Ellagitannins Renewed the Concept of Tannins
نویسندگان
چکیده
1.1 Old and New Concepts of Tannins The pharmacological activities of tannins described in medicinal books before the recent achievements on ellagitannin chemistry were mostly those of gallotannins and condensed tannins of poor chemical uniformity. The gallotannins extracted from Chinese or Turkish gall, sometimes called tannic acid, are variable mixtures of polygallates of carbohydrates. They cause irritation on skin and mucous membranes, although they have been utilized in some traditional medicinal applications, and are technically defined on the basis of their general capacity to bind to proteins and nitrogen basic compounds such as alkaloids. The condensed tannins, mixtures of oligomeric and polymeric flavanols (e.g., catechins), are chemically more unstable and heterogeneous, thus conforming to the
منابع مشابه
Structural Features and Biological Properties of Ellagitannins in Some Plant Families of the Order Myrtales
Plant tannins, including hydrolysable and condensed varieties, are well known antioxidants in medicinal plants, foods, and edible fruits. Their diverse biological properties and potential for disease prevention have been demonstrated by various in vitro and in vivo assays. A number of ellagitannins, the largest group of hydrolysable tannins, have been isolated from dicotyledoneous angiosperms a...
متن کاملIdentification of hydrolysable tannins in the reaction zone of Eucalyptus nitens wood by high performance liquid chromatography--electrospray ionisation mass spectrometry.
The first detailed analysis of the phenolic constituents of the reaction zones (tissue of antimicrobial defence) from the sapwood of a Eucalyptus spp. is presented. Plantation-grown Eucalyptus nitens trees with stem decay resulting from pruning wounds were sampled and extracts were prepared from healthy sapwood and from reaction zone tissue. Analysis by HPLC with ESI-MS revealed that a diverse ...
متن کاملEllagitannins of Davidia involucrata. I. Structure of Davicratinic Acid A and Effects of Davidia Tannins on Drug-Resistant Bacteria and Human Oral Squamous Cell Carcinomas.
We isolated a new ellagitannin, davicratinic acid A (5), together with four known ellagitannins, davidiin (1), granatin A (2), pedunculagin (3), and 3-O-galloylgranatin A (4), from an aqueous acetone extract of dried Davidia involucrata leaves. The known ellagitannins were identified based on spectroscopic data. The structure of davicratinic acid A (5), a monomeric ellagitannin possessing a uni...
متن کاملTannins of Constant Structure in Medicinal and Food Plants—Hydrolyzable Tannins and Polyphenols Related to Tannins
In addition to the commonly used classification as hydrolyzable tannins and condensed tannins, tannins can also be categorized into two other types: polyphenols of constant chemical structure (Type A) and polyphenols of variable composition (Type B). Both types of tannins and related polyphenols account for a large part of plant polyphenols, but accurate structure-activity correlations on a mol...
متن کاملHydrolyzable Tannins of Tamaricaceous Plants. 7.1 Structures and Cytotoxic Properties of Oligomeric Ellagitannins from Leaves of Tamarix nilotica and Cultured Tissues of Tamarix tetrandra.
Partially unacylated new oligomeric hydrolyzable tannins, nilotinin T2 (1, trimer) and nilotinin Q1 (2, tetramer), together with four known trimers, nilotinin T1 (3) and hirtellins T1-T3 (4-6), and a dimer, tamarixinin B (7), were isolated from the aqueous acetone extracts of leaves of Tamarix nilotica. Among them, the new trimer 1 and the known trimers 4 and 6, in addition to the partially una...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2009