Squalene (12.5, 50, and 200 μM; 24 h) impacts MCF10A epithelial cells in a way that depends on dose: decreasing the amounts of intracellular ROS, avoiding H2O2-induced oxidative damage, and guarding against H2O2-induced oxidative damage DNA oxidative damage[2].

Reactive oxygen species and antimicrobial malondialdehyde levels in lipoproteins are decreased by squalene (0.25–1 g/kg; given chow; diet for 11 weeks), which also encourages changes in HDL-cholesterol and paraoxonase 1 [3].

Animal/Disease Models: Male mouse model (wild type, Apoa1 and Apoe deficient) [3]
Doses: 0.25 g/kg, 1 g/kg
Route of Administration: Feeding; Diet results for 11 consecutive weeks: HDL in mice Protein cholesterol and paraoxonase 1 were increased, and oxidative stress was diminished.

Absorption, Distribution and Excretion
Squalene is used in the oil phase of some emulsion vaccine adjuvants, but its metabolic process as a vaccine component after intramuscular injection in humans remains unclear. This study constructed a physiologically based pharmacokinetic (PBPK) model to simulate tissue distribution after intramuscular injection of squalene in water-in-oil (SQ/W) emulsion, to quantitatively assess the tissue distribution of squalene in humans after a single intramuscular injection. The PBPK model incorporated relevant physicochemical properties of squalene; estimation of the SQ/W emulsion lysis time course; anatomical and physiological parameters of the injection site and surrounding tissues; and local preferential lymphatic transport. The model predicted that the squalene would be cleared from the deltoid muscle within six days after a single intramuscular injection of the SQ/W emulsion. Most of the injected squalene would be distributed to draining lymph nodes and adipose tissue. The model indicated that squalene decayed slowly in the latter compartment, likely due to its partitioning into neutral lipids and lower biotransformation in that compartment. Parallel pharmacokinetic modeling of mouse muscle showed that the kinetics of the SQ/W emulsion were consistent with the immunokinetic time course of previously reported commercial squalene-containing adjuvants in this species. In summary, this study provides important pharmacokinetic predictions regarding the metabolism of squalene-containing emulsions in humans. These findings may contribute to understanding the immunokinetics of this type of novel vaccine adjuvant and may aid in future quantitative risk analyses incorporating mechanisms of action data. More than 60% of ingested squalene is absorbed in the small intestine; it then enters systemic circulation via the lymphatic system in the form of chylomicrons. In the blood, squalene is primarily carried by very low-density lipoproteins and distributed to various tissues throughout the body. Most squalene is distributed to the skin. Animal studies have shown that squalene is slowly absorbed through the skin, while both squalane and squalene have very low absorption rates in the gastrointestinal tract. Metabolism/Metabolites This review summarizes the oxidation process of squalene, a unique human compound produced by sebaceous glands. This chemical transformation has important effects at multiple levels. Squalene byproducts, primarily in the form of peroxides, can lead to acne formation, promote inflammatory acne, and potentially alter skin texture (wrinkles). This paper elucidates the experimental conditions for oxidative and/or photo-oxidative mechanisms, suggesting they may serve as biomarkers of the effects of air pollution on the skin. Ozone, long-wave UVA rays, and cigarette smoke have been identified as strong oxidants of squalene. This paper presents several in vitro, ex vivo, and in vivo experiments as examples to investigate ingredients or products that can enhance or counteract such chemical changes, which generally have adverse effects on various skin tissues. This study employed proton transfer reaction mass spectrometry (PTR-MS) for direct air analysis of volatile products generated from the reaction of ozone with human skin lipids. A series of small-scale in vitro and in vivo experiments were first conducted, followed by experiments on human subjects in a simulated office environment. The latter used actual ozone mixing ratios (approximately 15 ppb with human presence). Detected products included monofunctional and bifunctional compounds containing carbonyl, carboxyl, or α-hydroxy ketone groups. Three previously unreported dicarbonyl compounds were identified, and two previously unreported α-hydroxy ketones were preliminarily identified. The compounds detected in this study (excluding acetone) have been overlooked in previous indoor pollutant surveys, reflecting the limitations of current routine analytical methods used to monitor indoor air. The results are in perfect agreement with the Krich mechanism, which describes the reaction of ozone with squalene (the most abundant monounsaturated component in skin lipids) and several free or esterified forms of unsaturated fatty acids. Quantitative product analysis confirmed that squalene is a major ozone scavenger at the interface between indoor air and the human body envelope. The reaction of ozone with human skin lipids reduces the mixing ratio of ozone in indoor air but increases the mixing ratio of volatile products and may increase the concentration of low-volatility products on the skin surface. Some volatile products, particularly dicarbonyl compounds, may be respiratory irritants. Some low-volatility products may be skin irritants. Squalene is metabolized to cholesterol.

Toxicity Summary
Identification and Uses: Squalene is a liquid. It is typically derived from shark liver and sometimes from olive oil. It is used in traditional medicines, experimental drugs, and dietary supplements. Squalene is a component of some vaccine adjuvants, which are added to vaccines to enhance the immune response. For example, this is the case with MF59, an adjuvant added to the FLUAD influenza vaccine. Squalene itself is not an adjuvant, but emulsions of squalene with surfactants can indeed enhance the immune response. Squalene is also found in various foods and cosmetics. Human Exposure and Toxicity: Squalene is not highly irritating or sensitizing to human skin. Limited contact sensitization studies have shown that squalene is not a significant contact allergen or irritant. Since 1997, 22 million doses of the FLUAD influenza vaccine have been safely administered. Each dose contains approximately 10 mg of squalene. No serious adverse events have been reported associated with this vaccine; only some mild local reactions have been observed. Clinical studies of squalene-containing vaccines have been conducted in infants and young children without revealing any safety concerns. Squalene is considered one of several potential exposure factors contributing to chronic multisymptomatic disease (CMD) in Gulf War veterans, and it is believed to be present in anthrax vaccines. However, further studies have found no association between squalene antibody levels and CMD. Most adults, regardless of whether they have received a squalene-containing vaccine, possess anti-squalene antibodies. The genotoxicity of the vaccine adjuvant squalene has been assessed using human lymphocyte assays for chromosomal aberrations (CA), sister chromatid exchange (SCE), and micronucleus (MN) frequencies, as well as a comet assay. In all in vitro treatments, squalene did not affect the frequencies of CA and MN. A significant increase in sister chromatid exchange (SCE) was observed 24 hours after treatment at almost all concentrations. In all in vitro treatments, squalene did not significantly affect comet tail length (CTL) (except at 2500 μg/mL) or comet tail intensity (CTI). Therefore, squalene cannot be considered genotoxic to human lymphocytes. Animal studies: Acute animal toxicity of squalene was low across all routes. 100% squalene is non-irritating to rabbit skin and eyes. Dietary squalene promotes changes in high-density lipoprotein cholesterol and paraoxygenase 1 in mice, and reduces reactive oxygen species in lipoproteins and plasma malondialdehyde levels. Intraperitoneal injection of squalene emulsions at concentrations of 20% and 10% induced enhanced inflammatory responses, while a 5% concentration induced milder inflammatory responses. In rat lymphocyte genotoxicity assays, squalene significantly increased or decreased CTL and CTI at certain doses.

---

Interactions
This study aimed to identify endogenous lipid mediators of the metabolic and inflammatory responses of human keratinocytes to solar ultraviolet radiation. Physiologically relevant doses of simulated solar UVA+UVB were irradiated onto primary cultures of human skin surface lipids (SSL) or normal human epidermal keratinocytes (NHEK). The attenuation of photosensitizing lipid-soluble components α-tocopherol, squalene (Sq), and cholesterol in SSL was analyzed, and the photooxidation product of squalene (SqPx) was quantitatively isolated from irradiated SSL. Low-dose solar UVA+UVB induction of time-dependent inflammatory and metabolic responses was achieved when directly applied to NHEK cells. To mimic the effects of UVA+UVB, NHEK cells were exposed to intact or photooxidized SSL, Sq or SqPx, 4-hydroxy-2-nonenal (4-HNE), and the photooxidation product of tryptophan, 6-formylindolo[3,2-b]carbazole (FICZ). FICZ activated only the UV-specific metabolic response, namely the aryl hydrocarbon receptor (AhR) mechanism and the expression of its downstream CYP1A1/CYP1B1 genes; while 4-HNE mildly stimulated the expression of inflammatory UV markers IL-6, COX-2, and iNOS genes. In contrast, SqPx induced most of the UVA+UVB-specific metabolic and inflammatory responses via AhR, EGFR, and G protein-coupled arachidonic acid receptor (G2A). These results suggest that squalene (Sq) may be a major sensor of solar ultraviolet radiation in human subcutaneous adipose tissue (SSL), and its photooxidation products mediate/induce keratinocyte metabolic and inflammatory responses to UVA+UVB, which may be related to inflammation in sun-exposed oily skin. Reactive oxygen species (ROS) are closely associated with the pathogenesis of Parkinson's disease (PD); therefore, antioxidants have attracted much attention as a potential approach to prevent the disease. Squalene is a natural triterpenoid compound and an intermediate in cholesterol biosynthesis, known to possess ROS scavenging activity. Squalane is synthesized by complete hydrogenation of squalene and does not possess ROS scavenging activity. We investigated the effects of oral administration of squalene or squalane on a PD mouse model established by intraventricular injection of 6-hydroxydopamine (6-OHDA). Administration of squalene 7 days before and after a single injection of 6-hydroxydopamine (6-OHDA) prevented the decrease in striatal dopamine (DA) levels; however, administration of the same dose of squalane increased DA levels. Neither squalene nor squalane administration over 7 days altered the activities of catalase, glutathione peroxidase, or superoxide dismutase in the striatum. Squalane increased the level of thiobarbituric acid reactants (TBARS, a marker of lipid peroxidation) in the striatum. Both squalane and squalene increased the linoleic acid/linolenic acid ratio in the striatum. These results suggest that administration of squalene or squalane causes similar changes in the fatty acid composition of the striatum without affecting the activity of reactive oxygen species scavenging enzymes. However, squalane exacerbates oxidative damage in the striatum and aggravates the toxicity of 6-OHDA, while squalene prevents this damage. The effects of squalene or squalane treatment in this model suggest their potential use and risks in the treatment of Parkinson's disease. A mouse study has demonstrated that squalene provides radiation protection against lethal whole-body radiation. This study aimed to evaluate the protective effect of squalene against the genotoxicity of the chemotherapy drug doxorubicin (Dox) using two genotoxicity assays—the micronucleus assay and the comet assay. Mice in different groups were fed squalene at doses of 1 and 4 mmol/g body weight (100 or 400 μL of squalene oil) 4 hours before or 1 hour after Dox (20 mg/kg) treatment. Twenty-four hours after Dox treatment, the incidence of micronuclei in bone marrow erythrocytes was assessed, and induced DNA strand breaks in cardiac tissue were detected using the basic comet assay. As expected, doxorubicin (Dox) significantly induced the formation of micronuclei in polychromatic (immature) erythrocytes and total erythrocytes. In mice treated with squalene both before and after doxorubicin administration, the frequency of doxorubicin-induced micronucleated erythrocytes was significantly reduced. Squalene itself apparently did not induce the formation of micronuclei in bone marrow erythrocytes. Comet assays also showed that, compared with the control group, mice treated with doxorubicin exhibited significantly increased DNA damage, particularly single-strand breaks. Administration of squalene before and after doxorubicin treatment effectively reduced doxorubicin-induced DNA damage. Squalene itself does not induce any significant DNA damage. Post-treatment was more effective in preventing doxorubicin-induced DNA damage compared to doxorubicin pretreatment. Data suggest that the combined use of squalene and doxorubicin helps reduce adverse reactions of doxorubicin in cancer chemotherapy, such as the increased incidence of adverse mutagenic side effects.
For more complete data on squalene interactions (9 in total), please visit the HSDB record page.

---

Non-human toxicity values
Intravenous LD50 in mice: 1800 mg/kg
Oral LD50 in mice: 5 g/kg

[1]. SQUALENE: PHYSIOLOGICAL AND PHARMACOLOGICAL PROPERTIES. Eksp Klin Farmakol. 2015;78(6):30-6.

[2]. Squalene protects against oxidative DNA damage in MCF10A human mammary epithelial cells but not in MCF7 and MDA-MB-231 human breast cancer cells. Food Chem Toxicol. 2010 Apr;48(4):1092-100.

[3]. Dietary squalene increases high density lipoprotein-cholesterol and paraoxonase 1 and decreases oxidative stress in mice. PLoS One. 2014 Aug 12;9(8):e104224.

Trans-squalene is a clear, slightly yellow liquid with a faint odor. Its density is 0.858 g/cm³. Squalene is a triterpenoid compound composed of 2,6,10,15,19,23-hexamethyltetracosane, with double bonds at positions 2, 6, 10, 14, 18, and 22, all in an all-E configuration. It is a human metabolite, a plant metabolite, a Saccharomyces cerevisiae metabolite, and a mouse metabolite. Squalene was originally extracted from shark liver oil. It is a natural 30-carbon isoprene compound and an intermediate metabolite in cholesterol synthesis. It is not prone to lipid peroxidation and has skin-protective properties. Squalene is widely distributed in human tissues, typically bound to very low-density lipoproteins, and transported in serum. Squalene is being investigated as an adjuvant therapy for cancer.
Squalene has been reported to exist in red algae (Erythrophleum fordii), hybrid amaranth (Amaranthus hybridus), and other organisms with relevant data.
Squalene is a metabolite of Saccharomyces cerevisiae, produced by or present in the yeast.
It is a naturally occurring 30-carbon triterpenoid.
See also: olive oil (one of its components); shark liver oil (one of its components).
Mechanism of Action

Squalene is an isoprene compound with a structure similar to β-carotene and is an intermediate metabolite in cholesterol synthesis. Approximately 60% of dietary squalene is absorbed in the human body. It is typically bound to very low-density lipoprotein, transported in serum, and widely distributed in human tissues, with the highest concentration in the skin, where it is a major component of skin surface lipids. Squalene is not prone to peroxidation and appears to act as a quencher of singlet oxygen in the skin, protecting the skin surface from lipid peroxidation damage caused by ultraviolet radiation and other ionizing radiation. Squalene supplementation in mice significantly enhanced their cellular and nonspecific immune functions in a dose-dependent manner. Squalene may also act as a "scavenger" of highly lipophilic exogenous substances. Due to its nonpolar nature, it has a higher affinity for non-ionized drugs. In animal studies, dietary squalene supplementation lowered cholesterol and triglyceride levels. In humans, squalene may help enhance the efficacy of certain cholesterol-lowering drugs. Currently, the primary therapeutic use of squalene is as adjuvant therapy for various cancers. Although epidemiological, experimental, and animal evidence suggests its anticancer properties, no human trials have yet been conducted to verify the role of this nutrient in cancer treatment regimens.
Based on the previous discovery that coproporphyrin secreted by Propionibacterium acnes can produce singlet oxygen, we hypothesized that singlet oxygen generated under ultraviolet irradiation would promote the peroxidation of lipids on the skin surface. We found that under ultraviolet irradiation, coproporphyrin-derived singlet oxygen effectively oxidized squalene, and the rate constant of squalene peroxidation was ten times higher than that of other skin surface lipids tested. UVA was more effective than UVB in promoting this response. Furthermore, we found that topical application of squalene peroxide induced hyperpigmentation of the skin by increasing the release of prostaglandin E2 from guinea pig keratinocytes. These results suggest that singlet oxygen-induced squalene peroxide formation plays a key role in photoinduced skin damage.

---

Therapeutic Uses
Exploring Treatments: There is an association between cardiovascular disease and periodontal disease, but no cardiovascular treatments targeting periodontal disease have been tested. We investigated the effects of squalene, hydroxytyrosol, and coenzyme Q10 on gingival tissue in rabbits fed an atherosclerotic diet. Forty-eight rabbits were divided into six groups. The control group was fed a standard diet for 80 days. The remaining groups were fed an atherosclerotic diet for 50 days. Afterward, one group of rabbits was sacrificed, and the remaining rabbits were fed a standard diet or a diet supplemented with coenzyme Q10, squalene, or hydroxytyrosol for another 30 days. Compared with the control group, rabbits with atherosclerosis showed higher levels of gingival mucosal fibrosis and endothelial cell activation, and lower cell density (P<0.05). Hydroxytyrosol reduced endothelial cell activation (P<0.05), and squalene further reduced fibrosis (P<0.05). These results indicate that hydroxytyrosol and squalene (a natural product of extra virgin olive oil) can reverse gingival vascular changes induced by an atherosclerotic diet.
Experimental Treatment: Squalene has shown antiproliferative activity in animal cancer studies…Squalene may have some radioprotective effects…Animal experiments suggest that squalene may also have cholesterol-lowering effects…
Experimental Treatment: Squalene is being investigated as an adjuvant therapy for certain cancers. In animal models, it has been shown to effectively inhibit lung tumors. In animal models, squalene also showed chemopreventive effects against colon cancer.
Experimental Treatment: Squalene supplementation in mice enhanced immune function…
For more complete data on the therapeutic uses of squalene (8 items in total), please visit the HSDB record page.

---

Drug Warnings
Infants, children, pregnant women, and breastfeeding women should avoid taking squalene supplements.
Mild gastrointestinal symptoms, such as diarrhea, may occur when taking squalene supplements.
Squalene should not be confused with squalamine, a special steroid found in sharks with antibacterial properties.
Squalene is not intended to treat gastritis, joint pain, or inflammation, nor is it intended to improve lung function.

C30H50

410.7180

410.391

111-02-4

638072

Colorless to light yellow liquid

0.8±0.1 g/cm3

429.3±0.0 °C at 760 mmHg

−75 °C(lit.)

254.1±22.2 °C

0.0±0.5 mmHg at 25°C

1.492

13.09

0

0

15

30

578

0

C([H])([H])(/C(/C([H])([H])[H])=C(\[H])/C([H])([H])C([H])([H])/C(/[H])=C(\C([H])([H])[H])/C([H])([H])C([H])([H])/C(/[H])=C(\C([H])([H])[H])/C([H])([H])C([H])([H])/C(/[H])=C(\C([H])([H])[H])/C([H])([H])[H])C([H])([H])/C(/[H])=C(\C([H])([H])[H])/C([H])([H])C([H])([H])/C(/[H])=C(\C([H])([H])[H])/C([H])([H])[H]

YYGNTYWPHWGJRM-AAJYLUCBSA-N

InChI=1S/C30H50/c1-25(2)15-11-19-29(7)23-13-21-27(5)17-9-10-18-28(6)22-14-24-30(8)20-12-16-26(3)4/h15-18,23-24H,9-14,19-22H2,1-8H3/b27-17+,28-18+,29-23+,30-24+

(6E,10E,14E,18E)-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~16.67 mg/mL (~40.59 mM)

Solubility in Formulation 1: ≥ 1.67 mg/mL (4.07 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: 1.67 mg/mL (4.07 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 1.67 mg/mL (4.07 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

 (Please use freshly prepared in vivo formulations for optimal results.)