Background: The Terminalia arjuna has been reported for the antimicrobial activity using
classical methods of extraction in the literature. As novel extraction methods have gained importance
to carry out the extraction of different plant materials, hence it was planned to extract Terminalia arjuna
stem bark in a better way and evaluate the change in antimicrobial activity of the improved extracts.
Objective: The extraction and evaluation of antimicrobial activity of stem bark of Terminalia arjuna
were performed, analyzed and compared using different extraction methods viz. RTE, SE and USAE
in this article.
Methods: The central composite design among the response surface methods was adopted to carry out
the optimization of different parameters of ultrasound-assisted extraction. The central composite design
was used for optimization and the values of parameters for an optimized batch of ultrasoundassisted
extraction were 800 W power, 10 minutes time and 1:80 ratio of solid/solvent ratio. The invitro
antimicrobial activity was performed using the tube dilution method taking ciprofloxacin and
fluconazole as standard antibacterial and antifungal agents.
Results: The value of estimated total percentage yield was 12.8 % which upon experimentation was
obtained as 12.7 %. The extraction efficiency of USAE was found better as compared to the RTE and
SE in terms of the extraction yield 4.2% and 6.8 % respectively. The extraction time of the conventional
RTE and SE (2 days and 7 days) was also reduced to minutes (10 to 20 min.) in USAE hence
was found to be better. The antimicrobial activity of the selected extracts was performed using tube
dilution method on selected strains of bacteria S. aureus, B. subtilis, E. coli and fungal A. niger and C.
albicans. The results obtained suggested that the USAE technique showed best results as compared to
the other extraction methods and the standard drugs taken (MIC values of 3.12, 1.56, 3.12, 1.56 and
3.12 µg/mL respectively).
Conclusion: Hence, it was concluded that ultrasound is an effective technique of extraction and has
enhanced the antimicrobial principles of the Terminalia arjuna stem bark.