Biochanin A

Renal fibrosis is a hallmark of chronic kidney disease (CKD). Smad3 serves as the principal transcription factor mediating the pro-fibrosis effects of TGF-β signaling in renal fibrosis. Biochanin A (BCA), a natural isoflavone, has been shown to attenuate renal fibrosis by inhibiting TGF-β signaling but the detailed mechanisms remain unresolved. This study aimed to elucidate the specific mechanisms by which BCA modulates TGF-β signaling.

Renal fibrosis models were established both in vitro, using TGF-β1-stimulated mouse renal tubular TCMK1 cells, and in vivo, employing mice with unilateral ureter obstruction (UUO). RNA-seq was conducted to identify BCA-regulated genes. The AnimalTFDB4.0 database was utilized to predict transcription factors with potential binding to Smad3 promoter. The activities of TGF-β signaling and the cloned mouse Smad3 promoter were assessed using luciferase reporter assays. Plasmid transfection was performed using polyethylenimine in TCMK1 cells or ultrasound microbubbles in UUO kidneys. Gene expression was analyzed by RT-PCR, western blot, and immunohistochemistry assays.

BCA significantly inhibited TGF-β signaling activity and suppressed TGF-β1-induced fibrotic gene expression in TCMK1 cells. RNA-seq and in silico analyses identified Smad3 as the key gene downregulated by BCA, while leaving Smad2 unaffected. This selective transcriptional suppression of Smad3 by BCA was validated by luciferase reporter assays using the cloned Smad3 promoter. Furthermore, transcription factor binding prediction identified that Klf6, a transcription factor downregulated by BCA, has binding potential to the Smad3 promoter and promotes Smad3 transcription. Klf6 expression was induced in TGF-β1-stimulated TCMK1 cells and UUO kidneys, but this induction was abolished upon BCA treatment. Importantly, Klf6 overexpression restored Smad3 expression and counteracted the anti-fibrosis effects of BCA in both TGF-β1-stimulated TCMK1 cells and UUO kidneys.

TGF-β-responsive Klf6 transcriptionally transactivates Smad3 expression. BCA exerts anti-renal fibrosis effects by inhibiting the Klf6-Smad3 signaling axis, underscoring its therapeutic potential in the treatment of CKD.

In this study, nine endophytic fungi capable of producing multiple phenolic compounds were screened and identified from 152 fungi isolated from pigeon pea in a natural habitat (Honghe, Yunnan Province, China). Talaromyces neorugulosus R-209 exhibited the highest potential for phenolic compound production. L-phenylalanine feeding was used to enhance phenolic compound production in T. neorugulosus R-209 cultures. Under the optimal feeding conditions (l-phenylalanine dose of 0.16 g/L and feeding phase of 6 days), the yields of genistein, apigenin, biochanin A, and cajaninstilbene acid increased by 15.59-fold, 7.20-fold, 25.93-fold, and 10.30-fold over control, respectively. T. neorugulosus R-209 fed with l-phenylalanine was found to be stable in the production of phenolic compounds during ten successive subcultures. Moreover, bioactivities of extracts of T. neorugulosus R-209 cultures were significantly increased by l-phenylalanine feeding. Overall, l-phenylalanine feeding strategy made T. neorugulosus R-209 more attractive as a promising alternative source for the production of health-beneficial phenolic compounds in the nutraceutical/medicinal industries.