Chaenomeles chinensis

Fig. 7.7.1. NMR spectra of some proanthocyanidin polymers in d -acetone/water (1 1, v/v) a. An epicatechin (procyanidin) homopolymer, one of the most common encountered in nature, from Chaenomeles chinensis fruit b. A gallocatechin (prodelphinidin) homopolymer from Watsonia ard-nerei leaves c. A mixed gallocatechin-4 and epigallocatechin-4 (prodelphinidin) polymer from immature flowers of Trifolium repens...

Fig. 7.7.2. Structure of an average molecule of the procyanidin polymer from Chaenomeles chinensis fruits as deduced from high-field NMR. a = branched chain b = linear chain. T unit = H R = flavanoid. M unit R or R = H R or R = R = flavanoid J unit R = R = R = flavanoid B unit R or R = flavanoid R or R = R = H...

It has also been observed that proanthocyanidins normally accumulate in plant tissue as polymers rather than lower oligomers (dimers or trimers). This implies that the major biosynthetic route is directed toward the synthesis of proanthocyanidin units to form those polymers, in contrast to the formation of lesser amounts of monomeric flavan-3-ols. For instance, the total production of epicatechin, including that present as monomer and as a terminal (B) unit in the polymers, is only 10% that of epicatechin-4 procyanidin units, in the tannins extracted from the unripe fruits of Chaenomeles chinensis (L. J. Porter, unpublished observations). 

V. oreophilum, Vitex labrusca, V. agnus-castus Actinidia polygama Belamcanda chinensis Belamcanda chinensis Chaenomeles speciosa Lemna minor... 

Haslam (57) noted earlier that two distinct and very common patterns may be distinguished in the procyanidins (i) those based on epicatechin-4 (T and M) units with also an epicatechin terminal (B) unit, and (ii) those based on epicatechin-4 (T and M) with a contrasting catechin terminal (B) unit. Those included in Type (i) were procyanidins from Malus pumila, Crataegus oxyacantha, Theobroma cacao, Cotoneaster sp., Cydonia oblonga, Prunus cerasus, and Aes-cuius hippocastanum. We have confirmed that this holds true for the procyanidin polymers as well, and others of this type include those from Chaenomeles chinen-sis, Persea americana, and Actinidia chinensis. 

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