RESUMO
The potential of the Copaifera langsdorffii leaves extract to prevent stone formation was analyzed by means of an ethylene glycol (EG) animal model of nephrolithiasis and an in vitro crystallization assay. Different doses of the C. langsdorffii leaves extract were administered to rats treated with EG. Urine biochemical parameters were quantified. CaOx deposits count and analysis of osteopontin expression were conducted on kidneys fixed in formalin. The in vitro assay was performed by turbidimetry. Phytochemical analyses of the extract were accomplished by HPLC-UV-DAD, and several compounds were isolated. C. langsdorffii leaf extract was able to avoid stone formation. The number of deposits was 50.30 ± 31.29 at the higher extract dose, compared to the value of 179.5 ± 45.96 achieved with the EG control. Significantly lower oxalate levels and OPN expression and increased citrate levels were observed after extract administration. In the in vitro assay, the extract diluted the formed crystals. Phytochemical analyses showed that the extract is rich in phenolic compounds that are capable of preventing stone formation. Thus, on the basis of our results, we suggest that the C. langsdorffii leaf extract has potential application in the prevention of kidney stone formation.
RESUMO
AIM OF THE STUDY: Yacon [Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, Asteraceae] is an Andean species that has traditionally been used as an anti-diabetic herb in several countries around the world, including Brazil. Its hypoglycaemic action has recently been demonstrated in normal and diabetic rats. However, studies about the safety of prolonged oral consumption of yacon leaf extracts are lacking. Thus, this work was undertaken to evaluate the repeated-dose toxicity of three extracts from yacon leaves: the aqueous extract (AE) prepared as a tea infusion; the leaf-rinse extract (LRE), which is rich in sesquiterpene lactones (STLs); and a polar extract from leaves without trichomes, or polar extract (PE), which lacks STLs but is rich in chlorogenic acids (CGAs). MATERIALS AND METHODS: The major classes of the compounds were confirmed in each extract by IR spectra and HPLC-UV-DAD profiling as well as comparison to standard compounds. The toxicity of each extract was evaluated in a repeated-dose toxicity study in Wistar rats for 90 days. RESULTS: The PE was rich in CGAs, but we did not detect any STLs. The AE and LRE showed the presence of STLs. The polar extract caused alterations in some biochemical parameters, but the animals did not show signs of behavioural toxicity or serious lesions in organs. Alterations of specific biochemical parameters in the blood (creatinine 7.0 mg/dL, glucose 212.0 mg/dL, albumin 2.8 g/dL) of rats treated with AE (10, 50 and 100 mg/kg) and LRE (10 and 100 mg/kg) pointed to renal damage, which was confirmed by histological analysis of the kidneys. CONCLUSIONS: The renal damage was associated with increased blood glucose levels after prolonged oral administration of the AE. This observation suggested that the hypoglycaemic effect observed after treatment for 30 days in an earlier study is reversible and was likely the result of renal injury caused by the toxicity of yacon. Because STLs were detected in both AE and LRE, there is strong evidence that these terpenoids are the main toxic compounds in the leaves of the yacon. Based on our results, we do not recommend the oral use of yacon leaves to treat diabetes.