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Flavan-3-ols and 2-diglycosyloxybenzoates from the leaves of Averrhoa carambola.
- Source :
-
Fitoterapia . Jan2020, Vol. 140, pN.PAG-N.PAG. 1p. - Publication Year :
- 2020
-
Abstract
- Averrhoa carambola L. (Oxalidaceae) was widely cultivated for fruits (star fruit), whereas the value of leaves remains to be discovered. Our study on the leaves yielded five flavan-3-ols (1 – 5) and two 2-diglycosyloxybenzoates. Their structures were determined by spectroscopic and chemical methods. Epicatechin-(5,6-bc)-4β-(p -hydroxyphenyl)-dihydro-2(3 H)-pyranone (1) and benzyl 2-β- d -apiofuranosyl-(1 → 6)-β- d -glucopyranosyloxybenzoate (6) were new structures. 6-(S −2-Pyrrolidinone-5-yl)epicatechin (4) and 6-(R -2-pyrrolidinone-5-yl)epicatechin (5) were obtained as monomeric diastereomer for the first time and their absolute configurations were determined by electronic circular dichroism (ECD) computation. Epicatechin-(7,8-bc)-4α-(p -hydroxyphenyl)-dihydro-2(3 H)-pyranone (2), epicatechin-(7,8-bc)-4β-(p -hydroxyphenyl)-dihydro-2(3 H)-pyranone (3), and methyl 2-β- d -apiofuranosyl-(1 → 6)-β- d -glucopyranosyloxybenzoate (7) were not previously reported from the genus Averrhoa. Compounds 1 – 5 showed more potent 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities and ferric reducing antioxidant power (FRAP) than l -ascorbic acid. Meanwhile 1 and 3 exhibited lipase and α-glucosidase inhibitory activities, respectively. The results clarified the structures of flavan-3-ols and 2-diglycosyloxybenzoates in the leaves and their antioxidant, lipase, and α-glucosidase inhibitory activities. Graphic abstract Unlabelled Image • New flavan-3-ol and 2-diglycosylxoybenzoate were isolated from A. carambola leaves • The absolute configurations of two diastereomers were determined by ECD computation • The isolates showed antioxidant, lipase, and α-glucosidase inhibitory activities [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0367326X
- Volume :
- 140
- Database :
- Academic Search Index
- Journal :
- Fitoterapia
- Publication Type :
- Academic Journal
- Accession number :
- 140466942
- Full Text :
- https://doi.org/10.1016/j.fitote.2019.104442