cnestis ferruginea of the family Connaraceae is a common plant found in the tropics [10]. Traditionally, it is used to treat migraine (root), headache (root), toothache (root), sinusitis (root), constipation (leaf or root), and conjunctivitis (fruit) [10]. It is used in the management of skin diseases and also in the management of wounds though this has not been scientifically studied [11]. Scientifically, C. ferruginea has been proven to exhibit several biological activities. The hydroethanolic leaf extract of C. ferruginea has been studied to have wound healing activity [12]. The methanol root extract has been reported to exhibit analgesic and anti-inflammatory properties [13, 14]. The methanol and ethyl acetate leaf extracts of C. ferruginea have been reported to possess hypoglycaemic properties [15]. The aqueous, ethanol, and petroleum ether fractions of the leaf, stem, bark, and root extracts of C. ferruginea exhibit antioxidant activity [16]. The aqueous root extract of C. ferruginea has been reported to possess antistress potentials [17]. Also, it is worth mentioning that different chemicals are found in plants, which sometimes may be hazardous as causing corrosion and irritations to the skin [18]. For this reason, toxicity studies are very important in establishing the safety of plant use. This study therefore investigates the dermal toxicity and wound healing properties of root bark of C. ferruginea.