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Browsing RDI-Article by Subject "Antioxidant activity"

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    Antioxidant Activities, Total Phenolic Compounds and Fucoxanthin of Marine Benthic Diatoms Amphora subtropica BUUC1502 and Thalassiosira sp.
    (Graphicsite, 2023-09-26) Pakawan Setthamongkol; Nisa Siranonthana; Ranchayanee Chalermmueang; Yutthaya Yuyen; Janjarus Watanachote; Rachanimuk Hiransuchalert; Maliwan Kutako
    This research’s aim was to study antioxidant activities, total phenolic compounds and fucoxanthin of crude extract of marine benthic diatoms, Amphora subtropica BUUC1502 and Thalassiosira sp. These two diatoms were cultured in a Guillard F/2 media, which was prepared from sea water with a salinity at 30 psu for 8 days. It was found that A. subtropica BUUC1502 shows better growth than Thalassiosira sp. (p<0.05). Whereas the biomass yield of Thalassiosira sp. is higher than of A. subtropica BUUC1502 (p<0.05). The diatoms were extracted using methanol solvent (99.8%). Crude extracts of A. subtropica BUUC1502 and Thalassiosira sp. yielded 0.38±0.01 and 0.36±0.00 g/g DW, respectively. The total phenolic compounds and fucoxanthin of them were similar (p>0.05) with 2.92-3.09 mg GAE/g crude extract and 18.85-19.74 mg/g DW, respectively. The IC50 of DPPH free radical inhibition of crude extracts from A. subtropica BUUC1502 and Thalassiosira sp. is 231.75±40.75 and 179.84±27.90 µg/mL, respectively, while the IC 50 of ABTS free radical inhibition is 68.28±7.31 and 46.90±1.83 µg/mL, respectively. The results of this research show that these two marine benthic diatoms may be an antioxidant source that can be used in various related fields.
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    Antioxidant Activity and Allelopathic Potential of Lippia nodiflora (L.) Michx on Germination and Growth of Neptunia javanica Miq. seeds
    (Graphicsite, 2023-09-26) Wipa Tupchiangmai; Wantana Mongkolvisut
    The research objective was to evaluate the antioxidant activity, the allelopathic potential on germination growth of Neptunia javanica Miq. seeds and the total phenolic content (TPC) of crude extracts and fractions from Lippia nodiflora (L.) Michx. In this research, the ethanol crude extracts of leaves (LE), stems (SE) and roots (RE) from L. nodiflora were subjected to study the antioxidant activity by using DPPH free radical scavenging assay and the allelopathic potential on germination seeds of N. javanica. The RE extract had the highest antioxidant activity with IC50 value of 136.87 ppm. The allelopathic effect of LE extract at a concentration of 20 mg/mL completely inhibited the seed germination of N. javanica. The LE fractions were separated by liquid-liquid partition with hexane and ethyl acetate system to afford the leaf hexane fraction (LH), leaf ethyl acetate fraction (LEtOAc) and leaf hydroethanolic fraction (LW). The antioxidant, TPC and allelopathic activities of all fractions were investigated. The antioxidant activity of LW (158.21) and LEtOAc (175.45) fractions were better than those of LE (296.87) extracts, while LH fraction showed the lowest antioxidant activity at 722.08 ppm. The active allelopathic compounds in LEtOAc at a concentration of 10 mg/mL showed complete inhibition of radicle and hypocotyl on germination seed growth and 50% of seed growth inhibition (IC50) was 3.14 mg/mL. Crude extracts and fractions showed more inhibited radicle growth than hypocotyl growth of N. javanica seeds. The TPC of leaves crude extracts and fractions were the highest. Interestingly, the total phenolic content of LEtOAc fraction, was the highest (0.072 mg GAE/g) that was related to the good allelopathic properties, compared with other fractions and crude extracts. Our results indicate that the ethanolic crude extracts and an ethyl acetate fraction of L. nodiflora leaves can be applied to weed control, especially for N. javanica.