title: In vitro antioxidant and, α-glucosidase inhibitory activities and comprehensive metabolite profiling of methanol extract and its fractions from Clinacanthus nutans.
abstract: BACKGROUND
  This study was aimed to evaluate antioxidant and α-glucosidase inhibitory activity, with a subsequent analysis of total phenolic and total flavonoid content of methanol extract and its derived fractions from Clinacanthus nutans accompanied by comprehensive phytochemical profiling.
  
  
  METHODS
  Liquid-liquid partition chromatography was used to separate methanolic extract to get hexane, ethyl acetate, butanol and residual aqueous fractions. The total antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging and ferric reducing antioxidant power assay (FRAP). The antidiabetic activity of methanol extract and its consequent fractions were examined by α-glucosidase inhibitory bioassay. The chemical profiling was carried out by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC Q-TOF MS).
  
  
  RESULTS
  The total yield for methanol extraction was (12.63 ± 0.98) % (w/w) and highest fractionated value found for residual aqueous (52.25 ± 1.01) % (w/w) as compared to the other fractions. Significant DPPH free radical scavenging activity was found for methanolic extract (63.07 ± 0.11) % and (79.98 ± 0.31) % for ethyl acetate fraction among all the fractions evaluated. Methanol extract was the most prominent in case of FRAP (141.89 ± 0.87 μg AAE/g) whereas most effective reducing power observed in ethyl acetate fraction (133.6 ± 0.2987 μg AAE/g). The results also indicated a substantial α-glucosidase inhibitory activity for butanol fraction (72.16 ± 1.0) % and ethyl acetate fraction (70.76 ± 0.49) %. The statistical analysis revealed that total phenolic and total flavonoid content of the samples had the significant (p < 0.05) impact on DPPH free radical scavenging and α-glucosidase inhibitory activity.
  
  
  CONCLUSIONS
  Current results proposed the therapeutic potential of Clinacanthus nutans, especially ethyl acetate and butanol fraction as chemotherapeutic agent against oxidative related cellular damages and control the postprandial hyperglycemia. The phytochemical investigation showed the existence of active constituents in Clinacanthus nutans extract and fractions.
authors.affiliation: Faculty of Pharmacy, International Islamic University Malaysia (IIUM), Kuantan Campus, 25200, Kuantan, Pahang, Malaysia.
authors.forename: Md Ariful
authors.initials: MA
authors.lastname: Alam
authors.affiliation: Faculty of Pharmacy, International Islamic University Malaysia (IIUM), Kuantan Campus, 25200, Kuantan, Pahang, Malaysia. zaidul@iium.edu.my.
authors.forename: I S M
authors.initials: IS
authors.lastname: Zaidul
authors.affiliation: Department of Food Science and Nutrition, King Saud University, Riyadh, 11451, Saudi Arabia.
authors.forename: Kashif
authors.initials: K
authors.lastname: Ghafoor
authors.affiliation: Faculty of Science, International Islamic University Malaysia (IIUM), Kuantan Campus, 25200, Kuantan, Pahang, Malaysia.
authors.forename: F
authors.initials: F
authors.lastname: Sahena
authors.affiliation: Institute of Tropical Agriculture, University Putra Malaysia, 43400 UPM, Serdang, Selangor Darul Ehsan, Malaysia.
authors.forename: M A
authors.initials: MA
authors.lastname: Hakim
authors.affiliation: Institute of Tropical Agriculture, University Putra Malaysia, 43400 UPM, Serdang, Selangor Darul Ehsan, Malaysia.
authors.forename: M Y
authors.initials: MY
authors.lastname: Rafii
authors.affiliation: Faculty of Agricultural Engineering and Technology, Bangladesh Agricultural University, Mymensingh, Bangladesh.
authors.forename: H M
authors.initials: HM
authors.lastname: Abir
authors.affiliation: Department of Pharmaceutical Technology and Industry, Faculty of Pharmacy, Cyberjaya University College of Medical Science, No. 3410, Jalan Teknokrat 3, Cyber 4, 63000, Cyberjaya, Selangor Darul Ehsan, Malaysia.
authors.forename: M F
authors.initials: MF
authors.lastname: Bostanudin
authors.affiliation: Faculty of Pharmacy, International Islamic University Malaysia (IIUM), Kuantan Campus, 25200, Kuantan, Pahang, Malaysia.
authors.forename: V
authors.initials: V
authors.lastname: Perumal
authors.affiliation: Faculty of Pharmacy, International Islamic University Malaysia (IIUM), Kuantan Campus, 25200, Kuantan, Pahang, Malaysia.
authors.forename: A
authors.initials: A
authors.lastname: Khatib
mesh_terms: D027901:Acanthaceae / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D065089:Glycoside Hydrolase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D018547:Plant Stems / Q000737:chemistry; D000520:alpha-Glucosidases / Q000737:chemistry / Q000378:metabolism
chemical_list: D000975:Antioxidants; D065089:Glycoside Hydrolase Inhibitors; D010936:Plant Extracts; D000520:alpha-Glucosidases
keywords: Activity phytochemical profiling; Antioxidant activity; Clinacanthus nutans; Reducing power; Total flavonoid; Total phenolic; α-glucosidase inhibitory activity