碱法提取喜树碱工艺的研究

通过正交试验设计,探讨了以稀NaOH溶液为溶剂从喜树果实中提取喜树碱的工艺条件。确定的最佳工艺条件为:NaOH溶液浓度为0.3%,NaOH溶液用量16ml/g原料·次,提取时间为3~4h,提取温度为室温。     

污染土壤重金属的生物有效性和移动性评价：四种方法比较

重金属在土壤中的积累可增加土壤对生态环境的危害,而这种危害与土壤中重金属的活性有关.本文以植物体重金属浓度和地表径流重金属浓度为依据,比较研究了总量法、化学形态分级法、有效成分提取法和淋洗法4种方法评价污染土壤中重金属的生物有效性和移动性的可行性.结果表明,不同方法的评价结果有较大的差异.由于不同土壤的重金属组成有很大的差异,总量法难以反映土壤重金属的生物有效性和移动性;化学形态分级法中的交换态重金属可较好地反映土壤重金属的生物有效性和移动性,有机质结合态和碳酸盐结合态的某些重金属与其生物有效性和移动性也有一定的联系,而氧化物结合态、残余态重金属与重金属的生物有效性和移动性无关;用淋洗方法溶出的重金属量可很好地反映地表径流中重金属的浓度,也可较好地反映重金属的生物有效性;5种化学提取剂提取有效态重金属的结果表明,稀盐(0.01 mol·L^-1 CaCl₂)和1 mol·L^_-1 NH₄OAc提取的土壤重金属量与植物中重金属的积累和地表径流中重金属浓度均显著相关,可较好地表征土壤中重金属的生物有效性和移动性,其中稀盐(0.01 mol·L^-1 CaCl₂)提取的重金属最适于评价重金属的可移动性.     

从天然橡胶中提取白坚木皮醇的研究

目的：选择适合于工业化生产的从胶清中提取白坚木皮醇的方法。方法：运用普通的化工技术对胶清进行凝固、浓缩和净化处理,再采用化学拆分法（Ｒｅｓｏｌｕｔｉｏｎ）从肌醇衍生物中提取白坚木皮醇。结论：本项研究得出的提取方法,其提取率约占胶清重量的０．２％～０．３％。提取的产品纯度达９７％以上,ＦＷ（ＣＥ）１９５,ｍｐ．１９１℃,「α」Ｄ＾２９－８０．３。该提取方法可以进行工业化生产。     

Unveiling antimicrobial activity of microalgae Chlorella sorokiniana (UKM2), Chlorella sp. (UKM8) and Scenedesmus sp. (UKM9)

Microalgae represent promising sources of bioactive compounds for pharmaceutical and industrial applications. The emergence of antibiotic resistant bacteria leads to the need to explore new cost-effective, safe, and potent bioactive compounds from the microalgae. This study aimed to investigate the potential of local microalgae for their antimicrobial properties and bioactive compounds. Three local microalgae namely Chlorella sorokiniana (UKM2), Chlorella sp. UKM8, and Scenedesmus sp. UKM9 biomass methanol extracts (ME) were prepared and tested against Gram-positive and Gram-negative bacteria. Chlorella sp. UKM8-ME showed the highest antibacterial activity. UKM8-ME minimum inhibitory concentrations were in the range of 0.312 to 6.25 mg/mL. Cytotoxicity evaluation using MTT assay showed that the microalgae methanolic extracts did not exhibit cytotoxicity against Vero-cells. The UKM8-ME was mainly containing 28 compounds from the Gas Chromatography-Mass Spectrometry (GC–MS) analysis. Major compounds of UKM8-ME included phenol (18.5%), hexadecanoic acid (18.25%), phytol (14.43%), 9,12-octadecadienoic acid (13.69%), and bicyclo[3.1.1]heptane (7.23%), which have been previously described to possess antimicrobial activity. Hence, Chlorella sp. (UKM8) methanol extracts showed promising antibacterial activity. More comprehensive studies are required to purify these antimicrobial compounds and develop our understanding on their mechanism in UKM8-ME to unleash their specific potential.     

High-throughput Synthesis of Carbohydrates and Functionalization of Polyanhydride Nanoparticles

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity¹. Several biodegradable polymers have been studied as vaccine delivery vehicles¹; in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses^2-12.The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices.The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses^10,11,13 C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation^14,15. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods^16,17.Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described¹⁰. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs^10,11 and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).     

Extraction enhancing mechanism of steam exploded Radix Astragali

Plant extraction occupies a vital status in the fine chemical industry, and steam explosion has been confirmed to be an effective pretreatment to enhance the extraction performance. In order to reveal the extraction enhancing mechanism of steam explosion, innovatively from the view of plant porous medium, we characterized porous properties of steam exploded Radix Astragali and established the correlation of porous properties and saponins extraction performance of Radix Astragali. The results indicated that average pore diameter was the most relevant to extraction parameters with R-square > 0.99 among various porous properties, which can effectively characterize the extraction performance. Area percentage of middle and large pores (100–100,000 nm) of Radix Astragali was increased from 8.25% to 91.57% after steam explosion and the increase of these pores was the major factor for enhancing extraction performance. Based on the close correlation of extraction parameters and porous properties, the extraction mechanistic model of steam exploded Radix Astragali was proposed. Altered porous properties improved the solute–solvent accessibility and internal mass transfer in the extraction process. Such findings are anticipated to prompt the enhancing effects and widespread application of steam explosion technology in plant extraction, and further identify research directions that lead to more efficient extraction.     

Assessment of phenolics-enriched extract and fractions of olive leaves and their antioxidant activities

Recent studies suggest that olive leaf is a significant source of bioactive phenolic compounds comparable to olive oil and fruits. Identifying appropriate extraction methods is thus an important step to increase the yield of such bioactive components from olive leaf, which is otherwise agricultural waste. The present study evaluates phenolic contents and compositions of olive leaf extracted by several solvent methods and to further establish their antioxidant activities using various radical scavenging systems. Total flavonoid and phenolic contents were significantly higher in the 80% ethanol extract, butanol, and ethylacetate fractions than hexane, chloroform and water fractions (p < 0.05). Oleuropein was identified as a major phenolic compound with considerable contents in these major three fractions and the extract that correlated with their higher antioxidant and radical scavenging. These results indicate that olive leaf contains significant amounts of oleuropein and phenolics, important factors for antioxidant capacity, which can be substantially modified by different extraction methods.     

Nematicidal activity of powder and extracts of Melia azedarach fruits against Meloidogyne incognita

Pulverised lyophilised (dehydrated) Melia azedarach (Meliaceae) fruits (PMF) were tested in a dose–response pot experiment against juveniles (J2) of the root-knot nematode Meloidogyne incognita. Successively, with different extraction procedures, a polar (melia methanol extract, MME) and a non-polar (melia oil, MO) fragments were obtained and their effects were tested on nematode motility and development, in dose and time response bioassays and pot experiments. An EC₅₀ value was calculated for all experiments. A dose–response effect was found in pot bioassays using PMF and, after an incubation period of 24 and 48 h, the EC₅₀ values were calculated at 0.41% and 0.34% w/w, respectively. Motility bioassays revealed a dose and time dependent response effect, after exposure to MME, but not to MO. Doses of MME higher than 0.08% were nematicidal, whereas lower ones were nematostatic (the loss of motility as a result of the presence of the substance was reversible). In a pot experiment, MME doses higher than 2.5% w/w caused 100% nematode control with EC₅₀ value of 0.916% w/w.     

Extraction of chlorophylls and carotenoids from dry and wet biomass of isolated Chlorella Thermophila: Optimization of process parameters and modelling by artificial neural network

Chlorophylls and carotenoids can be extracted from microalgae using various solvents. However, there is lack of studies regarding the comparison of extraction yield of these pigments from wet and dry microalgal biomass using different combination of cell disruption methods. Therefore, in this work, we have investigated the comparison of the extraction yield of chlorophylls and carotenoids from the wet and heat-dried microalgal biomass (isolated Chlorella thermophila) using ethanol. Extraction parameters such as homogenisation time, homogenisation speed, solvent temperature, solid-solvent ratio, boiling time and microwave time have been optimised. Chlorophyll extraction yield was observed to be 2.7 fold higher from wet biomass than dry biomass while carotenoid yield was 6.7 fold higher. Highest chlorophyll yield (∼60 mg/g-dry biomass) was observed at 6 min of homogenisation time, 10,000 rpm, solid solvent ratio of 1 mg/mL and 58 °C of solvent temperature from wet biomass with extraction efficiency of ∼94 %. Highest carotenoid yield was noticed following the same conditions of chlorophyll extraction except 4 °C of solvent temperature. The modelling of the extraction process was performed using artificial neural network (ANN) which may be useful for the scale-up of the extraction process at the industrial level.     

Cellulose extraction from wood chip in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl)

In the present study, 1-allyl-3-methylimidazolium chloride (AmimCl), an ionic liquid (IL), was used to extract cellulose from pine, poplar, Chinese parasol, and catalpa wood chips. Results show that pine is the most suitable wood species for cellulose extraction with ILs. Its cellulose extraction rate can reach as high as 62% under optimized conditions and its cellulose content is as high as 85% when DMSO/water is used as the precipitant. The dissolution process can be clearly observed by hot stage optical microscopy, and the reaction time can be significantly reduced by microwave irradiation. ¹³C CP/MAS NMR, FTIR, XRD, and SEM were used to analyze the cellulose-rich extracts of pine. Results show that IL dissolves pine wood by destroying inter and intramolecular hydrogen bonds between lignocelluloses. The major component of pine extract is cellulose with a homogeneous and dense structure. After extraction, AmimCl can be easily recycled and reused.