Stabilization-oriented preformulation study of photolabile menatetrenone (vitamin K2)

Vitamin K (phylloquinone and menaquinones) in foods - Optimisation of extraction, clean-up and LC-ESI-MS/MS method for quantification

Growing evidence of vitamin K's importance in human health beyond blood coagulation and bone health necessitates its further research. A method involving extraction, lipase treatment, clean-up, and detection and quantification by LC-ESI-MS/MS of phylloquinone (PK), menaquinone-4 (MK-4), menaquinone-7 (MK-7) and menaquinone-9 (MK-9) was developed, and single-laboratory validated. The matrices included in the validation were hazelnut, cheese, broccoli, and pork. The LC-method runtime was 9 min. The LOQ for PK, MK-4 and MK-7 was 0.5 µg/100 g food, while for MK-9 it was 2.5 µg/100 g food. The intra- and inter-day precision was <15% for endogenous and spiked levels, except for low content at 4 times the LOQ. Trueness was assessed to be in the range 94-125% for spiking at levels approximately 4 and 10 times LOQ. It is further shown that deuterium labelled MK-7 can be used as an internal standard for MK-9.

Prodrugs for Skin Delivery of Menahydroquinone-4, an Active Form of Vitamin K2(20), Could Overcome the Photoinstability and Phototoxicity of Vitamin K2(20)

The effective delivery of menahydroquinone-4 (MKH), an active form of menaquinone-4 (MK-4, vitamin K₂₍₂₀₎), to the skin is beneficial in the treatment of various skin pathologies. However, its delivery through the application of MK-4 to the skin is hampered due to the photoinstability and phototoxicity of MK-4. This study aimed to evaluate the potential of ester prodrugs of MKH for its delivery into the skin to avoid the abovementioned issues. The ester prodrugs, MKH 1,4-bis-N,N-dimethylglycinate hydrochloride (MKH-DMG) and MKH 1,4-bis-hemisuccinate (MKH-SUC), were prepared using our previously reported methods. Photostability was determined under artificial sunlight and multi-wavelength light irradiation, phototoxicity was determined by intracellular ROS formation and cell viability of UVA-irradiated human epidermal keratinocyte cells (HaCaT), and delivery of MKH into HaCaT cells was assessed by measuring menaquinone-4 epoxide (MKO) levels. MKH prodrugs showed higher photostability than MK-4. Although MK-4 induced cellular ROS and reduced cell viability after UVA irradiation, MKH prodrugs did not affect either ROS generation or cell viability. MKH prodrugs enhanced intracellular MKO, indicating effective delivery of MKH and subsequent carboxylation activity. In conclusion, these MKH prodrugs show potential for the delivery of MKH into the skin without photoinstability and phototoxicity.

Photodegradation study of a new activator of the cystic fibrosis chloride channel, the 6-hydroxy-10-chlorobenzo[c]quinolizinium chloride (MPB-07)

The photodegradation of 6-hydroxy-10-chlorobenzo[c]quinolizinium chloride (MPB-07), a new activator of the transmembrane conductance regulator chloride channel, was studied in aqueous solutions exposed to artificial daylight (2300 Lux intensity). Various conditions of pH, concentration, and temperature were used. MPB-07 concentration was determined at regular time intervals by reversed-phase HPLC. MPB-07 stability was also studied at pH 7.4 in the dark. Results showed that in all the conditions tested MPB-07 underwent rapid photodegradation, apparently following first-order kinetics. Rate constants were dependent on the initial MPB-07 concentration, temperature, and pH. At pH 7.4, and for concentrations from 1 to 125 microM, half-lives ranged from 0.681 +/- 0.047 to 4.54 +/- 0.28 h. The Arrhenius plot was linear and activation energy was calculated to be 20.7 kJ x mol(-1). Analysis by chemical ionization-mass spectrometry showed that the chlorine atom of the MPB-07 molecule might be replaced by an OH group during the photodegradation process. In the dark, MPB-07 in solutions at pH 7.4 was found to be stable over a 6-week period. In conclusion, MPB-07 is a highly photolabile molecule that should be carefully protected from light when used.

Evaluation of photostability of solid-state dimethyl 1,4-dihydro-2, 6-dimethyl-4-(2-nitro-phenyl)-3,5-pyridinedicarboxylate by using Fourier-transformed reflection-absorption infrared spectroscopy

Effect of particle size on the photostability of dimethyl 1, 4-dihydro-2,6-dimethyl-4-(2-nitro-phenyl)-3,5-pyridinedicarboxylate (nifedipine) powder and its tablet was investigated using high-pressure liquid chromatography (HPLC) method and Fourier-transformed infrared reflection-absorption spectroscopy (FT-IR-RAS) under the non-destructive condition. The nifedipine content on the surface of the tablet was determined based on the absorbance at 1682 cm(-1) attributable to the C=O stretch vibration in FT-IR-RAS spectra before and after irradiation by fluorescent lamp. The photodegradation followed apparently the first-order kinetics for any sample. The apparent photodegradation rate constant of nifedipine powder increased with decrease of the particle size, while that of its tablet was approximately constant irrespective of particle size. Semilogarithmic plots of the apparent degradation rate constant for nifedipine tablet against the reciprocal of illuminance demonstrated a linear relationship similar to that of the Arrhenius-type behavior.