PMC

The inhibition of TRPM2 and Orai1 channels abolishes manuka honey-induced Ca²⁺ entry. (A) Manuka honey-induced Ca²⁺ entry was dramatically reduced in the presence of either 10 µM Econazole or 1 µM Pyr6 (30 min preincubation for each drug) and completely abolished by the simultaneous treatment with both drugs. Manuka honey was added at 4% v/v. The arrow indicates the addition of manuka honey after 60 s. Data are presented as means ± SEM of [Ca²⁺]_i traces recorded in different cells. Number of cells: manuka honey: 40 cells from 3 exp; manuka honey + Econazole 10 µM: 50 cells from 3 exp; manuka honey + Pyr6 1 µM: 50 cells from 3 exp; manuka honey + Econazole 10 µM + Pyr6 1 µM: 50 cells from 3 exp. (B) Mean ± SEM of the Ca²⁺ response to 4% v/v manuka honey recorded at the peak (light bars) and at the plateau (dark bars) under the designated treatments. Data are presented as means ± SEM of [Ca²⁺]_i measured by confocal imaging at peak maxima. Number of cells as in (A). Different letters above the bars indicate statistical difference determined by Two-way ANOVA with Bonferroni’s correction (p < 0.01). (C) The mRNA quantity of Stim1-2, Orai1-3 and TRPM2 transcripts was determined by qRT-PCR and is represented as mean relative expression ± SD (n = 3). (D) Expression of TRPM2 gene in HaCaT cells after RNAi. The mRNA quantity of TRPM2 was determined by qRT-PCR and is represented as mean relative expression ± SD (n = 3, * p < 0.001, t-test). (E) The Ca²⁺ response to 4% v/v manuka honey was suppressed in HaCaT cells transfected with a RNAi selectively targeting TRPM2. The arrow indicates the addition of manuka honey after 60 s. Data are presented as means ± SEM of [Ca²⁺]_i traces recorded in different cells. Number of cells: manuka honey: 40 cells from 3 exp; manuka honey after RNAi for TRPM2: 40 cells from 3 exp. (F). Mean ± SEM of the Ca²⁺ response to 4% v/v manuka honey recorded at the peak (light bars) and at the plateau (dark bars) under the designate treatments. Number of cells as in (E). Different letters above the bars indicate statistical difference determined by two-way ANOVA with Bonferroni’s correction (p < 0.01).

PCA scores plot of preprocessed HS-GC-IMS spectra of Fennel honey, Agastache honey, Pomegranate honey, and Manuka 12+ honey. A1: Fennel honey; A2: Agastache honey; A3: Pomegranate honey; A4: Manuka 12+ honey.

Ca²⁺ toolkit involvement. (A) The Ca²⁺ signaling response due to 4% manuka honey was significantly reduced in the presence of econazole (10 µM, 30 min pre-incubation). The arrow shows the honey addition after 60 s. Data are mean ± SEM of [Ca²⁺]_i traces assessed in different cells. Sample size: manuka honey + econazole: 40 cells from 3 exp; manuka honey: 40 cells from 3 exp. Insert. Mean ± SEM of the peak Ca²⁺ response measured under the chosen treatments. Number of cells as in A. Asterisks on bars indicate the statistical differences determined by two-way ANOVA followed by Bonferroni correction (**** p < 0.0001, * p < 0.05). (B) The Ca²⁺ response to 4% manuka honey was reduced in the presence of U73122 (10 µM, 30 min pre-incubation) and caffeine (10 mM, 30 min pre-incubation). The arrow specifies honey addition after 60 s. Data are mean ± SEM of [Ca²⁺]_i traces measured in cells. Number of cells: manuka honey: 40 cells from 3 exp; manuka honey + U73122: 40 cells from 3 exp; manuka honey + caffeine: 40 cells from 3 exp. Insert. Mean ± SEM of the peak Ca²⁺ response measured under the indicated treatments. Sample size as in B. Asterisks as in insert A (**** p < 0.0001, ** p < 0.01).

MICs of the E. coli isolates tested against a variety of Manuka and medical-grade honey. (A) All the Manuka honey MIC data used in this review, identifying an ungraded Manuka honey and Manuka honey UMF16+ as the most effective; and (B) all the medical-grade honey MIC data used in this review, identifying the three Surgihoneys as the most effective.