Pharmacognosy with the Basics of Plant Biochemistry - Kovalyov V. M. 2004

Special Part
Peptides and Proteins
Characteristics of Some Important Representatives of Peptides and Proteins

Glutathione is one of the most widespread tripeptides found in plants, Bacteria, and animals.

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Glutathione (L-y-glutamyl-L-cysteinylglycine)

Its intracellular concentration ranges from 0.5 to 10 mM, significantly exceeding that of Cysteine. The presence of the SH group allows glutathione to exist in both reduced and oxidized forms. Its biological function is to protect the SH groups of Enzymes and other Proteins from oxidation. Glutathione reduces H2O2 and other peroxides, scavenges free radicals, facilitates the Transport of Amino acids across Cell membranes, and serves as a cofactor for A number of enzymes.

Fungal Peptides. Toxic Polypeptides have been isolated from mushrooms of the genus Amanita; they are classified as phytotoxins and will be discussed below. Several ergot Alkaloids also contain a peptide fragment. Cyclosporine A is a nine-amino-acid peptide isolated from Fungi of the genera Tolypocladium and Cylindrocarpon. The immunosuppressive properties of cyclosporine A are utilized in organ transplantation. Unlike other immunosuppressants, it is non-toxic to Bone Marrow Cells and lymphocytes.

Some peptides exhibit antibacterial activity and are used as medicinal agents.

Gramicidin S is a cyclic decapeptide produced by the soil-dwelling spore-forming bacterium Bacillus brevis. Chemical analyses have shown that the cyclic Structure of gramicidin includes: valine, Ornithine, leucine, phenylalanine, and Proline. The phenylalanine in this molecule is unusual, as its D-isomer had not previously been found in natural compounds. The antibiotic gramicidin is used for the Treatment and Prevention of purulent inflammatory processes.

Cyclopeptides also include the polymyxin group of Antibiotics, which are produced by spore-forming bacteria of the genus Bacillus polymyxa.

Hirudin is the primary peptide found in the Salivary Glands of the medicinal leech, Hirudo medicinalis, belonging to the phylum Annelida. Three subspecies of the medicinal leech are used for therapeutic purposes: Hirudo medicinalis officinalis (the apothecary medicinal leech), Hirudo medicinalis medicinalis (the medicinal leech), and Hirudo medicinalis orientalis (the eastern medicinal leech). It inhabits slow-moving or stagnant waters and marshes in the central and southern Regions of the European part of the continent, as well as in Transcaucasia. This species is endangered (listed in the Red Data Book in 1984). By a decision of the International Committee for the Protection of Species, commercial harvesting of leeches from natural Water bodies has been banned since 1997. Medicinal leeches are cultivated in specialized bio-factories (JSC "Biokon", Ukraine, Donetsk; JSC "Rospharmacia", Russia, Moscow Oblast). The body of the leech is covered with a tough cuticle and features yellow-orange stripes on its dorsal side. It consists of 33 segments, the first four of which form the anterior sucker, shaped like a tri-radiate slit with three jaw tubercles, each bearing 60 Teeth. The sucker surrounds the Oral Cavity, which connects to a small Esophagus and a large Stomach consisting of 10 pairs of lateral caeca. This allows the leech to ingest an amount of Blood two to three times its own body weight. This blood is digested over a period of 9 to 24 months.

The salivary Glands of the leech contain several polypeptides: the Thrombin inhibitor hirudin (molecular weight 7,100), bdellins—inhibitors of Trypsin and plasmin (molecular weights 7,000 and 5,600), and eglin—an inhibitor of Chymotrypsin and cathepsin (molecular weights 6,600–6,900). The Introduction/19.html">Primary Structure of hirudin comprises 65 amino acid residues. The uniqueness of its structure is determined by the presence of three Disulfide Bonds in its N-terminal region. The C-terminal region is rich in acidic Amino Acids and is responsible for the binding of hirudin to thrombin. It is believed that the reactive center of hirudin is represented by a Lysine residue. Leeches also produce the enzymes hyaluronidase, collagenase, destabilase, a histamine-like substance, and Prostaglandins.

The medicinal leech was used as a therapeutic agent by Pliny the Elder, Claudius Galen, and Avicenna. Leeches feed exclusively on the blood of animals or humans. In hirudotherapy, leeches are applied to reflexogenic points. This method is used to treat Hypertension, thrombophlebitis, cerebral vessel thrombosis, hemorrhoids, inflammatory processes, Nervous system disorders, Skin conditions, and in gynecology. Preparations made from leeches, such as the medication Hirudon and the ointment "Hiruf", possess anti-inflammatory and thrombolytic properties. Hirudon is also incorporated into a range of cosmetic products.

Interferons are highly specific proteins produced by the cells of vertebrates and humans in response to Inducers (Viruses, double-stranded viral RNAs, mitogens). Based on their site of production, they are divided into three groups.

1. Leukocyte interferon (alpha-interferon) is a mixture of proteins produced by leukocytes.

2. Fibroblast interferon (beta-interferon) consists of one or more Glycoproteins synthesized by fibroblasts (cells capable of producing Connective Tissue fibrous structures) upon exposure to double-stranded RNA.

Alpha- and beta-interferons have a Molecular Weight of approximately 20,000. Human alpha-interferons lack a glycosidic moiety and comprise 165–166 amino acid residues. Beta-interferons are glycoproteins whose protein component is built from 165 amino acids. They are synthesized as precursors from which the signal peptide is cleaved to yield mature interferons. Functionally, alpha- and beta-interferons are similar and bind to the same cell receptors. They are used as antiviral, immunoregulatory, and antitumor agents.

3. Immune interferon (gamma-interferon) is a simple protein or glycoprotein synthesized by T lymphocytes in response to mitogens (staphylococcal enterotoxin, certain Lectins, etc.). Its protein moiety has a molecular weight of 155,000 and consists of 143 amino acid residues, featuring two potential glycosylation sites. T lymphocytes synthesize gamma-interferon as an inactive precursor, from the C-terminus of which a variable number of Amino acids are cleaved off, resulting in the heterogeneity of gamma-interferon. Unlike alpha- and beta-interferons, immune interferon is acid-labile at pH 2. It exhibits weak antiviral activity alongside more pronounced immunomodulatory and antitumor effects.

Human alpha-interferon or recombinant alpha-interferon produced via Genetic Engineering is used as an antiviral, immunomodulatory, and antitumor agent.

High-protein products utilized in therapeutic and prophylactic formulations include royal jelly and spirulina.

Royal Jelly (Apilacum). Worker bees feed the queen bee with royal jelly, which is secreted by their mandibular glands. The secretion is deposited into a special wax cell containing the queen larva. Royal jelly (apilac) is harvested from queen cells using a spatula or under vacuum in aseptic conditions. Contamination leads to the inactivation of the jelly. Apilac is freeze-dried (lyophilized) in a vacuum at 45 °C and stored at 0 °C in airtight containers due to its instability.

Royal jelly is a thick, whitish-yellowish, sour-tasting cream-like mass with a specific odor. It contains albumins and globulins, 22 amino acids, Lipids, CARBOHYDRATES, Trace Elements (magnesium, manganese, calcium, chromium, nickel, cobalt, zinc, iron, sulfur), Vitamins (B₁, В₂, В₅, В₆, В₁₂, PP, H, C), enzymes, hormone-like substances, acetylcholine, DNA, and RNA.

Royal jelly is a biologically active and nutritious product with antiviral and antimicrobial properties; it stimulates METABOLISM, lowers Cholesterol levels, promotes hematopoiesis, regulates endocrine gland function, and boosts Immunity.

Apilac and apilactose preparations are prescribed for weak children, the elderly, and debilitated patients.

Spirulina (Spirulina Turpin) is a genus of multicellular filamentous organisms belonging to the family Hormogoniophyceae, class Cyanobacteria, kingdom Mychota.

Spirulina is a natural component of plankton in water bodies of Africa (Lake Chad) and Central America. In many countries, it is biotechnologically cultivated as a valuable protein source, most commonly using two species: Spirulina platensis and S. maxima.

The protein content in spirulina biomass reaches 60–70%, with a digestive assimilation rate of 80–90%. The protein profile is characterized by a well-balanced and high content of Essential Amino Acids. In addition, it contains carbohydrates (10–20%), Fatty acids (5–5.7%), including gamma-linolenic and palmitic acids; carotenoids (0.22–0.34%), chlorophyll, phycocyanin, polyphosphates, and Nucleic Acids. Spirulina biomass is rich in B-group vitamins (B₁, В₂, В₅, В₆, В₁₂), PP, E, ß-carotene, Folic acid, and Inositol. Key trace elements present include iodine and iron.

Spirulina has found wide application as a dietary Supplement rich in protein, vitamins, and microelements (such as Spirulina preparations, Splat, and complex food supplements).