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Số người truy cập: 50,124,523

 A DFT analysis on the radical scavenging activity of oxygenated terpenoids present in the extract of the buds of Cleistocalyx operculatus
Tác giả hoặc Nhóm tác giả: Thi Chinh Ngo, Duy Quang Dao,* Minh Thong Nguyen and Pham Cam Nam
Nơi đăng: RSC Advances; Số: 7;Từ->đến trang: 39686–39698;Năm: 2017
Lĩnh vực: Tự nhiên; Loại: Bài báo khoa học; Thể loại: Quốc tế
TÓM TẮT
The antioxidant capacity of twenty-one oxygenated monoterpene and oxygenated desquiterpenecompounds in the extract from Cleistocalyx operculatus has been computationally evaluated. Calculated by (RO)B3LYP/6-311++G(2df,2p)//B3LYP/6-311G(d,p) model chemistries, the thermochemical parameters, namely BDE, IE, PDE, PA and ETE in the gas phase, water and ethanol were determined. In addition, quantum descriptors, which allow the evaluation of the reactivity and stability of the resulting radicals like chemical potential (m), hardness (h) and global electrophilicity (u) were also computed. Potential energy surfaces of the reactions between CH3OOc and HOc radicals with falcarinol and vetivone, two typical and potential antioxidant molecules, were established to give more insight into the antioxidant mechanism. The obtained results underline falcarinol as the most effective antioxidant with the lowest BDE of 66.5 kcal/moland PA of 341.3 kcal/mol in the gas phase. Among the reactions on falcarinol, the H-abstraction at C3–H position by both CH3OOc and HOc radicals are favorable with the energy barriers of -18.7 and- 54.7 kcal/mol, respectively. Moreover, NBO analysis helps to clarify the mechanism of antioxidant action which shows that the third lone pair of electrons on O1-atom of CH3OO radical is donated to an unoccupied antibonding orbital on C3–H, and on the C4-C5, C6-C7 triple bonds. Similarly, attack of CH3OOc and HO radicals vetivone demonstratesthat H-abstraction reactions are also more feasible than the addition ones with H values of -7.3 and -41.9 kcal/mol, respectively. For all considered reactions, the antioxidant molecules preferentially interact with HO radical
ABSTRACT
The antioxidant capacity of twenty-one oxygenated monoterpene and oxygenated desquiterpenecompounds in the extract from Cleistocalyx operculatus has been computationally evaluated. Calculated by (RO)B3LYP/6-311++G(2df,2p)//B3LYP/6-311G(d,p) model chemistries, the thermochemical parameters, namely BDE, IE, PDE, PA and ETE in the gas phase, water and ethanol were determined. In addition, quantum descriptors, which allow the evaluation of the reactivity and stability of the resulting radicals like chemical potential (m), hardness (h) and global electrophilicity (u) were also computed. Potential energy surfaces of the reactions between CH3OOc and HOc radicals with falcarinol and vetivone, two typical and potential antioxidant molecules, were established to give more insight into the antioxidant mechanism. The obtained results underline falcarinol as the most effective antioxidant with the lowest BDE of 66.5 kcal/moland PA of 341.3 kcal/mol in the gas phase. Among the reactions on falcarinol, the H-abstraction at C3–H position by both CH3OOc and HOc radicals are favorable with the energy barriers of -18.7 and- 54.7 kcal/mol, respectively. Moreover, NBO analysis helps to clarify the mechanism of antioxidant action which shows that the third lone pair of electrons on O1-atom of CH3OO radical is donated to an unoccupied antibonding orbital on C3–H, and on the C4-C5, C6-C7 triple bonds. Similarly, attack of CH3OOc and HO radicals vetivone demonstratesthat H-abstraction reactions are also more feasible than the addition ones with H values of -7.3 and -41.9 kcal/mol, respectively. For all considered reactions, the antioxidant molecules preferentially interact with HO radical
[ c7ra04798c.pdf ]
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