title: Antioxidant, Metal Chelating, Anti-glucosidase Activities and Phytochemical Analysis of Selected Tropical Medicinal Plants.
abstract: The purpose of this investigation was to determine the antioxidant potentials and anti-glucosidase activities of six tropical medicinal plants. The levels of phenolic constituents in these medicinal plants were also quantified and compared. Antioxidation potentials were determined colorimetrically for scavenging activities against DPPH and NO radicals. Metal chelating assay was based on the measurement of iron-ferrozine absorbance at 562 nm. Anti-diabetic potentials were measured by using α-glucosidase as target enzyme. Medicinal plants' total phenolic, total flavonoid and hydroxycinnamic acid contents were determined using spectrophotometric methods, by comparison to standard plots prepared using gallic acid, quercetin and caffeic acid standards, respectively. Radical scavenging and metal chelating activities were detected in all medicinal plants, in concentration-dependent manners. Among the six plants tested, C. nutans, C. formosana and H. diffusa were found to possess α-glucosidase inhibitory activities. Spectrophotometric analysis indicated that the total phenolic, total flavonoid and hydroxycinnamic acid contents ranged from 12.13-21.39 mg GAE per g of dry sample, 1.83-9.86 mg QE per g of dry sample, and 0.91-2.74 mg CAE per g of dry sample, respectively. Our results suggested that C. nutans and C. formosana could potentially be used for the isolation of potent antioxidants and anti-diabetic compounds. To the best of our knowledge, this study represents the first time that C. nutans (Acanthaceae family) was reported in literature with glucosidase inhibition activity.
authors.affiliation: Centre for Biodiversity Research, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia. ; Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia.
authors.forename: Fai-Chu
authors.initials: FC
authors.lastname: Wong
authors.affiliation: Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia.
authors.forename: Ann-Li
authors.initials: AL
authors.lastname: Yong
authors.affiliation: Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia.
authors.forename: Evon Peir-Shan
authors.initials: EP
authors.lastname: Ting
authors.affiliation: Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia.
authors.forename: Sim-Chyi
authors.initials: SC
authors.lastname: Khoo
authors.affiliation: Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Hean-Chooi
authors.initials: HC
authors.lastname: Ong
authors.affiliation: Centre for Biodiversity Research, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia. ; Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Malaysia.
authors.forename: Tsun-Thai
authors.initials: TT
authors.lastname: Chai
keywords: Anti-glucosidase; Antioxidation; Caffeic acid; Diabetes; Gallic acid; Phenolic compounds; Quercetin