Estrogenic effects of phytoestrogens derived from Flemingia strobilifera in MCF-7 cells and immature rats

Phytoestrogen (PE) has received considerable attention due to the physiological significance of its estrogenicity. Flemingia strobilifera (FS) has been used as a folk medicine in Asia for the treatment of inflammation, cancer, and infection; however, the estrogenic effects and chemical components of FS have not yet been reported. We aimed to uncover the estrogenic properties and PEs derived from FS using phytochemical and pharmacological evaluation. PEs from FS extract (FSE) were analyzed by NMR, HPLC, and MS. To evaluate estrogenic activity, FSE and its compounds were evaluated by in vitro and in vivo assays, including human estrogen receptor alpha (hERα) binding, estrogen response element (ERE)-luciferase reporter assays, and uterotrophic assays. FSE and its compounds 1-5 showed binding affinities for hERα and activated ERE transcription in MCF-7 cells. Additionally, FSE and compounds 1-5 induced MCF-7 cell proliferation and trefoil factor 1 (pS2) expression. In immature female rats, significant increases in uterine weight and pS2 gene were observed in FSE-treated groups. We identified estrogenic activities of FSE and its bioactive compounds, suggesting their possible roles as PEs via ERs. PEs derived from FSE are promising candidates for ER-targeted therapy for post-menopausal symptoms.

Antimicrobial and antioxidant flavonoids from the leaves of Oncoba spinosa Forssk. (Salicaceae)

Background

Naturally occurring flavonoids have been reported to possess various pharmacological properties. The aim of this study was to evaluate the antimicrobial and antioxidant activities of the MeOH extract and flavonoids from the leaves of Oncoba spinosa, a plant used for the treatment of syphilis, wounds and sexual impotence.

Methods

The plant extract was prepared by maceration in methanol and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The MeOH extract and its isolated compounds were evaluated for their antibacterial and antifungal activities by broth microdilution method. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. The samples were tested spectrophotometrically for their hemolytic properties against human red blood cells.

Results

The fractionation of the MeOH extract afforded five known flavonoids including kaempferol (1), quercetin (2), apigenin-7-O-β-D-glucuronopyranoside (3), quercetin 3-O-β-D-galactopyranoside (4) and quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5). The MeOH extract displayed weak to moderate antimicrobial activities (MIC = 256–2048 μg/ml). Quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5) and quercetin (2) were respectively the most active compounds against bacteria (MIC = 8–64 μg/ml) and fungi (MIC = 64 – 128 μg/ml). These tested samples also showed high radical-scavenging activities (EC₅₀ = 5.08 – 70.56 μg/ml) and gallic acid equivalent antioxidant capacities (TEAC = 53.76 – 89.86 μg/ml) when compared with vitamin C (EC₅₀ = 4.72 μg/ml). The MeOH extract and compounds 2–5 were non-toxic to human red blood cells indicating their high selectivity to be used as antimicrobial and antioxidant drugs.

Conclusion

The MeOH extract of O. spinosa as well as compounds 2 – 5 could be a potential source of natural antimicrobial and antioxidant products.