Antidepressant Effect of Shaded White Leaf Tea Containing High Levels of Caffeine and Amino Acids.

The young leaves of green tea become lighter in color than usual when protected from sunlight by a shading net for about two weeks while growing. These leaves are called "shaded white leaf tea" or SWLT. In the eluate of SWLT, the amount of amino acids (361 mg/L) was significantly higher than that in regular tea (53.5 mg/L). Since theanine and arginine, the first and second most abundant amino acids in SWLT, have significant antistress effects, we examined the antistress effect of SWLT on humans. SWLT or placebo green tea (3 g) was eluted with room-temperature water (500 mL). Participants consumed the tea for one week prior to pharmacy practice and continued for 10 days in the practice period. The state-trait anxiety inventory, an anxiety questionnaire, tended to be scored lower in the SWLT group than the placebo, but other stress markers showed no differences. The effect of the difference in SWLT components examined with mice showed that aspartic acid and asparagine, which are abundant in SWLT, counteracted the antistress effects of theanine and arginine. Large amounts of caffeine also interfered with SWLT's antistress effect. Thus, SWLT, which is high in caffeine and amino acids, suppressed depressant behavior in mice.

Amino acid content and acetylcholinesterase inhibition of Huperzia saururus infusion and decoction.

UNLABELLED: CONTEXT. Huperzia saururus (Lam.) Trevis. (Lycopodiaceae), an autochthonous plant species in Argentina, is used as a memory improver in traditional medicine. It was studied for this reason and the purified alkaloid extract did show significant activity on learning and memory. The species is mostly consumed in the form of infusions and decoctions. OBJECTIVES: To evaluate the activity of the H. saururus infusion and decoction as inhibitors of acetylcholinesterase (AChE) and to determine the amino acid content in both extracts. MATERIAL AND METHODS: Infusion and decoction were purified by ionic exchange chromatography and analyzed by high-performance liquid chromatography HPLC-UV, and the AChE inhibition of these extracts was evaluated by using the Ellman method. RESULTS: Both infusion and decoction exerted strong AChE inhibitory activities (IC50=7.2 ± 0.4 and 22.7 ± 5.6 µg/mL, respectively). Among nine amino acids, arginine (Arg) was identified in a concentration greater than 9 mg/100 g of dried aerial parts in both extracts. DISCUSSION AND CONCLUSION: This high content of Arg could be considered a contributing factor to the activity on memory previously demonstrated for the H. saururus alkaloid extract, since Arg is implicated indirectly in mnemonic processes as a precursor in nitric oxide synthesis. Thus, the central effect of H. saururus could involve two different mechanisms, the cholinergic mechanism and the nitric oxide pathway.

L-(-)-(N-trans-cinnamoyl)-arginine, an acylamino acid from Glinus oppositifolius (L.) Aug. DC.

An amino acid derivative, L-(-)-(N-trans-cinnamoyl)-arginine, was isolated from the whole plant of Glinus oppositifolius (L.) Aug. DC. along with kaempferol 3-O-galactopyranoside, isorhamnetin 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-galactopyranoside, vitexin, vicenin-2, adenosine and L-phenylalanine. The structure determinations were based on analyses of chemical and spectroscopic methods.

3-Methylarginine from Pseudomonas syringae pv. syringae 22d/93 suppresses the bacterial blight caused by its close relative Pseudomonas syringae pv. glycinea.

The epiphyte Pseudomonas syringae pv. syringae 22d/93 (Pss22d) produces a toxin that strongly inhibits the growth of its relative, the plant pathogen P. syringae pv. glycinea. The inhibition can be overcome by supplementing the growth medium with the essential amino acid, L-arginine; this suggests that the toxin acts as an inhibitor of the arginine biosynthesis. The highly polar toxin was purified by bioassay-guided fractionation using ion-exchange chromatography and subsequent RP-HPLC fractionation. The structure of the natural product was identified by HR-ESI-MS, HR-ESI-MS/MS, and NMR spectroscopy experiments as 3-methylarginine. This amino acid has previously only been known in nature as a constituent of the peptide lavendomycin from Streptomyces lavendulae. Results of experiments in which labeled methionine was fed to Pss22d indicated that the key step in the biosynthesis of 3-methylarginine is the introduction of the methyl group by a S-adenosylmethionine (SAM)-dependent methyltransferase. Transposon mutagenesis of Pss22d allowed the responsible SAM-dependent methyltransferase of the 3-methylarginine biosynthesis to be identified.

Peptide leucine arginine, a potent immunomodulatory peptide isolated and structurally characterized from the skin of the Northern Leopard frog, Rana pipiens.

On the basis of histamine release from rat peritoneal mast cells, an octadecapeptide was isolated from the skin extract of the Northern Leopard frog (Rana pipiens). This peptide was purified to homogeneity using reversed-phase high performance liquid chromatography and found to have the following primary structure by Edman degradation and pyridylethylation: LVRGCWTKSYPPKPCFVR, in which Cys(5) and Cys(15) are disulfide bridged. The peptide was named peptide leucine-arginine (pLR), reflecting the N- and C-terminal residues. Molecular modeling predicted that pLR possessed a rigid tertiary loop structure with flexible end regions. pLR was synthesized and elicited rapid, noncytolytic histamine release that had a 2-fold greater potency when compared with one of the most active histamine-liberating peptides, namely melittin. pLR was able to permeabilize negatively charged unilamellar lipid vesicles but not neutral vesicles, a finding that was consistent with its nonhemolytic action. pLR inhibited the early development of granulocyte macrophage colonies from bone marrow stem cells but did not induce apoptosis of the end stage granulocytes, i.e. mature neutrophils. pLR therefore displays biological activity with both granulopoietic progenitor cells and mast cells and thus represents a novel bioactive peptide from frog skin.