Design, Preparation, and Physicochemical Characterisation of Alginate-Based Honey-Loaded Topical Formulations

Abstract

Honey has widespread use as a nutritional supplement and flavouring agent. Its diverse bioactivities, including antioxidant, antimicrobial, antidiabetic, anti-inflammatory, and anticancer properties, have also made it an aspirant natural product for therapeutic applications. Honey is highly viscous and very sticky, and its acceptance as a medicinal product will require formulation into products that are not only effective but also convenient for consumers to use. This study presents the design, preparation, and physicochemical characterisation of three types of alginate-based topical formulations incorporating a honey. The honeys applied were from Western Australia, comprising a Jarrah honey, two types of Manuka honeys, and a Coastal Peppermint honey. A New Zealand Manuka honey served as comparator honey. The three formulations were a pre-gel solution consisting of 2-3% (w/v) sodium alginate solution with 70% (w/v) honey, as well as a wet sheet and a dry sheet. The latter two formulations were obtained by further processing the respective pre-gel solutions. Physical properties of the different honey-loaded pre-gel solutions (i.e., pH, colour profile, moisture content, spreadability, and viscosity), wet sheets (i.e., dimension, morphology, and tensile strength) and dry sheets (i.e., dimension, morphology, tensile strength, and swelling index) were determined. High-Performance Thin-Layer Chromatography was applied to analyse selected non-sugar honey constituents to assess the impacts of formulation on the honey chemical composition. This study demonstrates that, irrespective of the honey type utilised, the developed manufacturing techniques yielded topical formulations with high honey content while preserving the integrity of the honey constituents. A storage stability study was conducted on formulations containing the WA Jarrah or Manuka 2 honey. The samples, appropriately packaged and stored over 6 months at 5, 30, and 40 °C, were shown to retain all physical characteristics with no loss of integrity of the monitored honey constituents.

Keywords: High-Performance Thin-Layer Chromatography; honey; honey-loaded formulation; physicochemical characteristics.

Figure 1

Determination of spreadability: (a) Placement of 1 g of honey sample within a circle of 2.4 cm diameter on a glass plate; (b) Placement of an upper glass plate with standardized weight on the sample; (c) Measurement of the final diameter of the sample after 5 min.

Figure 2

Determination of the dimensions of wet and dry sheets: (a) Positions for measuring thickness; (b) Positions for measuring length.

Figure 3

Gross morphology of the WA Jarrah honey-loaded wet and dry sheets as seen under a stereomicroscope (5× magnification): (a) Wet sheet (surface view); (b) Dry sheet (surface view); (c) Wet sheet (cross-sectional view); (d) Dry sheet (cross-sectional view).

Figure 4

Representative force (N) and displacement (mm) curve: (a) honey-based wet sheet; (b) honey-based dry sheet.

Figure 5

Representative tensile stress–strain curve: (a) honey-based wet sheet; (b) honey-based dry sheet.

Figure 6

Jarrah (JAR) honey—red box indicates the monitored bands at Rf 0.20 and 0.53; Track 1—4,5,7-trihydroxyflavone (internal standard), Track 2—neat JAR honey extract (system suitability test), Tracks 3–5—neat JAR honey extracts, Tracks 6–8—JAR honey pre-gel solution extract, Tracks 9–11—JAR honey wet sheet extracts, and Tracks 12–14—JAR honey dry sheet extracts; image taken at 366 nm.

Figure 7

Peak profile: (a) Neat JAR honey extract; (b) JAR honey pre-gel solution extract; (c) JAR honey wet sheet extract; (d) JAR honey dry sheet extract. Red boxes highlight monitored bands (Rf Rf 0.20 and 0.53).

Figure 8

Coastal Peppermint (CP) honey—red box indicates the monitored bands at Rf 0.20 and 0.53; Track 1—4,5,7-trihydroxyflavone (internal standard), Track 2—neat CP honey extract (system suitability test), Tracks 3–5—neat CP honey extract, Tracks 6–8—CP honey pre-gel solution extract, Tracks 9–11—CP honey wet sheet extract, and Tracks 12–14—CP honey dry sheet extract; image taken at 366 nm.

Figure 9

Peak profile: (a) Neat CP honey extract; (b) CP honey pre-gel solution extract; (c) CP honey wet sheet extract; (d) CP honey dry sheet extract. Red boxes highlight monitored bands (Rf 0.20 and 0.53).

Figure 10

WA Manuka honey 1 (WAM1)—red box indicates the monitored bands at Rf 0.38 and 0.53; Track 1—4,5,7-trihydroxyflavone (internal standard), Track 2—WAM1 honey extract (system suitability test), Tracks 3–5—WAM1 honey extract, Tracks 6–8—WAM1 honey pre-gel solution extract, Tracks 9–11—WAM1 honey wet sheet extract, and Tracks 12–14—WAM1 honey dry sheet extract; image taken at 366 nm.

Figure 11

Peak profile: (a) Neat WAM1 honey extract; (b) WAM1 honey pre-gel solution extract; (c) WAM1 honey wet sheet extract; (d) WAM1 honey dry sheet extract. Red boxes highlight monitored bands (Rf 0.38 and 0.53).

Figure 12

WA Manuka honey 2 (WAM2)—red box indicates the monitored bands at Rf 0.20 and 0.38; Track 1—4,5,7-trihydroxyflavone (internal standard), Track 2—WAM2 honey extract (system suitability test), Tracks 3–5—WAM2 honey extract, Tracks 6–8—WAM2 honey pre-gel solution extract, Tracks 9–11—WAM2 honey wet sheet extract, and Tracks 12–14—WAM2 honey dry sheet extract; image taken at 366 nm.

Figure 13

Peak profile: (a) Neat WAM2 honey extract; (b) WAM2 honey pre-gel solution extract; (c) WAM2 honey wet sheet extract; (d) WAM2 honey dry sheet extract. Red boxes highlight monitored bands (Rf 0.20 and 0.38).

Figure 14

NZ Manuka (NZM) honey—red box indicates the monitored bands at Rf 0.32 and 0.39; Track 1—4,5,7-trihydroxyflavone (internal standard), Track 2—NZM honey extract (system suitability test), Tracks 3–5—NZM honey extract, Tracks 6–8—NZM honey pre-gel solution extract, Tracks 9–11—NZM honey wet sheet extract, and Tracks 12–14—NZM honey dry sheet extract; image taken at 366 nm.

Figure 15

Peak profile: (a) Neat NZM honey; (b) NZM honey pre-gel solution formulation; (c) NZM honey wet sheet; (d) NZM honey dry sheet. Red boxes highlight monitored bands (Rf 0.32 and 0.39).

Figure 16

Representative HPTLC image taken at 254 nm after development with ethyl acetate. Track 1: HMF (1 mg/mL) aqueous solution; Track 2–7: WA Manuka honey 2 extracts at 1, 2, 3, 4, 5, and 6 months of storage at 30 °C; and Tracks 8–13: WA Manuka honey 2 at 1, 2, 3, 4, 5, and 6 months of storage at 40 °C. Red box highlights monitored band (Rf 0.41).