Modifiers basified

Supercritical Fluid Extraction of Alkaloids Using Basified Modifiers 420... 

Certain free bases of alkaloids were found to be quite soluble in pure supercritical C02 even under mild supercritical conditions. However, the alkaloids were not extracted as much as expected from their solubilities [37]. This discrepancy was assumed to be due to the fact that most alkaloids exist in the form of salts in the plant. Alkaloids have been extracted from plant materials traditionally by extraction processes with the addition of ammonia or calcium hydroxide. Accordingly, the use of basified modifiers in SFE, rather than simple polar modifiers was investigated, in the hope that the extraction efficiencies of alkaloids from their plant of origin would be enhanced. 

This chapter documents enhancements of the efficiency of SFE extraction of alkaloids from plant matrices using basified modifiers. Hence (1) The pure compound solubility of some free bases in pure supercritical C02 has been measured by investigating the effects of temperature, pressure or density of C02 (2) The solubilities of the alkaloidal salts were compared with those of their free bases in order to evaluate the difference of their solubilities influenced by a changing from free bases to salts (3) Polar solvents such as methanol and water, as initial modifiers, were used for the enhancement of the solubilities (4) The solubilities of the salts by non-basified modifiers such as neat methanol or water were compared with those of methanol or water basified with diethylamine (5) The effect of modifiers employed on the desorption of the compounds from a matrix were measured and compared with each other (5) On the basis of the results of pure compound extractability, SFE was performed on alkaloids from the plant... 

Figure 3. Solubilities of hyoscyamine (I) and scopolamine (2) free bases in supercritical CO, [39]. Reprinted from J. Chromatogr. A, 863, Y. H. Choi et al., Strategies for supercritical fluid extraction of hyoscyamine and scopolamine salts using basified modifiers, 47-55 (1999), with permission from Elsevier Science.

Generally, alkaloidal salts are insoluble in nonpolar solvents but their free bases are quite soluble in the solvents. Therefore, the basified modifier should be introduced into the SFE to solubilize alkaloids in CO,. For the evaluation of the effects of basified modifiers, diethylamine was added to methanol or water at a 10% (v/v) concentration level. Then, the basified modifiers were continuously incorporated into the extraction cell at concentrations of 1, 5, and 10 % (v/v). The effects of methanol basified with diethylamine as a modifier on the solubilities of hyoscyamine (1) and scopolamine (2) are shown in Figure 8. The addition of diethylamine (10% v/v) into methanol dramatically enhanced the solubilities of the alkaloidal hydrochloride salts compared with those of pure methanol alone. This may be due to the fact that methanol basified with diethylamine changed the salts to the free bases. 

Another example for SFE of alkaloids using basified modifiers was reported for cephalotaxine (7) from Cephalotaxus wilsoniana leaves [45]. In this report, basified methanol was found to greatly enhance the extraction efficiency relative to any other modifiers (Figure 13). 

There have been reported numerous advantages of SFE for the extraction of natural products including reduction of extraction cost and time, environmental acceptance, and lack of toxicity to human health compared with conventional organic solvent extraction. However, the high polarity of alkaloids due to salt formation in plant tissue has made it difficult to extract them using SFE. In order to develop a universally acceptable SFE method for alkaloids present in plant materials, a basified modifier has been introduced to the SFE of selected alkaloids. On the basis of these results, it is believed that SFE using basified modifiers can be used as an alternative to conventional solvent extraction for alkaloids from plant material. 

Choi YH, Chin Y-W, Kim J, Jeon SH, Yoo K-P (1999) Strategies for supercritical fluid extraction of hyoscyamine and scopolamine salts using basified modifiers. J Chromatogr, A 863 (Copyright (C) 2012 American Chemical Society (ACS). All Rights Reserved.) 47-55. doi 10.1016/s0021-9673(99)00962-0... 

Effect of Modifiers Basified with Diethylamine on the Solubility... 

Figure 10. Effect of methanol (A) and water (B) basified with diethylamine (10% v/v) as a modifier on the solubilities of ephedrine derivative hydrochloride salts in C02 at 80 °C and 34.0 MPa. ME = methylephedrine (3) NE = norephedrine (4) E = ephedrine (5) PE = pseudoephedrine (6) [41]. Reproduced with permission from Vieweg Publishing 1999.

In both results of solubility and desorption from filter papers, diethylamine in methanol as a modifier was found to offer greater efficiency for SFE of the alkaloids than any other modifiers employed. The yields of hyoscyamine (1) and scopolamine (2) from the roots and aerial parts by SFE and conventional organic solvent extraction are listed in Tables 2 and 3. The SFE yields from both plant parts were greatly enhanced by the addition of methanol basified with diethylamine. From the results of solubility and desorption from filter paper, methanol and diethylamine/methanol (10% v/v) were much more efficient for both compounds than water and diethylamine/water (10% v/v) because of their low miscibility with C02. The extraction profile of hyoscyamine (1) when present in plant material was in good agreement with that when extracted as a pure compound. However, in the case of scopolamine (2), there... 

Although there are some differences in the degree of enhancement of extractability, among the modifiers employed in this study, 10% methanol basified with diethylamine was found to be optimal for the extraction of hyoscyamine (1) and scopolamine (2) from both the roots and aerial parts of Scopolia japonica. While the recoveries from the roots and aerial parts of S. 

Highly sensitive spectrofluorometric measurements have been used extensively in pentazocine analysis especially in measurements from biological sources. The method developed early by Berkowitz, Way and coworkers (27,4-9,50,51.52) has been modified and extended by other investigators (53.54-, 55,56). Pentazocine levels in plasma, urine, brain, and intestine have been determined by this method. Briefly the tissue or fluid is basified with a... 

---