Cataract is an eye disorder due to cloudiness in the lens of the eye which can reduce vision function. [1] Senile cataract is clouding of the lens in the eye caused by a degeneration process and is found after the age of 50 years. [2] This clouding disorder is influenced by age and is one of the causes of vision loss. The process of aggregation of proteins forming senile cataracts is related to the pathway for the formation of amyloid structures. With age the activity of β-secretase increases. [3] β- and γ-secretase are enzymes that catalyze Amyloid-β Precursor Protein (APP) into β-amyloid (Aβ) structures (Strooper and Annaert, 2000). β-amyloid (Aβ) has a strong association with oxidative stress. [4] Free radicals, including some Reactive Oxygen Species (ROS) such as SO2, H2O2, and SOH can cause structural damage to the crystalline lens and contribute to cataract formation. [5] The decrease in α-Crystalline with age causes the damaged βγ-Crystalline (misfolding or unfolding) continue to increase. α-Crystallin, a protein that is the main support system of adult eye lens fiber cells, recognizes the conformer features of proteins and separates misfolded / unfolded conformer proteins from one another. If the population of α-crystalline is limited then the eye lens will be filled with damaged βγ- Crystalline and not folded properly, this protein also contributes to the growing aggregates and eventually causes eye cloudiness. [6]
Untreated senile cataracts can cause visual disturbances to blindness. The definitive treatment for cataracts is surgery, such as Intracapsular Cataract Extraction, Extracapsular Cataract Extraction, and Phacoemulsification, but this method is considered not free from complications, so other efforts are needed to prevent and treat further eye lens disorders. [7] There have been several studies using vitamin C and E to slow the growth of cataracts, but they have not been effective. Research also mentions the use of natural ingredients that have proteolytic potential in senile cataracts are papaya and ginger. [8]
Papain is a protease class enzyme that is used in various industrial fields such as food and medicine. This protease enzyme comes from the papaya plant (Carica papaya L.). Papain can be obtained from papaya sap, from the fruit, stems and leaves. The part of the plant which are stems, leaves and young papaya contain a white sap containing papain. [9] Papain has proteolytic activity against proteins, acid esters, amide chains and short chain peptides such as lysine, phenylanine, and arginine. Previous studies have shown that the enzyme papain can reduce opacity in the eye. [10]
Zingibain or ginger protease, which was first reported as a new protease source in 1973, exhibits remarkable proteolytic activity. Zingibain is a meat tenderizer that is very active against collagen and other connective tissue proteins. The good freezing activity of milk is also attributed to zingibain so it is used in the preparation of ginger milk curd in southern China. Zingibain is an enzyme found in ginger, ginger is a plant that belongs to the zingiberaceae family. Zingibain was shown to have high activity against protein substrates [11].
The protease enzyme derived from the papaya plant (papain enzyme) and ginger (zingibain enzyme) has a proteolytic effect that has the potential to lyse β-amyloid (Aβ) protein so that it can be an alternative treatment for cataracts. Previous studies have shown that the use of plant-based proteases such as the enzyme papain can reduce the development of vitreous opacity in the eye. [12] However, there are no studies on the enzymes papain and zingibain related to proteolytic effects on β-amyloid protein. So that research is needed to assess the potential of active ingredients for the preventive effect in senile cataract therapy.
In this study, we used a drug design method using the chemical activity of a candidate drug molecule through computational methods. This method has advantages over laboratory scale studies, such as the ability to determine the amino acids associated with enzymatic reactions. [13] The method commonly used for drug design based on the bioinformatics approach is the In Silico docking simulation. This method is used to assist the virtual screening process in search of candidate drug molecules (ligands) based on the value of the interaction between ligands and receptors. Docking simulations can be used to assess interactions between candidate drug molecules and cell receptors. [14].
Research related to papain and zingibain against β-amyloid (Aβ) protein has never been conducted before. So it is interesting for the authors to examine this and great hope that later this research will be continued with In Vivo and In Vitro research in the prevention of cataracts.