Antimicrobial activity and the major components of the essential oil of Plectranthus cylindraceus

R. G. Marwah, M. O. Fatope*, M. L. Deadman, J. E. Ochei, S. H. Al-Saidi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Aims: The traditional uses of the aerial parts of fresh Plectranthus cylindraceus by the Dhofaris in Oman were investigated on the basis of antimicrobial properties and composition of its herb oil. Methods and Results: The minimal inhibitory concentration (MIC) values of the herb oil of P. cylindraceus against human pathogenic bacteria and yeast were assessed using the broth microdilution method, and the percentage growth inhibition of fungi was determined according to the poisoned food technique. The oil exhibited good activity against Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis and Candida albicans with MIC values in the range of 7.8-62.5 μg ml -1 and also inhibited the growth of Microsporum canis, Microsporum gypseum, Trichophyton rubrum, Alternaria alternata, Bipolaris sp., Curvularia lunata, Fusarium oxysporum and Stemphylium solani for about a week at 250 μg ml-1. The two most abundant components of the oil were identified as carvacrol (46.8%) and α-terpinolene (18.2%) based on gas chromatography-mass spectra (GC-MS) and 13C nuclear magnetic resonance (NMR) analyses. Conclusions: The oil has a pleasant odour and showed broad spectrum antimicrobial activity. Such bioactivity could be attributed in part to carvacrol. Significance and Impact of the Study: This study has demonstrated the broad spectrum antimicrobial activity of the herb oil of P. cylindraceus as well as the organic composition of this plant extract. This study provides scientific insight into the ancient practice of utilizing P. cylindraceus as a fragrant disinfectant.

Original languageEnglish
Pages (from-to)1220-1226
Number of pages7
JournalJournal of Applied Microbiology
Issue number4
Publication statusPublished - Oct 2007


  • Carvacrol
  • Dermatophytes
  • Dhofaris
  • Essential oil
  • Plectranthus cylindraceus

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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