|Year : 2021 | Volume
| Issue : 1 | Page : 17-21
In-silico investigation of active component: Epicatechin in Acacia catechu on Salivary α- amylase
Preethi Arunachalam, Ramya Ramadoss, Amritha James, Lekshmy Jayan, Vasanthi Vinoth, Bose Divya
Department of Oral and Maxillofacial Pathology and Microbiology, SRM Dental College, Chennai, Tamil Nadu, India
|Date of Submission||01-Dec-2020|
|Date of Decision||12-Feb-2021|
|Date of Acceptance||16-Feb-2021|
|Date of Web Publication||30-Mar-2021|
Dr. Preethi Arunachalam
Department of Oral and Maxillofacial Pathology and Microbiology, SRM Dental College, Ramapuram, Chennai - 600 089, Tamil Nadu
Background: Xerostomia is a common condition which affects majority of the people due to its multifarious etiologies. Although several treatment modalities are under practice, natural herbs show a great deal of beneficial effects recently. Saliva contains a considerable amount of proteins, among which the enzyme salivary α-amylase forms the major bulk. Acacia catechu is habitually known as Katha or Karangali, and the preparations are made from the heartwood or the leaves of this plant and have been used for decades and also as a thirst quencher. The relationship between the use of this decoction and saliva secretion has been a debate among researchers. Although there are no comprehensive validations behind the theory between amylase activity and A. catechu, virtual screening techniques such as docking could help to throw light on this theory. Aim: This study aimed to evaluate the binding efficacy of active ingredient of A. catechu on salivary α-amylase using molecular docking approach. Materials and Methods: The active ingredients of A. catechu were identified using an extensive literature search. The chemical structure of the identified ligand (epicatechin gallate) and the target protein (salivary alpha-amylase) was obtained using PubChem and molecular docking was analyzed using SYBYL2.0®. Results: Epicatechin gallate showed the highest binding affinity for human salivary amylase when compared to the other ligand molecules. Conclusion: The current study thus elucidates that A. catechu can possibly be effective as a stimulatory agent for patients suffering from xerostomia.
Keywords: Acacia catechu, epicatechin, molecular docking, salivary α amylase, thirst quencher, xerostomia
|How to cite this article:|
Arunachalam P, Ramadoss R, James A, Jayan L, Vinoth V, Divya B. In-silico investigation of active component: Epicatechin in Acacia catechu on Salivary α- amylase. SRM J Res Dent Sci 2021;12:17-21
|How to cite this URL:|
Arunachalam P, Ramadoss R, James A, Jayan L, Vinoth V, Divya B. In-silico investigation of active component: Epicatechin in Acacia catechu on Salivary α- amylase. SRM J Res Dent Sci [serial online] 2021 [cited 2021 Jul 31];12:17-21. Available from: https://www.srmjrds.in/text.asp?2021/12/1/17/312473
| Introduction|| |
Bioinformatics is “an interdisciplinary scientific branch of life sciences that includes the analysis of molecular sequence and genomics data or protein prognostication, and profiling it.” Molecular docking is a type of bioinformatics that decodes the interaction between two or more molecules to provide a stable adduct, thereby letting us know the binding properties of the target and the ligand–protein of any structural complex. Xerostomia, otherwise called dry mouth, is a subjective symptom due to lack of saliva which affects the majority population, mainly the elders, patients under medication for diabetes, hypertension, and patients undergoing radiotherapy. Despite the number of treatment modalities proposed, there is less evidence proven for a permanent remedy so far. Acacia catechu is a widely known herb in India for its various pharmacological effects. The components of the herb have been shown multifarious properties and it is considered an effective thirst quencher. Although there are no comprehensive validations behind the theory between amylase activity and A. catechu, Salivary amylase being one of the primary enzymes of saliva and an easily available component to assess various parameter, it was taken for virtual screening such as the docking approach which would help to throw light on their molecular aspect.
Prior to the wet lab assessments, to find the efficacy of the A. catechu on salivary secretion, molecular approach was done to check for the feasibility and reliability of the hypothesis. Thus, the current study aims to evaluate the binding efficacy of the active ingredient of A. catechu on salivary α-amylase using a molecular docking approach.
| Materials and Methods|| |
Selection of ligand and target protein
A series of five molecules were recognized as active components in A. catechu as epicatechin gallate, kaempferol, poriferasterol, D-galactose, and gallic acid using PUBMED, EMBASE, Cochrane Library, and Google Scholar. The keywords were used such as “A. catechu,” “Xerostomia,” and “salivary amylase” and the final selections of the molecules were done based on their chemical structure and properties.
The chemical structure of the above-mentioned five active compounds was then obtained from the PubChem database in the structure data file format [Table 1]. For the compounds which lacked an existing three-dimensional structure in PubChem, the sketch molecule function of SYBYL was used. The partial atomic charge of these molecules was obtained using the Gasteiger-Huckel method and Tripos force field was used for energy minimization. All these procedures were performed with the help of SYBYL2.0® software.
Pharmacophore-based virtual screening
Virtual screening is an explicit technique used in the identification of potent molecules for its various biological functions. Water molecules were removed during the processing of the target and ligand molecules. These molecules were further screened by employing “Lipinski's rule of five, fitness score, and ADME properties.” Finally, the affinity of the molecule to the substrate of interest is evaluated by molecular docking.
Experimental methodology done using SYBYL2.0® software is summarized in [Figure 1].
After running virtual molecular docking of all these components with human salivary α-amylase [Figure 2], the scores were tabulated for each. The scores recorded were the total score which is the entire docking score, crash score which is “the degree of inappropriate penetration by the ligand into the protein,” polar score that contributes to the polar nonhydrogen bonding interactions to the total score which implies the significant role of the angles of the bond, and glide (G) score approximates the ligand binding free energy. The scores for individual molecules are given in [Table 2] and the binding site of epicatechin gallate on salivary α-amylase is shown in [Figure 3].
|Table 2: Binding affinity between epicatechin and human salivaryα-amylase|
Click here to view
| Results|| |
Following the docking procedure, epicatechin gallate showed the highest binding affinity for human salivary amylase [Figure 3] when compared to the other compounds. A single hydrogen bond was formed for kaempferol and gallic acid, two hydrogen bonds formed for D-galactose, and no affinity was found for poriferasterol, while epicatechin expressed eight hydrogen bonds over human salivary amylase marking the strong union formed.
| Discussion|| |
Human salivary alpha-amylase is an enzyme that is found in the oral cavity belonging to the glycoside hydrolase family. This enzyme has multifarious constituents that includes various amino acids, enzymes, mucins, electrolytes such as calcium, chloride, sodium, and magnesium, and immunoglobulins.,
Saliva contains a considerable amount of proteins, among which the enzyme salivary α-amylase contributes the most. Salivaryαamylase is produced majorly by the parotid gland and the enzyme is otherwise called ptyalin. Xerostomia, also known as dry mouth, is a subjective symptom comprising of reduced or absence of salivary flow rate. It is mostly seen in elderly patients who take medications due to systemic diseases such as diabetes mellitus, rheumatoid arthritis, renal failure, and hypertension and patients who undergo radiation treatment and chemotherapy for head-and-neck cancer. As a consequence, the oral tissues often become ulcerated and also lead to dental caries along with sore throat, oral pain, burning sensation of the mouth, difficulty in speaking and swallowing, and impaired taste sensation that leads to loss of appetite which invariably develop to malnutrition., In patients with xerostomia, the major salivary glands are predominantly impaired, and hence, the secretion of amylase is equally affected. In fact, during the first cycle of irradiation, there is an acute increase in the secretion of salivary amylase and then leads to a state of hyperamylasemia which leads to the inability of production of amylase. These studies imply the importance of assessing salivary amylase and are considered as a potential biomarker. The habitual treatment methods to improve salivary secretion are wetting of the lips and drinking water regularly, chewing of gums, use of artificial salivary substitutes, and drugs that induce salivary secretion. Recently, the uses of herbal medicine are followed as an alternative treatment modality which is said to increase the salivary secretion.
A. catechu is a common tree, mostly confined to the drier regions of India belonging to the Leguminosae family. Commonly known as Katha or Karangali in the native languages, it is widely used in the Indian subcontinent for a variety of pharmacological and nonpharmacological purposes. Numerous chemical compounds have been identified within the “bark” and “leaves” of A. catechu by several authors. The main molecular constituents of A. catechu can be generally categorized into flavonoids, alkaloids, glycosides, tannins, and sugars. Among the chemical constituents of A. catechu, catechin, epicatechin, and epigallocatechin are known to the active ingredients. Research in A. catechu is relatively new with the studies being reported only since the last decade. A. catechu is utilized for multiple purposes on a routine basis. It has been used as a hemostatic agent to decrease bleeding. The concentrated extracts derived from A. catechu have various beneficial effects including improving digestion, reducing body temperature, and aiding in wound healing. It has also been used in the management of cough, diarrhea, and skin-related lesions like ulcers, boils, and eruptions. It also constitutes a diverse array of Ayurvedic formulations. The seeds obtained from acacia are also said to have hypoglycemic and hypotensive potential in rat models. A. catechu bark extract also shows modulatory effects in oral squamous cell carcinoma as it caused cytotoxicity in oral squamous cell carcinoma. A 28-day repeated oral toxicity trial was conducted in rats to evaluate the potential side effects of the herb followed by a 2-week recovery period assessment which identified the no-observable adverse effects as the oral dose of 2000 mg/kg/day. The components of the herb have also shown the property of an effective thirst quencher and were considered to show an immunomodulatory effect.
The advent of molecular docking attempts to predict the structure of intermolecular complexes formed between the ligand and the target molecules and is a beneficial way for a rational drug discovery approach. The current study is a preliminary approach to find the binding efficacy of the ligand and target molecules. Hence, structure-based computational studies such as inverse docking were beyond our scope of research at this point. However, there are negligible studies of A. catechu using the docking approach. In the current study, docking analysis was demonstrated between the active components of A. catechu and human salivary amylase. Among all the active components, epicatechin gallate which is a flavonoid alone revealed an adequate binding capacity with human salivary amylase, by showing the formation of hydrogen bonds in eight different sites. Although there are studies suggesting the inhibition of pancreatic alpha-amylase by catechu, our study shows a contradiction. Our results were in accordance with the study conducted by Choi et al. who evaluated the efficacy of epigallocatechin-3-gallate (EGCG) in comparison with amifostine on salivary gland dysfunction in radiation therapy. The histologic finding showed production of rich mucin and decreased periductal, perivascular fibrosis which proved that EGCG supplementation had a potent antioxidant effect and could be indicated prior to radiotherapy for protection of salivary glands. The study conducted by Gurav Minakshi et al. assessed the aqueous extract of A. catechu which showed an increased rate of digestion of starch by stimulating salivary amylase. The catechin-containing natural formula partially restored salivary function and provided objective improvement in salivary output in patients with xerostomia. Although the exact mechanism behind the secretagogue activity of A. catechu remains obscure, the presence of these active ingredients and the studies conducted to prove their significance could pave way for understanding the underlying mechanism that contributes to increased salivary secretion, yet it employs us to research furthermore on the salivary stimulatory effect of A. catechu by conducting wet-bench techniques.
| Conclusion|| |
The present study shows the binding efficacy of the active component of A. catechu on human salivary amylase. This opens the way to demonstrate the herb, A. catechu can possibly be effective as a stimulatory agent for patients suffering from salivary dysfunction, through wet-bench analysis and clinical trial.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]