Study On Extraction, Separation, Purification And Bioactivity Of Nimbin

The aim of the dissertation is to identify the chemical structure of nimbin; found quantityanalysis method of nimbin by HPLC; do researches concretely on the effect of traditionalsolvent extraction which was compared with ultrasonic-assisted and microwave-assistedextraction on nimbin yield from neem kernels; try to find a quick, economical and effectiveprocess to get nimbin monomer; determine the indoor growth inhibiting and poison effect ofnimbin crude extract from traditional solvent method to Helicoverpa armigera (Hubner) andcompare the poison effect with azadirachtin extract at the same time.1. The results of melting point, UV, IR, HPLC-MS, and NMR have shown us thecorrectness of the chemical structure of nimbin which has been prepared in the laboratory.2. The reversed-phase HPLC method was used in quantitaty measurement of nimbinwith a ODS column(150×4.6mm i.d., 10μm). An isocratic solvent system consisting ofmethanol and water(70:30, V/V) was prepared and used as the mobile phase at a flow rate of1.0mL min^-1. The detection wavelenth was chosed at 217nm with a UV detector. The retaintime of nimbin was at about 11.3min; the expression to calculate the mass of nimbin wasdescribed as follows: X=(Y—40398)/1811050, Y-peak area, X-nimbin mass(μg).3. Traditional solvent extraction technology of nimbin from neem kernels has bennstudied in detail for the first time and the most influencing factor was ratio of material to liquidfollowed with extraction time and temperature. The optimal conditions obtained by orthogonaltests were ratio of material to liquid 1:5(w/v), extraction temperature 40℃and extractiontime 3h×3. Under the optimal conditions, the content and yield of nimbin was 3.406ï¼…,72.197ï¼…respectively with acetic ester as the most feasible extraction solvent.4. The effect of ultrasonic-assisted and microwave-assisted process on the yield of nimbinhas been researched for the first time. After analyzing the effect of ultrasonic, microwave time,ultrasonic microwave power, ratio of material to liquid detailedly, unluckily, we found theyields of nimbin were all lower than traditional solvent extraction process, but solventquantity and extraction time was all less than traditional solvent extraction process either.5. A new quick, economical and effective process to acquire pure nimbin has been gotten as follows, the first time silica gel column chromatography→the second time Florisilcolumn chromatography→methanol crystallization, then 96.072ï¼…pure nimbin wasreached naturally.6. The indoor poison and growth inhibiting effect of nimbin crude extract by traditionalsolvent extraction process against two instars Helicoverpa armigera was determined. After fivedays treatment, we have gotten three conclusions as follows: (1) the growth inhibiting effectwas more notable than poison effect, for example, when nimbin crude extract was diluted to800 times, the rate of index slip was 74.59ï¼…after five days treatment. (2) the poison effect wasalso notable, eg. when even diluted to 1600 times, the emendatable mortality rate reached55.32ï¼…, while it was more smaller only 24.44ï¼…even when azadirachtion extract was dilutedto 100 times after five days treatmen. (3) as the nimbin crude extract concentration descended,the rate of index slip and mortality all also fell, Meanwhile, the effect was more slowly. (4)LC₅₀ (nimbin crude extract) of Helicoverpa armigera after five days treatment was 1616.5ppm.