Polax 2l polarimeter

Growth was monitored by measuring turbidity at 600 nm (OD₆₀₀), cell counts, and biomass dry weight (DW). Cells were counted in a Bürker chamber; the DW was determined with a thermo-balance (MB 64 M, VWR, Radnor, PA, USA) (20).
Arabitol and residual glycerol in culture supernatants—clarified by centrifugation (10,000 rpm for 5 min at 4 °C) and filtration at 0.22 μm—were analyzed in HPLC with refractive index detector (1200 System, Agilent Technologies, Waldbronn, Germany). Isocratic elution was carried out at 60 °C with 0.8 mL/min of 5 mM H₂SO₄ through an ion exclusion column (Aminex HPX-87 H, Bio-Rad, Hercules, CA, USA) [27 (link)]. ¹ H- spectra were recorded at 298 K on Bruker FT-NMR Advance 400 (400.13 MHz). Chemical shift values are given in ppm relative to TMS and were determined by taking as reference the isotopic impurity signals DMSO-d6 (2.50 ppm). Prior to NMR analysis, the supernatant of the improved fed-batch cultures was lyophilized overnight with a Alpha 1–2 LD Laboratory (Christ, Germany). Polarimetric analysis was carried out using a Polax-2 L polarimeter (Atago, Japan).

All reagents and solvents used were of analytical grade. Melting points or temperatures of decomposition were measured using open capillary tubes on a Gallenkamp (variable heater) melting point apparatus. The UV-Vis spectra were obtained using a Genesis 10 UV-Vis spectrophotometer at the Central Science Laboratory, Obafemi Awolowo University, Ile-Ife, Nigeria. The infrared spectra (KBr) were recorded on a Genesis II FT-IR spectrophotometer at North-West University, Mafikeng Campus, South Africa. Optical rotations were measured using Atago Polax-2L polarimeter at the Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Ile-Ife. Magnetic susceptibility was obtained using a Sherwood scientific balance, Kwara State University, Nigeria. Antimicrobial activities of the complexes was determined at the Department of Pharmaceutics, Obafemi Awolowo University, Ile-Ife. Brine shrimp lethality bioassay was carried out at the Department Biochemistry and Molecular Biology, Obafemi Awolowo University, Ile-Ife.
The syntheses, characterization, and the antimicrobial studies for the glycinato complexes have been reported previously [33 (link)]. However, the cytotoxic activity is reported here for the first time.

Thin layer chromatography (TLC) analysis was performed on TLC silica gel 60 F254 aluminum sheet 20 × 20 cm (Merck, Darmstadt, Germany). A silica gel column (0.040–0.063 mm granule size), a sephadex LH-20 column (particle size dry 18–111 µm), and a C18 column (40–63 particle size) were used for chromatographic isolation of the extract constituents. Fourier-transform infrared (FT-IR) spectra were recorded with attenuated total reflectance (ATR) mode on a PerkinElmer spectrum GX (Perkin Elmer, Waltham, MA, USA). Optical rotations were measured using a POLAX-2L polarimeter (Atago, Japan). An Agilent 1260 infinity high performance liquid chromatography instrument via an electrospray ionization (ESI) interface to a 6540 ultrahigh definition accurate mass Q-TOF (Agilent Technologies, Palo Alto, CA, USA) was conducted. Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AV400 (Bruker, Billerica, MA, USA) spectrometer at 400 MHz for proton and 100 MHz for carbon. The absorbance was measured using hybrid Multi-Mode Detection Synergy H1 (Model H1MF) (Bio-TeK Instruments, Winooski, VT, USA). The high performance liquid chromatography (HPLC) was performed using Agilent Technology (model 1260 infinity with fraction collector, Santa Clara, CA, USA).