title: Bioactivity-guided isolation of antioxidant triterpenoids from Betula platyphylla var. japonica bark.
abstract: The bark of Betula platyphylla var. japonica (Betulaceae) has been used to treat pneumonia, choloplania, nephritis, and chronic bronchitis. This study aimed to investigate the bioactive chemical constituents of the bark of B. platyphylla var. japonica. A bioassay-guided fractionation and chemical investigation of the bark of B. platyphylla var. japonica resulted in the isolation and identification of a new lupane-type triterpene, 27-hydroxybetunolic acid (1), along with 18 known triterpenoids (2-19). The structure of the new compound (1) was elucidated on the basis of 1D and 2D NMR spectroscopic data analysis as well as HR-ESIMS. Among the known compounds, chilianthin B (17), chilianthin C (18), and chilianthin A (19) were triterpene-lignan esters, which are rarely found in nature. Compounds 4, 6, 7, 17, 18, and 19 showed significant antioxidant activities with IC50 values in the range 4.48-43.02μM in a DPPH radical-scavenging assay. However, no compound showed significant inhibition of acetylcholine esterase (AChE). Unfortunately, the new compound (1) exhibited no significance in both biological activities. This study strongly suggests that B. platyphylla var. japonica bark is a potential source of natural antioxidants for use in pharmaceuticals and functional foods.
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Hee Jeong
authors.initials: HJ
authors.lastname: Eom
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Hee Rae
authors.initials: HR
authors.lastname: Kang
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Ho Kyong
authors.initials: HK
authors.lastname: Kim
authors.affiliation: College of Korean Medicine, Gachon University, Seongnam 461-701, Republic of Korea.
authors.forename: Eun Bee
authors.initials: EB
authors.lastname: Jung
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06520, United States.
authors.forename: Hyun Bong
authors.initials: HB
authors.lastname: Park
authors.affiliation: College of Korean Medicine, Gachon University, Seongnam 461-701, Republic of Korea. Electronic address: kkang@gachon.ac.kr.
authors.forename: Ki Sung
authors.initials: KS
authors.lastname: Kang
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea. Electronic address: khkim83@skku.edu.
authors.forename: Ki Hyun
authors.initials: KH
authors.lastname: Kim
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D029662:Betula / Q000737:chemistry*; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013729:Terpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D002800:Cholinesterase Inhibitors; D010936:Plant Extracts; D013729:Terpenes; D000110:Acetylcholinesterase
keywords: Antioxidant; Betula platyphylla var. japonica; Betulaceae; DPPH radical scavenging; Triterpenoids