37064-38-3Relevant academic research and scientific papers
Tannins from Betel Nuts
Ma, Ying-Tsun,Hsu, Feng-Lin,Lan, Shu-Jan J.,Chen, Chieh-Fu
, p. 77 - 81 (2007/10/03)
From the acetone extract of fresh betel nuts, two procyanidin pentamers, two procyanidin tetramers and three procyanidin trimers, along with (+)-catechin, (-)-epicatechin, procyanidin A-1, procyanidin B-1, procyanidin B-2, and procyanidin B-7 were isolated. Based on 1H NMR and 13C NMR spectral data as well as the results of thiolysis degradation, the chemical structures of two series of oligomeric arecatannins A and B have been established. The arecatannins from betel nuts were found to be condensed-type tannins which possess (-)-epicatechin unit and (+)-catechin units. All arecatannins had C4-C8 linked (-)-epicatechin in the upper units whereas the (+)-catechin in the terminal unit had C4-C8 or C4-C6 linkage.
Tannins and Related Compounds. LXXVII. Novel Chalcan-flavan Dimers, Assamicains A, B and C, and a New Flavan-3-ol and Proanthocyanidins from the Fresh Leaves of Camellia sinensis L. var. assamica KITAMURA
Hashimoto, Fumio,Nonaka, Gen-ichiro,Nishioka, Itsuo
, p. 77 - 85 (2007/10/02)
Three novel chalcan-flavan dimers, assamicains A (1), B (2) and C (3), and a new flavan-3-ol (14) and proanthocyanidins (19,20) have been isolated, together with the known flavan-3-ols (4-13), proanthocyanidins (15-18,21), theasinensins (22-24) and hydrolyzable tannins (25,26), from the fresh leaves of Camellia sinensis var. assamica (Camelliaceae), and their structures have been established on the basis of spectroscopic evidence in conjunction with thiolytic degradation and enzymatic hydrolysis. - Keywords: Camellia sinensis var. assamica; Camelliaceae; polyphenol; assamicain; chalcan-flavan dimer; proanthocyanidin; theasinensin; flavan-3-ol; hydrolyzable tannin; black tea
PROCYANIDINS AND POLYPHENOLS OF LARIX GMELINI BARK
Shen, Zhaobang,Haslam, Edwin,Falshaw, Christopher P.,Begley, Michael J.
, p. 2629 - 2636 (2007/10/02)
Key Word Index - Larix gmelini; Pinaceae; bark; catechins; procyanidins; biflavonoids; larixinol.Methanol extracts of Larix gmelini bark yielded (-)-epiafzelechin, (+)-catechin and (-)-epicatechin, dimeric procyanidins B-1, B-2, B-3 and B-4 and oligomeric procyanidins.Chemical degradation of the oligomers using toluene-α-thiol and acetic acid showed the oligomers to have flavan-3-ol terminal units possessing either the 2,3-trans (catechin) or 2,3-cis (epicatechin) stereochemistry, with the former predominating.Likewise the extension units were shown to consist of flavan-3-ol units with 2,3-trans or 2,3-cis stereochemistry in roughly equal proportion.The average degree of oligomerization was calculated as 6-7 and the number average molecular weight as 1700-2000.The structure of the residual procyanidins remaining in the bark after methanol extraction is also briefly commented upon.Larixinol is shown to have an unusual spirobiflavonoid structure and a pathway of biogenesis is proposed.
