Cyanobacteria such as Spirulina platensis secretes numerous biomolecules while consuming CO2 for photosynthesis which can reduce the environmental pollution as it can also be grown in wastewater. These biomolecules can be further processed in numerous pathways such as feed, fuel, pharmaceuticals, and nutraceuticals. This study aims to screen the potential molecular mechanisms of pigments from cyanobacteria as antidiabetic type-2 candidates through molecular docking. The activities of the test compounds were compared to commercial diabetic drugs, such as acarbose, linagliptin and polydatin. The results indicated that the binding affinity of pheophytin, β-carotene, and phycocyanobilin to α-amylase were 0.4, 2, and 2.6 kcal/mol higher than that of acarbose with α-amylase. Binding affinity between pheophytin, β-carotene, and phycocyanobilin with α-glucosidase were found to be comparable, which resulted 1.2, and 1.6 kcal/mol higher than that of acarbose with α-glucosidase. Meanwhile, binding activity of β-carotene and phycocyanobilin with DPP-IV were 0.5 and 0.3 kcal/mol higher than that of linagliptin with DPP-IV, whereas pheophytin, β-carotene, and phycocyanobilin with Glucose-6-phosphate dehydrogenase (G6PD) were 0.2, 1, and 1.4 kcal/mol higher from that of polydatin with G6PD. Moreover, pheophytin, β-carotene and phycocyanobilin were likely to inhibit α-amylase, α-glucosidase, and DPP-IV competitively, while uncompetitively for G6PD. Thus, the integration of molecular docking and experimental approach, such as in vitro and in vivo studies may greatly improve the discovery of true bioactive compounds in cyanobacteria for type 2 diabetes mellitus drugs and treatments.
One of potential inhibitors which is widely used for the clinical treatment of COVID-19 in comorbid patients is Angiostensin Converting Enzyme-1 (ACE1) inhibitor. A safer peptide-based ACE1 inhibitor derived from salmon skin collagen, that is considered as the by-product of the fish processing industry have been investigated in this study. The inhibitory activity against ACE1 was examined using in vitro and in silico methods. In vitro analysis includes the extraction of acid-soluble collagen, characterization using FTIR, Raman, UV-Vis, XRD, cytotoxicity assay, and determination of inhibition against ACE1. In silico method visualizes binding affinity, molecular interaction, and inhibition type of intact collagen and active peptides derived from collagen against ACE1 using molecular docking. The results of FTIR spectra detected amide functional groups (A, B, I, II, III) and imine proline/hydroxyproline, while the results of Raman displayed peak absorption of amide I, amide III, proline/hydroxyproline ring, phenylalanine, and protein backbone. Furthermore, UV-Vis spectra showed typical collagen absorption at 230 nm and based on XRD data, the chain types in the samples were α-helix. ACE1 inhibition activity was obtained in a concentration-dependent manner where the highest was 82.83% and 85.84% at concentrations of 1000, and 2000 µg/mL, respectively, and showed very low cytotoxicity at the concentration less than 1000 µg/mL. In silico study showed an interaction between ACE1 and collagen outside the active site with the affinity of - 213.89 kcal/mol. Furthermore, the active peptides of collagen displayed greater affinity compared to lisinopril, namely HF (His-Phe), WYT (Trp-Tyr-Thr), and WF (Trp-Phe) of - 11.52; - 10.22; - 9.58 kcal/mol, respectively. The salmon skin-derived collagen demonstrated ACE1 inhibition activity with a non-competitive inhibition mechanism. In contrast, the active peptides were predicted as potent competitive inhibitors against ACE1. This study indicated that valorization of fish by-product can lead to the production of a promising bioactive compound to treat COVID-19 patient with diabetic comorbid.