Elsevier

Food Chemistry

Volume 298, 15 November 2019, 125091
Food Chemistry

Complexation of curcumin with Lepidium sativum protein hydrolysate as a novel curcumin delivery system

https://doi.org/10.1016/j.foodchem.2019.125091Get rights and content

Highlights

  • Lepidium sativum protein hydrolysate (LSPH)-based curcumin (CUR) complexation was successfully achieved.

  • The LPSH (10–30 kDa) complex exhibited a good colloidal stability at pH 3.0.

  • The aqueous solubility, stability and even bioaccessibility were significantly enhanced.

  • The LPSH (10–30 kDa) could be a potential strategy for a delivery system.

Abstract

The complexation of Lepidium sativum protein hydrolysate (LSPH) with a lipophilic molecule, curcumin (CUR), and its effect on curcumin in vitro bioaccessibility/stability, functional and antioxidant activity were investigated. Fluorescence spectroscopy of the LSPH/CUR complex confirmed the presence of hydrophobic interactions that led to the complex formation. The LSPH (10–30 kDa) fraction showed a compact complexation with curcumin at pH 3.0 with excellent aqueous solubility, stability, and bioaccessibility. Further, complexation enhanced the aqueous solubility of curcumin more than 856-fold. In vitro sequential simulated gastric and intestinal digestion indicated that the bioaccessibility of curcumin was increased from 67% to 95% post complexation. The functional attributes suggest that the LSPH/CUR complex has good foam-forming capacity and emulsion stability, which are crucial for food product formulations. The results indicate that, since LSPH is a dietary protein, it might possibly be formulated as a functional food and as an excellent lipophilic bioactive molecule delivery vehicle in food formulations.

Introduction

In the past decade, complexations between proteins and lipophilic molecules, especially polyphenolic compounds, have attracted attention of many researchers and nutraceutical industries. The increased interest is mainly due to the ability of formed complexes to enhance water solubility, stability and bioavailability of the bioactive compounds with a targetted release in the GI tract (Ahmed, Li, McClements, & Xiao, 2012). Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)1,6-heptadiene-3,5-dione], an important lipophilic polyphenol, is found in the rhizome of turmeric (Curcuma longa) and the crude extract is used indigenously in numerous herbal medicines; it is commonly comprised of three key compounds: curcumin, demethoxy-curcumin, and bisdemethoxycurcumin (Chen, Li, & Tang, 2015). Among the three, curcumin is the major active constituent that contributes to several biological and pharmacological activities, such as anti-inflammatory, antioxidant, anti-cancer, antiproliferative, antimicrobial and antiangiogenic properties (Bhatia et al., 2016). However, the applications of curcumin in functional food and nutraceutical formulations are limited due to its limited water solubility and poor bioavailability.

Many studies have shown the potential of animal-derived protein molecules to act as a carrier to improve the solubility and bioavailability of curcumin. Previous reports concluded that casein (Rahimi Yazdi and Corredig, 2012, Sahu et al., 2008), β-lactoglobulin nanoparticle (Sneharani, Karakkat, Singh, & Rao, 2010), β-casein micelle (Esmaili et al., 2011, Pan et al., 2013) and bovine serum albumin (Yang, Wu, Li, Zhou, & Wang, 2013) increased the solubility of various molecules by balancing the ratio of hydrophilic-to-hydrophobic amino acids with a peculiar micellar structure that aids complexation. Beside the animal-derived proteins, plant-based proteins are also regarded as safe and economical with significant health benefits (Satija & Hu, 2018). The complexation with soy protein isolate (Chen et al., 2015, Tang and Li, 2013, Tapal and Tiku, 2012), pea protein (Donsì, Senatore, Huang, & Ferrari, 2010), flaxseed hydrolysate (Akbarbaglu et al., 2019) and zein colloidal particles (Patel, Hu, Tiwari, & Velikov, 2010) has demonstrated the improvement in solubility and stability of curcumin. However, many of these proteins in native form failed to show proper functional characteristics for food applications. Therefore, the natural proteins are modified by various methods, such as enzymatic hydrolysis, to improve their solubility, emulsification capability and foaming capacity (Akbarbaglu et al., 2019).

The plant-based proteins are environmentally sustainable dietary sources of proteins and their demand from vegans is increasing, with only limited experimental results available to address the possible application of the proteins in this respect (Karaca, Low, & Nickerson, 2011). In our study, Lepidium sativum seed protein isolates were used as the carrier for curcumin complexation. Lepidium sativum, a shrub native to the Indian subcontinent, belongs to the Cruciferae family and is a cheap and abundant renewable source of proteins. The object of our research was to evaluate the feasibility of molecular weight-based Lepidium sativum protein hydrolysate fractions as potential complexation agents for curcumin. This study systematically investigated the preparation, characterization and functional evaluation of protein-based curcumin complex as an effective nutraceutical and functional food ingredient.

Section snippets

Material

Curcumin (CUR, 95%) was purchased from ICN Biomedicals, Inc. (Aurora, Ohio). Lepidium sativum seeds were purchased from APMC market, Mumbai. 2,2-Diphenyl-1-picrylhydrazyl, 2,4,6-Tris(2-pyridyl)-s-triazine (TPTZ), was from Sigma Aldrich and the rest of the chemicals were of analytical grade from the Merck Company.

Production of enzymatic hydrolysate

To prepare LSPH/CUR complex, a freeze-dried Lepidium sativum protein hydrolyzed molecular fraction was used. Prior to enzymatic hydrolysis, defatted Lepidium sativum seedcake was

Complexation of curcumin with LSPI

Curcumin (diferuloylmethane), a lipophilic polyphenol found in turmeric (Curcuma longa), exhibits potential biological and pharmacological activities. However, its applicability as a health-promoting agent in various formulation developments is often limited due to its poor water-solubility and chemical instability, as well as low and variable bioavailability. In this study, we used LSPH (MWCO > 30 kDa, 10–30 kDa, 5–10 kDa and <5 kDa) as an emulsifier and stabilizer at pH 3.0, 3.5 and 4.0 to

Conclusion

This study has shown that the LSPH (10–30 kDa) fraction can undergo a compact complexation with curcumin at pH 3.0 that significantly improves its solubility (in the aqueous phase), stability and even bioaccessibility. The functional attributes of the LSPH/CUR complex, especially the foam and emulsion forming capacities, were promising for its applications in food product formulations. Furthermore, the antioxidant activity of LSPH increased after complexation with curcumin. The present work

Declaration of Competing Interest

None declared.

Acknowledgment

The authors are thankful for the Basic Scientific Research Fellowship in Sciences by the University Grants Commission, Government of India, for providing financial assistance (Grant number: 2812/UGC-SAP) during this investigation.

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