Alsaud, Noor, Shahbaz, Kaveh, and Farid, Mohammed (2021) Antioxidant and antibacterial evaluation of Manuka leaves (Leptospermum scoparium) extracted by hydrophobic deep eutectic solvent. Chemical Engineering Research and Design, 174. pp. 96-106.

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Abstract

Manuka (Leptospermum scoparium) has been studied as a valuable shrub as its leaves are rich in bioactive components such as β-caryophyllene. This study investigated the extractability of hydrophobic deep eutectic solvent (HDES) namely menthol:lactic acid HDES for the total phenolic content (TPC) and antioxidant activity from β-caryophyllene-rich Manuka leaves. Results were also compared with ethanol and n-hexane extracts. The ethanolic extract possessed the highest amount of TPC (86.08 ± 6.22 mg GAE/g DW) among tested extracts. The extraction of TPC using HDES was at a sufficient level (79.82 ± 0.75 mg GAE/g DW), while n-hexane presented poor yield (2.74 ± 0.70 mg GAE/g DW). Higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power were found to be in ethanolic extract. The antibacterial effects of Manuka extract obtained by HDES was also assessed and the results were compared with the antibacterial effect of HDES, lactic acid, commercial Manuka essential oil, steam distilled Manuka oil, and β-caryophyllene pure oil. E. coli, Pseudomonas aeruginosa and Staphylococcus epidermidis were tested using agar disc diffusion method. Results revealed that lactic acid, HDES, and Manuka-HDES extract showed toxicity towards the tested bacteria indicating that the bactericidal effect of the Manuka extract was due to the lactic acid as a forming compound. This study verified the possibility of extracting and characterising different bioactive compounds from Manuka leaves using menthol:lactic acid HDES in a single step and thus it could be explored for broader industrial applications.

Item ID:	86787
Item Type:	Article (Research - C1)
ISSN:	1744-3563
Copyright Information:	© 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Date Deposited:	21 Aug 2025 01:43
FoR Codes:	40 ENGINEERING > 4004 Chemical engineering > 400409 Separation technologies @ 100%
SEO Codes:	24 MANUFACTURING > 2414 Processed non-food agriculture products (excl. wood, paper and fibre) > 241403 Plant extracts @ 100%
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