Species differences in the gut stimulatory effects of radish seeds

This study describes the gastrointestinal (GI) prokinetic effects of the aqueous extract of radish seeds (Rs.Cr). Rs.Cr, which tested positive for terpenes, flavonoids, phenols, alkaloids and saponins, showed a spasmogenic effect in isolated rabbit jejunum and ileum, rat stomach fundus and ileum, and guinea-pig ileum and jejunum. Rs.Cr was around 10 times more potent in the guinea-pig tissues and this effect was resistant to atropine, pyrilamine or SB203186 while the spasmogenic effect in the rat and rabbit tissues was atropine sensitive. The extract exhibited atropine-sensitive GI prokinetic and laxative effects in vivo in mice. In the atropinized rabbit jejunum, Rs.Cr produced a spasmolytic effect independent of Ca(++) or K(+) channels, adrenergic or opioid receptor involvement. Activity-directed fractionation of Rs.Cr yielded four fractions, all showing effects similar to that of the parent extract. Rs.Cr and its fractions were found to be non-lethal up to 10 g kg(-1) in mice for 24 h, except for the petroleum fraction, which showed 50% mortality at high doses. Some known radish compounds (spermine, spermidine, putrescine and sinigrin) were also tested and found to be devoid of any activity. The study shows species-specific spasmogenic effects of radish in rabbit, rat and mouse via muscarinic receptors but through an uncharacterized pathway in guinea-pig tissues. Additionally, a dormant relaxant effect was also seen, while the three polyamines and one glucosinolate from radish were found to be inactive, indicating that the compound(s) responsible for the activities reported remains to be isolated.