COMPARISON OF HOT AND COLD EXTRACTION OF WHITE TEA (Camellia sinensis) IN TERMS OF PROXIMATE COMPOSITION, TOTAL PHENOLICS, TOTAL CATECHINS, AND RADICAL SCAVENGING CAPACITY, AND IN SILICO STUDY OF CATE
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2024-01-09
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Abstract
Pathological conditions that are affected by poor lifestyle and environmental pollution are factors that could generate an excess of reactive oxygen species (ROS) and other free radicals in the body. Naturally, humans have a natural defense system to neutralize the ROS and free radicals called endogenous antioxidants, including superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). This study aims (1) to obtain the best quality white tea beverages (WTB) prepared by hot and cold extraction of silvery leaf buds of tea (Camellia sinensis) in terms of proximate composition, ascorbic acid, phenolics, catechins, and radical scavenging activity and (2) to study the binding mode between the epigallocatechin gallate, epigallocatechin, quercetin, and ascorbic acid of white tea and human first-line defense antioxidant enzymes. WTB-H10 (white tea extracted in hot water for 10 minutes) contains 0.12% protein, 0.45% fat, 13.20 mg/100g ascorbic acid, 153.3260 µg/mL total phenolic content (TPC) and 1981.25 µg/mL total catechin content (TCC). In comparison, WTB-C3.0 (white tea extracted in cold water for 3 hours) contains 0.14% fat, 0.08% carbohydrate, 4.40 mg/100g ascorbic acid, 242.0240 µg/mL TPC, and 356.80 µg/mL TCC. WTB-H10 and WTB-C3.0 show powerful radical scavenging activity with IC50 values of 8.80 ± 0.06 and 11.47 ± 0.07 µg/mL. Those properties mean that WTB-H10 is the best extraction method with a high level of nutrition, TPC, TCC, and very strong radical scavenging activity; thus, it will be recommended for daily consumption to support human health. In the molecular docking simulation, the binding affinity of ascorbic acid, quercetin, EGC, and EGCG with CAT are -2.57, -5.33, -5.77, and -6.31 kcal/mol. In GPX, the binding affinity of ascorbic acid, EGC, quercetin and EGCG are -2.14, -2.91, -2.91, and -3.75 kcal/mol. While in SOD, the binding affinity of EGCG, EGC, ascorbic acid, and quercetin are -4.02, -4.15, -4.15, and -5.55 kcal/mol. The molecular docking simulation revealed that EGCG possesses the best binding affinity to human CAT and GPX compared to ascorbic acid, EGC, and quercetin. EGCG binds several important amino acids such as His194, Phe198 His235 and Gln442 through hydrogen bonding with human CAT. EGCG also binds Pro151, Phe198, Arg203, Tyr215, Phe446 and Val450 by hydrophobic interactions and binds Arg203 with human CAT. In complex with human GPX, EGCG exhibits interaction with Gln45, Lys48, Thr49, Gln79 and Asn137 by hydrogen bonds, Ala43 and Trp136 by hydrophobic interactions. EGC reveals the best binding affinity to human SOD1. EGC creates four hydrogen bonds with Gln22, Lys23, Pro28 and Glu100, hydrophobic interaction with Lys30 and Trp32 and also electrostatic interaction with Glu21. In 100ns MD simulation, human catalase shows more stable complex with EGC than EGCG with RMSD average value of EGC is 0.408 Å, high fluctuation residue is 55 residues and MM/GBSA energy is -12.13 ± 0.69. Conversely, EGCG creates more stable complex with human GPX than EGC. EGCG exhibits more stable complex with RMSD average value is 1.357 Å, high residue fluctuation less than 5 Å in 3 residue and MM/GBSA energy is -13.04 ± 0.99. Those results indicated that both EGCG and EGC have potential as antioxidant agent by radical scavenging mechanism and stimulating antioxidant enzymes activity.
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Camellia sinensis; catechins; catalase; glutathione peroxidase; superoxide dismutase, Tidak ada keyword, Tidak ada keyword