Marine Actinobacteria are emerging as new resources for bioactive natural products with promise in novel drug discovery. In recent years, the richness and diversity of marine Actinobacteria from the South China Sea and their ability in producing bioactive products have been investigated. The objective of this work is to isolate and identify bioactive secondary metabolites from a marine actinobacterium SCSIO 1934 derived from sediments of South China Sea. The strain was identified as a Streptomyces spieces by analyzing its 16S rDNA sequence. Streptomyces sp. SCSIO 1934 was fermented under optimized conditions and seven bioactive secondary metabolites were isolated and purified by chromatographic methods including colum chromatography over silica gel and Sephadex LH-20. Their structures were elucidated as 17-O-demethylgeldanamycin (1), lebstatin (2), 17-O-demethyllebstatin (3), nigericin (4), nigericin sodium salt (5), abierixin (6), respectively, by detailed NMR spectroscopic data (1H, 13C, COSY, HSQC and HMBC). This work provided a new marine actinobacterium Streptomyces sp. SCSIO 1934, capable of producing diverse bioactive natural products.
Anti-Bacterial Agents ; chemistry ; China ; DNA, Ribosomal ; chemistry ; genetics ; Geologic Sediments ; microbiology ; Oceans and Seas ; RNA, Ribosomal, 16S ; genetics ; Streptomyces ; chemistry ; classification ; genetics ; isolation & purification

Objective:To observe the changes of visual acuity and fixation properties of eyes with idiopathic macular hole (IMH) before and after surgery.Methods:A prospective clinical study. From September 2019 to December 2020, 25 patients with 25 eyes of IMH diagnosed in Department of Ophthalmology of The Fourth People's Hospital of Shenyang were included in the study. All patients underwent pars plana vitrectomy (PPV) combined with internal limiting membrane stripping. All eyes underwent best corrected visual acuity (BCVA), optical coherence tomography (OCT), and microperimetry before and after surgery. The BCVA examination was carried out using the Snellen visual acuity chart, which was converted into logarithmic minimum resolution angle (logMAR) visual acuity during statistics. The 12° macular sensitivity (MS) and bivariate contour ellipse area (BCEA) were measured by MP-3 microperimetry. The minimum diameter (MIN) and base diameter (BASE) of the macular hole were measured by OCT; the distance between the preferred retinal location (PRL) and the center of the fovea was measured by Image-proplus 6.0 image processing software. At 1 and 3 months follow-up after surgery, the same equipment and methods as before surgery were used to conduct related examinations. The changes of BCVA, PRL distance from the fovea, MS, BCEA, and macular hole shape before and after surgery were compared and observed. One-way analysis of variance was used to compare the indicators before and after surgery. Pearson correlation analysis was used for the correlation between BCVA and preoperative BCVA, PRL and foveal center distance at 3 months after surgery. The correlation between MIN, BCVA, PRL and foveal center before surgery distance, MS, BCEA and BCVA at 3 months after surgery were analyzed by multiple linear regression.Results:Among 25 eyes of 25 cases, 1 male had 1 eye, and 24 females had 24 eyes. The macular hole in stage Ⅲ and Ⅳ were 11 eyes and 14 eyes, respectively. MIN and BASE were 537.68±200.09 and 905.48±278.79 μm, respectively. One month after surgery, the hiatus was closed. Before surgery and 1 and 3 months after surgery, the logMAR BCVA of the affected eyes were 0.80±0.17, 0.70±0.21, 0.60±0.25, and the MS were 22.20±3.86, 23.60±3.14, 24.38±2.68 dB, the distances between PRL and the center of the fovea were 537.72±426.05, 402.00±395.06, 236.80±219.54 μm, and BCEA were 7.90±3.43, 6.40±2.67, 4.80±2.32 deg 2. Compared with before operation, BCVA ( F=7.047, 20.104) and MS ( F=1.980, 5.390) were significantly improved at different time after operation, the distance between PRL and fovea center ( F=1.265, 9.530), BCEA ( F=2.762, 13.617) were decreased, the difference were statistically significant ( P<0.05). The results of correlation analysis showed that BCVA at 3 months after surgery was significantly associated with preoperative MIN ( r=0.810), BASE ( r=0.664), BCVA before surgery and 1 month after surgery ( r=0.854, 0.940), preoperative and surgical MS at 1 month after surgery ( r=-0.548, -0.578), distance between PRL and foveal center before surgery and at 1 month after surgery ( r=0.833, 0.915), BCEA before surgery and at 1 month after surgery ( r=0.636, 0.732) were significantly correlated ( P<0.05). The results of multiple linear regression analysis showed that the distance between PRL and foveal center before surgery and BCVA were risk factors for poor prognosis of BCVA at 3 months after surgery. Conclusions:The BCVA and MS of eyes with IMH are significantly improved after surgery, and the distance between PRL and foveal center and BCEA decreased. BCVA, PRL and foveal center distance before surgery are risk factors for poor visual acuity after surgery.