Antiphotoaging effects of solvent fractions isolated from Allomyrina dichotoma larvae extract

Abstract

Skin aging is affected by a variety of factors, including ultraviolet rays, oxidative stress, medications, smoking, and genetics. Among them, photo-aging accounts for about 80% of skin aging. The present study was evaluated to verify the potential of Allomyrina dichotoma larvae, which has recently been attracting attention as an edible insect, as an anti-aging substance. UVB irradiation at 100 mJ/cm² was sufficient to induce photo-aging of fibroblasts within 24 h, which was alleviated after treatment with 70% ethanol extract of Allomyrina dichotoma larvae extract (ADLE). To obtain an extract from ADLE, which has a relatively high content of polyphenol compounds containing physiological activity, fractional solvent extraction was carried out using organic solvents such as hexane, chloroform, ethyl acetate, and butanol. Additionally, ethyl acetate and butanol fractions contributed to the inhibition of UVB-induced ROS production, cell damage, and senescence of fibroblasts. It was also confirmed that the two fractions can regulate the expression of MMP-1 and AP-1. In particular, the ethyl acetate fraction showed an excellent effect in recovering collagen decomposed by UVB. Therefore, these results suggest that ADLE has potential as a natural insect-derived biomaterial to inhibit UVB-induced photo-aging.

Keywords: Allomyrina dichotoma larvae; Collagen; Human dermal fibroblast; Photo-aging; Ultraviolet B.

Fig. 1

Effect of UVB irradiation on photo-aging in HDF cells. HDF cells were irradiated with the indicated amount (20–1000 mJ/cm²) of UVB and each activity was measured after 24 h incubation. (A) Cell viability was measured by MTT assay. (B) Intracellular ROS level was stained with DCFH-DA and analyzed by fluorescence reader. (C) Changes in SA-β-galactosidase activity was examined by commercial assay kit. (D) The protein expression levels of AP-1, MMP-1 and COL1A1 were measured according to the Western blot procedure. The results are shown as the means ± SD (n = 3–5), normalized to the percentage of non-irradiated control. *p < 0.05 and ***p < 0.001 as compared to non-irradiated control.

Fig. 2

Effect of ADLE solvent fractions on ROS generation, mitochondrial dysfunction, and SA-galactosidase activity induced by UVB in HDF cells. (A) Cells were treated with ADLE or its solvent fraction at various concentration for 24 h, and viability was measured by MTT. After 100 mJ/cm² UVB irradiation, cells were treated with ADLE or its solvent fractions at 100 μg/mL for 24 h and (B) cell viability was measured using MTT. (C) Intracellular ROS level was measured by DCFH-DA and (D) SA-β-galactosidase activity was examined by commercial assay kit. (E) Mitochondrial membrane potential was assayed by JC-1 detection kit. Data represent mean ± SD (n = 3–5), normalized to the percentage of CON. ***p < 0.001 versus CON. ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus UVB. CON: non-irradiated, UVB: 100 mJ/cm² UVB irradiated only.

Fig. 3

Effect of ethyl acetate fraction of ADLE on UVB-induced COL1A1 and MMP-1 expression in HDF cells. After 100 mJ/cm² UVB irradiation, cells were treated with ADLE with or without its solvent fractions at 100 μg/mL for 24 h. (A) Protein expression levels of COL1A1, MMP-1 and AP-1 were measured according to the Western blot analysis and normalized to α-tubulin. (C) Extracellular MMP-1 production was measured using an ELISA kit. (B, D, E) The signal intensity was quantified using Image J software. CON: non-irradiated control, UVB: 100 mJ/cm² UVB-irradiated without sample. Values are presented as mean ± SD (n = 3–5), normalized to the percentage of CON. **p < 0.01, ***p < 0.001 versus CON. ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus UVB. CON: non-irradiated, UVB: 100 mJ/cm² UVB irradiated only.