ng excitation at 310 nm. (C). Fluorescence emission spectra of rHDL (a) and rHDL/res (b) were recorded with ten g protein in PBS. For comparison, emission spectrum of resveratrol in DMSO is shown (c). Quenching analysis of rHDL/res. 
rHDL/res (ten g protein) was treated with escalating concentrations of KI in PBS (A) or 16-DSA in DMSO (B), along with the fluorescence emission intensity recorded at each and every concentration. Data are plotted as F/F0 versus quencher concentration. Representative information from 3 independent experiments are shown.
Characterization of rHDL and rHDL/res particles. A & B. Transmission electron microscopy. Negative staining of rHDL (A) and rHDL/res (B) was carried with ten g protein. The bar represents 20 nm. Arrows draw attention to discoidal particles. C. Non-denaturing PAGE. rHDL and rHDL/res have been electrophoresed on 40% acrylamide gradient gel. The far left lane bears the high molecular mass standards; the molecular mass and their corresponding Stokes’ diameters are indicated; lane 1) rHDL, and lane 2) rHDL/res. Arrows draw attention to particle heterogeneity in lane 1.
The phospholipid and protein composition of rHDL/res had been 2.68 mg/ml (three.94 mM) and three.84 mg/ml (138 M), respectively, yielding a lipid: protein molar ratio of 29:1. The corresponding concentrations for rHDL had been three.47 mg/mL (5.1 mM) and 3.75 mg/mL (134 M), respectively (lipid: protein molar ratio of 38:1). The amount of resveratrol in the rHDL/res was determined to be 167 M by RP-HPLC (Fig B in S1 File). The final lipid: protein: resveratrol ratio in rHDL/res was calculated to be ~30:1:1. To determine if the presence of resveratrol in rHDL affects the LDLr binding ability of apoE3-NT, co-IP was carried out using sLDLr bound to anti-c-Myc agarose [31]. Following incubation of rHDL or rHDL/res with sLDLr, the receptor-bound complexes have been captured by anti-c-Myc bound to agarose and detected by HRP conjugated polyclonal apoE antibody, Fig 4A, or anti-c-Myc antibody, Fig 4B. The information show that the presence of resveratrol does not alter the LDLr binding ability of apoE3 in rHDL/res (lane 2). To enable direct visualization of cellular uptake of resveratrol, NBD-labeled derivative of resveratrol (res/NBD) was synthesized (Fig 5, Top). NBD is significantly lipophilic compared to other green fluorophores such as 1381289-58-2 chemical information fluorescein [35], with its lipophilicity comparable to that of resveratrol. Briefly, the synthesis involved statistical protection of 2 of the three free phenolic groups by alkylation of resveratrol, A, with methyl iodide to give intermediate B, Fig 5. This allowed us to insert an ethylene amine functional group on the free phenolic group for subsequent reaction with NBD. Intermediate B was reacted with 2-chloro-N,N-dimethylethyleneamine to give C, followed by N-demethylation to give D. Finally, reaction with NBD-Cl gave E, 5-ethoxy-(2-N-methyl-4-amino-7-nitrobenzofurazan)-3,4′-dimethoxy-(Z)-stilbene (res/NBD) in acceptable yield (31%). (REF1: U.S. Provisional Patent Application Serial No. 62/077,780 Filed: November 10, 2014; Our Reference No.: 1958937.00002. REF2: Birendra Babu Adhikari, Sahar Roshandel, Ayu Fujii). The final product, res/NBD, was characterized by NMR (Figs C, D and E in S1 File) and mass spectrometry (Fig F in S1 File); it was found to retain the main structural features of resveratrol and was obtained in sufficient yields for subsequent uptake studies. The absorbance spectrum of res/NBD in DMSO (Fig 1A, spectrum d) reveals peaks at ~330 nm and 480 nm,