Background: Traditional medicine practitioners in Nigeria employ a range of plant preparations as wound healing agents. In spite of the use of local plants in wound
healing, there is only scant literature on the wound healing components of these plants to support the continued therapeutic application of these herbal remedies.
Methodology: A literature and ethnobotanical survey was conducted to determine the most widely used plants in south-western Nigeria to treat wounds. Crude extracts of the nine most widely used plants were then subjected to preliminary bioassays for fibroblast stimulation, antioxidant and antibacterial properties. Ethanolic extract of Bridelia ferruginea leaves with the most activity in the three bioassays was then subjected to bioguided fractionation. The isolated fractions were subjected to further bioassays of fibroblast stimulation, antioxidant, antibacterial properties and cytokine release. The phytochemicals in the most bioactive fractions were then identified by HPLC, MS and NMR spectroscopy. Results: The literature and ethnobotanical survey identified thirty-six plants used for wound healing. The nine species (most frequently cited by the practitioners) selected for study were: B. ferruginea, Par/da biglobosa, Ageratum conyzoides, Ocimum gratissimum, Tridax procumbens, Sida acuta, Vernonia amygdalina, Acalypha wilkesiana and Lawsonia inermis. Significant
fibroblast growth stimulatory activity was detected for B. ferruginea (1 to 30 μg/ml) and P. biglobosa (15 to 30 μg/ml). Extracts from the remaining seven plants either
had no effect on fibroblast proliferation or were cytotoxic. All the plants showed varying degrees of antioxidant properties against the DPPH radical with IC 50 varying from 3.8 to 62.5 μg/ml for P. biglobosa and L. inermis and T. procumbens. When the extracts were tested against hydrogen peroxide-induced damage, A. wilkesiana (15.6 μg/ml)was the most protective and T. procumbens (250 μg/ml) the least active.
Activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa was also investigated. Generally, ethanolic extracts were more active than aqueous with MIC varying from 0.3 to 7.6 mg/ml for the selected plants. Bioassay-guided fractionation of B. ferruginea led to the isolation of compounds which were tested in bioassays. When these compounds were identified
by HPLC, MS and NMR spectroscopy, this revealed five known compounds, myricetin, quercetin, myricetin-3-O-rhamnoside, quercetin-3-O-rutinoside and quercetin-3-(9-rhamnoside, of which quercetin-3-O-rhamnoside has not previously been reported in B. ferruginea. These compounds showed some proliferation activity on the normal human skin fibroblasts (FS5). They also had DPPH radical scavenging activity and showed protective activity of normal human skin fibroblasts against hydrogen peroxide-induced damage. Quercetin and myricetin exhibited good activity against the bacteria tested. These compounds at 10 jig/ml inhibited the production of IL-6 and IL-8 in human dermal fibroblasts. These results confirm that some plants used by Nigerian traditional medicine healers in particular B. ferruginea contain key constituents which could justify their use for wound healing.
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