Three new kavalactone dimers from Piper methysticum (kava).

Three new dimeric kavalactones, designated as diyangonins A-C (1-3), along with two known analogs were isolated from the roots of Piper methysticum. Their structures were elucidated by means of extensive analysis of their 1D, 2D NMR, and mass spectroscopic data. All these dimers possess a skeleton featuring a cyclobutane ring connecting two kavalactone units in head-to-tail or head-to-head mode. Compounds 1-5 were evaluated for their cytotoxic activities against human tumor cell lines.

Methionyl-Methionine Promotes α-s1 Casein Synthesis in Bovine Mammary Gland Explants by Enhancing Intracellular Substrate Availability and Activating JAK2-STAT5 and mTOR-Mediated Signaling Pathways.

BACKGROUND: Interest is increasing in the role of peptide-bound amino acids (AAs) in milk protein synthesis because studies have found that the uptake of some essential AAs by the mammary gland cannot meet the requirements for milk protein synthesis. Although the role of dipeptides in milk protein synthesis is clearly established, little is known about the underlying mechanisms. OBJECTIVE: The objective of this study was to determine whether small peptides can be taken up intact by the peptide transporters in mammary tissue explants and the underlying mechanisms of the effects of methionyl-methionine (Met-Met) supplementation on milk protein synthesis. METHODS: Mammary tissue explants were cultured in conditional medium and then treated with different concentrations of Met-Met that replaced 0%, 5%, 10%, 15%, 20%, and 25% of free Met for another 24 h. In some experiments, explants were cultured with an optimal dose of Met-Met with or without the inhibitors of peptide transporter 2 [PepT2; diethylpyrocarbonate (DEPC), 0.1 mmol/L] and aminopeptidase N (APN; bestatin, 20 µmol/L) for 24 h. RESULTS: The substitutions of 15% free Met with Met-Met significantly promoted α-s1 casein (αs1-CN) expression in the mammary explants (P < 0.05). The inhibition of the PepT2 by DEPC or APN by bestatin significantly decreased the Met-Met-stimulated increase of αs1-CN expression (P < 0.05). Compared with the control group (0% Met-Met), absorption of Val, Met, Leu, Phe, Lys, and His was improved, and mRNA abundance of the neutral and basic AA transporter was increased in the 15% Met-Met group (P < 0.05). In addition, the mRNA abundance of the mammalian target of rapamycin (mTOR), p70 ribosomal S6 kinase 1 gene, eukaryotic initiation factor 4E binding protein 1 gene , Janus kinase 2 (JAK2), and signal transducer and activator of transcription 5 (STAT5) was increased in the 15% Met-Met-treated group (P < 0.05). CONCLUSION: Met-Met promoted αs1-CN synthesis in cultured bovine mammary gland explants, and this stimulation may be mediated by enhanced intracellular substrate availability and by activating JAK2-STAT5 and mTOR signaling pathways.

[Progress on the miRNA related with mammary gland development and lactation].

MicroRNAs (miRNAs) are non-coding RNAs that play important roles in post transcriptional regulation. They are involved in the regulation of mammary gland development and lactation. In this paper, we summarized the expression pattern of miRNAs which varied with tissues and lactation stages, and the functions of several miRNAs are also briefly reviewed. The objective of this work is to give reference for further study on miRNAs in mammary gland, and to provide theoretical basis and ideas for the use of miRNAs in improving healthy development of mammary gland and regulating the efficiency of lactation and the quality of milk.

Two new lignans from the stems of Schisandra bicolor.

Two new lignans, named zuihonins E (1) and F (2), were isolated from the stems of Schisandra bicolor Cheng var. tuberculata Law. The structures of the new lignans were elucidated on the basis of extensive spectroscopic analysis, including 1D, 2D NMR, and MS experiments, and their absolute stereochemistry was determined by circular dichroism spectrum. Compounds 1 and 2 did not inhibit the growth of hepatoma carcinoma cell (HepG2), lung carcinoma cell (A549), and human breast carcinoma (MCF-7) cell lines.