Improved Methods of Extraction and In Vitro Evaluation of Antimicrobial Potential of Stem Bark of Terminalia arjuna

Abstract

he 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.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.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.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).Hence, it was concluded that ultrasound is an effective technique of extraction and has enhanced the antimicrobial principles of the Terminalia arjuna stem bark.