Efficacy of aspilia pluriseta schweinf in cutaneous wound healing in a mouse model
The skin is more predisposed to wounds because of its direct contact with the environment. The aim of treating wounds is to both hasten their healing and preclude undesirable consequences that may arise in the process. Plant products for wound healing are cheap and locally available; they are also purportedly safer than conventional therapies and so they may provide a viable alternative to expensive conventional wound remedies especially for poor communities in developing countries. Aspilia pluriseta has been used in a number of traditional medicine systems to treat lacerations, bruises and burns and it is reputed to aid the healing of such cutaneous lesions. The aim of this study was to evaluate the efficacy of Aspilia pluriseta in healing cutaneous wounds and to also test its safety when applied on the skin. An Aspilia pluriseta ointment was formulated for wound healing studies. Full thickness excision wounds were created on male adult Swiss albino mice and treated with the ointments in order to evaluate the influence of the plant material on wound healing. The ointment was applied to two groups of experimental mice. The first group (n=8) and second group (n=8) were treated with 10% and 20% A. pluriseta based ointment, respectively. A third and fourth group (n=8 each) were treated with the vehicle ointment alone (Simple Ointment, British Pharmacopeia) and Silver sulfadiazine (Silverex Cream®) as the negative and positive controls, respectively. All the mice in the experimental and control groups were treated daily for 21 days. Wound area measurements were taken every three days and biopsies for histology were taken on the 7th, 14th and 21st days post-treatment. The A. pluriseta powder was extracted by cold maceration using methanol to be tested for antimicrobial activity. The methanol-free extract was dissolved in dimethyl sulfoxide (DMSO) and distilled water and tested for activity using five bacteria and one fungus by broth macrodilution method. The extract was screened qualitatively for major groups of phytochemical compounds. The 20% A. pluriseta based ointment was tested for skin sensitization potential in guinea pigs. It was applied once a week onto the shaved left flank of three guinea pigs for three weeks (induction phase). It was then applied onto the right flank of the guinea pigs (challenge phase) 7 days after the last treatment of the induction phase, and the animals observed 24 hours later for allergic skin reaction. Descriptive statistics were done for quantitative data and one-way analysis of variance was used to compare the means of responses between treatment groups. P-values less than 0.05 were considered statistically significant. The A. pluriseta ointment preparation enhanced wound healing to an extent that was comparable to that of the standard drug (Silverex Cream®) in terms of epithelialization time (15.5±1.118 days compared to 16.5±0.616 days for the 20% A. pluriseta ointment and standard drug, respectively) and wound contraction (28.17±3.725 and 57.75±6.178 percent wound area reduction on the 6th and 9th days post-wounding, respectively for the 20% A. pluriseta powder ointment compared to 14.98±7.194 and 36.37±4.871 for the standard drug on the same days). Histopathology revealed that the plant material accelerated remodeling in the wounded tissue and increased the amount of collagen in the scar compared to the negative control. The extract had marginal antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Streptococcus agalactiae with a Minimum Inhibitory Concentration (MIC) of between 50 mg/ml and 200 mg/ml and Minimum Bactericidal Concentration (MBC) ranging from 100 to 800 mg/ml. The extract contained triterpeniods, tannins, glycosides, saponins and phenols. The 20% A. pluriseta ointment induced moderate sensitization in guinea pigs.