Tlc

HPLC LC-MS GC-MS Reaction tests

DNA analysis

FIGURE 4.3 Flow chart for authentication of botanical materials. (Image courtesy of Hans Wohlmuth, Southern Cross University, Lismore, NSW, Australia.)

Lastly, an authoritative description should be prepared from whole, unmilled samples of the plant part (see the "Use of Whole Materials versus Powders" section). This allows for the observation of the internal three-dimensional arrangement of the tissues. Such internal structures can be viewed with the preparation of transverse and longitudinal sections. Characterizations from prepared sections provide critical information because, as noted previously, the arrangement of the tissues within a plant is much more diagnostic of a species than are the tissues, which are common to many species. The amount of structural information contained within a given sample decreases dramatically from whole plant parts that can be sectioned to the cut drug to the powder (Figures 4.4 and 4.5). Following these five primary criteria will give the greatest assurance that one is working with a microscopic characterization that is considered authoritative (Table 4.1).

In whole material or material that is coarsely chopped or sliced, a deviation of the arrangement of tissues from what is expected in the material under examination is an indication of the presence of an adulterant. However, once material is powdered, adulterants can only be detected if the microscopist is astute enough to find fragments of tissue that are not characteristic of the botanical being studied or that occur at far higher or lower frequencies than expected. Such fragments might include leaf epidermis with diagnostic trichomes and stomatal complexes, floral parts, crystals, or a crystal sheath surrounding a vein or attached to fibers. Powdered aerial plant parts are far easier to identify than roots and rhizomes because many of their diagnostic features can be found in surface views of fragments; in underground organs, the arrangement of tissues that is diagnostic is lost in powders.

In powdered samples, fragments of epidermis, cork, fibers, and vessels typically remain intact and recognizable; however, delicate tissues such as the cambium and sieve cells are completely disintegrated and trichomes are often shattered, making characterization difficult. Crystals, which are highly diagnostic, may or may not separate from the tissue in which they occur, depending on how they are arranged in the plant. Unlike whole material, which can be identified using an authoritative description, powder cannot be reliably identified as to species unless it is compared against a BRM.

Sample selection for the development of microscopic descriptions is best done with the use of a stereomicro-scope that has a magnification of at least 10-20x. Use of a stereomicroscope allows for foreign matter such as other plant parts or filth to be easily recognized and separated. It can also ensure that material showing structural degradation due to mold is not chosen for examination.

If these five criteria are met, the characterization can be considered authoritative and appropriate to use as an identity standard.

FIGURE 4.4 (a) Decreasing reliability in making an identity determination with increased comminution of herbal material. (b) Whole roots of goldenseal. (c) Cut; and (d) powdered roots of goldenseal (Hydrastis canadensis). (Image (b) courtesy of Martin Wall Photography, Greensboro, NC; images (c-d) courtesy of Roy Upton, Soquel, CA.)

FIGURE 4.4 (a) Decreasing reliability in making an identity determination with increased comminution of herbal material. (b) Whole roots of goldenseal. (c) Cut; and (d) powdered roots of goldenseal (Hydrastis canadensis). (Image (b) courtesy of Martin Wall Photography, Greensboro, NC; images (c-d) courtesy of Roy Upton, Soquel, CA.)

FIGURE 4.5 Differentiation between microscopic observation of a whole plant part and a powder. (a) Cross section of goldenseal (Hydrastis canadensis) root showing characteristic arrangement of tissue elements; (b) powder of goldenseal root showing scalariform vessels, starch granules, and granular masses. (Image courtesy of Prof. Dr. Reinhard Länger, AGES PharmMed, Vienna, Austria.)

FIGURE 4.5 Differentiation between microscopic observation of a whole plant part and a powder. (a) Cross section of goldenseal (Hydrastis canadensis) root showing characteristic arrangement of tissue elements; (b) powder of goldenseal root showing scalariform vessels, starch granules, and granular masses. (Image courtesy of Prof. Dr. Reinhard Länger, AGES PharmMed, Vienna, Austria.)

Additional factors should be considered when reviewing characterizations of some materials—most particularly, the effects of processing on the structural elements of botanicals. This is predominantly a consideration with ayurvedic and Chinese botanicals that are processed before use or before they are entered into trade. For example, the root of processed Asian ginseng (Panax ginseng) is anatomically identical to that of unprocessed root except that the steaming process turns the starch granules into gelatinous masses that give the parenchyma cells a swollen appearance (Figure 4.6). Roots of astragalus (A. mongholicus) and dong quai (Angelica sin-ensis) are often soaked and pounded, which can destroy or alter the structural tissues of the material.

Another consideration is that cultivated material may present demonstrably different morphological characteristics than material that is wild harvested (Figure 4.7). Such differences should also be taken into account.

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