Antioxidant and Anti-Inflammatory Activities of Endemic Plants of the Australian Wet Tropics

Yeshi, Karma, Ruscher, Roland, Miles, Kim, Crayn, Darren, Liddell, Michael, and Wangchuk, Phurpa (2022) Antioxidant and Anti-Inflammatory Activities of Endemic Plants of the Australian Wet Tropics. Plants, 11 (19). 2519.

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Plants have been a vital source of natural antioxidants since ancient times. Plants growing under various abiotic stress conditions often produce more defensive secondary metabolites such as phenolics, flavonoids, and terpenoids during adaptation to the environment. Many of these secondary metabolites are known to possess antioxidant and anti-inflammatory properties. This study tested seven plants sourced from the mountaintop areas (above 1000 m elevation) of Mount Lewis National Park (falls under the Wet Tropics of Queensland), Australia, for their antioxidant and anti-inflammatory activities. Of the seven studied plants, hydroethanolic extracts of six plants (Leptospermum wooroonooran, Ceratopetalum hylandii, Linospadix apetiolatus, Garcinia brassii, Litsea granitica, and Polyscias willmottii) showed high 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging activity in a dose-dependent (25–1000  g/mL) manner. At the highest concentration of 1 mg/mL, the DPPH free radical scavenged percentage varied between 75.4% and 92.3%. Only the species Alyxia orophila was inactive in the DPPH free radical scavenging assay. Pseudo-IC50 values of the extracts’ ferric reducing antioxidant power (FRAP) based on dose-response curves showed a significant positive correlation with total phenolic content. Five out of the seven plants, namely G. brassii, C. hylandii, L. apetiolatus, L. wooroonooran, and A. orophila, showed inhibitory effects on the secretion of proinflammatory cytokines, tumour necrosis factor (TNF), and interleukins (IL)-23 in a lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMCs) assay. The results of this study demonstrate the value of tropical mountaintop plants in the biodiscovery of antioxidant and anti-inflammatory lead compounds.

Item ID: 76265
Item Type: Article (Research - C1)
ISSN: 2223-7747
Keywords: antioxidant; anti-inflammatory; mountaintop plants; phenolics; flavonoid; DPPH; reducing power
Copyright Information: Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Funders: National Health and Medical Research Council (NHMRC)
Projects and Grants: NHMRC APP1183323
Date Deposited: 10 Oct 2022 23:41
FoR Codes: 34 CHEMICAL SCIENCES > 3404 Medicinal and biomolecular chemistry > 340401 Biologically active molecules @ 50%
41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50%
SEO Codes: 19 ENVIRONMENTAL POLICY, CLIMATE CHANGE AND NATURAL HAZARDS > 1901 Adaptation to climate change > 190102 Ecosystem adaptation to climate change @ 50%
28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280105 Expanding knowledge in the chemical sciences @ 50%
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