logP - octanol-water partition coefficient calculation
logP and logD Calculation. Introduction; Symbols; Definition of Partition Coefficient P and Distribution Coefficient D; Micro Partition Coefficient; Relation Between. Interactive logP prediction. Molinspiration methodology for logP calculation is very robust and is able to Several our customers reported very good correlation between Molinspiration calculated logP and various drug transport properties. material explains the theory behind the logP and logD calculation: The partition coefficient is the ratio of the concentration of the compound.
It is suited to smaller molecules, particularly those with non-complex aromaticity or those which do not contain electronic systems that are known to have unexpected contributions to logP. This is an attempt to allow for larger electronic effects.
It is fast, being a table look-up technique, and many free software use this too. The smarter hybrid algorithms know the state of each atom and thus how much of a contribution its neighbours add. Fragment contributions are then added up, with correction factors.
On-line Lipophilicity/Aqueous Solubility Calculation Software
The rationale here is that sometimes atomistic approaches do not adequately model the nuances of electronic or intramolecular interactions, which may be better modelled by using whole fragments. This method tends to be better for systems with complex aromaticity, and larger molecules — on the condition that the molecule contains features that are similar to those from which the modelling was conducted. In the case of very obscure motifs in your molecules, then the model from which the prediction is made may not have a very good correlation.
Property based methods… There are a whole host of methods for determining logP using properties, empirical approaches, 3-D structures e. Most of these methods are reasonably computationally intense, and are buried in the world of informatics and stats, but one is worthy or particular note: It is very fast, and so historically it was employed for large datasets, and was included in several property prediction software, such as Dragon, and ADMET Predictor Simulations Plus, Inc.
Nowadays as computational speed has increased, MlogP is used less, as more accurate methods become manageable, even at large library sizes.
logP and logD Calculation
So, which method do you use? ChemAxon uses multiple methods including hybrid VG and fragment e. Our calculation method takes into account the effect of the counterion ion concentration on logD and logP. Symbols Throughout this document we use the following symbols: Pi upper case the macro partition coefficient, where subscript i refers to the ionization state of species included in Pi. Definition of Partition Coefficient P and Distribution Coefficient D The partition coefficient is the ratio of the concentration of the compound in octanol to the concentration of the compound in water.
The distribution coefficient is the ratio of the sum of the concentrations of all species of the compound in octanol to the sum of the concentrations of all species of the compound in water.
Based on acid dissociation reactions, we can introduce the concept of a partition coefficient for cationic and anionic species and for neutral species.
The following gives the definition of partition and distribution coefficients for ionized and unionized species.
- cLogP Calculation
- Not all LogP’s are calculated equal: CLogP and other short stories
The partition and distribution coefficients for multiprotic compounds are defined in much the same way as for monoprotic compounds, using the following formulas. In this example we suppose that the compound A1A2B1B2 contains two acidic and two basic ionization sites.Correlation in SPSS - P-Value
This compound has 16 protonation states in aqueous solution. The microspecies which are assigned to the protonation states are summarized in Table 1.