NMR and Computational Studies as Analytical and High-Resolution Structural Tool for Complex Hydroperoxides and Diastereomeric Endo-Hydroperoxides of Fatty Acids in Solution-Exemplified by Methyl Linolenate

A combination of selective 1D Total Correlation Spectroscopy (TOCSY) and 1H-13C Heteronuclear Multiple Bond Correlation (HMBC) NMR techniques has been employed for the identification of methyl linolenate primary oxidation products without the need for laborious isolation of the individual compounds. Complex hydroperoxides and diastereomeric endo-hydroperoxides were identified and quantified. Strongly deshielded C–O–O–H 1H-NMR resonances of diastereomeric endo-hydroperoxides in the region of 8.8 to 9.6 ppm were shown to be due to intramolecular hydrogen bonding interactions of the hydroperoxide proton with an oxygen atom of the five-member endo-peroxide ring. These strongly deshielded resonances were utilized as a new method to derive, for the first time, three-dimensional structures with an assignment of pairs of diastereomers in solution with the combined use of 1H-NMR chemical shifts, Density Functional Theory (DFT), and Our N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) calculations.

A New Amide From Piper maingayi Hk.F. (Piperaceae)

Phytochemical investigation from the leaves and stem extracts of Piper maingayi Hk.F. resulted in the isolation of a new amide, N-isobutyl-15-(3″,4″-methylenedioxyphenyl)-2 E,4 E,12 Z-pentadecatrienamide (1), together with sesamin (2), piperumbellactam A (3), cepharadione A (4), cepharadione B (5), piperolactam A (6), oleic acid (7), methyl linolenate (8), β-sitosterol (9), butyl dodecanoate (10), and isovanillic acid (11). Their structures were established by the analysis of their spectroscopic (1D and 2D NMR) and spectrometric (MS) data, as well as by comparison with those reported in the literature. Compound (1) exhibited strong inhibition against lipoxygenase (15-LOX) at IC50 42.5 μM and antibacterial activity toward Bacillus subtillis and Pseudomas aeruginosa with minimum inhibitory concentration (MIC) value of 250 μg/mL each.

Extraction of Papaya Leaves (Carica papaya L.) Using Ultrasonic Cleaner

Extraction of papaya leaves (Carica papaya L.) using Ultrasonic Cleaner has been performed. Papaya leaves were extracted for 6 hours in a methanol as solvent. The results of phytochemical screening showed that methanol extract contained secondary metabolites of flavonoids, alkaloids, tepenoid, saponin, and phenolic classes. Methanol extract was then partitioned liquid-liquid with n-hexane. Quantitative analysis of partitioning of n-hexane using papaya leaves using Gas Chromatography-Mass Spectrometry (GC-MS) showed the presence of neophytadiene (1.59%), palmitic acid (1.35%) and methyl linolenate (3.33%). The results showed that Ultrasonic Cleaner can be used to ultrasonic-assisted extraction of natural products especially for papaya leaves.

Extraction of Papaya Leaves (Carica papaya L.) Using Ultrasonic Cleaner

Extraction of papaya leaves (Carica papaya L.) using Ultrasonic Cleaner has been performed. Papaya leaves were extracted for 6 hours in a methanol as solvent. The results of phytochemical screening showed that methanol extract contained secondary metabolites of flavonoids, alkaloids, tepenoid, saponin, and phenolic classes. Methanol extract was then partitioned liquid-liquid with n-hexane. Quantitative analysis of partitioning of n-hexane using papaya leaves using Gas Chromatography-Mass Spectrometry (GC-MS) showed the presence of neophytadiene (1.59%), palmitic acid (1.35%) and methyl linolenate (3.33%). The results showed that Ultrasonic Cleaner can be used to ultrasonic-assisted extraction of natural products especially for papaya leaves.