Effects of plant sterols derived from Aloe vera gel on human dermal fibroblasts in vitro and on skin condition in Japanese women

Abstract

Background: Aloe is known for its topical use for treating wounds and burns. Many previous studies reported the healing effects of Aloe vera. However, there are few clinical studies on the effect of orally administered A. vera gel on the skin. Aloe sterols are a type of plant sterols that have the capability to regulate the metabolism of glucose and lipids. In a recent study, we confirmed that ingested Aloe sterols reached the peripheral tissues through the bloodstream. However, their influence on dermal fibroblasts has not been investigated.

Methods: First, we investigated the capability of Aloe sterols (cycloartenol and lophenol) to stimulate human dermal fibroblasts in vitro. Then, we investigated the effect of intake of Aloe vera gel powder (AVGP) containing 40 μg Aloe sterols on the skin conditions in Japanese women with dry skin in a randomized, double-blind, placebo-controlled trial.

Results: After cocultivation with Aloe sterols, the production of collagen and hyaluronic acid increased by approximately two-fold and 1.5-fold, and gene expression levels of these enzymes responsible for their synthesis were also observed in human dermal fibroblasts. An increase in arm skin hydration was observed at 8 weeks in the AVGP group, whereas a slight decrease in arm skin hydration was noted in the placebo group. However, there was no statistical difference between AVGP and placebo groups in skin moisture. In subgroup analysis, the change in the mean wrinkle depth was significantly lower in the AVGP group than in the control group. In addition, percent body fat after 8 weeks was significantly lower in the AVGP group. No AVGP intake-dependent harmful phenomenon was observed during the intake period.

Conclusion: The present study confirms that daily oral Aloe sterol-containing AVGP significantly reduced facial wrinkles in women aged ≥40 years, and Aloe sterols stimulate collagen and hyaluronic acid production by human dermal fibroblasts.

Keywords: aloe sterol; collagen; wrinkle.

Figure 1

Effects of Aloe sterols on (A) collagen and (B) HA production in human dermal fibroblasts. Cells were incubated for 48 hours in the absence or presence of 0.02–2 μM Cyc and Lop. The collagen and HA contents of the culture supernatant were determined with a soluble collagen assay and an HA ELISA assay kit. Cell viability was assessed by WST-8 (C). Notes: The data are expressed as the mean ± SD (n=3). *P<0.05 and **P<0.001 vs control (0 μM). Abbreviations: HA, hyaluronic acid; Con, control; Cyc, cycloartenol; Lop, lophenol; ELISA, enzyme-linked immunosorbant assay; SD, standard deviation.

Figure 2

Effects of Aloe sterols on the gene expression of enzymes responsible for the synthesis of collagen (COL1A1 and COL3A1) and HA (HAS2 and HAS3) in human dermal fibroblasts. Notes: Cells were incubated for 6 hours in the absence or presence of 0.02–2 μM and 0.02–2 μM Cyc and lophenol (Lop), and changes in gene expression relative to control (0 μM) were determined by qRT-PCR. The data are expressed as mean ± SD (n=3). *P<0.05 and **P<0.001 vs control. Abbreviations: Con, control; Cyc, cycloartenol; Lop, lophenol; qRT-PCR, real-time reverse transcription polymerase chain reaction; SD, standard deviation.

Figure 3

Effects of oral AVGP therapy on the facial wrinkles of participants with dry skin aged ≥40 years. Notes: Participants ingested placebo or AVGP tablets containing Aloe sterols for 8 weeks, and measurements were taken after 0 week, 4 weeks, and 8 weeks of therapy. (A) Maximal width of the largest wrinkle (mean ± SEM). (B) Mean wrinkle depth (mean ± SD). •, placebo group, n=12; ○, AVGP group, n=14. *P=0.035 vs placebo. Abbreviations: AVGP, Aloe vera gel powder; SEM, standard error of the mean; SD, standard deviation.

Figure 4

Effects of oral AVGP therapy facial skin hydration. Notes: Participants ingested placebo or AVGP tablets containing Aloe sterols for 8 weeks, and measurements were taken after 0 week and 8 weeks. Silicone skin replicas of the left crow’s feet were analyzed with a corneometer to determine the skin hydration level. The images present typical replicas for two subjects of each group. Abbreviation: AVGP, Aloe vera gel powder.