The flavonoid fraction (FF) from Drynaria fortunei was investigated to determine its biological activity expression in three acute renal failure animal models. Guinea pigs received 100 mg/kg of gentamicin (GM group), 100 mg/kg of GM plus 10 mg/kg of FF (GMFF group), 10 mg/kg of FF (FF group) or saline (saline group) intramuscularly for 14 days. The blood urea nitrogen (BUN) and creatinine levels were found to be significantly higher in the GM group (22.70+/-3.84 mg/dL, 0.68+/-0.05 mg/dL) than in the GMFF group (17.10+/-1.04 mg/dL, 0.58+/-0.09 mg/dL), the FF group (17.40+/-1.01 mg/dL, 0.49+/-0.20 mg/dL) and the saline group (17.50+/-1.22 mg/dL, 0.50+/-0.02 mg/dL). Mice were treated once with 6 mg/kg of mercuric chloride, followed by 10 mg/kg of FF or saline. On days 3, 4 and 5, BUN and creatinine levels were found to be significantly higher in the HgCl2-saline group (74.00+/-39.20 mg/dL, 59.30+/-31.20 mg/dL, 74.00+/-37.30 mg/dL and 0.53+/-0.17 mg/dL, 0.48+/-0.15 mg/dL 0.33+/-0.15 mg/dL) than in the HgCl2-FF group (19.50+/-4.90 mg/dL, 43.00+/-26.30 mg/dL, 38.50+/-13.80 mg/dL and 0.23+/-0.05 mg/dL, 0.30+/-0.12 mg/dL, 0.15+/-0.06 mg/dL).After surgery for 5/6-nephrectomy, ten mice received FF at a dose of 10 mg/kg/day and eight received saline for 42 days. The saline group survived for 12-62 days and the FF group survived for 20-320 days. The FF group had a significantly longer survival time than the saline group (p<0.05). Regeneration of kidney tubular cells and significantly enlarged convoluted tubules were noted in the pathology study of the FF group. In conclusion, the present study suggests that FF prevents nephrotoxicity, improves kidney function and promotes kidney primary epithelial tubular cell regeneration.

A flavanoid fraction (FF) from Drynaria fortunei, was investigated to see if it has the protective and ameliorative effects against gentamicin (GM) ototoxicity in guinea pigs (n = 36). Eleven (GM-group) animals received GM 100 mg/kg/day. Eleven (GMFF-group) animals received the same dose of GM but 2 days prior were dosed with FF (10 mg/kg/day) for 2 weeks. Seven (S-group) animals received saline and seven (FF-group) animals received the same dose of FF as the GMFF-group. The thresholds of tone-burst auditory evoked response (ABR) at 2 k, 8 k, and 32 k Hz were determined to be as follows: GM-group: 90 dB, 92 dB and 72 dB, GMFF-group: 30 dB, 37 dB and 38 dB, FF-group: 28 dB, 25 dB and 29 dB, S-group: 30 dB, 28 dB and 39 dB. The GM-group had a significantly higher hearing threshold than the other groups (p < 0.05). The GMFF- and FF-groups had hearing thresholds similar to the S-groups (p > 0.1). Repair of damaged hair cells was observed histologically. The percentage of the damaged outer hair cells (OHC) and inner hair cells (IHC) were determined to be as follows: GM-group: 43% and 20%, GMFF-group: 20% and 2%, FF-group: 9% and 2% and S-group: 4% and 1%. The GMFF-group showed less damage to the OHC (p > 0.05) and significantly less damage to the IHC (p < 0.05) than the GM-group. FF did not change the antimicrobial activity of GM and it did not show any intrinsic antibacterial effect. FF did not affect the kinetics of GM during the course of the experiment.

This lends strong support to the original idea that the Kidney has a significant influence over bone-formation, as suggested by some long-standing Chinese medical beliefs, kaempferol may also serve to stimulate kidney repair and indirectly stimulate bone formation.