In vitro screening of the antispasmodic effect of Citrus extract based product and its main flavonoids on porcine intestine

Since Citrus flavonoids have been proved to possess pronounced antispasmodic properties [1,2], it seems reasonable to verify if they might be applicable as potential mitigation agents in swine diarrhoea by acting as spasmolytic agents on intestine smooth muscle. Nor-Spice AB®, a product containing Citrus extract, is currently used in pigs for its prebiotic effect but its impact on gut motility remains unrecognized. Therefore, the aim of this study was to evaluate the antispasmodic effect of Nor-Spice AB® and main flavonoids of Citrus extract, hesperetin and naringenin, on segments of the jejunum collected from domestic pigs.

The experiments were performed on jejunum tissues collected from routinely slaughtered pigs. The experiments were conducted under isometric conditions.

The results showed that Nor-Spice AB®, hesperetin and naringenin cause a dose-dependent modification of carbamoylcholine (CCh)-induced contractility. If used at low concentrations, i.e. 0.01 – 1µL/mL and 0.1 – 1µM for Nor-Spice AB® and flavonoids, respectively, all agents generate significant increase in the contractile activity. In contrast, if applied at higher doses both Citrus extract product and individual phytoconstituents reduce CCh-evoked contraction of the smooth muscle.

Tab. 1

Test substance	Concentration range	Induced effect	% of CCh-induced contraction (control) Mean values ± SD
Nor-Spice AB®	0.001µL/mL	myorelaxant	77.5 ± 21.5
	0.01 – 1 µl/mL	contractile	100.8 ± 12.9 – 120.3 ± 20.8
	10 – 100µL/mL	myorelaxant	58.9 ± 15.4 – 82.7 ± 10.1
Hesperetin	0.1 – 1µM	contractile	106.6 ± 15.8 – 160.3 ± 14.9
	10 – 100µM	myorelaxant	32.5 ± 38.2 – 94.9 ± 38.4
Naringenin	0.1 – 1µM	contractile	97.5 ± 25.6 – 149.2 ± 16.8
	10 – 100µM	myorelaxant	62.6 ± 10.6 – 91.4 ± 7.1

In conclusion, the obtained data suggest that hesperetin and naringenin might be responsible for the effect of Nor-Spice AB® on jejunum contractility. The desired antispasmodic effect can be expected only if Citrus extract based product is used as feed additive in relatively high doses.

[1] Gharzouli K, Holzer P. Pharmacology 2004; 70: 5 – 14

[2] Yang ZH, Pan A, Zuo WL, Guo JH, Zhou WL. J Ethnopharmacol 2014; 155: 1177 – 1183.