Target prediction and antioxidant analysis on isoflavones of demethyltexasin: a DFT study.

Glycosylated flavonoids are often found in supplementary food sources and are structurally more active than aglycones, as the glycosyl unit offers better solubility, stability, and functionality. The most common glycosyl units present in most secondary metabolites are glucoside and rhamnoside attached to flavonoid moiety. In the present work, 4'-O-glycosylated (4'-O-glucoside and 4'-O-rhamnoside) demethyltexasin, a soy isoflavone bearing a chromen nucleus, is investigated through a green route aided by density functional theory. Antioxidant activity is computed via three different antioxidant mechanisms, in which hydrogen atom abstraction is facilitated effectively in both gas and solvent phases. The 6-OH site (A-ring) in both isoflavone demethyltexasin glucoside (DMTG) and isoflavone demethyltexasin rhamnoside (DMTR) acted as better radical scavenging sites. Charge localization in B-ring is well altered by the glycosyl and rhamnosyl groups attached. Target prediction analysis supports DMTG with good binding ability with the selected homosapien class targets. The results depict that even though the flavonoid possessing rhamnosyl unit induces charge delocalization at the 4'-O position, it offers resistance toward antioxidant activity when compared to glycosyl moeity. Graphical abstract The contour representation of antioxidants demethyltexasin 4'-O- glucoside (DMTG) and demethyltexasin 4'-O- rhamnoside (DMTR) against reactive oxygen species(ROS).

Experimental and theoretical investigation of p-n alkoxy benzoic acid based liquid crystals - a DFT approach.

In the present study structural effects of alkoxy chain lengths and mesogen properties of hydrogen bonded (nOBASA) complexes (n=5, 6, 7) have been studied by density functional theory (DFT) calculations and Fourier Transform Infrared (FT-IR) spectrum. The B3LYP/6-311G(d,p) level of theory has been adopted for all the computations. The experimental FT-IR (400-4000cm(-1)) spectrum was recorded on the solid phase of the molecule. The intermolecular hydrogen bond formation has been conformed from the optimized geometry. The vibrational assignments, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies were calculated. The stability of molecule arising from hyper-conjugative interactions and charge delocalization were analyzed using natural bond orbital (NBO) analysis. The electron density (ED) in the σ(*) and π(*) anti-bonding orbital and second order delocalization energies confirmed the occurrence of intermolecular charge transfer. The energetic behavior of the title compounds in solvent phase is examined using the B3LYP/6-311G(d,p) method by applying the Onsager and polarizable continuum model. The molecular electrostatic potential (MEP) surface was generated over the optimized geometry of the molecule to obtain the chemical reactivity of the molecule. The charge distribution of the mesogen molecules has been calculated. The reliability of the methods used has been assessed by comparing the theoretical results obtained from the experimental findings. Moreover, the mesomorphic behavior and the nematic phase stabilities for each molecule have been predicted using calculated local charge distribution. The simulated FT-IR spectrum of 5OBASA was agreed with experimentally observed spectrum.

Experimental and theoretical investigations on the antioxidant activity of isoorientin from Crotalaria globosa.

The increasing interests in naturally occurring flavonoids are well known for their bioactivity as antioxidants. The present investigations with combined experimental and theoretical methods are employed to determine the radical scavenging activity and phytochemicals present in Crotalaria globosa, a novel plant source. Preliminary quantification of ethanolic extract of leaves shows high phenolic and flavonoid content than root extract; also it is validated through DPPH assay. Further analysis is carried out with successive extracts of leaves of varying polarity of solvents. In DPPH and FRAP assays, ethyl acetate fraction (EtOAc) exhibit higher scavenging activity followed by ethanol fraction (EtOH) whereas in NOS assay ethanol fraction is slightly predominant over the EtOAc fraction. The LC-MS analysis provides tentative information about the presence of flavonoid C-glycoside in EtOAc fraction (yellow solid). Presence of flavonoid isorientin has been confirmed through isolation (PTLC) and detected by spectroscopy methods (UV-visible and (1)HNMR). Utilizing B3LYP/6-311G (d,p) level of theory the structure and reactivity of flavonoid isoorientin theoretically have been explored. The analysis of the theoretical Bond dissociation energy values, for all OH sites of isoorientin reveals that minimum energy is required to dissociate H-atom from B-ring than A and C-rings. In order to validate the antioxidant characteristics of isoorientin the relevant molecular descriptors IP, HOMO-LUMO, Mulliken spin density analysis and molecular electrostatic potential surfaces have been computed and interpreted. From experimental and theoretical results, it is proved that isoorientin can act as potent antiradical scavenger in oxidative system.

Experimental and DFT studies on the antioxidant activity of a C-glycoside from Rhynchosia capitata.

Rhynchosia capitata (=Glycine capitata) Heyne ex roth, was found to possess polyphenolics including flavonoids, which acts as potential antioxidant. The study of ethanolic extract of roots and leaves reveals that the leaves possess high polyphenolics including flavonoids than roots. This was also confirmed by DPPH radical scavenging activity. Leaf powder of the plant was extracted with different solvents by soxhlet apparatus in the order of increasing polarity. The DPPH scavenging activity of methanol fraction was found to be high compared to the crude extract and other fractions. Nitric oxide scavenging activity was dominant in chloroform fraction compared to methanol fraction. Presence of flavonoids especially vitexin, a C-glycoside in methanol and chloroform fractions were confirmed by high pressure thin layer chromatography (HPTLC) analysis. The structural and molecular characteristics of naturally occurring flavonoid, vitexin was investigated in gas phase using density functional theory (DFT) approach with B3LYP/6-311G(d,p) level of theory. Analysis of bond dissociation enthalpy (BDE) reveals that the OH site that requires minimum energy for dissociation is 4'-OH from B-ring. To explore the radical scavenging activity of vitexin, the adiabatic ionization potential, electron affinity, hardness, softness, electronegativity and electrophilic index properties were computed and interpreted. The nonvalidity of Koopman's theorem has been verified by the computation of Eo and Ev energy magnitudes. Interestingly, from BDE calculations it was observed that BDE for 4'-OH, 5-OH and 7-OH are comparatively low for vitexin than its aglycone apigenin and this may be due to the presence of C-8 glucoside in vitexin. To substantiate this, plot of frontier molecular orbital and spin density distribution analysis for neutral and the corresponding radical species for the compound vitexin have been presented.

Anti-oxidant treatment in obstructive sleep apnoea syndrome.

PURPOSE: To investigate whether oral intake of N-acetylcysteine (NAC) is a treatment option in patients with obstructive sleep apnoea syndrome (OSAS). METHODS: Twenty patients with OSAS were enrolled in the study. After polysomnography (PSG), they were randomly assigned to receive a placebo (n = 10) and NAC (n = 10). A repeat PSG was done after the treatment period of 30 days. Fasting venous samples were collected for various biochemical analysis. RESULTS: In the patients of NAC group, compared to their baseline values, slow wave sleep as sleep percent time (27.9 +/- 2.7 vs 42.3 +/- 4.2; p < 0.01) and sleep efficiency (90.8 +/- 1.3 vs 94.4 +/- 1.5; p < 0.05) improved considerably. The apnoea-hypopnoea index (61.2 +/- 8.5 vs 43.1 +/- 8.6; p < 0.05), apnoea related arousals (22.2 +/- 7.6 vs 11.6 +/- 4.7; p < 0.05), longest apnoeic episode duration (seconds) (54.9 +/- 7.1 vs 37.8 +/- 5.6; p < 0.01), oxygen desaturation events per hour (51.8 +/- 7.7 vs 37 +/- 7.8; p < 0.01) and epworth sleepiness score (16.6 +/- 0.8 vs 9.2 +/- 0.9; p < 0.001) decreased significantly. The relative snore time (%) (10.2 +/- 2.9 vs 4.9 +/- 1.9; p < 0.01), number of snore episodes (63.8 +/-23.9 vs 28.2 +/- 9.9; p < 0.05) and duration of longest snore episode (min) (2.5 +/- 0.7 vs 0.6 +/- 0.1; p < 0.05) also decreased significantly. Such responses were not evident in the placebo group. N-acetylcysteine produced significant decrease in lipid peroxidation and increase in total reduced glutathione. CONCLUSIONS: Oral NAC administration appears to have a therapeutic potential in the treatment of OSAS. It is proposed that long-term treatment with NAC in patients with OSAS may reduce their dependency on continuous positive airway pressure therapy.

Antioxidant behavior of mearnsetin and myricetin flavonoid compounds--a DFT study.

The molecular characteristics of two naturally occurring flavonoid compounds mearnsetin and myricetin have been computed using density functional theory (DFT) approach with B3LYP/6-311G(d,p) level of theory. The computation and analysis of bond dissociation enthalpy magnitudes for all the OH sites for both the compounds clearly denotes the contribution of the B-ring for the antioxidant activity. The analysis has also indicated the higher values of BDE on the C5-OH radical species in both the compounds. The computed vibrational frequency analysis indicates the absence of imaginary frequency in the neutral as well as radical species of both the flavonoid compounds. The ionisation potential (IP) analysis was found to be within the range of the IP of synthetic food additives. In addition, various molecular descriptors such as electron affinity, hardness, softness, electronegativity, electrophilic index have also been calculated and the validity of Koopman's theorem is verified. The plot of frontier molecular orbital and spin density distribution analysis for neutral and the corresponding radical species for both the compounds have been computed and interpreted. The polar nature and their polarizing capacity are well established through the analysis of dipole moment and polarisability magnitudes.

Studies on the phyllosphere microflora of tapioca (Manihot utilissima Pohl).

Studies on the phyllosphere microflora of tapioca (Manihot utilissima Pohl.) revealed that incidence of bacteria, fungi, and actinomycetes is indipendent of the variety, but dependent on the age. The bacteria and fungi increased with increasing age of the leaf and were more on mature leaves, whereas no such difference was noticed in the occurrence of actinomycetes. The large majority of the isolates, that were Gram-negative bacteria, was also amino acid-requiring. The chromogenic types occurred in greater abundance. The phyllosphere mycoflora consisted mainly of species of Asperigullus, Penicillium, Mucor, Curvularia, Alternaria, Helminthosporium, Fusarium, Hormicium, and Pullularia, at first three being predominant. There was no correlation between HCN content of leaves and microorganisms in the phyllosphere, Regarding the interrelationship between different groups of microorganisms in the phyllosphere, a positive correlation between fungi and actinomycetes and bacteria and actinomycetes in two (M. 4 and H. 105/44) varieties and a negative correlation for fungi and actinomycetes in one (H. 12/49) were obtained. The effect of leaf exudate and leaf, root, and tuber extracts on the germination of the conidia of three saprobic fungi, viz., Curvalaria sp., Alternaria sp., and Helminthosporium sp. was tested. While the leaf exudate and tuber extracts slightly stimulated the germination of the conidia of the fungi, the leaf extract exerted a selective inhibitory effect on the germination of the conidia of Curvalaria sp., but not on the conidia of Helminthosporium sp. and Alternaria sp.