Abstract

Provided are a diimide derivative represented by formula I, a preparation method therefor and the use thereof. The diimide derivative has a good anti-tumor activity, and the anti-proliferative activity against various cancer cells is significantly better than those of similar compounds. Provided are a diimide derivative represented by formula I, a preparation method therefor and the use thereof. The diimide derivative has a good anti-tumor activity, and the anti-proliferative activity against various cancer cells is significantly better than those of similar compounds.

IPC Classes  ?

• C07D 221/14 - Aza-phenalenes, e.g. 1,8-naphthalimide
• A61K 31/47 - QuinolinesIsoquinolines
• A61K 31/496 - Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
• A61P 35/00 - Antineoplastic agents
• C07D 221/18 - Ring systems of four or more rings

Abstract

Disclosed is a composition of cefoperazone sodium and tazobactam sodium. High performance liquid chromatography analysis of the composition shows that the composition has specific chromatogram characteristics. The composition can be combined with another agent to form a significantly stable product. When the composition is combined with a solution for injection, the resulting solution can have a stable pH value and a stable degree of clarity for a long time. When the composition is used to prepare a drug, the drug will have a good therapeutic effect and a low risk of adverse reactions. Further disclosed is a quality control method for cefoperazone sodium and tazobactam sodium, with which the quality of the composition can be efficiently controlled to obtain a drug capable of being combined with another agent to form a product with excellent stability. The present invention can offer benefits for improving drug quality, medication safety, effectiveness, and the like, thus having good application prospects.

IPC Classes  ?

• A61K 31/546 - Compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula , e.g. cephalosporins, cefaclor, cephalexine containing further heterocyclic rings, e.g. cephalothin
• A61P 31/04 - Antibacterial agents
• A61K 31/4192 - 1,2,3-Triazoles
• A61K 31/431 - Compounds containing 4-thia-1-azabicyclo [3.2.0] heptane ring systems, i.e. compounds containing a ring system of the formula , e.g. penicillins, penems containing further heterocyclic ring systems, e.g. ticarcillin, azlocillin, oxacillin

Abstract

Provided is a fused ring diimide derivative having a chemical structure of formula I. Further provided is a preparation method therefor. The fused ring diimide derivative has excellent anti-tumor activity, and the anti-proliferative activity on various cancer cells is significantly better than that of similar compounds. Provided is a fused ring diimide derivative having a chemical structure of formula I. Further provided is a preparation method therefor. The fused ring diimide derivative has excellent anti-tumor activity, and the anti-proliferative activity on various cancer cells is significantly better than that of similar compounds.

IPC Classes  ?

• C07D 221/14 - Aza-phenalenes, e.g. 1,8-naphthalimide
• C07D 209/66 - Naphtho [c] pyrrolesHydrogenated naphtho [c] pyrroles with oxygen atoms in positions 1 and 3
• C07D 221/18 - Ring systems of four or more rings
• C07D 491/06 - Peri-condensed systems
• A61P 35/00 - Antineoplastic agents

Abstract

Provided are a diimide derivative, a preparation method therefor and the use thereof. The diimide derivative has a good anti-tumor activity, and the anti-proliferative activity against various cancer cells is significantly better than those of similar compounds. (I)

IPC Classes  ?

• C07D 221/14 - Aza-phenalenes, e.g. 1,8-naphthalimide
• C07D 401/12 - Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links
• A61K 31/496 - Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
• A61P 35/00 - Antineoplastic agents

Abstract

A drug, food and application of an anti-coronavirus infection, the drug or food containing lysozyme or a combination that comprises lysozyme; the lysozyme or a combination thereof can be used to prepare a drug for anti coronavirus infection and preventing or treating coronavirus-related diseases or symptoms, or food for assisting in anti coronavirus infection and assisting in preventing or treating coronavirus-related diseases or symptoms. The present disclosure has a good preventive and therapeutic effect on coronavirus infection or related diseases or symptoms thereof; in addition, the present application can accelerate the elimination of the virus in vivo, accelerate the speed of coronavirus nucleic acid tests in vivo turning negative, shorten the course of a patient's illness, effectively prevent and reduce the spread of coronavirus, and also has important social benefits and good application prospects.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 31/704 - Compounds having saccharide radicals attached to non-saccharide compounds by glycosidic linkages attached to a carbocyclic compound, e.g. phloridzin attached to a condensed carbocyclic ring system, e.g. sennosides, thiocolchicosides, escin, daunorubicin, digitoxin
• A61P 31/14 - Antivirals for RNA viruses
• A61P 11/00 - Drugs for disorders of the respiratory system
• A61P 1/00 - Drugs for disorders of the alimentary tract or the digestive system
• A23L 33/105 - Plant extracts, their artificial duplicates or their derivatives

Abstract

Disclosed are a pharmaceutical composition containing cefoperazone sodium and tazobactam sodium, and an application thereof. In the pharmaceutical composition, the weight ratio of cefoperazone sodium to tazobactam sodium is 6:1. In the treatment of renal insufficiency combined with bacterial infection, the pharmaceutical composition can effectively increase clinical efficacy and also significantly reduce the incidence of adverse reactions, thereby excellently ensuring efficacy and safety. Also provided is a pharmaceutical composition that effectively reduces the production of related substances, significantly increasing the quality of the product containing cefoperazone sodium and tazobactam sodium in a ratio of 6:1, and can further ensure stability of the drug in use as well as during storage and transportation.

IPC Classes  ?

• A61K 31/546 - Compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula , e.g. cephalosporins, cefaclor, cephalexine containing further heterocyclic rings, e.g. cephalothin
• A61P 13/12 - Drugs for disorders of the urinary system of the kidneys
• A61P 31/04 - Antibacterial agents
• A61P 11/00 - Drugs for disorders of the respiratory system
• A61P 13/02 - Drugs for disorders of the urinary system of urine or of the urinary tract, e.g. urine acidifiers
• A61K 31/4192 - 1,2,3-Triazoles
• A61K 31/431 - Compounds containing 4-thia-1-azabicyclo [3.2.0] heptane ring systems, i.e. compounds containing a ring system of the formula , e.g. penicillins, penems containing further heterocyclic ring systems, e.g. ticarcillin, azlocillin, oxacillin

Abstract

Disclosed is a drug combination for preventing or treating irritable bowel syndrome. The drug combination comprises dosmalfate and lysozyme.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61P 1/00 - Drugs for disorders of the alimentary tract or the digestive system
• A61K 9/00 - Medicinal preparations characterised by special physical form
• A61K 31/7048 - Compounds having saccharide radicals and heterocyclic rings having oxygen as a ring hetero atom, e.g. leucoglucosan, hesperidin, erythromycin, nystatin

Abstract

The use of lysozyme or combinations comprising the lysozyme in preparing a medicament for preventing or treating the novel coronavirus pneumonia COVID-19 and in preparing a food for assisting in preventing or treating the novel coronavirus pneumonia COVID-19 is disclosed. The lysozyme or the combination of the lysozyme, as provided by the present invention, can effectively inhibit cell damage caused by the novel coronavirus, inhibit the inflammatory factors expression induced by the novel coronavirus, ameliorate airway obstruction and decreased expiratory volume caused by lung lesions, and ameliorate intestinal barrier dysfunction. The lysozyme or the combination of the lysozyme has good effects on patients with high viral load, respiratory distress, impaired intestinal function, etc., and can reduce the novel coronavirus infection rate and the incidence rate of severe novel coronavirus pneumonia.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61P 31/14 - Antivirals for RNA viruses
• A61K 31/704 - Compounds having saccharide radicals attached to non-saccharide compounds by glycosidic linkages attached to a carbocyclic compound, e.g. phloridzin attached to a condensed carbocyclic ring system, e.g. sennosides, thiocolchicosides, escin, daunorubicin, digitoxin
• A61K 31/215 - Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids
• A61K 31/513 - PyrimidinesHydrogenated pyrimidines, e.g. trimethoprim having oxo groups directly attached to the heterocyclic ring, e.g. cytosine
• A61K 31/427 - Thiazoles not condensed and containing further heterocyclic rings
• A61K 31/4965 - Non-condensed pyrazines
• A61K 31/7056 - Compounds having saccharide radicals and heterocyclic rings having nitrogen as a ring hetero atom, e.g. nucleosides, nucleotides containing five-membered rings with nitrogen as a ring hetero atom
• A61K 31/675 - Phosphorus compounds having nitrogen as a ring hetero atom, e.g. pyridoxal phosphate
• A61K 31/4706 - 4-Aminoquinolines8-Aminoquinolines, e.g. chloroquine, primaquine
• A61K 31/4045 - Indole-alkylaminesAmides thereof, e.g. serotonin, melatonin
• A61K 45/06 - Mixtures of active ingredients without chemical characterisation, e.g. antiphlogistics and cardiaca
• A61K 38/21 - Interferons

Abstract

The embodiments of the present invention relate to the technical field of medicine, in particular to a β-lactamase inhibitor composition with a stable quality, the use thereof and a method therefor. The pharmaceutical composition of the embodiments of the present invention has improved hygroscopicity and better stability, so that the stability of materials in a preparation process can be ensured, and the pharmaceutical composition is particularly suitable for further preparing compound antibiotics. Moreover, experiments show that the β-lactamase inhibitor composition of the embodiments of the present invention can better improve the sensitivity of antibiotics to drug-resistant bacteria, and the prepared compound antibiotics have a stronger antimicrobial activity to drug-resistant bacteria.

IPC Classes  ?

• A61K 31/43 - Compounds containing 4-thia-1-azabicyclo [3.2.0] heptane ring systems, i.e. compounds containing a ring system of the formula , e.g. penicillins, penems
• A61K 31/431 - Compounds containing 4-thia-1-azabicyclo [3.2.0] heptane ring systems, i.e. compounds containing a ring system of the formula , e.g. penicillins, penems containing further heterocyclic ring systems, e.g. ticarcillin, azlocillin, oxacillin
• A61K 31/546 - Compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula , e.g. cephalosporins, cefaclor, cephalexine containing further heterocyclic rings, e.g. cephalothin
• A61P 31/04 - Antibacterial agents

Abstract

Disclosed in the present invention is use of lysozyme in the preparation of a drug for preventing or treating a uric acid-related disease, a drug for reducing uric acid, and a drug for promoting uric acid excretion. Also disclosed in the present invention are a pharmaceutical composition for preventing or treating a uric acid-related disease, a pharmaceutical composition for reducing uric acid, and a pharmaceutical composition for promoting uric acid excretion, and a method for preventing or treating a uric acid-related disease, reducing uric acid and promoting uric acid excretion.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61P 19/06 - Antigout agents, e.g. antihyperuricemic or uricosuric agents
• A61K 9/00 - Medicinal preparations characterised by special physical form

Abstract

Disclosed are a pharmaceutical composition containing lysozyme and the use thereof in the preventing psoriasis, treating of psoriasis, and/or preventing of psoriasis recurrence. The pharmaceutical composition can significantly prolong the time before disease recurrence and significantly reduce the recurrence rate of diseases compared with the use of traditional oral drugs, immunosuppressive agents, biological agents, etc.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 45/06 - Mixtures of active ingredients without chemical characterisation, e.g. antiphlogistics and cardiaca
• A61P 17/06 - Antipsoriatics
• A61K 9/00 - Medicinal preparations characterised by special physical form

Abstract

A compound for regulating body weight imbalance, a composition thereof and an application thereof. The inventor unexpectedly discovered that diosmin hydrogen sulfate derivatives have the effects of regulating body weight imbalance, and are expected to be developed as safe and effective weight imbalance regulators or used as synergists to improve the regulatory effects of existing weight imbalance regulators.

IPC Classes  ?

• A61K 31/7048 - Compounds having saccharide radicals and heterocyclic rings having oxygen as a ring hetero atom, e.g. leucoglucosan, hesperidin, erythromycin, nystatin
• A61P 3/04 - AnorexiantsAntiobesity agents

Abstract

Acinetobacter baumannii infection, characterized in the following: by mass, the amount of ceftazidime used in the sulbactam and ceftazidime composition comprising 10% to 90% of the amount of sulbactam used.

IPC Classes  ?

• A61K 31/54 - Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with at least one nitrogen and at least one sulfur as the ring hetero atoms, e.g. sulthiame
• A61K 31/43 - Compounds containing 4-thia-1-azabicyclo [3.2.0] heptane ring systems, i.e. compounds containing a ring system of the formula , e.g. penicillins, penems
• A61K 31/546 - Compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula , e.g. cephalosporins, cefaclor, cephalexine containing further heterocyclic rings, e.g. cephalothin
• A61P 31/04 - Antibacterial agents

Abstract

Provided is a combination for lowering blood sugar, comprising lysozyme and dosmalfate. Also provided are an application of the composition and a method for the composition. Lysozyme and dosmalfate have significant synergistic effects in lowering blood sugar, and can improve gastrointestinal dysfunction of hyperglycemic patients. In addition, the combination also has synergistic and attenuating effects on other hypoglycemic drugs, and therefore has a particular clinical value for blood sugar lowering and hyperglycemia related diseases or symptoms.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 31/7048 - Compounds having saccharide radicals and heterocyclic rings having oxygen as a ring hetero atom, e.g. leucoglucosan, hesperidin, erythromycin, nystatin
• A61P 3/10 - Drugs for disorders of the metabolism for glucose homeostasis for hyperglycaemia, e.g. antidiabetics

Abstract

Provided is a fused ring diimide derivative having a chemical structure as represented by formula I. Further provided is a preparation method therefor. The fused ring diimide derivative has excellent anti-tumor activity, and the anti-proliferative activity on various cancer cells is significantly better than that of similar compounds.

IPC Classes  ?

• C07D 221/14 - Aza-phenalenes, e.g. 1,8-naphthalimide
• C07D 401/06 - Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
• C07D 401/12 - Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links
• A61K 31/496 - Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
• A61P 35/02 - Antineoplastic agents specific for leukemia
• A61P 35/00 - Antineoplastic agents

Abstract

A combination for treating Alzheimer's disease and a use thereof, specifically, a combination based on Modafinil and acetaminophen, and a use thereof for preparing a drug to treat Alzheimer's disease. According to research, when combining Modafinil and acetaminophen for treating Alzheimer's disease, the effect of Modafinil is significantly enhanced by acetaminophen, and test results show that the combination of the two has a synergistic effect; also, acetaminophen eliminates certain adverse reactions to Modafinil, such as anxiety and tension.

IPC Classes  ?

• A61K 31/165 - Amides, e.g. hydroxamic acids having aromatic rings, e.g. colchicine, atenolol, progabide
• A61K 31/167 - Amides, e.g. hydroxamic acids having aromatic rings, e.g. colchicine, atenolol, progabide having the nitrogen atom of a carboxamide group directly attached to the aromatic ring, e.g. lidocaine, paracetamol
• A61K 31/445 - Non-condensed piperidines, e.g. piperocaine
• A61K 31/13 - Amines, e.g. amantadine
• A61P 25/00 - Drugs for disorders of the nervous system
• A61P 25/28 - Drugs for disorders of the nervous system for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia

Abstract

Disclosed in the present invention are an application of lysozyme or a combination comprising the lysozyme in preparation of a medicine for preventing or treating COVID-19, and an application in preparation of food for assisting in preventing or treating COVID-19. The lysozyme or the combination thereof provided by the present invention can effectively inhibit cell damage caused by novel coronavirus, inhibit inflammatory factor expression induced by novel coronavirus, improve airway obstruction and expiratory volume reduction caused by pulmonary lesions, and improve intestinal barrier dysfunction. The lysozyme or the combination thereof has a good effect on high virus load, respiratory distress, intestinal function impairment and the like of patients, and can reduce the infection rate of novel coronavirus and severe cases of COVID-19. In addition, because the lysozyme is extremely high in safety, the lysozyme also has a very important value for preventing unconfirmed people at a high risk for infection from infecting novel coronavirus.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 9/00 - Medicinal preparations characterised by special physical form
• A61P 31/14 - Antivirals for RNA viruses
• A61P 31/12 - Antivirals

Abstract

A drug, food and application of an anti-coronavirus infection, the drug or food containing lysozyme or a combination that comprises lysozyme; the lysozyme or a combination thereof can be used to prepare a drug for resisting coronavirus infection and preventing or treating coronavirus-related diseases or symptoms, or food for assisting in resisting coronavirus infection and assisting in preventing or treating coronavirus-related diseases or symptoms. Lysozyme or a combination thereof can effectively inhibit the cell damage and inflammatory reaction caused by coronavirus, relieve symptoms of the digestive system, and improve airway obstruction, decreased expiratory volume and intestinal barrier function. The present invention has a good preventive and therapeutic effect on coronavirus infection or related diseases or symptoms thereof; in addition, the present application can accelerate the elimination of the virus in vivo, accelerate the speed of coronavirus nucleic acid tests in vivo turning negative, shorten the course of a patient's illness, effectively prevent and reduce the spread of coronavirus, and also has important social benefits and good application prospects.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 31/704 - Compounds having saccharide radicals attached to non-saccharide compounds by glycosidic linkages attached to a carbocyclic compound, e.g. phloridzin attached to a condensed carbocyclic ring system, e.g. sennosides, thiocolchicosides, escin, daunorubicin, digitoxin
• A61K 45/06 - Mixtures of active ingredients without chemical characterisation, e.g. antiphlogistics and cardiaca
• A61P 31/14 - Antivirals for RNA viruses
• A61P 11/00 - Drugs for disorders of the respiratory system
• A61P 1/00 - Drugs for disorders of the alimentary tract or the digestive system
• A23L 33/10 - Modifying nutritive qualities of foodsDietetic productsPreparation or treatment thereof using additives
• A23L 33/17 - Amino acids, peptides or proteins

Abstract

Disclosed is a drug combination for preventing or treating irritable bowel syndrome. The drug combination comprises dosmalfate and lysozyme.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61K 31/7048 - Compounds having saccharide radicals and heterocyclic rings having oxygen as a ring hetero atom, e.g. leucoglucosan, hesperidin, erythromycin, nystatin
• A61P 1/04 - Drugs for disorders of the alimentary tract or the digestive system for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants

Abstract

Disclosed in the present invention is use of lysozyme in preparation of a drug for preventing or treating a uric acid-related disease, a drug for reducing uric acid, and a drug for promoting uric acid excretion. Also disclosed in the present invention are a pharmaceutical composition for preventing or treating a uric acid-related disease, a pharmaceutical composition for reducing uric acid, a pharmaceutical composition for promoting uric acid excretion, and a method for preventing or treating a uric acid-related disease, reducing uric acid, and promoting uric acid excretion.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61P 19/06 - Antigout agents, e.g. antihyperuricemic or uricosuric agents
• A61P 13/12 - Drugs for disorders of the urinary system of the kidneys

Abstract

Disclosed are a pharmaceutical composition containing lysozyme and the use thereof in preventing psoriasis, treating psoriasis and/or preventing psoriasis recurrence. The pharmaceutical composition can significantly prolong the time before disease recurrence and significantly reduce the recurrence rate of diseases compared with the use of traditional oral drugs, immunosuppressive agents, biological agents, etc.

IPC Classes  ?

• A61K 38/47 - Hydrolases (3) acting on glycosyl compounds (3.2), e.g. cellulases, lactases
• A61P 17/06 - Antipsoriatics

Abstract

A compound for regulating body weight imbalance, a composition thereof and an application thereof. The inventor unexpectedly discovered that diosmin hydrogen sulfate derivatives have the effect of regulating body weight imbalance, and are expected to be developed as safe and effective weight imbalance regulators or used as synergists to improve the regulatory effects of existing weight imbalance regulators.

IPC Classes  ?

• A61K 31/7048 - Compounds having saccharide radicals and heterocyclic rings having oxygen as a ring hetero atom, e.g. leucoglucosan, hesperidin, erythromycin, nystatin
• A61P 3/04 - AnorexiantsAntiobesity agents
• A61P 1/04 - Drugs for disorders of the alimentary tract or the digestive system for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants

Abstract

The application of a sulbactam and ceftazidime composition in the preparation of a drug for treating a carbapenem-resistant antibiotic Acinetobacter baumannii infection, characterized in the following: by mass, the amount of ceftazidime used in the sulbactam and ceftazidime composition comprising 10% to 90% of the amount of sulbactam used.

IPC Classes  ?

• A61K 31/545 - Compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula , e.g. cephalosporins, cefaclor, cephalexine
• A61K 31/54 - Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with at least one nitrogen and at least one sulfur as the ring hetero atoms, e.g. sulthiame
• A61P 31/04 - Antibacterial agents
• A61P 31/00 - Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics

Abstract

Provided are a diimide derivative, a preparation method therefor and the use thereof. The diimide derivative has a good anti-tumor activity, and the anti-proliferative activity against various cancer cells is significantly better than those of similar compounds. (I)

IPC Classes  ?

• A61K 31/496 - Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
• C07D 221/14 - Aza-phenalenes, e.g. 1,8-naphthalimide
• C07D 401/12 - Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links