Apigenin acts as a partial agonist action at estrogen receptors in vivo

Decamethylcyclopentasiloxane affects estradiol production in female rats but not H295R cells

Sex hormones, such as androgens and estrogens, are predominantly produced in the gonads (ovaries and testes) and adrenal cortex. Endocrine-disrupting chemicals (EDCs) are substances that mimic, block, or interfere with hormones in the endocrine systems of humans and organisms. EDCs mainly act via nuclear receptors and steroidogenesis-related enzymes. In the OECD conceptual framework for testing and assessment of EDCs, several well-known assays are used to identify the potential disruption of nuclear receptors both in vivo and in vitro, whereas the H295R steroidogenesis assay is the only assay that detects the disruption of steroidogenesis. Forskolin and prochloraz are often used as positive controls in the H295R steroidogenesis assay. Decamethylcyclopentasiloxane (D5) was suspected one of EDCs, but the effects of D5 on steroidogenesis remain unclear. To establish a short-term in vivo screening method that detects the disruption of steroidogenesis, rats in the present study were fed a diet containing forskolin, prochloraz, or D5 for 14 days. Forskolin increased plasma levels of 17β-estradiol (E2) and testosterone as well as the mRNA level of Cyp19 in both the adrenal glands and ovaries. Prochloraz induced the loss of cyclicity in the sexual cycle and decreased plasma levels of E2 and testosterone. D5 increased E2 levels and shortened the estrous cycle in a dose-dependent manner; however, potential endocrine disruption was not detected in the H295R steroidogenesis assay. These results demonstrate the importance of comprehensively assessing the endocrine-disrupting effects of chemicals on steroidogenesis in vivo.

Tailoring Potential Natural Compounds for the Treatment of Luminal Breast Cancer

Breast cancer (BC) is the most diagnosed cancer worldwide, mainly affecting the epithelial cells from the mammary glands. When it expresses the estrogen receptor (ER), the tumor is called luminal BC, which is eligible for endocrine therapy with hormone signaling blockade. Hormone therapy is essential for the survival of patients, but therapeutic resistance has been shown to be worrying, significantly compromising the prognosis. In this context, the need to explore new compounds emerges, especially compounds of plant origin, since they are biologically active and particularly promising. Natural products are being continuously screened for treating cancer due to their chemical diversity, reduced toxicity, lower side effects, and low price. This review summarizes natural compounds for the treatment of luminal BC, emphasizing the activities of these compounds in ER-positive cells. Moreover, their potential as an alternative to endocrine resistance is explored, opening new opportunities for the design of optimized therapies.

Preparation of blue fluorescent copper nanoclusters for sensitive and selective sensing of apigenin in pharmaceutical samples

One-pot means was performed for the rapid preparation of copper nanoclusters (Cu NCs), which were employed as a fluorescence system for the sensitive apigenin measurement in pharmaceutical samples. Herein, CuCl₂ aqueous solution was reduced to Cu NCs through ascorbic acid and the Cu NCs were protected through trypsin under 65 ℃ for 4 h. The entire preparation process was rapid, facile and environmentally friendly. The trypsin-capped Cu NCs were demonstrated through ultraviolet-visible spectroscopy, fluorescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and fluorescence lifetime, respectively. The Cu NCs revealed blue fluorescence with emission wavelength around 465 nm under the excitation wavelength of 380 nm. The fluorescence weakening feature of Cu NCs with apigenin was observed. On this basis, a facile and sensitive turn-off fluorescent nanoprobe for the sensing of apigenin in real samples was developed. The logarithm of relative fluorescence intensity revealed a good linear relationship with apigenin contents from 0.5 μM to 300 μM with the detection limit of 0.079 μM. The Cu NCs-based fluorescent nanosensor have been employed to measure the apigenin amounts in real samples such as medical saline, bovine and human serum. The results revealed excellent potential of this Cu NCs-based fluorescent nanoprobe for the convention computation of apigenin amounts in real samples.

The phytoestrogenic potential of flavonoid glycosides from Selaginella moellendorffii via ERα-dependent signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella moellendorffii (SM) has been applied as an ethnic drug to treat conditions such as osteoporosis, idiopathic thrombocytopenic purpura, and chronic inflammation. It is known to be rich in flavonoids, including apigenin glycosides and unique elements of bioflavonoids.

AIM OF THE STUDY

To investigate estrogen-like constituents of SM and the possible mechanism.

MATERIALS AND METHODS

We identified the main components in liquid chromatography and liquid chromatography-mass spectrometry. The estrogenic effects were examined using a recombinant yeast screening assay, an E-screen cell proliferation assay, and an in vivo uterotrophic assay.

RESULTS

Flavonoid glycosides extract, some flavonoid glycosides, and apigenin showed estrogen agonistic activity in the yeast screening assay. They also induced cell proliferation in estrogen receptor-positive (ER+) cells but not in estrogen receptor-negative (ER-) cells. Consistently, the protein expression of ERα, phosphorylation protein kinase B (p-AKT), phosphatidylinositol 3 kinase (PI3K), phosphorylation mammalian target of rapamycin (p-mTOR), phosphorylation 38,000-Da protein (p-P38), and phosphorylation extracellular-regulated kinase 1/2 (p-ERK1/2) elevated following treatment with flavonoid glycoside extract (P < 0.01 or P < 0.05). These effects could be blocked by ER antagonist or ERα antagonist but not be blocked by ERβ antagonist. In vivo assay, flavonoid glycoside extract could significantly increase body weight, serum estradiol level, uterine wet weight, alter uterine morphology, and promote ERα protein expression (P < 0.01 or P < 0.05).

CONCLUSIONS

ERα induction via mitogen-activated protein kinases (MAPK) and PI3K/Akt/mTOR pathways might be the possible mechanism underlying the phytoestrogen effect of SM, and the flavonoid glycosides might be the critical estrogenic constituents.