Curcumin micronization by supercritical fluid:in vitroandin vivobiological relevance

Abstract

Curcumin, a polyphenol extracted from the rhizome of Curcuma longa L. (Zingiberaceae), is shown to have antioxidant, anti-inflammatory, neuroprotective, anxiolytic, and antidepressant properties in both preclinical and clinical studies. However, its low bioavailability is a limitation for its potential adoption as a therapeutic agent. The process of micronization can overcome this barrier by reducing the particle size and increasing the dissolution rate, potentially improving the bioavailability of the compounds of interest. In this study, we compared the in vitro antioxidant effects of curcumin (CUR) and micronized curcumin (MC) and studied their effects on behavioral and neurochemical parameters in zebrafish submitted to unpredictable chronic stress (UCS). MC (1 g/L) presented higher antioxidant activity in vitro as compared to CUR, as measured by iron-reducing antioxidant power (FRAP), 1,1-diphenyl-2-2-picyryl-hydrazyl radical removal (DPPH), and deoxyribose tests. UCS increased total distance traveled in the social interaction test (SI), while decreased crossings, time, and entries to the top area in the novel tank test (NTT). No effects of UCS were observed in the open tank test (OTT). The behavioral effects induced by UCS were not blocked by any curcumin preparation. UCS also decreased non-protein thiols (NPSH) levels, while increased glutathione reductase (GR) activity and thiobarbituric acid reactive substances (TBARS) levels on zebrafish brain. MC presented superior antioxidant properties than CUR in vivo, blocking the stress-induced neurochemical effects. Although this study did not measure the concentration of curcumin on the zebrafish brain, our results suggest that micronization increases the bioavailability of curcumin, potentiating its antioxidant activity both in vitro and in vivo. Our study also demonstrates that counteracting the oxidative imbalance induced by UCS is not sufficient to block its behavioral effects.

Micronized Curcumin Causes Hyperlocomotion in Zebrafish Larvae

“…Although curcumin has antioxidant effects in several studies both in vitro and in vivo [28,51,52], we did not find an increase in antioxidant protection related to the non-enzymatic antioxidant GSH (represented by NPSH), nor a decrease in basal lipid peroxidation levels (represented by TBARS) in zebrafish larvae. In our previous study, acute exposure to curcumin and micronized curcumin had no significant antioxidant effects in adult zebrafish.…”

“…In our previous study, acute exposure to curcumin and micronized curcumin had no significant antioxidant effects in adult zebrafish. We hypothesize that these effects are only observed when there is an increase in the production of reactive oxygen species or oxidative damage, in higher concentrations of the curcumin and/or for a longer period of exposure in adult and larval zebrafish [17,28].…”

“…However, curcumin has low bioavailability in vivo, compromising its use [23,24]. Micronization, a process that uses a supercritical fluid to change physicochemical aspects of substances, has been shown to improve the biological effects of substances such as N-acetylcysteine, resveratrol, and curcumin [5,[25][26][27][28]. In our previous studies, both curcumin and micronized curcumin (10 mg/kg, intraperitoneal) were unable to block the behavioral effects of acute restraint stress (90 minutes) [29] and unpredictable chronic stress (14 days) [28], while robust antioxidant effects were observed for micronized but not for its conventional preparation in adult zebrafish [28].…”

Non-micronized and micronized curcumin do not prevent the behavioral and neurochemical effects induced by acute stress in zebrafish

“…1. Initially, animals were treated with 1% DMSO, 10 mg/kg CUR, or 10 mg/kg MC (n= 24).These doses were standardized in our previous study [31]. After the treatment, the experimental groups were subdivided into control (non-stressed group, S-) or acute restraint stress (ARS) (stressed group, S+).…”

“…The OTT was conducted as described previously [10,31,34]. Animals were individually placed in the center of a circular arena made of opaque white plastic (24 cm diameter, 8 cm walls, 2 cm water level) and recorded for 10 min.…”