AChE	acetylcholinesterase
AD	applicability domain
Adjusted MSE	adjusted mean square errors
Adjusted MSECV	adjusted mean square errors of leave-ten-out cross-validation
Adjusted SS	adjusted sum of squares
AI–AVII	astragalosides I–VII
BBB	blood–brain barrier
CNS	central nervous system
CSF	cerebrospinal fluid barrier
Fb	fraction unbound in brain
Fu	fraction unbound in plasma
Kin	influx rate constant
HPLC	High performance liquid chromatography
LDA	linear discriminant analysis
LFER	Linear free energy relationships
log(PSFubrain)	brain/plasma equilibration rate
logBB	logarithm of the ratio between the brain and the blood concentration
logPow	logarithm of n-octanol/water partition coefficient
LTO	leave-ten-out cross-validation
MLR	multiple linear regression
MW	molecular weight
PAMPA	parallel artificial membrane permeability assay
PLS	partial least square
PS	permeability surface area product
PSA	polar surface area
RMSE	root-mean-square error of calibration
RMSECV	root-mean-square error of leave-ten-out cross-validation
PRESS	predicted residual sum of squares
QSAR	quantitative structure–activity relationships
SE coefficient	standard error
SS regression	regression sum of squares
SS total	total sum of squares
VIF	variance inflation factors