茶皂素生产工艺及其应用的研究进展

本文综述了天然非离子表面活性剂茶皂素的生产工艺以及在实际中的应用 ,并就目前的生产和使用情况提出了一些看法和需要解决的问题。     

Improvement of Agrobacterium-mediated transformation of embryogenic calluses from maize elite inbred lines

Summary This study was carried out to evaluate the effects of purine synthesis inhibitor mizoribine, purine and pyrimidine synthesis inhibitors azaserine and acivicin, and surfactant Silwet L-77 on Agrobacterium-mediated transformation efficiency of embryogenic calluses from maize elite inbred lines Qi 319 and Ye 515. After transformation and three rounds of selection on 2.8 μM chlorsulfuron, resistant calluses were obtained subsequently, and morphologically normal plantlets were regenerated from 80 to 90% of the resistant calluses treated with the compounds. There were no obvious discrepancies between the frequencies of plantlet regeneration and the ratio of PCR positive plantlets of calluses treated with different compounds. Results of PCR assay with primers for betA showed that 40.2% (103/256) of the regenerated plantlets were positive. The percentage of resistant calluses was 2–3-fold higher than the control after being treated with 0.19–0.27 mM mizoribine. The most suitable concentration of azaserin was 0.36 mM, which gave a 4-fold increase in the percentage of resistant calluses. Acivicin at 0.28–0.84 mM yielded a 3–5-fold increase in the percentage of resistant calluses, which is significantly better than the control. When the calluses were treated with 0.01 or 0.02% Silwet L-77, the percentages of resistant calluses were 34.89 and 25.60%, respectively. We concluded that purine synthesis inhibitors, purine and pyrimidine synthesis inhibitor and the surfactant Silwet L-77 at optimal concentrations significantly improved the Agrobacterium-mediated transformation of maize calluses.     

Marine bacterioplankton can increase evaporation and gas transfer by metabolizing insoluble surfactants from the air–seawater interface

Hydrophobic surfactants at the air–sea interface can retard evaporative and gaseous exchange between the atmosphere and the ocean. While numerous studies have examined the metabolic role of bacterioneuston at the air–sea interface, the interactions between hydrophobic surfactants and bacterioplankton are not well constrained. A novel experimental design was developed, using Vibrio natriegens and ³H-labelled hexadecanoic acid tracer, to determine how the bacterial metabolism of fatty acids affects evaporative fluxes. In abiotic systems, >92% of the added hexadecanoic acid remained at the air–water interface. In contrast, the presence of V. natriegens cells draws down insoluble hexadecanoic acid from the air–water interface as an exponential function of time. The exponents characterizing the removal of hexadecanoic acid from the interface co-vary with the concentration of V. natriegens cells in the underlying water, with the largest exponent corresponding to the highest cell abundance. Radiochemical budgets show that evaporative fluxes from the system are linearly proportional to the quantity of hexadecanoic acid at the interface. Thus, bacterioplankton could influence the rate of evaporation and gas transfer in the ocean through the metabolism of otherwise insoluble surfactants.     

Modification of heavy metal uptake efficiency by modified chitosan/anionic surfactant systems

The presence of toxic heavy metals in natural environments entails a potential health hazard for humans. Metal contaminants in these environments are usually tightly bound to colloidal particles and organic matter. On the other hand, the potential of these metals towards chelation by different chelating agents presents a good characteristic for their removal from the environment. On this basis, two chitosan/anionic surfactant complexes were prepared and evaluated for their ability to remove heavy metals from aqueous solutions. The experimental results of the uptake of metal ions including Cu²⁺, Sn²⁺, Co²⁺ and Ni²⁺ are reported in this study. The results show that modified chitosan with short‐spacer group cross‐linkers has a higher potential for heavy metal uptake than long‐chain cross‐linker‐modified chitosan. Also, increasing the electronegativity of the heavy metals increases their uptake from the medium. Increasing the time of exposure of the heavy metals to the modified polymer increases the efficiency of the metal uptake process.     

Response of Solenopsis invicta (Hymenoptera: Formicidae) to potassium oleate water solution

Abstract In contrast to floating on the surface of distilled water, ants were immediately submerged after being placed in the potassium oleate (PO) water solution, which led to immobilization within minutes. However, some workers survived after being immersed in 0.03% PO water solution at 25°C for up to 640 min. Elevated temperature of the PO water solution is needed to kill ants within a shorter time frame. At 50°C and 0.13% PO concentration, total mortality was achieved with 10-min immersion for all ants, including brood and adult ants. Soil has a negative effect on the effectiveness of potassium oleate; however, such negative effect can be overcome by increasing either treatment temperature or duration of the treatment. In addition to immobilizing and lethal effect, PO repels ants. PO may have the potential to be incorporated into immersion treatment for the quarantine of imported fire ants to reduce the use of synthetic contact insecticides.     

Specific interaction restrains structural transitions of an amphiphilic peptide in pulmonary surfactant model systems: An in situ PM-IRRAS investigation

In situ polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) at the air-water interface has been used to determine secondary structure of the pulmonary surfactant model peptide, Hel 13-5, in the absence and the presence of phospholipid monolayers. Herein, fully saturated phospholipids of DPPC and DPPG are utilized to understand the effect of specific interaction between anionic DPPG and cationic Hel 13-5 on the peptide secondary structure. The spectrum frequency in the amide region (1500-1700 cm^− 1) obtained from PM-IRRAS has been confirmed by comparing with that from ATR-FTIR for the corresponding bulk films. The PM-IRRAS spectra of single Hel 13-5 monolayers indicate the α-helical contour in the amide region, which coincides with the result from CD measurements in aqueous solutions. In the presence of phospholipid monolayers, however, Hel 13-5 changes its conformation from the α-helix to the extended β-sheet as surface pressure increases upon compression at the interface, and this interconversion is found to be irreversible even during expansion process of monolayers. Furthermore, it is notable that the electrostatic interaction between DPPG and Hel 13-5 inhibits to some extent the interconversion to the β-sheet during compression. These features are completely different from the bulk behavior, which demonstrates different roles of native proteins in the bulk phase and at the interface for pulmonary functions. In addition, the conformational variation of Hel 13-5 does not indicate close correlation with surface activity, which is common characteristic even for reversible hysteresis curves in pulmonary surfactant systems. This suggests that the secondary structure of native proteins is not strongly related to the surface activity during respiration. This work contributes to secondary structure determination of Hel 13-5 in the phospholipid domains in situ at the air-water interface and will provide insight into the molecular and physiological mechanism for SP-B and SP-C actions across the interface.     

Solubilization of enzymes in water-in-oil microemulsions and their rapid and efficient release through use of a pH-degradable surfactant

α-Chymotrypsin and lysozyme were solubilized in a water/O-[(2-tridecyl, 2-ethyl-1,3-dioxolan-4-yl)methoxy]–O′-methoxy poly(ethylene glycol) (CK-2,13 surfactant)/isooctane water-in-oil microemulsion solution at 1.5–2 and 10 g l⁻¹ for 0.15 and 1.2 M CK-2,13, respectively. Upon contact with an equal volume of 0.1 M NaH₂PO₄/Na₂HPO₄ buffer, pH 5, a three-phase system (Winsor-III system) was formed, consisting of a surfactant-rich middle phase and aqueous and isooctane-rich “excess” phases. Both enzymes were rapidly released into the aqueous excess phase, with 70% recovery of each in 30 and 60 min for microemulsion solutions containing 0.15 and 1.2 M surfactant, respectively. The recovered enzymes retained >90% of their original specific activity.     

Interaction of cationic <Emphasis Type="Italic">meso</Emphasis>-porphyrins with liposomes,mitochondria and erythrocytes

Two series of cationic porphyrins meso-(3N-methylpyridinium)phenylporphyrin (3P1, 3P2c, 3P2t, 3P3 and 3P4) and meso-(4N-methylpyridinium)phenylporphyrin (4P1, 4P2c, 4P2t, 4P3 and 4P4) were studied to obtain a comprehensive understanding of factors that influence the binding of cationic porphyrins to liposomes and mitochondria, as well as their photodynamic efficiencies in erythrocytes. Binding and photodynamic efficiency were found to be inversely proportional to the number of positively charged groups and directly proportional to n-octanol/water partition coefficients (log P_OW), except for the cis molecules 3P2c and 4P2c. In the cis molecules, binding and photodynamic efficiency were much higher than expected, indicating that specific interactions not accounted by log P_OW enhance photodynamic efficiency. The effect of mitochondrial transmembrane electrochemical potentials on cationic porphyrin binding constants was estimated to be as large as 15%, and may be useful to selectively target this organelle when promoting photodynamic therapy to induce apoptosis.     

Gene delivery by cationic lipid vectors: overcoming cellular barriers

Non-viral vectors such as cationic lipids are capable of delivering nucleic acids, including genes, siRNA or antisense RNA into cells, thus potentially resulting in their functional expression. These vectors are considered as an attractive alternative for virus-based delivery systems, which may suffer from immunological and mutational hazards. However, the efficiency of cationic-mediated gene delivery, although often sufficient for cell biological purposes, runs seriously short from a therapeutics point of view, as realizing this objective requires a higher level of transfection than attained thus far. To develop strategies for improvement, there is not so much a need for novel delivery systems. Rather, better insight is needed into the mechanism of delivery, including lipoplex–cell surface interaction, route of internalization and concomitant escape of DNA/RNA into the cytosol, and transport into the nucleus. Current work indicates that a major obstacle involves the relative inefficient destabilization of membrane-bounded compartments in which lipoplexes reside after their internalization by the cell. Such an activity requires the capacity of lipoplexes of undergoing polymorphic transitions such as a membrane destabilizing hexagonal phase, while cellular components may aid in this process. A consequence of the latter notion is that for development of a novel generation of delivery devices, entry pathways have to be triggered by specific targeting to select delivery into intracellular compartments which are most susceptible to lipoplex-induced destabilization, thereby allowing the most efficient release of DNA, a minimal requirement for optimizing non-viral vector-mediated transfection. Dedicated to Prof. K. Arnold on the occasion of his 65th birthday.