Determination of Mangiferin and Homomangiferin in the Leaves of 93 Kinds of Mango

[Objectives]To determine the content of mangiferin and homomangiferin in mango leaves by HPLC.[Methods]The mangiferin and homomangiferin were separated and determined by Elite Hypersil C18(5μm,4.6 mm ID×250 mm)chromatographic column.Acetonitrile-0.1%(V/V)phosphoric acid solution was used as the mobile phase for gradient elution,the flow rate was 1.0 mL/min,the detection wavelength was 258 nm,the column temperature was 30℃,and the injection volume was 5μL.[Results]There was a good linear relationship between mangiferin and homomangiferin in the range of 0.0254-0.5080μg/μL(r=0.9999)and 0.000960-0.019200μg/μL(r=0.9999),respectively.The average recovery rate(n=6)of mangiferin and homomangiferin in mango leaves was 101.7%(RSD=2.0%)and 101.0%(RSD=1.7%),respectively.[Conclusions]There were great differences in the content of mangiferin and homomangiferin in the leaves of different varieties of mango.The experimental results could provide a scientific basis for further development and utilization of mango leaf resources.

Dimethyl Sulfoxide/Visible-Light Comediated Chemoselective C-S Bond Formation Between Tryptophans and Thiophenols Enables Site-Selective Functionalization of Peptides

Late-stage peptide modification showcases a huge potential for the construction of peptide libraries,and the investigation of structure-activity relationships.Herein we report a dimethyl sulfoxide/visible light comediated chemoselective modification of tryptophan residue by forging the C-S structure using thiophenols irradiated with blue light-emitting diodes at room temperature.This method shows excellent chemoselectivity toward the C-2 position of the tryptophan residue and good compatibility with diverse thiophenol derivatives bearing various functional groups.Both protected oligopeptides and unmasked bioactive peptides smoothly underwent site-selective modification,furnishing the corresponding products.Above all,this study provides a new competent toolkit for late-stage peptide modification,labelling,and peptide-drug conjugation and provides a clue for protein bioconjugation.