Effects of Sapindus mukorossi Seed Oil on Skin Wound Healing: In Vivo and in Vitro Testing

Abstract

Sapindus mukorossi seed oil is commonly used as a source for biodiesel fuel. Its phytochemical composition is similar to the extracted oil from Sapindus trifoliatus seeds, which exhibit beneficial effects for skin wound healing. Since S. mukorossi seed shows no cyanogenic property, it could be a potential candidate for the treatment of skin wounds. Thus, we evaluated the effectiveness of S. mukorossi seed oil in the treatment of skin wounds. We characterized and quantified the fatty acids and unsaponifiable fractions (including β-sitosterol and δ-tocopherol) contained in S. mukorossi seed-extracted oil by GC-MS and HPLC, respectively. Cell proliferation and migratory ability were evaluated by cell viability and scratch experiments using CCD-966SK cells treated with S. mukorossi oil. The anti-inflammatory effects of the oil were evaluated by measuring the nitric oxide (NO) production in lipopolysaccharide-treated RAW 264.7 cells. Antimicrobial activity tests were performed with Propionibacterium acnes, Staphylococcus aureus, and Candida albicans using a modified Japanese Industrial Standard procedure. Uniform artificial wounds were created on the dorsum of rats. The wounds were treated with a carboxymethyl cellulose (CMC)/hyaluronic acid (HA)/sodium alginate (SA) hydrogel for releasing the S. mukorossi seed oil. The wound sizes were measured photographically for 12 days and were compared to wounds covered with analogous membranes containing a saline solution. Our results showed that the S. mukorossi seed oil used in this study contains abundant monounsaturated fatty acids, β-sitosterol, and δ-tocopherol. In the in vitro tests, S. mukorossi seed oil prompted cell proliferation and migration capability. Additionally, the oil had significant anti-inflammatory and anti-microbial activities. In the in vivo animal experiments, S. mukorossi seed oil-treated wounds revealed acceleration of sequential skin wound healing events after two days of healing. The size of oil-treated wound decreased to half the size of the untreated control after eight days of healing. The results suggest that S. mukorossi seed oil could be a potential source for promoting skin wound healing.

Keywords: Sapindus mukorossi; anti-inflammatory; wound healing; β-sitosterol.

Figure 1

Pictures of the intact seed, seed shell and the kernel of the Sapindus mukorossi seed.

Figure 2

(a) Total ion chromatograms of S. mukorossi seed oil tested in this study. (b) δ-tocopherol and (c) β-sitosterol fractions from high-pressure liquid chromatography. # and * indicated the detected peaks of δ-tocopherol and β-sitosterol, respectively.

Figure 3

Nitric oxide (NO) release from the lipopolysaccharide (LPS)-treated RAW 264.7 cells decreased when the cells were pretreated with S. mukorossi seed oil. Data are from four independent experiments. The mean value of each group was normalized with LPS-only sample.

Figure 4

S. mukorossi seed oil significantly increased the viability of CCD-966SK cells by day 2. Data are presented as the mean ± SD. ** p < 0.01.

Figure 5

The control CCD-966SK cultured with S. mukorossi seed oil free medium at 0, 6, 12, and 24 h (a–d). S. mukorossi seed oil exhibits obvious effect on migration at 0, 6, 12, and 24 h (e–h) after incubation. The leading cells at the wound edge oriented toward the wound area 6 h after the scratch trauma was inflicted (black arrows).

Figure 6

The percentage of scratch-width closure measured by quantifying the images of the scratch assay at 0, 6, 12, and 24 h after incubation. Data are from four independent experiments. The mean value of each group was normalized with LPS-only sample.

Figure 7

Photomicrographs of the wounds in rats after topical treatment with and without S. mukorossi seed oil on days 0, 2, 4, 6, 8, 10, and 12.

Figure 8

Quantification of the wound size in the rats treated with and without S. mukorossi seed oil. Data are presented as the mean ± SD. * p < 0.05.