Chitosan Modification and Pharmaceutical/Biomedical Applications

Chitosan has received much attention as a functional biopolymer for diverse applications, especially in pharmaceutics and medicine. Our recent efforts focused on the chemical and biological modification of chitosan in order to increase its solubility in aqueous solutions and absorbability in the in vivo system, thus for a better use of chitosan. This review summarizes chitosan modification and its pharmaceutical/biomedical applications based on our achievements as well as the domestic and overseas developments: (1) enzymatic preparation of low molecular weight chitosans/chitooligosaccharides with their hypocholesterolemic and immuno-modulating effects; (2) the effects of chitin, chitosan and their derivatives on blood hemostasis; and (3) synthesis of a non-toxic ion ligand—D-Glucosaminic acid from Oxidation of D-Glucosamine for cancer and diabetes therapy.     

Inhibition of Na＋,K＋-ATPase in Housefly （Musca domestica L.） by Terpinen- 4-ol and Its Ester Derivatives

To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na＋,K＋-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong contact activity to housefly and the contact toxicities of its derivatives except Z3 were all superior or equivalent to terpinen-4-ol. All the 7 compounds had strong inhibition towards activity of Na＋,K＋-ATPase. With poisoning symptom exacerbating, the inhibition rates were gradually increased. In vitro, the IC50 of terpinen-4-ol, Z1, Z2, Z4, Z5, and Z6 was 155.89, 197.98, 96.02, 121.36, 124.85, and 153.74 μg mL% respectively. There was well correlation between the LDs0 of terpinen-4-ol derivatives to housefly and the IC50 of terpinen-4-ol derivatives to Na＋,K＋-ATPase in housefly. In conclusion, Na＋,K＋-ATPase was likely the target of terpinen-4-ol against insects.     

Transmission of the Chromosome 1 R in Winter Wheat Germplasm Aimengniu and Its Derivatives Revealed by Molecular Markers

In order to clarify the transmission of the rye chromosome 1R in winter wheat germplasm Aimengniu and its derivatives, 17 derivatives and 7 types of Aimengniu were examined through molecular-marker technology. The results showed that the chromosome arm 1RS of Neuzucht was transmitted to 5 of the 7 types of Aimengniu, i.e., Aimengniu Ⅱ and Aimengniu Ⅳ-Aimengniu VII, no segment of t RS was identified in Aimengniu Ⅰ or Aimengniu Ⅲ. As for the 17 derivatives, the 1RS chromosome arm of Aimengniu was transmitted to 11 derivatives, part segments of 1RS were found in 1 derivative, while no segment was found in the remaining 5 ones. The results provided the evidence that molecular-marker technology was an efficient approach and suitable for analysis of the transmission of chromosome 1R.     

Tandem size exclusion chromatography-Polyacrylamide gel electrophoresis of humic acids

Humic acids (HAs) from four soils were fractionated by size exclusion chromatography (SEC) on Sephadex G-75. Three fractions were obtained in all humic acids, collected and assayed by Polyacrylamide gel electrophoresis (PAGE). The unfractionated HA from each soil was used as reference. Each chromatographic fraction formed one electrophoretic zone corresponding closely to one band of the reference sample with some admixture of the fractions preceding or following. The results indicate that fractionation of HAs by tandem SEC-PAGE can be successfully used for obtaining fractions of reduced polydispersity and different electrophoretic mobilities. Pyrolysis/methylation-gas chromatography-mass spectrometry of the full size preparations of HA and fractions with exactly defined molecular size and electrophoretic mobility showed a different distribution in humic components, mainly lipids, lignin derivatives and N-containing compounds.     

Chemical constituents of Roldana lineolata

The new eremophilanolide 1, the known eremophilane derivatives 2 and 3, already described as part of mixtures, the known compounds hyperin, 2'-acetylhyperin and two calenduladiol esters were isolated from Roldana lineolata. Their structures were determined by spectroscopic methods. Compounds 1 and 2 as well as their acetylated and oxidized derivatives were tested against several fungi strains. Eremophilanolide 1 showed a mild activity against Trichophyton mentagrophytes.     

New norlignan derivatives from Curculigo capitulata

Two new norlignan derivatives, crassifoside I (1) and sinensigenin C (2), were isolated from the rhizomes of Curculigo capitulate, along with six known norlignan derivatives, 1,1-bis(3,4-dihydroxyphenyl)-1-(2-furan)-methane (3), crassifogenin B (4), crassifoside A (5), breviscaside A (6), crassifoside D (7), and curcapital (8). Their structures were elucidated on the basis of spectral evidence and comparisons with literature data. The ¹H and ¹³C NMR data of compound 3 was first assigned. Compounds 3–7 were isolated from this plant for the first time.     

Assessment of genetic diversity among selected groundnut germplasm. I: RAPD analysis

Assessment of genetic diversity in a crop species is prerequisite to its improvement. The use of germplasm with distinct DNA profiles will help to generate genetically diversified breeding populations. The aims of the present experiment were to study molecular diversity among selected groundnut accessions and identify those with distinct DNA profiles for mapping and genetic enhancement. Twenty‐six accessions and eight primers of a 10‐mer were selected for random amplified polymorphic DNA assay. The genetic similarity (S_ij) ranged from 59.0% to 98.8%, with an average of 86.2%. Both multidimensional scaling and unweighted pair‐group method with arithmetic averages (UPGMA) dendrograms revealed the existence of five distinct clusters. However, this classification could not be related to known biological information about the accessions falling into different clusters. Some accessions with diverse DNA profiles (ICG 1448, 7101, and 1471, and ICGV 99006 and 99014) were identified for mapping and genetic enhancement in groundnut.     

Components of resistance to late leaf spot and rust among interspecific derivatives and their significance in a foliar disease resistance breeding in groundnut (Arachis hypogaea L.)

Late leaf spot (LLS) and rust cause substantial yield losses and reduce the fodder and seed quality in groundnut (Arachis hypogaea L.). Adoption of resistant cultivars by the semi-arid tropic farmers is the best option to overcome yield losses. Knowledge on components of resistance to these diseases should facilitate the development of groundnut cultivars with enhanced resistance to LLS and rust. The objectives of the experiments were to study the genetic variability and relationships among components of resistance to LLS and rust, and assess their significance in disease resistance breeding. Fifteen interspecific derivatives for LLS and 14 for rust and a susceptible control, TMV 2, were evaluated in a randomised complete block design with two or three replications under greenhouse conditions. The experiments were repeated twice. Genotypic differences were highly significant for all the traits studied. Resistance to LLS is due to longer incubation and latent periods, lesser lesions per leaf, smaller lesion diameter, lower sporulation index, and lesser leaf area damage and disease score. Selection based on components of resistance to LLS may not lead to plants with higher retained green leaf area. The remaining green leaf area on the plant should, therefore, be the major selection criteria for resistance to LLS in breeding programs. Resistance to rust is due to longer incubation and latent periods, fewer pustules per leaf, smaller pustule diameter, lower sporulation index, and lesser leaf area damage and disease score. Rust resistant components appear to work additively, therefore, selection based on resistance components together with green leaf area retained on the plant should be the basis of selecting for resistance to rust in breeding programs. ICGV 99005, 99003, 99012, and 99015 for rust and ICGV 99006, 99013, 99004, 99003, and 99001 for LLS are the better parents for use in resistance breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Utilization of tom thumb source of pre-harvest sprouting tolerance in a wheat breeding programme

Summary Segegating populations of the cross Tordo (a spring white-grained Tom Thumb derivative) and Tr 454-16 (a spring white-grained Sonora-Gabo derivative) were studied for plant height, apparent -amylase synthesis (AAS) and response to gibberellic acid. Means, variances and heritabilities for these characters were computed and their association was studied by computing correlation coefficients. Plant height showed high heritability while AAS and response to GA₃ showed moderate heritability. Plant height was positively correlated with AAS and response to GA₃. The results pointed out the importance of using Tom Thumb as a source of pre-harvest sprouting tolerance in a wheat breeding programme, particularly in areas where wheat breeding is restricted to evolving white-grained cultivars.