Evaluation of wound healing and antibacterial properties of methanolic root extract of <i>Stephania dinklagei</i> (Engl.) Diels

Abstract

Background: Stephania dinklagei Diels (Engl.) is used in folkloric medicine in Southeastern Nigeria for the treatment of wounds and some bacterial-associated infections. This study evaluated the wound healing and antibacterial potential of Stephania dinklagei to validate or invalidate its folkloric use. Materials and Methods:The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of methanolic extract of S. dinklagei root (MESDR) against Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella spp. was determined by macro broth dilution. The extract at 20% and 10% were dosed orally to rats at 300mg/kg body weight (bw) in incision and dead space wound healing model to determine wound tensile strength and granulation tissue weight, respectively. The same extract concentrations were applied topically in excision wound model to determine the rate of wound contraction and epithelialization. Activities of superoxide dismutase (SOD) and catalase (CAT), and the levels of total protein (TP), malondialdehyde (MAL), hydroxyproline (HYP) and hexosamine (HEX) in excision wound biopsies were determined at days 7 and 14 post-wounding (pw). In the excision wound model, the extract concentrations were compared with gentamicin sulphate. Results: The MIC of S. dinklagei extract against P. aeruginosa, S. aureus, B. subtilis, E. coli and Klebsiella spp. were 8mg/ml, 3 mg/ml, 5mg/ml, 6mg/ml and 7mg/ml, respectively, while the corresponding MBC were 10 mg/ml, 5 mg/ml, 7mg/ml, 8mg/ml, and 9 mg/ml, respectively. The 20% extract gave significantly (P<0.05) higher tensile strength and granulation tissue weight than the 10% and gentamicin sulphate. Wound contraction and epithelialization occurred significantly (P<0.05) better and faster in wounds of animals treated with the 20% extract and gentamicin sulphate compared to those treated with 10% extract. TP of animals treated with 20% extract and those treated with the reference drug did not vary significantly (P>0.05) at day 14 pw. SOD and CAT activities, and MDA and HEX level of all the groups did not vary significantly (P>0.05) at day 14 pw. HYP level of the extract-treated groups significantly (P<0.05) decreased against the control. No significant difference existed in HYP level between the extract-treated groups. Conclusions: S. dinklagei possess antibacterial and wound healing properties which are comparable to those of gentamicin sulphate.

Antimicrobial activity of Nigerian medicinal plants

“…It is important that selected plant is identified by an expert/plant taxonomist and deposited in a reliable herbarium for future identification and reproducibility of study [ 27 ]. While most of the studies on antimicrobial activity of Nigerian medicinal plants reported expert identification of selected plant(s), only few papers [ 49 - 60 ] reported deposition of plant in herbarium with the accompanying voucher number. Selection of the plant part to be evaluated may be based on ethnomedical use, randomly or follow-up of antimicrobial activity [ 61 ].…”

“…The storage conditions of plant material (whole/extract) have been shown to affect the result of antimicrobial studies by impacting microbial efficacy [ 16 , 64 , 73 ]. Some papers on Nigerian plants reported storage of extract in refrigerator at 4°C [ 18 , 59 , 60 , 74 ]. This storage condition is good because the activity/growth of possible extract-contaminating organisms would be inhibited and this in a way enhances the reliability of the result [ 16 , 75 ].…”

“…South African studies reported little antimicrobial variability of plant extracts within 2 months interval [ 16 , 193 ]. Some papers on Nigerian plants focused on the antimicrobial screening together with other pharmacological investigations including toxicity [ 18 , 42 , 54 , 60 , 85 , 95 , 120 , 191 , 194 , 195 ]. Although medicinal plants are considered generally safe, they are known to contain potentially toxic, mutagenic, and/or carcinogenic substances [ 16 ]; therefore, it has been recommended that pharmacological studies should always be accompanied by toxicology screening [ 16 , 196 , 197 ].…”

“…which includes antispasmodic properties [ 66 , 85 ]. Some authors investigated wound healing properties of plants together with antimicrobial property [ 18 , 59 , 60 , 141 , 155 , 198 ] while some studies reported antioxidant and antimicrobial properties together [ 48 , 59 , 60 , 99 , 199 - 203 ]. Ajali and Okoye [ 194 ] reported the anti-inflammatory and antimicrobial properties of Olax viridis and MIC assay showed considerable broad-spectrum activity (MIC 2000-4000 μg/ml) against selected pathogens.…”

“…Plants used for oral complaints should be tested against Streptococcus mutans , Streptococcus sobrinus , Porphyromonas gingivalis , and Aggregatibacter actinomycetemcomitans [ 16 , 232 ]. Although, studies relating to ethnobotanical use of Nigerian plants have been largely neglected (in terms of using pathogens targeted in ethnomedical setting), few studies focused on ethnobotanical use of studied plant on wound healing [ 18 , 60 , 142 ] and oral infection [ 42 , 133 , 169 , 170 , 233 ] taking into account the possible impact of microbial infection.…”