An aqueous extract of Ammi visnaga fruits and its constituents khellin and visnagin prevent cell damage caused by oxalate in renal epithelial cells

Teas prepared from the fruits of Ammi visnaga L. (syn. “Khella”) have been traditionally used in Egypt as a remedy to treat kidney stones. It was the aim of our study to evaluate the effect of a Khella extract (KE) as well as the two major constituents khellin and visnagin on renal epithelial injury using LLC-PK1 and Madin-Darby-canine kidney (MDCK) cells. Both cell lines provide suitable model systems to study cellular processes that are possibly involved in the development of a renal stone. LLC-PK1 and MDCK cell lines were exposed to 300 μM oxalate (Ox) or 133 μg/cm2 calcium oxalate monohydrate (COM) in presence or absence of 10, 50, 100 or 200 μg/mL KE. To evaluate cell damage, cell viability was assessed by determining the release of lactate dehydrogenase (LDH). KE (e.g. 100 μg/ml) significantly decreased LDH release from LLC-PK1 (Ox: 8.46+0.76%; Ox + 100 μg/ml KE: 5.41+0.94%, p<0.001) as well as MDCK cells (Ox: 30.9+6.58%; Ox+100 μg/ml KE: 17.5+2.50%, p<0.001), which indicated a prevention of cell damage. Similar effects for KE were observed in both cell lines when COM crystals were added. In LLC-PK1 cells khellin and visnagin both decreased the % LDH release significantly in cells that were pretreated with Ox or COM crystals. However, khellin and visnagin exhibited different responses in MDCK cells. Whereas khellin slightly reduced the % LDH release after exposure of the cells to Ox and COM crystals, visnagin significantly decreased % LDH release only after COM crystal exposure. Overall both compounds were more active in LLC-PK1 than in MDCK cells. In summary, exposure of renal epithelial cells to Ox or COM crystals was associated with a significant release of LDH indicating cell injury. Our data demonstrate that KE as well as khellin and visnagin could prevent renal epithelial cell damage caused by Ox and COM and could therefore play a potential role in the prevention of stone formation associated with hyperoxaluria.