Effects of Melissa officinalis Extracts on Obesity and Anxiety

Abstract

Obesity is a significant global health concern that not only increases metabolic disorders risks but also impacts mental health, particularly affecting women due to hormonal fluctuations and societal pressures. This study investigated anti-obesity and anti-anxiety effects of lemon balm (Melissa officinalis) extracts in female C57BL/6 mouse (n = 16, 17 weeks old) fed a high-fat diet (HFD). We compared 2 extracts method: distilled water (LBD, n = 5) and 80% ethanol (LBE, n = 6), administered via oral gavage (200 mg/kg/day) for 6 weeks alongside HFD. Both extract groups showed lower weight increase ratio compared to the control group in experiment period (n = 5) (LBD: 27.74%, LBE: 29.71% vs. Control: 51.88%, p < 0.05). The extracts significantly decreased mesenteric white adipose tissue (mWAT) among WATs examined (mWAT and parametrial white adipose tissue [pWAT]). While both LBD and LBE reduced fatty acid synthase (FAS) mRNA expression in pWAT, only LBD reduced peroxisome proliferator-activated receptor gamma and FAS mRNA expression in mWAT. In elevated plus maze behavioral experiments, the LBD group displayed reduced anxiety-like behavior, spending significantly more time and travelling greater distances in the open arms compared to other groups (p < 0.05), independent of brain inflammatory markers. Our findings demonstrate lemon balm extracts simultaneously address both obesity and anxiety-like behaviors in female mice, with extraction solvent-dependent variations in efficacy and mechanism of action. These results suggest potential therapeutic applications for lemon balm as a functional food ingredient, particularly for women experiencing concurrent obesity and anxiety symptoms.

Keywords: Anxiety; Extraction solvent; Female; Lemon balm; Melissa officinalis; Obesity.

Figure 1. Basic information of experimental mouse. (A) The timeline of the experiment. (B, C) The consumption of food and water. (D) The changes of weight increase ratio in experimental period. (E) The liver weight which collected after sacrifice. The weight increase rate during the experiment period was expressed as a ratio of the amount increased compared to 0 week after the first weight measurement date was base line, and fat weight was calculated to the extent that the weight ratio of fat to weight was calculated, reducing the error in fat weight according to mouse size. Results were represented as mean ± standard deviation. Statistical significance was determined using one-way analysis of variance followed by Duncan’s multiples range tests.

Control, high-fat diet; LBD, high-fat diet + lemon balm distilled water extract; LBE, high-fat diet + lemon balm 80% ethyl alcohol extract. ^*,†Different symbols indicated significant differences (p < 0.05). LBD and LBE share same letter in linear graph.

Figure 2. Effect of Lemon balm extracts on anxiety-like behavior change and expression level of IL-6 and TNF-α in brain and liver. To access anti-anxiety effects of extracts, elevated plus maze was conducted. (A) The results of traveling time and distance in open arms. (B, C) The expression level of IL-6 and TNF-α in brain and liver by gel image and display graphs illustrating quantification of images obtained through gel electrophoresis using Image J. Graphic images were processed and analyzed with Image J to quantify the data, and the results are presented in graphical form. (D) The amount of AST and ALT in serum. Results were represented as mean ± standard deviation. Statistical significance was determined using one-way analysis of variance followed by Duncan’s multiples range tests.

Control, high-fat diet; LBD: high-fat diet + lemon balm distilled water extract; LBE, high-fat diet + lemon balm 80% ethyl alcohol extract; TNF-α, tumor necrosis factor-α; IL-6, interlukin-6; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; AST, aspartate aminotransferase; ALT, alanine aminotransferase. ^*,†Different symbols indicated significant differences (p < 0.05).

Figure 3. Effects of lemon balm extracts in WAT weight regulation and expression level of PPAR-γ and FAS. To access anti-obesity effects of extracts, PPAR-γ and FAS mRNA level were measured by reverse transcription polymerase chain reaction. GAPDH was used for control. (A) The tissue weight which collected after sacrifice. (B, C) The expression level of PPAR-γ and FAS in pWAT and mWAT by gel image and display graphs illustrating quantification of images obtained through gel electrophoresis using Image J. Graphic images were processed and analyzed with Image J to quantify the data, and the results are presented in graphical form. Results were represented as mean ± standard deviation. Statistical significance was determined using one-way analysis of variance followed by Duncan’s multiples range tests.

Control, high-fat diet; LBD, high-fat diet + lemon balm distilled water extract; LBE, high-fat diet + lemon balm 80% ethyl alcohol extract; pWAT, parametrial white adipose tissue; mWAT, mesenteric white adipose tissue; PPAR-γ, peroxisome proliferator-activated receptor gamma; FAS, fatty acid synthase; GAPDH, glyceraldehyde 3-phosphate dehydrogenase. ^*,†Different symbols indicated significant differences (p < 0.05).

Figure 4. Effects of lemon balm extracts in BAT weight regulation and expression level of PGC1-α. (A) The tissue weight which collected after sacrifice. (B) The expression level of PGC1-α in BAT. (C) The expression level of PGC1-α protein level in BAT. Graphic images were processed and analyzed with Image J to quantify the data, and the results are presented in graphical form. Results were represented as mean ± standard deviation. Statistical significance was determined using one-way analysis of variance followed by Duncan’s multiples range tests.

Control, high-fat diet; LBD, high-fat diet + lemon balm distilled water extract; LBE, high-fat diet + lemon balm 80% ethyl alcohol extract; BAT, brown adipose tissue; PGC1-α, peroxisome proliferator-activated receptor gamma coactivator 1-α. ^*,†Different symbols indicated significant differences (p < 0.05).