Tyrosinase inhibitory activity of Bangladeshi indigenous medicinal plants.

The tyrosinase-inhibitory activity of 15 kinds of Bangladeshi medicinal plants was evaluated. Methanol extracts were prepared for screening tests, and other kinds of extracts were also studied for those with high activity. Swertia chirata, Piper nigrum, Glycyrrhiza glabra, Piper longam and Ocimum americanum were screened as highly inhibiting samples. Methanol was found to be the most efficient solvent for extracting the active compounds. The 50% tyrosinase-inhibitory concentration of the Glycyrrhiza glabra methanol extract was 21.2 microg/ml.

Superoxide-scavenging and prolyl endopeptidase inhibitory activities of Bangladeshi indigenous medicinal plants.

The superoxide-scavenging and prolyl endopeptidase (PEP) inhibitory activities of 15 different kinds of Bangladeshi medicinal plants were evaluated. Methanol extraction was performed for the screening tests. Swertia chirata, Emblica officinalis, Zingiber officinale and Myristica malabarica were screened as superoxide-scavenging samples. Similarly, E. officinalis was identified as one of the strongest PEP inhibitory samples. The 50% (O2-)-scavenging and PEP-inhibitory concentrations from E. officinalis methanol extracts were found to be 13.17 and 26.10 microg/ml, respectively.

Superoxide-scavenging and Tyrosinase-inhibitory Activities of the Extracts of Some Chinese Medicines.

The superoxide-scavenging and the tyrosinase-inhibitory activities of 28 kinds of plants used as Chinese medicines were evaluated. Methanol/water extracts were used for the screening tests, and for those which represented high activities, other kinds of extracts were also studied. The extracts of Mallotus japonicus Muell. Arg. scavenged superoxide strongly; the half-inhibiting concentration (IC50) of its 50% methanol/water extract was 10.57 µg of dried material in 1 ml of reaction mixture. The extracts of Fntillaria thunbergii Miq., Carthamus tinctorius L., and Prunus persica (L.) Batsch had strong tyrosinase-inhibitory activities, and the extracts of Scutellariu baicalensis Georgi represented both kinds of activities. These facts suggested that Chinese medicines may be a treasure house of chemical compounds that have the superoxide-scavenging and the tyrosinase-inhibitory activities.

Taste evaluations of angiotensin I converting enzyme inhibitors, Leu-Lys-Tyr analogues.

Tastes of Leu-Lys-Tyr (LKY) analogues, a series of potent angiotensin I converting enzyme (ACE) inhibitory peptides were evaluated. Some of these analogues were found to be sweet, such as Val-Lys-Tyr and Ala-Orn-Tyr. Furthermore, the structural requirements for sweetness or decreasing the bitterness were investigated by considerations of the structure-taste relationship with LKY analogues.

Effects of normal and their branched alcohols with structurally minimal variation on kinetic parameters in thermolysin-catalyzed peptide hydrolysis and synthesis of N-(benzyloxycarbonyl)-L-phenylalanyl-L-phenylalanine and its methyl ester.

When higher alcoholic solvents were added to the reaction medium, and the enhancement of the enzyme activity, followed by its reduction then inactivation, were observed in thermolysin-catalyzed peptide hydrolysis and synthesis. The organic solvent content used was less than the saturating concentration in the buffer (i.e., water-organic one-phase system). The kinetic parameters, Km and kcat, at the alcoholic concentration giving maximal enzyme activity in these reactions changed linearly with increasing logP values of the alcohols and consequently kcat/Km as well. When the branched isomers of alcohols with structurally minimal variation of which logP was equivalent theoretically, were used as annexments, the kinetic parameters were also changed. The results, especially the changes of Km for each organic solvent, suggested that each alcohol should act at the active site of the enzyme in its own effective mode.

[Antibodies to poly (adenosine diphosphate-ribose) in systemic lupus erythematosus and drug induced lupus].

The difference between anti poly (ADP-ribose) antibodies was studied in patients with systemic lupus erythematosus (SLE), progressive systemic sclerosis (PSS) and drug-induced lupus (DIL). Radioimmunoassay showed that high concentrations of anti poly (ADP-ribose) antibodies (10.3-22.2%) were induced by phenobarbital, phenytoin, valproic acid (anti-epileptic agent) and procainamide (anti-arrhythmic agent). Poly (ADP-ribose) antibodies were separated by hydroxylapatite column chromatography. The average chain length of the polymer consisted of 2.4, 10.8 and 28.2 ADP-ribose units. Anti poly (ADP-ribose) antibodies from patients with SLE and PSS reacted with 2.4, 10.8, and 28.2 ADP-ribose units in RIA, but those from patients with DIL reacted only with 28.2 ADP-ribose units in RIA. The binding specificity of anti poly (ADP-ribose) antibodies from pregnant women was found to be very similar to that of the antibodies from case of DIL. The present results clearly demonstrated that anti poly (ADP-ribose) antibodies found in systemic autoimmune diseases bound not only to poly (ADP-ribose) with an average chain length of more than 20 ADP-ribose units, but also to oligo (ADP-ribose) with an average chain length of about 2 ADP-ribose units. Anti poly (ADP-ribose) antibodies found in DIL cases and pregnant women, however, bound only to poly (ADP-ribose) with an average chain length of more than 20 ADP-ribose units.