New biological properties of coffee melanoidins

Abstract

Water-soluble melanoidins isolated from roasted coffee induced ex vivo changes in the bioelectric and contractile activity of rat circular gastric smooth muscle tissues. They provoked a depolarization of smooth muscle cellular membranes and an increase in Ca²⁺-influx as evidenced by the increase in the frequency and amplitude of Ca²⁺-generated spike potentials. In the presence of 1 × 10⁻⁶ mol L⁻¹ acetylcholine and 1 × 10⁻⁶ mol L⁻¹ arecoline the melanoidin-evoked contraction was significantly reduced. M-cholinergic receptor blocking agents atropine, ipratropium, pirenzepine, and 4-DAMP also significantly reduced the melanoidin-provoked contraction. Nonspecific N-cholinergic receptor blockers hexamethonium and decamethonium (1 × 10⁻⁵ mol L⁻¹ each) did not influence the melanoidin-induced mechanical reaction. The melanoidins did not affect the strength of contractions evoked by adrenaline and dopamine (1 × 10⁻⁶ mol L⁻¹ each). The results obtained support the assumption that melanoidin-evoked contraction is a result of activation of muscarinic-type cholinergic receptors.

Ex Vivo and In Vivo Study of Some Isoquinoline Precursors

“…Another advantage is that retaining tissue function permits calculation of important pharmacological variables that are more meaningful in a tissue vs. a cellular setting; it comes closer to how the drugs examined would work in the body as a whole [21]. Previously [22][23][24][25][26], the isolated tissue bath was applied for ex vivo SM activity investigation of different compounds, including isoquinoline derivatives. Thus, we applied the same technique to the technique reported in this article with N-(1-(3,4-dimethoxyphenyl)propan-2-yl) amides.…”

Coffee’s Melanoidins. A critical review of contemporary scientific literature

“…In contrast, at high concentrations, melanoidins exert a bactericidal effect 9 attributed to their chelating capacity and to elucidate this phenomenon, three possible mechanisms have been proposed: (a) the bacteriostatic activity is due to Fe +3 ions chelation when, in solution, melanoidins are present in low concentration 4,7,9 , (b) in the presence of siderophores producing bacteria (i.e., molecules specialized in Fe +3 ions sequestration) then melanoidins chelate the siderophore-Fe +3 complex thus limiting the microorganism multiplication and (c) in high concentration, melanoidins can subtract Mg +2 ions from the bacterial cell membrane causing it to rupture 4,7,9,25 .…”

“…The ability to transfer H + ions thus turning free radicals (eg, NO + , NO -, ONOO -, H 2 O 2 , O 2 -, & OH -) into stable non-reactive molecules is one of the mechanisms through which melanoidins inhibit lipids oxidation which otherwise contributes to the development of atherosclerosis in humans 24,25,35 and in the case of processed foods they contribute by extending their shelf life by preventing oxidative rancidity of mono and polyunsaturated lipids 4,8,9 and by preventing the proliferation of microorganisms due to their bacteriostatic and bactericidal effect 8,9 . For this reason, they can be used as additives in the food industry.…”

“…Its antioxidant capacity is, in part, attributed to chlorogenic acids (CAs) bound to their molecular structure through undefined bonds and which is presumably manifested by its metallo-chelator and free radical cleaning activities 1,4,7,9,24,25,49 .…”

“…Using this technique, it has been calculated that they constitute between 23 to 25% of the dry weight of roasted coffee 1,2,4,16,[20][21][22][23][24] and 29 to 30% of the dry weight extracted from the coffee drink 1,7,20,21 . Additionally, the observed variations within this range are linked to the species/variety, the degree and type of roast & the infusion preparation method (Figure 2) 25 .…”