Studies on Tannins. IV

Tannins 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...

Studies on Self-Sterility. IV. Selective Fertilization.

INTRODUCTION .................................................................. 346 Discussion of the problem ..................................................... 348 Pollen-tube frequency distributions ............................................. 349 Influence of growth of compatible pollen tubes upon incompatible pollen tubes.. .. 352 SUMMARY AND DISCUSSION ....................................

Structural studies on human type IV collagen.

Type IV collagen was isolated from limited pepsin digests of human placenta by selective salt precipitation at acidic and neutral pH. The native protein was resistant to human skin collagenase but was cleaved by a rat mast cell protease. Molecular sieve chromatography of the reduced and alkylated material separated relatively homogeneous components of molecular weight 140,000 (140K) and 100,000...

Studies on Plasma Protein. IV. Leprosy

Does Propolis Contain Tannins?

Although polyphenols have been reported as common constituents of propolis, tannins have rarely been mentioned as its constituents. Propolis samples from seven localities in Brazil were analyzed for detection of proanthocyanidins (condensed tannins) and determination of the tannin content. Positive reaction for proanthocyanidins was observed for all samples tested. The contents of tannins varie...