Quantitative 1H NMR method for analyzing primaquine diphosphate in active pharmaceutical ingredients.

Thermal analysis, Fourier Transform IR, the isotropic chemical shift of 1H NMR in different solvents, their temperature dependence and spin-lattice relaxation time constant (T1), solution 1D and 2D NMR, and solid-state 13C and 31P NMR (magic angle spinning NMR) were employed to obtain full information and elucidate the structures of primaquine diphosphate (PQD) samples used for quality controlling malaria medicines. Additionally, a simple, rapid, specific, and reliable quantitative method (qNMR) was developed to determine the PQD level in the raw material of active pharmaceutical ingredients (APIs). The method was developed using ethylene carbonate (EC) as the internal standard and dimethylsulfoxide-d6 (DMSO-d6) as the NMR solvent. For the API qNMR, 1H NMR signals at 3.82 and 1.22 ppm were used. The qNMR methodology, through the linearity, range, LOD and LOQ, stability, precision, robustness, and accuracy, was validated within the requirements of guidelines. The accuracy of the qNMR was evaluated by comparing it to a pharmacopeial HPLC technique and there were no statistical differences (p > 0.05). The proposed qNMR method authentically supports and endorses the current pharmacopoeial methods used for determining the PQD content.

3-Ishwarone, a rare ishwarane sesquiterpene from Peperomia scandens Ruiz & Pavon: structural elucidation through a joint experimental and theoretical study.

3-Ishwarone, (1), a sesquiterpene with a rare ishwarane skeleton, was isolated from Peperomia scandens Ruiz & Pavon (Piperaceae). Its structure was unambiguously determined by 1D- and 2D-NMR and infrared analyses, as well as by comparative theoretical studies which involved calculations of 13C-NMR chemical shifts, using the Density Functional Theory (DFT) with the mPW1PW91 hybrid functional and Pople's 6-31G(d) basis set, and of vibrational frequencies, using the B3LYP hybrid functional and triple ζ Dunning's correlation consistent basis set (cc-pVTZ), of (1) and three of its possible diastereomers, compounds 2-4.

Synthesis and antitubercular activity of novel Schiff bases derived from d-mannitol.

Six Schiff base derivatives of d-mannitol, 1,6-dideoxy-1,6-bis-{[(E)-arylmethylidene]amino}-d-mannitol (6: aryl=XC(6)H(4): X=o-, m- and p- Cl or NO(2)), have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H(37)Rv using the Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in microg/mL. All three nitro derivatives exhibit significant activities: activities of (6d: X=o-NO(2)), (6e: X=m-NO(2)) and (6f: X=p-NO(2)) are 12.5, 25.0 and 25.0microg/mL, respectively. When compared with first line drugs, such as ethambutol, they can be considered as a good starting point to develop new lead compounds for the treatment of multidrug-resistant tuberculosis. Characterization of the new compounds 6 is generally achieved spectroscopically. The structure of compound 3 has been confirmed by X-ray crystallography.