Mechanistic study on the inhibition of α‐amylase and α‐glucosidase using the extract of ultrasound‐treated coffee leaves

Abstract

BackgroundOur previous studies have shown that ultrasound‐treated γ‐aminobutyric acid (GABA)‐rich coffee leaves have higher angiotensin‐I‐converting enzyme inhibitory activity than their untreated counterpart. However, whether they have antidiabetic activity remains unknown. In this study, we aimed to investigate the inhibitory activities of coffee leaf extracts (CLEs) prepared with ultrasound (CLE‐U) or without ultrasound (CLE‐NU) pretreatment on α‐amylase and α‐glucosidase. Subsequently, we evaluated the binding interaction between CLE‐U and both enzymes using multi‐spectroscopic and in silico analyses.ResultsUltrasound pretreatment increased the inhibitory activities of CLE‐U against α‐amylase and α‐glucosidase by 21.78% and 25.13%, respectively. CLE‐U reversibly inhibits both enzymes, with competitive inhibition observed for α‐amylase and non‐competitive inhibition for α‐glucosidase. The static quenching of CLE‐U against both enzymes was primarily driven by hydrogen bond and van der Waals interactions. The α‐helices of α‐amylase and α‐glucosidase were increased by 1.8% and 21.3%, respectively. Molecular docking results showed that the key differential compounds, including mangiferin, 5‐caffeoylquinic acid, rutin, trigonelline, GABA, caffeine, glutamate, and others, present in coffee leaves interacted with specific amino acid residues located at the active site of α‐amylase (ASP197, GLU233, and ASP300). The binding of α‐glucosidase and these bioactive components involved amino acid residues, such as PHE1289, PRO1329, and GLU1397, located outside the active site.ConclusionUltrasound‐treated coffee leaves are potential anti‐diabetic substances, capable of preventing diabetes by inhibiting the activities of α‐amylase and α‐glucosidase, thus delaying starch digestion. Our study provides valuable information to elucidate the possible antidiabetic capacity of coffee leaves through the inhibition of α‐amylase and α‐glucosidase activities. © 2023 Society of Chemical Industry.

Characterization of kombucha prepared from black tea and coffee leaves: A comparative analysis of physiochemical properties, bioactive components, and bioactivities

“…A study conducted in our laboratory employing molecular docking exhibited that 5‐CQA, 3, 5‐diCQA, mangiferin, rutin, GABA, caffeine, and trigonelline can bind to the amino acid residues located outside the active site of α‐glucosidase (Sun et al. 2023). This result indicated that they could potentially serve as inhibitors for α‐glucosidase found in the extract or kombucha prepared from coffee leaves.…”

“…Additionally, other studies reported that polyphenols, polysaccharides, flavonoids, tannin, quercetin, ursolic acid, anthocyanin, and procyanidins are potential inhibitors against α-glucosidase (Hossain et al, 2020). A study conducted in our laboratory employing molecular docking exhibited that 5-CQA, 3, 5-diCQA, mangiferin, rutin, GABA, caffeine, and trigonelline can bind to the amino acid residues located outside the active site of α-glucosidase (Sun et al 2023). This result indicated that they could potentially serve as inhibitors for α-glucosidase found in the extract or kombucha prepared from coffee leaves.…”

“…The activity of α-glucosidase was determined by the method of Sun et al (2023). Briefly, 50 µL of the sample was incubated with 50 µL of α-glucosidase (1 U/mL, dissolved in 25 mmol/L potassium phosphate buffer (PBS), pH = 6.9) at 37 • C for 10 min.…”

Coffee leaf extract inhibits advanced glycation end products and their precursors: A mechanistic study

“…The preparation of ultrasound‐induced GABA‐enriched coffee leaves and the CLE was carried out according to the method described in our previous study (Sun et al., 2023). The CLE prepared by the coffee leaves with or without ultrasound treatment was named CLE‐U and CLE‐NU, respectively.…”

“…GABA is an inhibitory neurotransmitter with a variety of bioactive functions, such as antidiabetic, antioxidant, and antihypertensive (Sun, Mehmood et al., 2022). Furthermore, our previous study revealed that ultrasound‐induced GABA‐enriched coffee leaf extract (CLE‐U) displayed higher inhibitory activity against α‐glucosidase and α‐amylase compared to its untreated counterpart (CLE‐NU) (Sun et al., 2023). However, the potential of CLE to impede the formation of AGEs and their precursors remains unexplored, as does the differentiation in inhibitory efficacy between CLE‐U and CLE‐NU, along with the underlying mechanisms governing this phenomenon.…”