Hello friends,
We are mainly interested in the isolation of phytochemicals from medicinal herbs. One of the main problem is that some of the extracts contain very high concentrations of sugar and amino acids. Hence, in order to study the biological effects of these phytochemcals, we were using higher concentrations of the crude sample (mg quantities). In most of the biological experiments higher quantity of the crude samples interfere/mask the effect of these phytochemicals. Can you please help me?

Dear Praveen,

I spent a number of years doing the kind of work you have described in your message. There are a couple of different approches you can use to deal with the simple sugars/salts and other unwanted material. First try, don't extract them or extract less of them, so try using higher organic content in your extraction solvent. This can help a lot. Second, a simple soild phase extraction method. I used to take some of my dried extract, dissloved in a solvent that contained the minimum amount of organic (MeOH or EtOH) needed to dissolve it, and passed it through a C18 cartridge, washing with water followed by washes with higher organic. We used to use home made cartridges but near the end we liked to use the Oasis cartridge from Waters (for smaller samples), we still used homemade ones for larger scale preperations. When you do this, you end up with a number of fractions, the one that passed through the cartridge, the water wash, the organic wash(s). The bad news is each of these fractions needs to be tested. We used HPLC to target our compounds, but bio-assays can be used as well. Third (and most complex), prep scale HPLC. Goods news/bad news here, the good news is you can get fairly pure coumpounds but the bad news is you can end up with a lot of fractions to test (at least at first).

Try and have an idea about the nature of your compounds of interest before you start, it will make your extraction/purification choices easier.

Hope this helps.

A.A.