Ocotea fasciculata presents yangambin (YAN) and its isomer epi-yangambin (EPI-YAN) as major lignans, which are employed as the plant markers for quality control purposes and as potential pharmacological compounds. However, a gap between the pure isomers and safety and efficacy protocols is faced by the scientific community. In this context, this work aimed to report (i) a new and advantageous purifying process in a semi-preparative scale for YAN and EPI-YAN isolation from Ocotea fasciculata, and (ii) an in vitro cytotoxicity study to estimate, for the first time, the LD50 values of the isolated epimers, as well as the influence of albumin concentration in cell culture medium. The best condition for epimers isolation was achieved in normal-phase liquid chromatography. The lignan fraction (LF), previously obtained from the plant ethanolic extract, was purified yielding 17% and 29% of YAN and EPI-YAN, respectively. The in vitro study demonstrated that YAN and EPI-YAN were safe, and only at the highest concentration studied, a decrease on cell viability was observed. The estimated LD50 value was higher than 1612 mg/kg for both epimers. The LF, on the other hand, demonstrated an estimated LD50 of 422 mg/kg. Lignan cytotoxicity studies also evidenced that the higher cell viability was related to the higher concentration of fetal bovine serum as a source of albumin in medium. This is the first time the LD50 and safety of the isolated epimers were estimated, opening up great perspectives of success in in vivo studies.
Curcumin has been traditionally used in food recipes
for biological
health benefits. However, these properties are compromised due to
its very low bioavailability. Thus, this work assessed the impact
of using natural potential bioenhancers to improve intestinal permeability
and understanding the interaction of flavonoids with curcuminoids
through molecular dynamic simulation. The intestinal permeability
(P
app) was measured on the human colon
carcinoma cell line (Caco-2). The P
app values measured on Caco-2 cell monolayers provided information regarding
the increased permeability of curcumin across the intestinal barrier
specially caused by the presence of citrus (100.45%), and milk thistle
extracts (81.70%) at level +1 showed the higher P
app increase (%) compared to level 0. With respect to
the soft standardized green propolis EPP-AF extract, the P
app increase was higher at level 0 (26.34%). Molecular
dynamic (MD) simulations of curcumin with naringin and silybin B confirmed
this increase of permeability of curcumin at higher concentrations
through non-covalent interactions. These results suggest the prominent
importance of the association of natural flavonoids as bioenhancers
to increase curcumin bioavailability and health benefits.
Background
Leishmaniasis is a neglected disease, and the current therapeutic arsenal for its treatment is seriously limited by high cost and toxicity. Nanostructured lipid carriers (NLCs) represent a promising approach due to high drug loading capacity, controlled drug release profiles and superior stability. Here, we explore the efficacy of a unique pH-sensitive amphotericin B-loaded NLC (AmB-NLC) in
Leishmania braziliensis
infection in vitro and in vivo.
Methods and Results
AmB-NLC was assessed by dynamic light scattering and atomic force microscopy assays. The carrier showed a spherical shape with a nanometric size of 242.0 ± 18.3 nm. Zeta potential was suggestive of high carrier stability (−42.5 ± 1.5 mV), and the NLC showed ~99% drug encapsulation efficiency (EE%). In biological assays, AmB-NLC presented a similar IC
50
as free AmB and conventional AmB deoxycholate (AmB-D) (11.7 ± 1.73; 5.3 ± 0.55 and 13 ± 0.57 ng/mL, respectively), while also presenting higher selectivity index and lower toxicity to host cells, with no observed production of nitric oxide or TNF-α by in vitro assay. Confocal microscopy revealed the rapid uptake of AmB-NLC by infected macrophages after 1h, which, in association with more rapid disruption of AmB-NLC at acidic pH levels, may directly affect intracellular parasites. Leishmanicidal effects were evaluated in vivo in BALB/c mice infected in the ear dermis with
L. braziliensis
and treated with a pentavalent antimonial (Sb
5+
), liposomal AmB (AmB-L) or AmB-NLC. After 6 weeks of infection, AmB-NLC treatment resulted in smaller ear lesion size in all treated mice, indicating the efficacy of the novel formulation.
Conclusion
Here, we preliminarily demonstrate the effectiveness of an innovative and cost-effective AmB-NLC formulation in promoting the killing of intracellular
L. braziliensis
. This novel carrier system could be a promising alternative for the future treatment of cutaneous leishmaniasis.
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