Development of a Sericin Hydrogel to Deliver Anthocyanins from Purple Waxy Corn Cob (Zea mays L.) Extract and In Vitro Evaluation of Anti-Inflammatory Effects

Abstract

Sericin-alginate hydrogel formulations with purple waxy corn (Zea mays L.) cob extract (PWCC) for topical anti-inflammatory application are developed and evaluated. The physical properties such as viscosity, pH, and anthocyanin release are examined and in vitro anti-inflammatory activities, such as NO inhibition and IL-6, IL-1β, TNF-α, iNOS, and COX-2 expression, are evaluated in LPS-stimulated RAW 264.7 murine macrophages. The sericin-alginate hydrogel is prepared by physical crosslinking through the ionic interaction of the polymers combined with anthocyanin from PWCC at pH 6.5. The hydrogel formulation with 2.00% w/v sericin, 0.20% w/v alginate, and 0.15% w/v PWCC (SN6) shows a suitable viscosity for topical treatment, the highest nitric oxide inhibition (79.43%), no cytotoxicity, and reduced expression of IL-6, IL-1β, and TNF-α mediators. Moreover, the SN6 formulation displays a sustained anthocyanin release over 8–12 h, which correlates with the Korsmeyer–Peppas model. The FT-IR spectrum of SN6 confirmed interaction of the sericin polymer with anthocyanins from PWCC via H-bonding by the shifted peak of amide I and amide III. In addition, the anthocyanin is stable in sericin hydrogels under heating-cooling storage conditions. Therefore, we suggest that this hydrogel formulation has potential as an anti-inflammatory agent. The formulation will be further investigated for in vivo studies and clinical trials in the future.

The Potential of Purple Waxy Corn Cob (Zea mays L.) Extract Loaded-Sericin Hydrogel for Anti-Hyperpigmentation, UV Protection and Anti-Aging Properties as Topical Product Applications

“…The swelling capacity (% Swelling) over 48 h of each hydrogel formulation containing alginate (S2, S4, S6), was higher than its respective formulation without alginate (S1, S3, S5) ( Figure 1 ). Swelling allows for the more rapid diffusion of anthocyanins from the hydrogel since the diffusion release mechanism occurs at the outer surface of the polymer, rather than the core porous structure [ 13 ]. Previous research reported that the kinetics release of hydrogels was achieved using the Korsmeyer–Peppas model, due to the electrostatic and H-bonding interactions between alginate, anthocyanin, and sericin in the hydrogel, which was confirmed by FT-IR spectroscopy.…”

“…Previous research reported that the kinetics release of hydrogels was achieved using the Korsmeyer–Peppas model, due to the electrostatic and H-bonding interactions between alginate, anthocyanin, and sericin in the hydrogel, which was confirmed by FT-IR spectroscopy. The release of anthocyanins was by rapid diffusion at the outer surface of the polymers in the hydrogel for up to 4 h, followed by the gradual swelling until 48 h, due to the cross-linking interactions between anthocyanins and the hydrophobic polymers [ 13 ].…”

“…In contrast, anthocyanins in the hydrogels either permeated the skin or were retained in the epidermis and dermis, where they could affect the fibroblasts [ 23 ]. This enhanced the topical delivery of anthocyanins from the sericin hydrogels and could help maintain the anthocyanin concentrations in the application areas while prolonging the effects and reducing the frequency of administration [ 13 ].…”

“…Hydrogels are three-dimensional networks of hydrophilic polymer chains capable of holding large amounts of water that can swell, depending on the environmental conditions, such as the pH, temperature, and ionic strength [ 12 ]. Natural polymers that are commonly used in hydrogels, control and improve the active ingredient delivery to target sites by allowing the diffusion through the mesh or pores of the polymeric network without side effects [ 13 ]. In addition, the diclofenac hydrogel was also reported to enhance the diclofenac skin permeation and absorption [ 14 ].…”

“…A previous report stated that an anthocyanin-loaded hydrogel exhibited the enhanced stability and prolonged anthocyanin release, as well as the downregulation of the iNOS, IL-6, IL-1β, and TNF-α pro-inflammatory mediators. These combined anti-inflammatory and wound-healing properties suggest the synergistic effects of anthocyanins and hydrogels [ 13 ].…”