Jiang-Hai Wang

Potential health-promoting effects of astaxanthin: A high-value carotenoid mostly from microalgae

The ketocarotenoid astaxanthin can be found in the microalgae Haematococcus pluvialis, Chlorella zofingiensis, and Chlorococcum sp., and the red yeast Phaffia rhodozyma. The microalga H. pluvialis has the highest capacity to accumulate astaxanthin up to 4-5% of cell dry weight. Astaxanthin has been attributed with extraordinary potential for protecting the organism against a wide range of diseases, and has considerable potential and promising applications in human health. Numerous studies have shown that astaxanthin has potential health-promoting effects in the prevention and treatment of various diseases, such as cancers, chronic inflammatory diseases, metabolic syndrome, diabetes, diabetic nephropathy, cardiovascular diseases, gastrointestinal diseases, liver diseases, neurodegenerative diseases, eye diseases, skin diseases, exercise-induced fatigue, male infertility, and HgCl₂-induced acute renal failure. In this article, the currently available scientific literature regarding the most significant activities of astaxanthin is reviewed.

Separation and determination of secoisolariciresinol diglucoside oligomers and their hydrolysates in the flaxseed extract by high-performance liquid chromatography

Flaxseed contains the largest amount of lignan secoisolariciresinol diglucoside (SDG) oligomers and is the richest dietary source of SDG. SDG oligomers in the flaxseed extract are often hydrolyzed to break the ester linkages for the release of SDG and the glycosidic bonds for the release of secoisolariciresinol (SECO). The hydrolysates of SDG oligomers are complicated because of the production of esters in an alcohol-containing medium. In this study, a new gradient reversed-phase high-performance liquid chromatography (HPLC) method has been developed to be suitable for the separation and determination of: (1) SDG oligomers extracted from the defatted flaxseed powder by a 70% aqueous methanol solution; (2) SDG oligomers and their alkaline hydrolysates, including SDG, p-coumaric acid glucoside and its methyl ester, ferulic acid glucoside and its methyl ester in an alkaline hydrolytic solution; and (3) the succedent acid hydrolysates, including secoisolariciresinol monoglucoside (SMG), SECO, anhydrosecoisolariciresinol (anhydro-SECO), p-coumaric acid and its methyl ester, ferulic acid and its methyl ester, 5-hydroxymethyl-2-furfural (HMF) and its degradation product in an acid hydrolytic solution. The content of SDG oligomers in a defatted flaxseed powder was found to be 38.5 mg/g on a dry matter basis, corresponding to a SDG content of 15.4 mg/g, which was determined after alkaline hydrolysis. Furthermore, this study presented a major reaction pathway for the hydrolysis of SDG oligomers.

Evaluation of ergosterol and its esters in the pileus, gill, and stipe tissues of agaric fungi and their relative changes in the comminuted fungal tissues

A gradient reversed-phase high-performance liquid chromatography (HPLC) method was developed for the rapid determination of free ergosterol, ergosteryl esters, and ergocalciferol. The HPLC method was used to evaluate the distribution of ergosterol and ergosteryl esters in the different parts (stipe, pileus, and gills) of the agaric fungi, Agrocybe aegerita, Termitomyces albuminosus, and Lentinus edodes, and the relative changes of free and esterified ergosterols during the degradation of ergosterol in the comminuted fungal tissues. The results showed that total ergosterol levels and the relative abundances of free to esterified ergosterols were different among the various species and in the different parts of these agaric fungi. The results also indicated that ergosteryl esters were more stable than free ergosterol. While the content of free ergosterol markedly decreased, substantial amounts of ergosteryl esters remained for a long period, and even an increase in the contents of ergosteryl esters was also found in some comminuted fungal tissues. Therefore, it is possible that free ergosterol in the cell membrane of the dead fungal hyphae undergoes degradation or esterification, by which excess free ergosterol may be removed, and stored in cytosolic lipid particles. It is suggested that free ergosterol (not total ergosterol) should be used as a biomarker for fungal biomass.

Hydrolysis kinetics of secoisolariciresinol diglucoside oligomers from flaxseed.

Flaxseed is the richest dietary source of the lignan secoisolariciresinol diglucoside (SDG) and contains the largest amount of SDG oligomers, which are often hydrolyzed to break the ester linkages for the release of SDG and the glycosidic bonds for the release of secoisolariciresinol (SECO). The alkaline hydrolysis reaction kinetics of SDG oligomers from flaxseed and the acid hydrolysis process of SDG and other glucosides were investigated. For the kinetic modeling, a pseudo-first-order reaction was assumed. The results showed that the alkaline hydrolysis of SDG oligomers followed first-order reaction kinetics under mild alkaline hydrolytic conditions and that the concentration of sodium hydroxide had a strong influence on the activation energy of the alkaline hydrolysis of SDG oligomers. The results also indicated that the main acid hydrolysates of SDG included secoisolariciresinol monoglucoside (SMG), SECO, and anhydrosecoisolariciresinol (anhydro-SECO) and that the extent and the main hydrolysates of the acid hydrolysis reaction depended on the acid concentration, hydrolysis temperature, and time. In addition, the production and change of p-coumaric acid glucoside, ferulic acid glucoside and their methyl esters and p-coumaric acid, ferulic acid, and their methyl esters during the process of hydrolysis was also investigated.

Distribution of nucleosides and nucleobases in edible fungi.

A gradient reversed-phase high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of seven nucleosides, adenosine, cordycepin (3-deoxyadenosine), cytidine, guanosine, thymidine, uridine, and inosine, and five nucleobases, adenine, cytosine, thymine, uracil, and hypoxanthine in Cordyceps sinensis, Cordyceps militaris, Ganoderma lucidum, Agrocybe aegerita, Termitornyces albuminosus, and Lentinus edodes. The results showed that total nucleoside and nucleobase contents ranged from 0.14 to 26.57 mg/g dry matter in these fungi. The higher total nucleoside and nucleobase levels (>10 mg/g dry matter) were found in the gills and the pilei of A. aegerita and T. albuminosus, and the gills of L. edodes. The lower levels (<1 mg/g dry matter) were detected in the stipe and the pileus of G. lucidum. The results indicated that A. aegerita, T. albuminosus, and L. edodes had much higher contents of nucleosides and nucleobases than C. sinensis, C. militaris, and G. lucidum. It is notable that the hymenophore tissues, which contained the spore-producing cells, such as the gills for A. aegerita, T. albuminosus, and L. edodes, the tubes for G. lucidum, and the perithecia for C. sinensis, were found to have considerably higher amounts of total nucleosides and nucleobases as compared to other parts of these fungi.

Changes of isoflavone profile in the hypocotyls and cotyledons of soybeans during dry heating and germination.

A gradient reversed-phase high-performance liquid chromatography (HPLC) method has been developed to be suitable for the separation and determination of 12 isoflavones in soybeans. Profiles of daidzein, genistein, glycitein, and their malonyl-, acetyl-, and nonconjugated beta-glycosides were determined in cotyledons and hypocotyls of soybeans as affected by dry heating and germination. The results showed that the compositions and concentrations of isoflavones were remarkably different in the two parts of soybeans, and hypocotyls contained a much higher content of isoflavones than cotyledons (e.g., 7.8-fold higher). In hypocotyls, daidzein and its glycoside conjugates (59.6%) were the most abundant isoflavones, being followed by glycitein (26.6%) and genistein series (13.8%). In cotyledons, genistein and its glycoside conjugates (61.9%) were the main isoflavones, being followed by daidzein series (38.1%), and no glycitein series was found. Both hypocotyls and cotyledons contained remarkably high amounts of malonylglycosides (69.1 and 69.4%, respectively) and beta-glycosides (27.1 and 25.4%), and only a very small quantity of aglycones (3.8 and 5.2%) and no acetylglycosides were detected. Acetylglycosides and beta-glycosides were the thermal decarboxylation and deesterification products, respectively, of malonylglycosides, which were thermally unstable. The relative rates of decarboxylation and deesterification reactions were different in cotyledons and hypocotyls at different temperatures. During the process of germination, beta-glycosides decreased, and malonylglycosides and aglycones increased, and then, malonylglycosides were the major fractions in germinating soybeans. Interestingly, the present study occasionally found a significant circadian change between malonylglycosides and aglycones with a nocturnal increase of aglycones and decrease of malonylglycosides during germination, and even aglycones became the most abundant forms at night. However, this mechanism is yet to be investigated.

Distribution of free and esterified ergosterols in the medicinal fungus Ganoderma lucidum

The fruiting bodies, spores, and lipid from the spores of Ganoderma lucidum have been widely used for medicinal purpose in China. Ergosterol content may be a suitable marker for evaluating the quality of ganoderma spore and ganoderma spore lipid (GSL) products. A gradient reversed-phase high-performance liquid chromatography method was developed for the simultaneous determination of free and esterified ergosterols in G. lucidum. The contents of free and esterified ergosterols in the different parts (the stipe, pileus, tubes, and spores) of G. lucidum and GSL were determined. The results showed that total ergosterol levels in the stipe, pileus, tubes, and spores of G. lucidum were between 0.8 and 1.6xa0mg/g. The relative abundances of free to esterified ergosterol were different in the different parts of G. lucidum. The spores and the tubes, the hymenophore tissue that contains the spore-producing cells, have a considerably higher percentage of ergosteryl esters (41.9 and 39.7% of total ergosterol) in comparison with the pileus and stipe tissues (3.6 and 6.2%).