Evaluation of the Antibacterial, Anti-inflammatory and Wound Healing Properties of Frankincense (Boswellia frereana).

Abstract

Chronic wounds, already a major clinical and healthcare issue, are expected to grow due to demographic changes, a rise in multi-health conditions, and an increase in conditions like peripheral vascular disease, diabetes, and obesity. Despite such different treatment choices, recurrent deficiencies in wound care have prompted interest in alternate therapy approaches and research over the last few decades. This research investigates the medicinal properties of Boswellia frereana, a tree exudate indigenous to Somaliland (northern Somalia) that is commonly used in traditional medicine. The objective of this study was to investigate it’s potential to treat chronic wounds through studying it’s antibacterial, antibiofilm, anti-inflammatory, and wound healing properties, in vitro. Following extractions, Gas Chromatography-Mass spectrometry (GC-MS) was used to identify the chemical components present in each extracts, alcoholic extracts and essential oils from different suppliers, whilst High Performance Liquid Chromatography (HPLC) was used to quantify the main chemical component, 3-epilupeol, present in the alcoholic extracts. The extracts were evaluated for their Antibacterial effect against the most common bacteria found in chronic wounds (Staphylococcus aureus, Pseudomonas aeruginosa and Methicillin- resistant Staphylococcus aureus) using well diffusion and broth microdilution techniques. The efficacy of B. frereana extracts in inhibiting and eradicating bacterial biofilm was assessed by crystal violet staining and the Live/Dead microbiological viability assay utilising Confocal Laser Scanning Microscopy (CLSM). MTT and scratch wound assays assessed the effects of these extracts on immortalised human skin keratinocytes (HaCaT) and fibroblast cell lines proliferation, migration, and cytotoxicity. Finally, To determining the effects of plant extracts on the production of a panel of inflammatory mediators, LPS-stimulated HaCaT cells were used to assess the anti-inflammatory effects of the extracts. GC-MS analysis identified two chemotypes of B. frereana frankincense, one high in α-Thujene and another high in α-Pinene. HPLC was found to be a more accurate analytical method, than GC-MS, for quantifying the 3-epilupeol content. The essential oil extracts, a-pinene, and b- pinene were all shown to possess significant antibacterial activity against Gram-positive pathogens in both planktonic and biofilm environments. Ethanolic extracts, essential oil, 3- IV epilupeol, and a-pinene induced HaCaT and fibroblast proliferation at low concentrations. However, only oil extracts and a-pinene (0.1 µg/mL) increased the migration of HaCaT cells. The anti-inflammatory study has shown that ethanolic extracts, essential oil, epilupeol, and α- pinene significantly reduced the protein levels of select inflammatory mediators, including IL- 1B, IL-6, IL-8 and TNF-α. This research confirms many reported ethnobotanical applications of frankincense to treat wounds and inflammation.