An Improved Protocol for the Synthesis and Purification of Yariv Reagents

Abstract

Yariv reagents are widely used tools to study plant proteoglycans known as the Arabinogalactan proteins (AGPs). Despite widespread use of the Yariv reagent in the study of AGPs and several reports of synthetic protocols, there remains a lack of a simple procedure to obtain pure Yariv reagents. We report our optimized protocols to address the purification issues faced upon synthesis of Yariv reagents. Additionally, we report challenges that make characterization difficult such as peak broadening in NMR due to Yariv-water interactions. We also show ways of processing Yariv reagents to overcome the characterization issues caused by peak broadening. File list (2) download file view on ChemRxiv YarivSynthManuscriptChemRXivSubmission.pdf (1.24 MiB) download file view on ChemRxiv YarivSynthManuscriptChemRXivSISubmission.pdf (8.91 MiB)

The Chirality of Aggregated Yariv Reagents Correlates with Their AGP‐Binding Ability**

“…To determine whether the helicity exhibited by 1 is seen with other Yariv reagents, compounds 2–9 were prepared and their CD spectra obtained. We have previously reported the syntheses of compounds 2 – 6 [13] . Compounds 7 – 9 were prepared using the same procedure, and characterization data is provided in the Supporting Information.…”

“…The β-D-glucosyl Yariv reagent (1) was prepared using our previously reported procedure. [13] The CD spectrum of 1 in aqueous solution, where it is known to aggregate, [8,11] indicates the presence of two major transitions (Figure 2). Each of these transitions display a bisignate positive Cotton effect (λ = 380 nm,…”

“…We have previously reported the syntheses of compounds 2-6. [13] Compounds 7-9 were prepared using the same procedure, and characterization data is provided in the Supporting Information. All of these Yariv reagents exhibit spectra with bisignate Cotton effects (Figure 3), indicating that they also form helical aggregates in solution.…”

The Chirality of Yariv Reagent Aggregates Correlates with AGP–binding Ability

“…This change in the UV/vis spectrum is also observed when the spectrum of 1 is obtained in DMSO (Figure S2), and the NMR spectrum of 1 in DMSO-d6 also shows clearly resolved sharp resonances with none of the broadening associated with aggregation. 7,21 As seen in Figure 2, the CD signal is reduced greatly in intensity in the presence of SDS, while in DMSO the CD signal is flat. Finally, we have prepared an analog of 2 containing a single azo-linked galactoside (S2), and its CD spectrum is essentially flat (Figure S6), although a very weak positive couplet (λ = 450 nm, Δε = 1.00 L•mol -aqueous solution arises due to the formation of chiral aggregates rather than due to the inherent chirality of the molecule.…”

“…Our results provide a basis for explaining the selectivity of AGP binding amongst the various Yariv reagents. The Yariv reagents 1-7 were synthesized using reported procedures 21 , and 8 was purchased from Biosupplies, Australia. The CD spectrum of 1 in water, where the Yariv reagent is known to aggregate, shows the presence of a strong CD signal (Figure 2).…”