Kinetic Analysis and Mechanism on the Inhibition of Chlorogenic Acid and Its Components against Porcine Pancreas α-Amylase Isozymes I and II

Abstract

Chlorogenic acid (5-caffeoylquinic acid, 5-CQA) is a kind of polyphenol and is richly included in green coffee beans. The inhibitory effects of 5-CQA and its components, caffeic acid (CA) and quinic acid (QA), on the two porcine pancreas alpha-amylase (PPA) isozymes, PPA-I and PPA-II, were investigated using p-nitrophenyl-alpha-D-maltoside as substrate at pH 6.9 and 30 degrees C. The inhibition potencies of the respective inhibitors against both PPA isozymes were almost the same and in the order of 5-CQA > CA >> QA. Their IC(50) values were 0.07-0.08 mM, 0.37-0.40 mM, and 25.3-26.5 mM, respectively. The inhibition mechanisms of 5-CQA and CA were investigated by kinetic analyses, and the inhibitor constants K(i) and K(i)' (for the free enzyme and enzyme-substrate complex, respectively) were determined. It was indicated that 5-CQA and CA showed mixed-type inhibition with K(i) > K(i)' against both PPA-I and PPA-II. The binding of PPA-I or PPA-II with 5-CQA or CA was all exothermic and enthalpy-driven. QA is a poor inhibitor, and its inhibitory mode was unique and hardly analyzed by a simple Michaelis-Menten-type interaction between the enzyme and inhibitor. However, it was shown that the inhibitory activity of CA was enhanced 5 times by ester-bond formation with QA in the form of 5-CQA. These results provide us with significant hints for the development of alpha-amylase inhibitors useful for the prevention of diabetes and obesity.

High antioxidant activity of coffee silverskin extracts obtained by the treatment of coffee silverskin with subcritical water

“…Therefore CS can be regarded as biomass which is expected to be utilised. Many investigators have reported the physiological functions of green and roasted coffee beans, such as a-amylase inhibition (Narita & Inouye, 2009, tyrosinase inhibition (Iwai, Kishimoto, Kakino, Mochida, & Fujita, 2004), and antioxidant activity (Richelle, Tavazzi, & Offord, 2001), etc. On the other hand, the physiological functions of CS reported until now are antioxidant activity (Borrelli, Esposito, Napolitano, Ritieni, & Fogliano, 2004), previotic property (Borrelli et al, 2004), and hyaluronidase inhibition (Furusawa, Narita, Iwai, Fukunaga, & Nakagiri, 2011), but the number of the reports is much less than that for coffee bean.…”

Study on the Postprandial Glucose Responses to a Chlorogenic Acid-Rich Extract of Decaffeinated Green Coffee Beans in Rats and Healthy Human Subjects

“…In our previous study (Narita and Inouye, 2009;Narita and Inouye, 2011), we investigated the inhibition of porcine pancreas alpha-amylase (PPA) isozymes PPA-I and PPA-II by 8 types of cinnamic acid derivatives in green coffee beans. All CQAs, FQAs, and diCQAs showed mixed-type inhibition against PPA with K i > K i ′, indicating that these compounds bind to the enzyme-substrate complex more tightly than to the enzyme.…”

Postprandial insulin and glucose levels are reduced in healthy subjects when a standardised breakfast meal is supplemented with a filtered sugarcane molasses concentrate

“…Hanhineva et al [21] extensively reviewed the literature concerning polyphenol effects on inhibition of α-amylase [22], α-glucosidase [23] and glucose transporter activity in the gut [24]; protection of pancreatic cells from cytokine toxicity and effects on insulin release [25]; improved glucose uptake into tissues [26]; induction of hepatic glucokinase activity [27]; inhibition of gluconeogenesis [28]; and activation of adenosine monophosphate-activated protein kinase [29].…”