Examination of Plant Drugs Containing Other Phenoloids

Biogenetic System of Plant Active Substances

The plant kingdom contains a complex biogenetic system of active substances. This hierarchy begins with Saccharides and Polyketides, leading into the broad category of Phenoloids. Within the Phenoloids, significant sub-groups include Phenol glycosides, Caffeic acid derivatives, Coumarins, Diarylheptanoids, Lignans, Flavonoids, Tannins, Naphthoquinones, Anthraquinones, and Terpenophenoloids. Other major categories in this system include Terpenoids and Azotoids. Specific focus is placed on caffeic acid derivatives, coumarins, diarylheptanoids, and phenol glycosides. Caffeic acid derivatives are characterized by a cinnamic acid base structure ($C_6 - C_3$).

Caffeic Acid Derivatives: Echinaceae Purpureae Herba

Bíbor kasvirág virágos hajtás (Echinacea purpurea L., Asteraceae) contains chlorogenic acid as a primary caffeic acid derivative. Other characteristic substances include alkamides and polysaccharides. Its medical applications are divided into internal and external uses. Internally, it is used for the prevention of recurrent upper respiratory infections as an immunomodulant. Externally, it is applied for inflammatory skin diseases. The molecular structure of chlorogenic acid involves multiple hydroxyl groups and a specific ester linkage between caffeic acid and quinic acid ($C_{16}H_{18}O_9$).

Caffeic Acid Derivatives: Rosmarini Folium and Melissae Folium

Rozmaring levél (Rosmarinus officinalis L., Lamiaceae) contains caffeic acid and rosmarinic acid, along with tannins, bitter substances, and essential oils. Internally, it serves as a digestive aid, while externally it functions as a hyperemizing and antirheumatic agent. Orvosi citromfű levél (Melissa officinalis L., Lamiaceae) contains rosmarinic acid, chlorogenic acid, and caffeic acid, complemented by essential oils. Its internal applications include the treatment of sleep disorders, anxiety reduction, and stimulating digestion. Externally, it is utilized for the treatment of herpes due to its antiviral properties.

Phenol Glycosides: Uvae Ursi Folium

Medveszőlőlevél (Arctostaphylos uva-ursi (L.) Spreng., Ericaceae) is characterized by phenol glycosides, primarily arbutin and methylarbutin, with a small amount of free hydrokinon (hydroquinone) and tannins. It is used for the treatment of symptoms associated with mild, recurring lower urinary tract infections. The arbutin molecule consists of a hydroquinone aglycone bound to a glucose moiety via a glycosidic bond.

Coumarin-Containing Drugs: Meliloti Herba and Aurantii Amari Epicarpium et Mesocarpium

Orvosi somkóró virágos hajtás (Melilotus officinalis (L.) Lam., Fabaceae) contains hydroxy- and methoxycoumarins such as umbelliferone and scopoletin. It is used internally to alleviate symptoms of mild venous circulatory insufficiency and externally for treating mild inflammatory skin symptoms. Keserű narancs epikarpium és mezokarpium (Citrus aurantium L. ssp. aurantium, Rutaceae) contains furanocoumarins, essential oil (limonene), and citrus flavonoids like hesperidin and naringin. This drug is primarily used for the isolation and extraction of citrus flavonoids.

Diarylheptanoids: Curcumae Longae Rhizoma and Curcumae Xanthorrhizae Rhizoma

Kurkuma gyökér (Curuma longa L., Zingiberaceae) contains diarylheptanoids such as curcumin, desmethoxycurcumin, and bis-desmethoxycurcumin, as well as essential oils. Jávai kurkuma gyökértörzs (Curcuma xanthorrhiza Roxb., Zingiberaceae) contains curcumin, desmethoxycurcumin, and essential oils. In these compounds, the substituents are defined as follows: for Curcumin, $R_1, R_2 = OCH_3$; for Desmethoxy-curcumin, $R_1 = OCH_3, R_2 = H$; for Bis-desmethoxy-curcumin, $R_1, R_2 = H$. Both drugs are applied to alleviate digestive complaints such as feelings of fullness, insufficient digestion, and flatulence.

Microscopic Identification of Rhizoma and Herba

Microscopic examination of Curcumae longae rhizoma powder reveals several characteristic elements. These include cortical fragments in surface view (A), reticulate or pitted vessels (B, C), and long, thick-walled unicellular covering hairs (D, E). It also contains epidermal fragments (F), parenchyma fragments carrying brownish-yellow oil masses with secretory cells (G), and cortical fragments in side view (H) showing the epidermal covering (Ha). In the case of Meliloti herba, examination shows covering hairs consisting of cells bent at right angles with a granular cuticle (A, B). Pollen grains with 3 germination pores (C) are present, along with epidermal pieces showing anomocytic stomatal apparatuses (Da, Db) and palisade parenchyma (Dc). Anthers (E, K), transport tissue from the stem with chambered fibers (F, Fb), spiral cell wall thickening (G), ground tissue containing calcium oxalate rosettes (J, Ja), and glandular hairs with multicellular heads and stalks (H) are also characteristic.

Chemical Identification of Echinacea Species via TLC

Differentiation between E. angustifoliae radix, E. pallidae radix, and E. purpureae radix is performed using Thin-Layer Chromatography (TLC/VRK). Samples are prepared by methanol (MeOH) extraction using ultrasound (UH) at room temperature, then concentrated to approximately $3\,ml$. For application, $10\,ml$ of extract is used alongside four standards: echinacoside, cynarin, caffeic acid, and chlorogenic acid. The stationary phase is developed using a mobile phase of toluene:ethyl-acetate:water:formic acid in a ratio of $5:95:10:10$. Visualization is achieved using Naturstoff-polyethylene glycol reagent under UV light ($365\,nm$). The Naturstoff reagent (1% methanolic diphenylboric acid-$\beta$-ethylamine ester) causes caffeic acid derivatives to show blue fluorescence at $365\,nm$, and polyethylene glycol increases detection sensitivity. Identification is based on the presence of specific markers: E. angustifolia contains caffeic acid, cynarin, chlorogenic acid, and echinacoside. E. pallida contains caffeic acid, chlorogenic acid, and echinacoside (lacks cynarin). E. purpurea contains caffeic acid and chlorogenic acid (lacks cynarin and echinacoside).

Fluorescence of Coumarins and Curcuminoids

Coumarins in Meliloti herba and Aurantii amari epicarpium et mesocarpium are identified by their fluorescence at $366\,nm$. Upon treatment with $20\,\%$ NaOH, the lactone ring opens, which increases fluorescence intensity and may change the color. Subsequent treatment with concentrated HCl causes recyclization, restoring the original fluorescence. For Curcumin samples (Curcumae longae rhizoma and Curcumae xanthorrhizae rhizoma), a methanol extract ($0.2\,g$ powdered drug in $25\,ml$ methanol, diluted to $50.0\,ml$) is used for TLC. Curcumin has a solubility in ethanol of $10\,mg/ml$ and in water of $< 0.1\,mg/ml$. The extensive conjugated double-bond system and keto-enol tautomerism result in intensive absorption maxima ($410-430\,nm$) and fluorescence at $365\,nm$. Under UV light ($365\,nm$), curcumin and desmethoxy-curcumin appear bright green, while bis-desmethoxycurcumin appears greenish-yellow.

Quantitative Determination of Dicinnaomyl-methane Derivatives

The determination of diarylheptanoids in turmeric samples according to Ph. Hg. VIII involves measuring absorbance at $425\,nm$ using methanol as a compensating liquid. A $2\,ml$ aliquot of the stock solution (prepared from $0.200\,g$ drug in $50.0\,ml$ methanol) is diluted to $25.0\,ml$. The calculation uses the specific absorption coefficient of curcumin ($A^{1\%}_{1cm} = 1607$) and the Lambert-Beer law ($A = A^{1\%}_{1cm} \times c \times l$). The percentage content of diarylheptanoids expressed as curcumin is calculated using the formula: $\% = \frac{50 \times A \times 25}{1607 \times 100} \times \frac{100}{m}$ which simplifies to: $\% = \frac{A \times 1250}{m \times 1607}$ where $A$ is the measured absorbance and $m$ is the weighed mass of the drug in grams.

Quantitative Determination of Arbutin in Bearberry

The arbutin content of Uvae ursi folium is determined via High-Performance Liquid Chromatography (HPLC-UV) at $280\,nm$. The test solution is prepared from $0.8000\,g$ of powdered drug extracted with water ($2 \times 20\,ml$) and adjusted to $50.0\,ml$. The stationary phase is a $C18$, $5\,\mu m$, $250 \times 4\,mm$ column. The mobile phase consists of methanol-water ($1:9, v/v$) with a flow rate of $1.2\,ml/min$. Arbutin demonstrates an UV spectrum with maxima at $223\,nm$ and $282\,nm$. Quantitative assessment is based on the peak area compared to a standard arbutin solution ($50.0\,mg$ in $50.0\,ml$ mobile phase). This is a reversed-phase HPLC method where the stationary phase is non-polar and the mobile phase is polar.

Quantitative Determination of Total Hydroxycinnamic Acid Derivatives

Total hydroxycinnamic acid derivatives, expressed as rosmarinic acid, are determined in Rosmarini folium and Melissae folium using spectrophotometry at $505\,nm$. The drug is extracted with $50\,\% V/V$ MeOH for 30 minutes. The test solution is treated with hydrochloric acid (to prevent precipitation), sodium nitrite (reagent), and sodium molybdate solution (stabilizer), followed by NaOH to develop a stable reddish color (from an unstable yellow). The calculation uses a specific absorption coefficient ($A^{1\%}_{1cm}$) of $400$. The percentage content is calculated as: $\% = \frac{50 \times A}{400 \times 10} \times \frac{100}{m} \times \frac{1}{10} \times 50 \times \frac{1}{50}$ which simplifies to: $\% = \frac{1.25 \times A}{m}$ where $A$ is the measured absorbance and $m$ is the weighed mass of the drug in grams.