Pharmacognostic studying of leaves of stevia
In the present study morphology, anatomical studies and qualitative responses of Stevia rebaudiana leaves has carried out.
Work purpose was to study external signs, an anatomic structure of leaves of stevia. To carry out with extraction from qualitative tests. To find a way of identification of leaves of stevia in herbal mixture.
Materials and methods were: stevia leaves from the consumer packings made in the Russian Federation and China, and contents the filter packages from consumer packing «Drink tea» «Sweet» (Tea black with a stevia and mint)" has studied.
External signs of leaves as medicinal raw materials (MRM) have studied with used a binocular microscope of MBS-10. For carrying out microscopic researches prepared slides according to "Technique of microscopic and microchemical research LRS" (Russian State Pharmacopoeia XI). Used LOMO microscope Mikmed - 1 with binocular AU-12 1,5х (an eyepiece 10х, lenses 10х, 20х, 40х). Photos have received by means of the Cannon power Shot A450 camera and edited in the Microsoft Office Picture Manager program. For carrying out qualitative tests used the cooled and filtered water and aqueous-alcoholic extraction from stevia leaves. Reactants: solution of 2,5% NaOH concentrated by HCl, magnesian shaving, 2% FeCl3 solution, 10% an aqueous solution of ink.
On external signs the integral raw materials represent short petiole leaves of an oval form. Leaf basis is the wedge shaped. Leaf margins is toothed. Color of leaves from the top party green, from the bottom - gray-green. The smell is absent.
At anatomic research of leaves of a stevia the following diagnostic signs are revealed: sinuous walls of cages of epidermis from both parties of a leaf. Stomatal apparatus is of anomocytic type with 4-5 near epidermal cells. On the bottom false skin often meet trichoms. They are located both on the sheet edge and on all sheet plate and are presented by prime multicellular hairs (on the average on 6-7 cells). Trichoms located on the sheet edge, often break off.
When receiving water and aqueous-alcoholic extraction at raw materials of the Chinese production more satu¬rated aroma and color of solution has noted. When carrying out histochemical reaction of powder of leaves with solution of ink observed on a black hum noise white spots. Existence in leaves of a stevia of mucilages is established. At vigorous agitation of water extraction from leaves of stevia observed the resistant and plentiful foam which is not disappearing within 15 minutes that testifies to availability of saponins. For presence studying flavonoids in stevia leaves to aqueous-alcoholic extraction added HCl and magnesian shaving (Shinod's test). Observed emergence of pink coloring. To the diluted water extraction from MRM added one drop of FeCl3 solution. In the first second noted emergence of black and green coloring that proves availability of tanning agents of the condensed group.
Qualitative tests on presence of saponins and flavonoids in MRM of the Chinese production yielded the negative result.
We investigated drink tea «Sweet» representing packed-up dosed production - collecting from leaves of tea, mint and a stevia. Leaves of black tea diagnosed visually. For establishment of differences between leaves of mint and a stevia studied anatomic diagnostic signs. Authenticity of leaves of mint established on existence in a micropreparation of etherolied pieces of iron of a spherical form, the endevice of diacytic type and prime multicellular hairs with a roughly warty surface. The micropreparation of leaves of stevia had prime multicellular hairs and anomocytic type of the stomatal apparatus.
Е. М. Раснер
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