The same principle holds when bioactive compounds are isolated by bioassay-guided fractionation. If the total activity is calculated at each step it is easy to determine if there is a loss of biological activity along the way. Even more important this approach makes it easier to discover the presence of synergistic effects. The situation is equivalent to the terms efficacy and potency used in pharmacology. The potency would be the activity in mg/ml of the extract and the efficacy would be the activity of the total plant material in ml/g. The principle can be demonstrated with the following example. If the crude extract to be fractionated, had a mass of 2800 mg with an MIC of 0.23 mg/ml the total activity in the crude would be 12174 ml. After the first fractionation the values in Table 1 were found.