Plants materials, hydrolysis

The source of senecifoline is uncertain since Barger and his co-workers (44) were not able to isolate any senecifoline from Senedo latifolius when they repeated the work of Watt (48) on carefully identified plant material. Hydrolysis (48) C.sHryNOs + HrO CsH.aNOr + C,oH,9, ( )... 

Fresh plant material is mixed with two volumes of methanol containing 0.3% concentrated HCl. If particularly labile compounds are known or found to be present, methanol containing 5% acetic acid may be used to advantage because this prevents hydrolysis of the acyl groups sometimes present on the sugar moieties while maintaining the low pH required to retain the pigments in the flavinium ion form. 

If the relevant residue cannot be properly determined using a routine multi-method, an alternative method must be proposed. In the case of residues consisting of a variety of structurally related compounds, a common moiety method may be acceptable in order to avoid the use of an excessive number of methods for individual substances. For example, the relevant residue of isoproturon in plant material is defined as the sum of isoproturon and all metabolites containing the 4-isopropylaniline group. Therefore, residues are determined following hydrolysis as 4-isopropylaniline and are expressed as 4-isopropylaniline equivalents. It is not necessary to validate the method individually for all possible metabolites which are covered by the residue definition (e.g., all metabolites which contain the 4-isopropylaniline group), provided that it is demonstrated that in the first step, the conversion to the common moiety is complete. However, common moiety methods often lack sufficient specificity, and should therefore be avoided if possible. If need be, their use must be justified. 

In subsequent smdies, it was shown that, atfer hydrolysis, about 42% of the total radioactive residue in grain may be identified as 4-fert-butylcyclohexanone. Moreover, 34-90% of the TRR was extracted by heating the plant material under reflux with a mixture of methanol and hydrochloric acid. The performance of that method was properly demonstrated by individual fortification experiments with the parent compound and the three primary metabolites (bold in Figure 1). 

Lineweaver and Ballou49 have proposed a pectinesterase unit ( PE. u. ) for expressing PM activity. One such unit is equivalent to 1/930 PMU under the same experimental conditions or the quantity of enzyme that, at 30° and optimum pH, will catalyze the hydrolysis of pectin at an initial rate of one milliequivalent ester bonds per minute in a standard substrate (0.5% citrus pectin containing 8-11% methoxyl) and 0.15 M sodium chloride. The use of the latter unit is unfortunate since the values obtained for the activity in ordinary plant materials are obtained in the third decimal place and because the experimental conditions are so... 

Relatively pure xylan isolated from the holocellulose of aspen (Populus) wood is said to contain 85% of xylose residues.78 One of the characteristic properties of xylan is its ease of hydrolysis. Because it hydrolyzes much more readily than cellulose, mild acid treatment may be employed to bring about preferential hydrolysis of xylan from plant material. Xylose is ordinarily prepared in the laboratory by direct sulfuric acid hydrolysis of the native xylan in ground corn cobs.74 Hydrolysis in hydrochloric acid proceeds rapidly, but decomposition to furfural also occurs to some extent.76 A commercial method for the production of D-xylose from cottonseed hulls76 and straw77 and from corn cobs17 78 has been described. 

The roots of the misidentified plant material Ipomoea murucoides were dried, pulverized, and macerated in chloroform. In reality, the analyzed plant material was /. arborescens as revealed by its chemistry which proved to be totally different from that identified for 7. murucoides (63), when the latter was fractionated by column chromatography. The basic hydrolysis of the resinous chromatographic fractions of this sample produced the same glycosidic acid derivative ultimately found in I. arborescens, i.e., murucinic acid (hexadecanoic acid, (115)-[((9-)S-d-... 

In general, absorbent sutures are composed of materials that are natural to mammals, such as catgut, and to materials that are either quite susceptible to hydrolysis and/or polymers derived from natural materials such as polyglactin, which is a copolymer of lactic and glycolic acid. Nonabsorbent sutures can be made from natural materials such as cotton, which is a plant material, polymers that range from being hydrophobic to hydrophilic, and steel. 

Effects of extracts with dry material and with fresh material were not correlated. This may be because drying plant material causes hydrolysis of glucosinolates to isothiocyanates, while autolysis of fresh crucifers yields predominantly nitriles (28). 

Alteration of essential-oil components during distillation can be recognized by comparing the oils obtained by steam distillation and by SFE. The hydrolysis of esters (like linalyl acetate) to the corresponding alcohols was observed in clary sage oils. The hydrolysis of thymol bound in glycosides resulted in different thymol concentrations in distilled thyme oils, which was proved by appropriate treatments (acidic and enzymatic) of the previously CO2-extracted plant material. 

Complex glycosides, which upon hydrolysis yield hydrogen cyanide, are commonly found among plant materials. The uixlcity of this class of compounds, found in Ihc biller almond, pits of stone fruits, sorghum, and lima beans, is directly related to HCN liberation upon digestive hydrolysis. 

Presence of native starch crystals. In plant materials, starch exists as semicrystalline, granular entities. Starch molecules, both amy-lose and amy lopectin, with their many intermo-lecular hydrogen bonds, give structure to the starch granule (Zobel, 1988). The crystalline regions formed by this intermolecular hydrogen bonding are somewhat resistant to enzyme hydrolysis and need to be broken prior to enzyme treatments. 

This is the classical method of extracting anthocyanins from plant materials. This procedure involves maceration or soaking of the plant material in methanol containing a small concentration of mineral acid (e.g., HC1). Methanol extraction is a rapid, easy, and efficient method for anthocyanin extraction. However, a crude aqueous extract with several contaminants is obtained, and methanol evaporation can result in hydrolysis of labile acyl linkages, which is aggravated by the presence of HC1. 

Metabolism of pectin. Pectin has only recently come, to be considered a part of the dietary fiber complex. Previously it was excluded because 1) it is not fibrous (except at the molecular level), 2) it escapes detection in standard fiber tests owing to its solubility, and 3) it usually does not survive intestinal passage. In a reassessment of which dietary components should be considered fiber, Trowell (49) proposed that dietary fiber include those constituents of food resistant to hydrolysis by man s alimentary enzymes. Spiller (50, 51) suggested that confusion surrounding the term "fiber" be avoided by using the term "plantix" to denote those plant materials of polymeric nature not attacked by human digestive enzymes. 

Wintergreen Gaultheria procumbens (Ericacae) or Betula lenta (Betulaceae) leaves bark 0.7-1.5 0.2-0.6 methyl salicylate (98%) flavour, antiseptic, antirheumatic prior to distillation, plant material is macerated with water to allow enzymic hydrolysis of glycosides methyl salicylate is now produced synthetically... 

Aconites, commonly called wolfsbane or monkshood, are species of Aconitum (Ranunculaceae), valued ornamental herbaceous plants, grown for their showy blue or purple flowers, which are shaped like a monk s cowl. Their alkaloid content, mainly in the roots, makes them some of the most toxic plants commonly encountered. The dried roots of Aconitum napellus were once used, mainly externally for relief of pain, e.g. in rheumatism. The toxic alkaloids (0.3-1.5%) are complex diterpene-derived esters. Aconitine (Figure 6.124) is the principal component (about 30%) and is a diester of aconine with acetic and benzoic acids. Hydrolysis products benzoylaconine and aconine are also present in dried plant material. These alkaloids appear to behave as neurotoxins by acting on sodium channels. All species of Aconitum and Delphinium are potentially toxic to man and animals and must be treated with caution. 

---