Formulation and in vitro-in vivo evaluation of black raspberry extract-loaded PLGA/PLA injectable millicylindrical implants for sustained delivery of chemopreventive anthocyanins.
OBJECTIVE
The objective of this study was to formulate and evaluate freeze-dried black raspberry (FBR) ethanol extract (RE) loaded poly(DL-lactic-co-glycolic acid) (PLGA) and poly(DL-lactic acid) (PLA) injectable millicylindrical implants for sustained delivery of chemopreventive FBR anthocyanins (cyanidin-3-sambubioside (CS), cyanidin-3-glucoside (CG) and cyanidin-3-rutinoside (CR)).


METHODS
Identification and quantitation of CS, CG, and CR in RE was performed by mass spectroscopy and HPLC. RE:triacetyl-beta-cyclodextrin (TA-beta-CD) inclusion complex (IC) was prepared by a kneading method and characterized by X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy (NMR) and UV-visible spectroscopy. RE or RE:TA-beta-CD IC-loaded PLGA or PLA implants were prepared by a solvent extrusion method. In vitro and in vivo controlled release studies were conducted in phosphate-buffered saline Tween-80 (pH 7.4, 37 degrees C) and after subcutaneous administration in male Sprague-Dawley rats, respectively. Anthocyanins were quantified by HPLC at 520 nm.


RESULTS
The content of CS, CG, and CR in RE was 0.2, 1.5, and 3.5 wt%, respectively. The chemical stability of anthocyanins in solution was determined to be pH-dependent, and their degradation rate increased with an increase in pH from 2.4 to 7.4. PLGA/PLA millicylindrical implants loaded with 5 or 10 wt% RE exhibited a high initial burst and short release duration of anthocyanins (35-52 and 80-100% CG + CR release after 1 and 14 days, respectively). The cause for rapid anthocyanins release was linked to higher polymer water uptake and porosity associated with the high osmolytic components of large non-anthocyanin fraction of RE. XRD, (1)H NMR and UV-visible spectroscopy indicated that the non-anthocyanin fraction molecules of RE formed an IC with TA-beta-CD, decreasing the hydrophilicity of RE. Formation of an IC with hydrophobic carrier, TA-beta-CD, provided better in vitro/in vivo sustained release of FBR anthocyanins (16-24 and 97-99% CG + CR release, respectively, after 1 and 28 days from 20 wt% RE:TA-beta-CD IC/PLA implants) over 1 month, owing to reduced polymer water uptake and porosity.


CONCLUSIONS
PLA injectable millicylindrical implants loaded with RE:TA-beta-CD IC are optimal dosage forms for 1-month slow and continuous delivery of chemopreventive FBR anthocyanins.
Department of Pharmaceutical Sciences, University of Michigan, 428 Church St., Ann Arbor, MI, USA.
Kashappa Goud H
KG
Desai
Karl F
KF
Olsen
Susan R
SR
Mallery
Gary D
GD
Stoner
Steven P
SP
Schwendeman
D000818:Animals; D000872:Anthocyanins / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use*; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry*; D007267:Injections; D019344:Lactic Acid / Q000737:chemistry; D008297:Male; D011091:Polyesters; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D027824:Rosaceae / Q000737:chemistry*
D000872:Anthocyanins; D000972:Antineoplastic Agents, Phytogenic; D003692:Delayed-Action Preparations; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)