Antibacterial and Wound Healing Activity of Dipterocarpus alatus Crude Extract Against Methicillin-resistant Staphylococcus aureus-induced Superficial Skin Infection in Mice

Abstract

Background: The bark oil of Dipterocarpus alatus Roxb. ex G. Don (resin tree) has been used for the treatment of ulcerated wounds in Ayurvedic medicine. However, information is still scarce about D. alatus extract and its constituents. Objectives: This study aimed to examine the antibacterial and wound healing effects of D. alatus crude extracts against methicillin-resistant Staphylococcus aureus (MRSA) in a superficial skin infection using a tape-stripping mouse model. Methods: Different parts (bark, leaves, twig, wood, and oleo-resin) of D. alatus were used for extraction. Crude extracts with two pure compounds (α,β-gurjunene and dipterocarpol) were examined for antibacterial activity against methicillin-susceptible S. aureus (MSSA) and MRSA in vitro. The in vivo antibacterial activity against MRSA was examined in a tape-stripping mouse model of superficial skin infection by evaluating transepidermal water loss (TEWL), colony counts from wound culture swabs, and H&E staining. Results: Dipterocarpus alatus twig extract showed the lowest MIC (250 µg/mL) and MBC (500 µg/mL) against MRSA among extracts from other D. alatus parts. In addition, α,β-gurjunene showed lower MIC (250 µg/mL) and MBC (250 µg/mL) against MRSA than dipterocarpol. In vivo, D. alatus twig extract significantly reduced the number of MRSA recovered from superficial wounds to levels comparable to the non-infected control group on the second day. Oleo-resin, D. alatus wood extract, α,β-gurjunene, and dipterocarpol also significantly reduced the number of MRSA. Moreover, D. alatus twig extract and dipterocarpol healed infected wounds at rates comparable to the non-infected control group. From H&E staining of wounds, fibrin accumulation and neutrophil infiltration were attenuated in mice treated with D. alatus twig extract and dipterocarpol. Conclusions: Dipterocarpus alatus twig extract and dipterocarpol possess antibacterial and wound healing properties against MRSA-induced superficial skin infection in mice.