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. 2022 Dec;133(6):3678-3689.
doi: 10.1111/jam.15805. Epub 2022 Sep 22.

Ultrasound-assisted facile synthesis of Boron-Heck-coupled sclareol analogues as potential antibacterial agents against Staphylococcus aureus

Salman Jameel  1   2 , Sadaqat Farooq  2   3 , Ifshana Gani  1   2 , Syed Riyaz-Ul-Hassan  2   3 , Khursheed Ahmad Bhat  1   2
Affiliations

Ultrasound-assisted facile synthesis of Boron-Heck-coupled sclareol analogues as potential antibacterial agents against Staphylococcus aureus

Salman Jameel et al. J Appl Microbiol. 2022 Dec.

Abstract

Aim: To evaluate the antimicrobial capability of sclareol and its derivatives against Staphylococcus aureus and its Methicillin-resistant strain (MRSA).

Methods and results: A new series of Boron-Heck-coupled sclareol analogues were prepared by structural modifications at the C-15 terminal double bond of sclareol using ultrasonication. The structural modifications were designed to keep the stereochemistry of all the five chiral centres of sclareol intact. A two-step reaction scheme consisting of Boron-Heck coupling of sclareol followed by Wittig reaction was carried out to produce novel sclareol congeners for antimicrobial evaluation. Three compounds SAJ-1, SAJ-2 and SB-11 exhibited strong antibacterial activity against S. aureus and Methicillin-resistant strain (MRSA) with MIC values between 3 and 11 μM. Among all the screened compounds, SAJ-1 and SAJ-2 showed the best antibiofilm profiles against both strains. Moreover, SAJ-1 and SAJ-2 acted synergistically with streptomycin against S. aureus while creating varying outcomes in combination with ciprofloxacin, penicillin and ampicillin. SAJ-1 also acted synergistically with ampicillin against S. aureus, while SB-11 showed synergism with ciprofloxacin against both pathogens. Moreover, SAJ-1 and SAJ-2 also inhibited staphyloxanthin production in S. aureus and MRSA and induced postantibiotic effects against both pathogens.

Conclusions: It can be inferred that SAJ-1, SAJ-2 and SB-11 may act as potential chemical entities for the development of antibacterial substances. The study revealed that SAJ-1 and SAJ-2 are the most suitable sclareol analogues for further studies towards the development of antibacterial substances.

Significance and impact of the study: SAJ-1, SAJ-2 and SB-11 show promising antibacterial properties against Staphylococcus aureus. Efforts should be made and more research should be done utilizing in vivo models to determine their efficacy as antibiotics.

Keywords: S. aureus; Boron-Heck coupling; MRSA; Sclareol; biofilm; boronic acid.

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References

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