A 90 day repeated oral toxicity study on plantamajoside concentrate from Plantago asiatica.

Plantago asiatica is distributed widely in East Asia. Since ancient times it has been used as a diuretic to treat acute urinary infections, and as an antiinflammatory, antiasthmatic, antioxidant, antibacterial, antihyperlipidemic and antihepatitis drug. The major compound, plantamajoside from P. asiatica, which is used as a marker compound in chemotaxonomic studies, was reported to have antibacterial activity, inhibition activity against cAMP phosphodiesterase and 5-lipoxygenase and antioxidant activity. However, there are no reports on the safety of plantamajoside. This study assessed the toxic effects of plantamajoside concentrate (PC), the purity of which was above 80%, in rats following administration at dose levels of 0, 500, 1000 and 2000 mg/kg body weight/day for 13 weeks, as recommended by the OECD guidelines. The results showed that there were no differences in body weight, food intake, water consumption, relative organ weight or the hematological and serum biochemical values among the different dosage groups. No death or abnormal clinical signs were observed during the experimental period. Therefore, the results suggested that no observed adverse effect level (NOAEL) of the PC in rats after oral administration is considered to be greater than 2000 mg/kg in rats under the conditions employed in this study.

Suppressive effects of nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression by Citrus reticulata extract in RAW 264.7 macrophage cells.

Immature peels of Citrus reticulata extract (CR) are widely used as traditional herbal medicine in Korea. We studied its effects on nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in RAW 264.7 macrophage cells. NO production was assessed by nitrite assay and iNOS expression was identified by reverse transcription-polymerase chain reaction (RT-PCR), Real-time PCR and Western blot. The promoter activity of iNOS gene was also determined by luciferase reporter gene assay using 5'-flanking region of murine iNOS gene. Activation of nuclear factor kappa B (NF-kappaB) was determined by electrophoretic mobility shift assay (EMSA). CR (20, 50, and 100 microg/ml) significantly inhibited the lipopolysaccharide (LPS)-induced NO production (P<0.01; 9.2+/-1.5, 4.8+/-0.6, and 3.3+/-0.4 microM), iNOS protein (38.1+/-3.8, 32.3+/-5.8, and 36.8+/-4.5%) and mRNA expression (34.2+/-4.1, 13.1+/-5.8, and 20.8+/-1.2%) in RAW 264.7 macrophage cells. CR (20, 50, and 100 microg/ml) also reduced the iNOS promoter activity (68.7+/-3.9, 50.6+/-5.6, and 45.9+/-3.9%) in piNOS-LUC-transfected cells. In addition, CR (20, 50, and 100 microg/ml) significantly inhibited the activity of NF-kappaB DNA binding activity in LPS-induced macrophage cells (P<0.05; 51.8+/-4.1, 32.7+/-5.5, and 35.7+/-2.9%). These results suggest that CR may suppress LPS-stimulated NO production by inhibiting of NF-kappaB.