Improved Antitumor Efficacy and Pharmacokinetics of Bufalin via PEGylated Liposomes
Yuan et al. Nanoscale Research Letters
Improved Antitumor Efficacy and Pharmacokinetics of Bufalin via PEGylated Liposomes
Jiani Yuan 0 1 3
Xuanxuan Zhou 0 1 3
Wei Cao 1 3
Linlin Bi 1 3
Yifang Zhang 2
Qian Yang 1 3
Siwang Wang 1 3
0 Equal contributors
1 Department of Natural Medicine & Institute of Materia Medica, School of Pharmacy, The Fourth Military Medical University , Xi'an , China
2 Shaanxi Pharmaceutical Development Center , Xi'an , China
3 Department of Natural Medicine & Institute of Materia Medica, School of Pharmacy, The Fourth Military Medical University , Xi'an , China
Bufalin was reported to show strong pharmacological effects including cardiotonic, antiviral, immune-regulation, and especially antitumor effects. The objective of this study was to determine the characterization, antitumor efficacy, and pharmacokinetics of bufalin-loaded PEGylated liposomes compared with bufalin entity, which were prepared by FDA-approved pharmaceutical excipients. Bufalin-loaded PEGylated liposomes and bufalin-loaded liposomes were prepared reproducibly with homogeneous particle size by the combination of thin film evaporation method and high-pressure homogenization method. Their mean particle sizes were 127.6 and 155.0 nm, mean zeta potentials were 2.24 and − 18.5 mV, and entrapment efficiencies were 76.31 and 78.40%, respectively. In vitro release profile revealed that the release of bufalin in bufalin-loaded PEGylated liposomes was slower than that in bufalin-loaded liposomes. The cytotoxicity of blank liposomes has been found within acceptable range, whereas bufalin-loaded PEGylated liposomes showed enhanced cytotoxicity to U251 cells compared with bufalin entity. In vivo pharmacokinetics indicated that bufalin-loaded PEGylated liposomes could extend or eliminate the half-life time of bufalin in plasma in rats. The results suggested that bufalin-loaded PEGylated liposomes improved the solubility and increased the drug concentration in plasma.
Bufalin; PEGylated liposome; High-pressure homogenization; Pharmacokinetics
Background
Cancer diseases are of enormous global significance as
the population of cancer patients which annually
increase may grow by half by 2020 [
1
]. Due to the
existence of the blood brain barrier (BBB) and multidrug
resistance, glioma tumor is one of the most
lifethreatening diseases without effective therapeutic agents
clinically [
2
]. Bufalin has been isolated and identified
from Venenum Bufonis, which are the secretions of the
skin and parotid venom glands of the toad Bufo bufo
gargarizans Cantor or Bufo melanostictus Schneider [
3
].
It has been reported to have strong pharmacological
effects including cardiotonic, antiviral, immune-regulation,
and especially antitumor effects [
4–7
]. However, the
poor solubility makes it difficult to disperse in the
aqueous solution and restricts application [8].
Liposomes have been regarded as a new drug delivery
system to improve poor drug solubility in hydrous
solution, enhance the bioavailability, increase the therapeutic
efficiency, and reduce the side effects [
9
]. Chiefly, it can
be helpful for agents loaded to pass through BBB and
delivery to the brain [
10
]. However, one of the major
shortcomings of liposomal formulation is its rapid
clearance from the blood due to the absorption of plasma
protein to the phospholipid membrane of liposomes,
which afterwards triggers the recognition and uptake on
the liposomes by the mononuclear phagocytic system.
Fortunately, when polyethylene glycol (PEG) is modified
on the surface of liposomes, this kind of phagocytose
can be sluggish. Hence, it is necessary to study
bufalinloaded PEGylated liposomes as long-circulating
liposomes to increase its aqueous solubility and improve its
pharmacokinetics [
11
].
Up to date, studies on the pharmacokinetics of bufalin
have not yet been paid much attention. Some reports
only focus on the pharmacokinetics of free bufalin in
aqueous solution per os administration. In the present
study, we developed PEGylated liposomes as a delivery
system of bufalin and compared the pharmacokinetic
difference among bufalin-loaded PEGylated liposomes,
bufalin-loaded liposomes, and bufalin entity in aqueous
solution by intravenous administration in rats.
Methods
Chemicals and Reagents
Bufalin (≥ 98% in purity) was purchased from BaoJi
Chenguang Technology Development Co., Ltd. (Baoji,
Shaanxi, China). L-α-phosphatidylcholine, cholesterol,
and
1,2-distearoyl-sn-glycero-3-phosphoethanolamineN-[methoxy(polyethylene glycol)-2000] (ammonium
salt; DSPE-PEG2000) were purchased from Sigma
Chemical Co., Ltd.(St. Louis, MO, USA) (the
molecular formulas of these substances were shown in
Additional file 1: Figure S1). The acetonitrile used
was of spectroscopic grade and purchased from
Honeywell (America). Chloroform and alcohol
(analytical grade) were purchased from Tianjin Kemiou
Chemical Reagent Co., Ltd. (China). All chemicals
were analytical or high-performance liqu (...truncated)