Identical secondary components

To ensure lot-to-lot consistency, standardization of extracts often relies on constituents as biomarkers for plant identity and potency. SJW Hypericum perforatum), a perennial shrub traditionally used as a mood enhancer and mild antidepressant, has been tested in dozens of clinical trials, with mixed results for efficacy. Some of its purported bioactive constituents include naphthodianthrones, including hypericin flavonoids phloroglucinols, including hyperforin and essential oils. For many years, hypericin was presumed to be the active component. As a result most extracts were standardized based on hypericin concentration. Recent data, however, support other components such as hyperforin and the flavanoids, that may also contribute to the therapeutic efficacy of the SJW extracts (33-35). Because these secondary components were previously unaccounted for in the standardization of the former clinical test articles, and because these constituents are chemically unrelated to and their content within the plant varies independently of hypericin, it has been argued that the potency of these constituents in any particular batch was unlikely to be similar to that of other batches. This variability between batches could explain the observed differences in the clinical trial results (36). 

Although there is notoriously no unanimous agreement on what the supervenience relationship is, the most popular view is that supervenience is a relationship of asymmetric dependence. Two macroscopic systems which have been constructed from identical microscopic components are assumed to show identical macroscopic properties, whereas the observation of identical macroscopic properties in any two systems need not necessarily imply identity at the microscopic level. In simpler terms, the phenomena we study in some secondary science are thought to be ontologically dependent upon relationships at the primary level whereas macroscopic identity need not imply microscopic identity. 

An unequivocal identification of an unknown compound is unlikely by chromatographic processes alone. Not the least of the reasons for this is the need for comparison to standards thereby assuming reasonable prior assurance of the possible identity of the unknown. It should be noted that in addition to retention time measurements obtained on two or more column systems, if reasonable care has been exercised, quantitative measures of the suspect compound should also correspond, thus providing an additional secondary identification. In other words, whatever the unknown compound may be, it cannot be a mixture of two components on one column and a single component on the second column without... 

Ribonuclease-S can be separated into S-peptide [residues 1-20 (21)] and S-protein [residues 21 (22)-124] by precipitation with trichloroacetic acid 73) or better, Sephadex chromatography in 5% formic acid 83). The best preparations of these components show no detectable hydrolytic enzymic activity and little if any transphosphorylation activity (see Section VI). Isolated S-peptide appears to have no regular secondary structure 83, 84) or 10-20% helicity 85, 86). (These slightly different interpretations are based on almost identical CD data.) When equimolar amounts of S-protein and S-peptide are mixed at neutral pH and room temperature or below, essentially full catalytic activity is recovered 73, 87). A schematic diagram is shown in Fig. 7. For a detailed summary of the preparative procedures see Doscher 88). 

The various classes of metallic phases that may be encountered in crystalline alloys include substantially pure elements, solid solutions of one element in another and intermetallic compounds. In crystalline form, alloys are subject to the same type of defects as pure metals. Crystalline alloys may consist of a solid solution of one or more elements (solutes) in the major (base) component, or they may contain more than one phase. That is, adjacent grains may have slightly or extremely different compositions and be of identical or disparate crystallographic types. Often, there is one predominant phase, known as the matrix, and other secondary phases, called precipitates. The presence of these kinds of inhomogeneities often results in the alloy having radically different mechanical properties and chemical reactivities from the pure constituent elements. (Noel)5... 

The data in Table 5-1 also demonstrate several other behaviors typical of reverse-phase chromatography. First, the elution order of the sample components is from the most polar, eluting first, to the most nonpolar, eluting last. Second, as the eluent is made more polar (more water), the sample compounds are less soluble in the mobile phase, and hence more soluble in the stationary phase. Therefore, retention is increased. The third behavior is that for every compound and stationary phase combination, a variety of solvent mixtures can be used as mobile phases to elute a compound with approximately the same k value. Mobile phases that have identical eluent strengths are referred to as isoeluotropic or equieluotropic for that compound. The general trend is for similar retention to exist in isoeluotropic mobile phases. However, isoeluotropic mobile phases sometimes have a different selectivity (a) for a pair of compounds due to secondary interactions between the solvent and analyte. 

A number of PS II inhibitor treatments, such as Tris-washing and NH2OH extraction, had been well established as releasing Mn from the OEC [109]. Aker-lund, Andersson and co-workers showed that these treatments also released the peripheral polypeptides [71]. Mathis and co-workers showed that the ns phases in P-680 reduction that occur in untreated preparations are replaced by fxs components in inhibited samples [180]. The predominant decay phase is pH dependent, =2 ijs at pH 8 and =45 /is at pH 5, and is attributed to P-680 reduction by a secondary donor, usually designated D in optical work, which is identical to the EPR-detectable Z species [180,194,195]. The bulk pH and salt concentration dependencies of this phase implicate local membrane pH in influencing its time course... 

Further evidence for the validity of the approach adopted by Baldwin et al. and Hughes et al. comes from a comparison of activation energies for the formation of the same sized rings but formed by either primary, secondary or tertiary hydrogen abstractions. According to the two component hypothesis advanced above the ring strain component should be identical in both cases and this is borne out by the following observations ... 

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