Hydrangea species

Allergic contact dermatitis to Hydrangea species has been reported, primarily in agricultural workers (Avenel-Audran et al. 2000 Bruynzeel 1986,1991 De Rooij et al. 2006 Kuligowski et al. 1992 Meijer et al. 1990 Rademaker 2003). 

In Chinese medicine, the roots, leaves, and flowers of certain Hydrangea species (e.g., H. macrophylla, H. strigosa Rehd., H. umbel-lata Rehd., aaAH.paniculata) are used to treat malaria and as diuretics and antitussives (jiangsu). 

You may be surprised to learn that many metal cations act as weak acids in water solution. A 0.10 M solution of A12(S04)3 has a pH close to 3 you can change the color of hydrangeas from red to blue by adding aluminum salts to soil At first glance it is not at all obvious how a cation such as Al3+ can make a water solution addic. However, the aluminum cation in water solution is really a hydrated species, A1(H20)63+, in which six water molecules are bonded to the central Al3+ ion. This spedes can transfer a proton to a solvent water molecule to form an H30+ ion ... 

In addition to lupines, poison-hemlock and Nicotiana spp., other plant species of the genera Genista, Prosopis, Lobelia, Cytisus, Sophora, Pinus, Punica, Duboisia, Sedum, Withania, Carica, Hydrangea, Dichroa, Cassia, Ammondendron, Liparia, and Colidium contain potentially toxic and teratogenic piperidine alkaloids. Many plant species or varieties from these genera may be included in animal and human diets (Keeler and Crowe, 1984). 

Cassava, lima beans, linseed, bamboo sprout, macadamia nuts, hydrangea, Rosaceae family (plum, peach, pear, apple, bitter almond, cherry). Sorghum species (Johnson grass, sorghum, Sudan grass, arrow grass), Linum species (flax, yellow pine flax)... 

That this cannot be the only mechanism reducing DHA in plant tissues seems evident from other considerations. Crook and Morgan (1943) found no evidence of the presence of a dehydroascorbic acid reductase in 8 out of 30 species of plants examined. Some plants which have been shown to reduce DHA readily, e.g., hydrangea (Rubin et al., 1937), do not possess an active dehydroascorbic acid reductase. 

Furthermore, rarely found in plant materials are also isocoumarins (3,4-benzo-2-pyrones or lH-2-benzopyran-l-ones), which are polyketides together with related stilbenes and coloured chalcones, but which are unlike other coumarins. Examples of dihydroisocoumarins are hydrangenol and phyllodulcin (10-141) located in the leaves of the large leaf hydrangea Hydrangea macrophylla, Hydrangeaceae) and similar species. Phyllodulcin... 

Of the leaves of numerous Hydrangea and Viburnum species tested for tannic substances and flavonoids (quercetin, cyanidin, kaemp-ferol, and luteolin), only those of H. arborescens and a subspecies of H. macrophylla were found to lack tannins and cyanidin but to contain comparable quantities of quercetin and kaempferol. This perhaps can give some indication as to the possible similarity in other constituents. 

Figure 6.12 Some examples of iridoids. Iridomyrmecin and dolichodial are from ants, chrysomelidial from a leaf beetle larva, anisomorphalfrom a stick insect, nepetalactone from aphids and the catnip plant, loganin from Strychnos fruits and Hydrangea bark, and actinidine accompanies iridoids in many species...

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