Typhae Pollen active subfraction exerts antiangiogenic effect in benign prostatic hyperplasia via regulating the VEGF signaling pathway and arachidonic acid metabolism.

BACKGROUND

Typhae Pollen is one of the earliest pollen varieties used in the world, whether as a herbal medicine or a dietary additive. Although Typhae Pollen has been reported to alleviate benign prostatic hyperplasia (BPH) and is widely used in traditional Chinese medicine (TCM) prescriptions, its active components and potential mechanisms of action remain insufficiently understood.

PURPOSE: This study aims to explore the therapeutic efficacy and molecular mechanism of Typhae Pollen active subfraction (TPAS) against BPH, as well as its active ingredients.

METHODS

The qualitative and quantitative analysis of the main components in TPAS was conducted using UPLC-QTOF-MS and UPLC-TQ-MS techniques. A testosterone propionate (TP)-induced BPH rat model was employed to evaluate the in vivo efficacy of TPAS. Then, a multi-faceted approach including network pharmacology and metabolomics was performed to reveal the molecular mechanisms of TPAS. Additionally, the active ingredients in TPAS were identified using the models of Tg (fli1:EGFP) zebrafish, human umbilical vein endothelial cells (HUVEC), and the human prostate benign hyperplasia cells (BPH-1).

RESULTS

TPAS mainly composed of the flavonoid glycosides and dihydroflavonoids, and the sum of the contents of 8 flavonoids was 290.05 mg/g in TPAS, including typhaneoside, isorhamnetin 3-O-neohesperidoside, kaempferol 3-O-neohesperidoside, and naringenin (NAR). In vivo findings showed that TPAS alleviated prostate enlargement, decreased prostate epithelial tissue thickness, and inhibited androgen levels. Next, network pharmacology analysis demonstrated that TPAS may suppress angiogenesis in BPH by inhibiting VEGF signaling and arachidonic acid metabolism. While TPAS significantly inhibited the expression of CD31, VEGFA, p-VEGFR2/VEGFR2, ALOX5 and COX-2 in prostate tissues, and also decreased the levels of bFGF, LTB4 and PGE2. Moreover, metabolomic analysis suggested that 12 differential metabolites (DMs) regulated by TPAS were involved in arachidonic acid metabolism and steroid hormone biosynthesis. Importantly, association analysis with network pharmacology identified 12 targets represented by COX-2, ALOX5, ALOX12, PLA2G6, AKR1C3, and CYP19A1. Notably, TPAS significantly reduced the levels of the above proteins highly expressed in BPH rats. In addition, NAR (a natural dietary flavonoid) was considered as the principal bioactive component in TPAS, which exerted remarkable effects in inhibiting the growth of intersegmental vascular (ISVs) in Tg (fli1:EGFP) zebrafish, the proliferation, migration and tube formation of HUVECs, and arachidonic acid metabolism in BPH-1 cells.

CONCLUSIONS

The present study demonstrates that TPAS exerts antiangiogenic effect in BPH via suppressing the VEGF signaling pathway and arachidonic acid metabolism. These findings provide a new source of natural pollen for the clinical treatment of BPH. Especially, this study is the first to systematically elucidate the mechanism of action of a flavonoid-rich extract of Typhae Pollen for improving BPH.