1. Asymmetric Total Synthesis of Griseofamine B and Its Three Stereoisomers
Tao Sheng, Caiyun Ma, Guangyan Zhang, Xuan Pan, Zhanzhu Liu J Nat Prod. 2022 Apr 22;85(4):1128-1133. doi: 10.1021/acs.jnatprod.2c00069. Epub 2022 Mar 3.
The first total synthesis of griseofamine B is described starting from l-4-bromo tryptophan methyl ester hydrochloride via five steps and in 18% overall yield. Its three stereoisomers were also synthesized following the same procedure with the yields of 5%, 19%, and 5%, respectively. In vitro antibacterial activities were also evaluated. All four compounds exhibited less potent activity than griseofamine A.
2. The Effects of Irisin on Nω-Nitro-L-arginine Methyl Ester Hydrochloride-Induced Hypertension in Rats
Nurettin Aydoğdu, Özlem Yalçınkaya Yavuz, Ebru Taştekin, Pınar Tayfur, Oktay Kaya, Nihayet Kandemir Balkan Med J. 2019 Oct 28;36(6):337-346. doi: 10.4274/balkanmedj.galenos.2019.2019.5.113. Epub 2019 Sep 5.
Background: The cause of about 95% of hypertension, an important public health problem, is unknown. Intensive studies are underway to understand the physiopathology of hypertension. Irisin, a newly discovered hormone, has been reported to dilate vascular smooth muscle and lower blood pressure acutely. Aims: To investigate the effects of chronic irisin treatment on blood pressure and renal functions in a hypertension model established by nitric oxide synthase inhibition by treatment with Nω-nitro-L-arginine methyl ester hydrochloride. Study design: Animal experimentation. Methods: Male Sprague-Dawley rats were divided into four groups (n=8). Control and irisin groups received an intravenous saline injection, hypertension and hypertension + irisin (hypertension + irisin) groups received 1.5 mg/100 g Nω-nitro-L-arginine methyl ester hydrochloride. Nω-nitro-L-arginine methyl ester hydrochloride (150 mg/L) was added to the drinking water of rats in groups hypertension and hypertension + irisin for three weeks. In the second week of the experiment, irisin (50 nmol/day) was given to rats in groups irisin and hypertension + irisin, and saline was administered to rats in groups control and hypertension for two weeks through subcutaneously placed osmotic minipumps. Blood pressure was measured by the tail-cuff plethysmography method. On the twenty-first day of the experiment, 24-hour urine, blood, and both kidneys of the rats were collected. Results: The hypertension group had elevated systolic, diastolic, and mean arterial blood pressure values compared with the control group, with decreased glutathione levels in tissue and serum, but an increase in serum oxidized glutathione level (p<0.05). Histopathologically, increased tubular injury, cast formation, glomerular sclerosis, and peritubular fibrosis levels were observed (p<0.05). Irisin treatment did not cause any significant change in blood pressure, renal functions, and injury scores. However, renal nitric oxide levels significantly increased, and endothelial nitric oxide synthase immunoreactivity was determined to be reduced (p<0.05). Conclusion: Treatment with chronic irisin at a physiological dose does not reduce blood pressure in an experimental model of hypertension. In different models of experimental hypertension, the effects of irisin administration at different doses and at different periods should be thoroughly investigated.
