The higher loading and large microsize of MS particles result in more rigid compounds.
The second are class with more rigid compounds containing phenoxy or other cyclic groups on both ends of the molecule exemplified by ZR-10183, ZR-10131 and pyriproxyfen (Class II structures 81, 85, 86).
More flexible compounds 10 12 display affinities for Kef similar to those of the more rigid compounds (e.g., compounds 6 and 12) in both the fluorescence and DSF assays.
Interestingly, 4α-acyloxy-2α-bromopicropodophyllotoxins were easily converted to a more rigid compound 14 by an intramolecular Friedel Crafts alkylation reaction in the presence of BF3·Et2O when the reaction time was prolonged to 4 18 h.
Considering that the mean MW of TCMCD1 is significantly larger than that of ACD1, natural compounds in TCMCD1 are substantially more rigid than compounds in ACD1.
One could make an argument for the use of more rigid bivalent compounds.
In brief, TCMCD3 compounds are slightly more hydrophilic than MDDR1 compounds and greatly more hydrophilic than ACD3 compounds, more soluble and more rigid than MDDR1 and ACD3 compounds, and have more complicated structures, especially ring systems, than MDDR1 and ACD3 compounds.
On average, TCMCD3 compounds are a little more hydrophilic than MDDR1 compounds and substantially more hydrophobic than ACD3 compounds, more soluble and more rigid than MDDR1 and ACD3 compounds, and have more complicated structures, especially ring systems, than MDDR1 and ACD3 compounds.
Only in the case of the more rigid bicyclic amino acid 3Tic (compound 27), was the peptide backbone also conformationally changed.
Follow-up optimization of 49– 51 led to replacement of the alkyl linker, which was implicated in poor bioavailability and poor metabolic properties, with more rigid structural elements inspired by compound 52.
Boundaries between small compounds, peptides, and peptide mimetics are blurred; small compound PPI disruptors (PPIDs) are heavier, more hydrophobic, more rigid, and more planar than conventional small compound drugs, and peptide motifs are often included in their structure as part of their rational design [ 59, 60].
