Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur, Tamil Nadu, India.
Department of Chemical Engineering, Ming Chi University of Technology, Taishan, Taipei, Taiwan.
PLoS One. 2018 Mar 1;13(3):e0193717. doi: 10.1371/journal.pone.0193717. eCollection 2018.
Enzyme hydrolysates (trypsin, papain, pepsin, α-chymotrypsin, and pepsin-pancreatin) of Tinospora cordifolia stem proteins were analyzed for antioxidant efficacy by measuring (1) 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging activity, (2) 2,20-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radical scavenging capacity, and (3) Fe2+ chelation. Trypsin hydrolysate showed the strongest DPPH• scavenging, while α-chymotrypsin hydrolysate exhibited the highest ABTS+ scavenging and Fe2+ chelation. Undigested protein strongly inhibited the gastrointestinal enzymes, trypsin (50% inhibition at enzyme/substrate ratio = 1:6.9) and α-chymotrypsin (50% inhibition at enzyme/substrate ratio = 1:1.82), indicating the prolonged antioxidant effect after ingestion. Furthermore, gel filtration purified peptide fractions of papain hydrolysates exhibited a significantly higher ABTS+ and superoxide radical scavenging as compared to non-purified digests. Active fraction 9 showing the highest radical scavenging ability was further purified and confirmed by MALDI-TOF MS followed by MS/MS with probable dominant peptide sequences identified are VLYSTPVKMWEPGR, VITVVATAGSETMR, and HIGININSR. The obtained results revealed that free radical scavenging capacity of papain hydrolysates might be related to its consistently low molecular weight hydrophobic peptides.
采用 1,1-二苯基-2-苦基肼基（DPPH•）自由基清除活性、2,20-连氮基-双-（3-乙基苯并噻唑啉-6-磺酸）（ABTS+）自由基清除能力和 Fe2+螯合能力来分析三叶鬼针草茎蛋白的酶解产物（胰蛋白酶、木瓜蛋白酶、胃蛋白酶、α-糜蛋白酶和胃蛋白酶-胰蛋白酶）的抗氧化功效。胰蛋白酶水解产物表现出最强的 DPPH•清除能力，而 α-糜蛋白酶水解产物表现出最高的 ABTS+清除能力和 Fe2+螯合能力。未消化的蛋白质强烈抑制胃肠酶，胰蛋白酶（酶/底物比为 1:6.9 时 50%抑制）和 α-糜蛋白酶（酶/底物比为 1:1.82 时 50%抑制），表明摄入后抗氧化作用延长。此外，木瓜蛋白酶水解物的凝胶过滤纯化肽级分表现出比未纯化的消化物更高的 ABTS+和超氧自由基清除能力。显示出最高自由基清除能力的活性级分 9 进一步纯化，并通过 MALDI-TOF MS 确认，随后进行 MS/MS，鉴定出可能的主导肽序列为 VLYSTPVKMWEPGR、VITVVATAGSETMR 和 HIGININSR。研究结果表明，木瓜蛋白酶水解物的自由基清除能力可能与其始终较低的分子量疏水性肽有关。
