Bioguided chemical study of Boswellia dalzielii Hutch. (Burseraceae) for antibacterial agents and a new glucopyranoxylmethoxybenzyle

Boswellic Acids as Effective Antibacterial Antibiofilm Agents

Boswellic acids are biologically active pentacyclic terpenoid compounds derived from Boswellia sp. plants. Extracts containing these acids have a number of positive effects on human health, especially in the treatment of inflammation, arthritis, or asthma. With increasing resistance to common antibiotics, boswellic acid-containing extracts could serve as an alternative or work in synergy with commonly available preparations. This study aims to determine the effect of boswellic acids on suspension cells and biofilms of Staphylococcus epidermidis, Enterococcus faecalis, and Escherichia coli. The antimicrobial and antibiofilm effect found was compared with commonly available antibiotics to control these undesirable microorganisms. The synergistic effect of boswellic acids and common antibiotics on the growth of these microorganisms was also determined. All tested microorganisms showed a positive additive effect of antibiotics and boswellic acid extract. The most significant effect was found in Enterococcus faecalis ATCC 29212 in a combination of 0.2 × MIC80 erythromycin (0.2 mg/L) and 0.8 × MIC80 boswellic acid extract (16 mg/L).

Chemical composition and antimicrobial activity of Boswellia serrata oleo-gum-resin essential oil extracted by superheated steam

Oleo-gum-resin is a complex mixture of essential oils, polysaccharides, and resin acids. The objectives of the present study were to evaluate the variation in chemical components and antimicrobial activity of essential oils extracted by superheated steam at various temperatures. The optimum essential oil yield was obtained at the highest superheated steam temperature (210 °C). In total, twenty-one compounds were quantified by GC-MS with α-pinene as the major compound, followed by α-thujene, trans-verbenol, β-thujone, p-cymene, m-cymene, and sabinene. Antimicrobial activity was performed by disc diffusion, resazurin microtitre-plate and micro-dilution broth susceptibility assays in which essential oil extracted at 150 °C and 180 °C revealed the highest antibacterial and antifungal activity, respectively. It is concluded that superheated steam is an effective method for the isolation of essential oil from oleo-gum-resin that improves the recovery of essential oil as well as antimicrobial activity.