# Total flavonoids from Abelmoschus manihot (L.) improve diabetes nephropathy by regulating the gut–kidney axis

## TL;DR

This study shows that flavonoids from Abelmoschus manihot improve diabetic kidney disease by altering gut bacteria, blood metabolites, and kidney gene activity.

## Contribution

The study identifies the gut–kidney axis as a novel therapeutic mechanism for flavonoids in treating diabetic nephropathy.

## Key findings

- TFA reduced urinary albumin-creatinine ratio and altered gut microbiota in diabetic mice.
- TFA increased beneficial bacteria like Dietzia and Blautia while decreasing harmful ones like Bacteroidetes.
- TFA suppressed kidney gene pathways related to inflammation and cortisol production.

## Abstract

A recent clinical study demonstrated that Huangkui capsule (with its bioactive constituents being total flavones extracted from Abelmoschus manihot (L.), TFA) combined with irbesartan provides effective therapy for type 2 diabetes (T2D) patients with diabetic nephropathy (DN).

This study aimed to elucidate the therapeutic mechanisms of TFA in DN through the modulation of the gut–kidney axis.

The db/db mice were administered TFA, irbesartan, or vehicle. Urinary albumin-creatinine ratio (UACR) was measured by the enzyme-linked immunosorbent assay (ELISA). Intestinal bacterial composition was analyzed using 16S rRNA sequencing. Serum metabolites were quantified via LC-ESI-MS/MS. Kidney transcriptomics were assessed using Illumina platform-based RNA sequencing.

Administration of TFA reduced the UACR in db/db mice and significantly altered intestinal flora composition. Specifically, TFA elevated the abundance of Dietzia, Faecium, Streptococcus, and Blautia while reducing Bacteroidetes, Firmicutes, Enterobacteriaceae, Rikenellaceae, Fusivibrio, and Treponema. In serum metabolomic analysis, TFA increased the levels of quercetin 3-glucuronide and n-cinnamyl glycine but decreased cortisol concentrations. Concurrently, renal transcriptomics revealed the downregulation of key genes, including retnlg, ngp, mpo, camp, ctsg, elane, s100a8, s100a9, trem1, and mmp7, which primarily function in pathways related to neutrophil extracellular trap formation, steroid hormone biosynthesis, and cortisol synthesis/secretion. In contrast, irbesartan treatment did not significantly affect blood pressure or specific renal gene pathways in db/db mice.

TFA attenuates diabetic nephropathy (DN) progression through pharmacological mechanisms involving three key axes: (1) modulation of intestinal flora composition, (2) regulation of circulating metabolites, and (3) suppression of renal gene activity pathways. These findings highlight the gut–kidney axis as a central therapeutic target for TFA in DN management.