Dicorynamine and harmalan-N-oxide,two new β-carboline alkaloids from Dicorynia guianensis Amsh heartwood

The chemical investigations of Dicorynia guianensis heartwood led to the isolation of four new indole alkaloids for the first time in this plant. Compound (1) identified as spiroindolone 2′,3′,4′,9′-tetrahydrospiro [indoline-3,1′pyrido[3,4-b]-indol]-2-one, and compound (3) described as nitrone 1-methyl-4,9-dihydro-3H-pyrido [3,4-b] indole 2-oxide and were isolated for the first time as natural products. ABTS antioxidant activity guided their isolation.     

Reaction of the trichloromethyl and halothane-derived peroxy radicals with unsaturated fatty acids: A pulse radiolysis study

The absolute rates of reaction of the trichloromethylperoxy radical, CCl₃OO, derived from carbon tetrachloride and the halothane peroxy radical, CF₃CHClOO, with oleic, linoleic, linolenic and arachidonic acids have been determined using the fast reaction technique of pulse radiolysis. In general, the rates of reaction of the radical derived from carbon tetrachloride are approximately five times greater than those for the halothane related radical. In both cases the rate constant increases with increasing unsaturation of the fatty acid in agreement with the known greater susceptibility of polyunsaturated fatty acids to peroxidative decomposition.     

Quantitative analysis of the relationship between structure and antioxidant activity of tripeptides

Peptides from enzymatic hydrolysates of food proteins exhibit significant antioxidant activity. Several studies have attempted to determine the factors contributing to the antioxidant activity of peptides; however, the physicochemical properties and factors essential for the antioxidant activity of peptides are still unclear. In this study, in order to clarify the factors important for peptide antioxidant activity based on the properties of component amino acids, 55 tripeptides were synthesized from 20 natural amino acids and their antioxidant activity was measured using the Trolox equivalent antioxidant capacity (TEAC) assay system. The tripeptides were divided into two data sets: a training set comprising 50 compounds and a validated set comprising five compounds. The structure‐activity relationship of the training set was then analyzed using classical quantitative structure‐activity relationship (QSAR) analysis. The study findings demonstrate that the presence of a cysteine residue at any position, an aromatic amino acid at the C‐terminus, higher hydrophobicity of the N‐terminal residue, and smaller HOMO‐LUMO energy gap of the middle residue can significantly enhance the antioxidant activity. The activities of the five validated compounds were predicted using the constructed QSAR model, and a good correlation between measured and predicted activities was observed. The information obtained from the QSAR model could be useful for effective production of antioxidant peptides from food proteins such as egg white proteins.     

Comparative antioxidant-capacity and -content of leaves, bulbs, roots, flowers and fruit of Gethyllis multifolia L. Bolus and G. villosa Thunb. species

The total polyphenol, oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), radical cation scavenging ability, flavonol and flavanone contents were measured in the leaves, bulbs, roots, flowers and fruit (dry weight) of two natural populations of Gethyllis multifolia (Kukumakranka) and Gethyllis villosa. The flowers and fruit of G. multifolia and G. villosa showed higher, and in some cases significantly (P < 0.05) higher antioxidant activities when compared to the leaves, bulbs and roots. This, however, was not true for the flavanone content in both species. The total polyphenol content in the fruits of G. multifolia (21.54 mg GAE/g) and G. villosa (27.64 mg GAE/g) were found to be in agreement with those of raisins (28.30 mg GAE/g), blueberries (24 mg GAE/g) and strawberries (15.40 mg GAE/g). The FRAP values of G. multifolia flowers (76.66 μmole AAE/g) and fruit (91.51 μmole AAE/g) were found to be significantly (P < 0.05) higher than those of the other plant parts (16.76 to 39.08 μmol AAE/g). On the other hand, the flowers (590.23 μmol TE/g) and fruit (741.16 μmol TE/g) of G. villosa revealed a significantly (P < 0.05) higher ORAC when compared to the other plant parts (251.25 to 410.60 μmol TE/g). A strong correlation was evident in the fruit of both species between the total polyphenols and FRAP (r = 0.95), ORAC (r = 0.95) and flavonol content (r = 0.79).     

Phytochemical profiling and antioxidant potential of Daphne mucronata Royle and action against paracetamol-induced hepatotoxicity and nephrotoxicity in rabbits

The paracetamol-induced injuries of liver and kidneys in animals are mostly used to screen out the hepato and nephroprotective effect of extract or other therapeutic agents. In the present study total phenolic and flavonoid contents, in vitro antioxidant, and in vivo hepato/nephroprotective (on paracetamol-induced intoxication in experimental rabbits) potentials of the Daphne mucronata leaves methanolic extract were determined. For the identification of possible phytochemicals, HPLC (high performance liquid chromatography) analysis was carried out and a total of eight phenolic compounds; malic acid, gallic acid, chlorogenic acid, epigallocatechin gallate, quercetin, morin, ellagic acid, and rutin were identified. D. mucronata extract at doses of 250 and 500 mg/kg body weight were given for eight days to paracetamol intoxicated rabbits and the observed results were compared with standard Silymarin. The level of liver enzymes like aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, serum triglyceride, serum cholesterol, serum bilirubin, and kidneys biomarkers like serum urea, uric acid, and creatinine, as well as lipid peroxidation malondialdehyde contents were increased while the antioxidant enzymes like reduced glutathione and total antioxidant capacity were decreased. Furthermore, histopathological analysis of the liver and kidney tissues of control and treated groups also confirmed the hepatoprotective and nephroprotective effect of the D. mucronata which was most probably due to its high antioxidant phenolic and flavonoid phytoconstituents.     

Phytochemical composition,antioxidant, in vitro and in silico studies of active compounds of Curculigo latifolia extracts as promising elastase inhibitor

Curculigo latifolia is a plant in the Hypoxidaceae family commonly used in herbal medicine. The study objective was to evaluate the antioxidant and anti-elastase properties of C. latifolia extracts in vitro and silico as a candidate for antiaging active ingredients. This study identified secondary metabolites of the hexane (HE), ethyl acetate (EAE), and ethanol extracts (EE) from the root (R), stem (S), and leaf (L) organs by LC-ESI-MS and evaluated in vitro antioxidant and inhibitor elastase activity. An antioxidant evaluation was performed using ABTS, Beta Carotene Bleaching (BCB), and Ferric Reduction Antioxidant Power (FRAP). Evaluation of anti-elastase was carried out using elastase and followed by an in silico study of molecular docking using the target protein elastase (1B0F). Fifteen C. latifolia metabolites were identified in C. latifolia extracts, most of which were phenolic compounds. In antioxidant testing, REE, REAE, SEE, and SEAE extracts showed potent antioxidant activity based on the ABTS, BCB, and FRAP methods. In anti-elastase testing, it was found that SEE, REE, REAE, and RHE extracts gave powerful inhibition of elastase activity (in the ranges of 16.89 to 27.91 µg/mL). The in-silico study demonstrated the potential of the identified metabolites to bind to the target protein 1B0F involved in remodeling the skin aging process. This research concludes that the extracts from C. latifolia have the potential to serve as an active antiaging source.