Four coumarins were isolated from chloroform extract of the root of Peucedanum japonicum and identified as praeruptorin A(1), xanthotoxin (2), psoralen (3) and bergapten (4) on the basis of spectroscopic methods. The inhibitory activities of these coumarins on monoamine oxidase prepared by mouse brain were tested. The IC50 values of them were shown to be 27.4 microM (1), 40.7 microM (2), 35.8 microM (3), and 13.8 microM (4), in vitro.

A methanol extract of Zanthoxylum schinifolium stems at a concentration of 250 microg/ml showed potent inhibitory activity against monoamine oxidase (MAO) in a mouse brain. Activity-guided separation and purification of the extract yielded lacinartin (1) as an active coumarin compound. Lacinartin showed significant inhibitory effects on MAO in a dose-dependent manner. The IC(50) value on MAO activity was 9.2 microM. The MAO-A (IC(50) value, 5.7 microM) sensitivity to lacinartin was greater than that of MAO-B (IC(50) value, 28.6 microM). An enzyme kinetic study revealed that lacinartin inhibited MAO activity by a non-competitive mode.

No abstract

The red alga Kappaphycus striatum is an economically important species and extensively cultivated in Vietnam as a material source for carrageenan production. To evaluate carrageenan quality, the characterization of carrageenan extracted from this alga was investigated. As a result, chemical composition of carrageenan consists of 32.4% of 3,6 anhydrogalactose and 24.3% of sulfate. Gelling and metling temperatures are 34.4oC and 55.6oC, respectively. Gel strength of 1.5% is 615 g/cm2 and average molecular weight is about 267 kDa. Furthermore, FT-IR spectrum showed intense absorption bands at 930 cm-1 and 850 cm-1 that attributed to 1,4-linked 3,6 anhydro-α-D-galactose and 1,3-linked β-D-galactose-4-sulfate of kappa-carrageenan, respectively. 13C NMR spectrum indicated the signals for anomeric carbon of β-D-galactose-4-sulfate at 102.6 ppm and anomeric carbon of 3,6-anhydro-α-D-galactose at 95.3 ppm. 13H NMR spectrum showed peak signals at 3.57 ppm and 5.1 ppm that corresponds with O-methyl proton of 1,3-linked 6-O-methyl-D-galactose and α-anomeric proton of 3,6 anhydro-α-D-galactose residues, respectively. The results show that the carrageenan from the red alga Kappaphycus striatus is kappa-carrageenan with the repeating disaccharide unit consisting of 1,3-linked 6-O-methylated, β-D-galactose-4-sulfate and 1,4-linked 3,6 anhydro-α-D-galactose and did not contain iota-carrageenan. Therefore, this alga may promise to be a good source for carrageenan production for application in food or medicine.

In this study, different ratio of ethanol to hydrolysates obtained by hydrolyzing chitin by chitinase as well as concentration of hydrolysates was investigated to find the optimal value. The result showed that the optimal ratio of absolute ethanol to hydrolysates was 9:1. The further increase of this ratio up to 11:1 resulted only in insignificant increase of N-acetylglucosamine (NAG) recovery yield from 74.47 % to 75.39 % and NAG purity from 93.25 % to 93.44 %. Concentration of hydrolysate also affected the NAG recovery yield and NAG purity. The impurity of crystallization by cooling down the hydrolysates appeared only when hydrolysate was concentrated at a certain level. The mass of crystallization impurity was increased sharply from 0 to 0.082 mg/ml when hydrolysate's concentration was increased significantly from 1 to 7.9 fold, then slightly from 0.082 to 0.093 mg/ml as its concentration further increased up to 15.7 fold. Higher concentration of hydrolysate resulted in lower recovery yield but purer product. According to HPLC analysis, 93.25 % of NAG purity with recovery yield 74.47% was obtained at optimal ethanol/hydrolysates ratio and optimal concentration of hydrolysate.