Limnophila aromatica is commonly used as a spice and a medicinal herb in Southeast Asia. In this study, water and various concentrations (50%, 75%, and 100%) of methanol, ethanol, and acetone in water were used as solvent in the extraction of L. aromatica. The antioxidant activity, total phenolic content, and total flavonoid content of the freeze-dried L. aromatica extracts were investigated using various in vitro assays. The extract obtained by 100% ethanol showed the highest total antioxidant activity, reducing power and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The same extract also exhibited the highest phenolic content (40.5 mg gallic acid equivalent/g of defatted L. aromatica) and the highest flavonoid content (31.11 mg quercetin equivalent/g of defatted L. aromatica). The highest extraction yield was obtained by using 50% aqueous acetone. These results indicate that L. aromatica can be used in dietary applications with a potential to reduce oxidative stress.

Summary Nitrogen (N) deficiency triggers an accumulation of a storage lipid triacylglycerol (TAG) in seed plants and algae. Whereas the metabolic pathway and regulatory mechanism to synthesize TAG from diacylglycerol are well known, enzymes involved in the supply of diacylglycerol remain elusive under N starvation. Lysophosphatidic acid acyltransferase (LPAT) catalyzes an important step of the de novo phospholipid biosynthesis pathway and thus has a strong flux control in the biosynthesis of phospholipids and TAG. Five LPAT isoforms are known in Arabidopsis; however, the functions of LPAT4 and LPAT5 remain elusive. Here, we show that LPAT4 and LPAT5 are functional endoplasmic‐reticulum‐localized LPATs. Seedlings of the double knockout mutant lpat4‐1 lpat5‐1 showed reduced content of phospholipids and TAG under normal growth condition. Under N starvation, lpat4‐1 lpat5‐1 seedlings showed severer growth defect than the wild‐type in shoot. The phenotype was similar to dgat1‐4, which affects a major TAG biosynthesis pathway and showed similarly reduced TAG content as the lpat4‐1 lpat5‐1. We suggest that LPAT4 and LPAT5 may redundantly function in endoplasmic‐reticulum‐localized de novo glycerolipid biosynthesis for phospholipids and TAG, which is important for the N starvation response in Arabidopsis.

The complexation equilibria of L-norvaline (Nva) and ferulic acid (FA) were studied in aqueous solutions at room temperature (298 K) and in fixed ionic strength (0.15 mol 3 dm -3 NaNO 3 ) by means of potentiometry and spectrophotometry techniques. The ferric (Fe 3þ ), chromium (Cr 3þ ), and cupric (Cu 2þ ) complexing capacities of Nva and FA and their overall stability constants in aqueous solutions were obtained by the HYPERQUAD 2008 program from the potentiometric data. The concentration distributions of the various complex specia in solution were evaluated and discussed. The spectroscopic UV-visible measurements are carried out to give qualitative information about the confirmation of the complexes formed in these solutions. ' INTRODUCTIONIt is known that nonprotein amino acids, which are common in fodder plants, consumed animal feeds, and human foods, are a threat to human and animal health. 1 They possess a wide array of chemical structures and often contain functional groups not commonly present in natural products. 1,2 Some act as agonists or antagonists in the neurotransmission of higher animals. 1,2 Others influence the growth of fungi and bacteria. 1,2 Norvaline (C 5 H 11 NO 2 ) is an unusual nonproteinogenic branched-chain amino acid which has been of interest particularly in early enzymological research work. 3 Recently, it has been proved that L-norvaline (Nva) has antifungal activity as it inhibits arginase thus increasing arginine concentrations. 4 More specifically, Nva has been shown to inhibit homoserine dehydrogenase. 5 Moreover, some biological studies have indicated that Nva has antitubercular and antifungal actitvities. 6,7 Also, a lot of research has been focused on the role of antioxidant ferulic acid (FA) in several biological processes. 8 Taking into account the natural occurrence, biosynthesis, metabolism, and functions of nonprotein amino acids and phenolic acids, the study of their metal complexes gains much attention and is attracting more attention in equilibrium and biological chemistry. Hence, a study of metal-Nva-FA complexes may lead to better elucidation of the behavior of such compounds in biological systems and metal-Nva-FA interactions might be of therapeutic interest. A search in the literature shows that there has been quite a number of studies reported on the interaction between metal ions and Nva. 9-27 Most of these research works investigated the complexation equilibria of the copper(II), nickel(II), cobalt(II), manganese(II), uranyl(II), terbium(III), lanthanum(III), praseodymium(III), neodymium-(III), and trimethyltin(IV) metal ions with Nva using different electroanalytical techniques. However, there is no study conducted on the iron(III) or chromium(III) metal ion binary complexes of Nva, and any metal ion-norvaline mixed ligand complexes.Our recent publications describe the protonation equilibrium phenomena of essential amino acids, 28 hydroxamic acids, 29 phenolic compounds, 30 and nonprotein Nva, 31 L-canavanine 32 amino acids in aqueous and in aqueous-organic so...

No abstract

No abstract