# Green Extraction of Valuable Compounds from Rubber Seed Trees: A Path to Sustainability
## 6 Valuable Compounds in Rubber Seeds
### Squalene  
Squalene is a remarkable natural hydrocarbon found in various sources, including rubber seed oil. The study by [PERSON] et al. [56] revealed a significant finding that when the extraction conditions by supercritical carbon dioxide are set at 20 MPa and 60 \({}^{\circ}\)C, squalene constitutes a remarkable 78% of the oil composition. Its unique chemical structure and properties make it a versatile compound with applications spanning different industries, from cosmetics to pharmaceuticals. Squalene has earned recognition in the cosmetics industry for its exceptional moisturizing properties [57]. It is highly compatible with human skin due to its structural similarity to the skin's natural lipids, specifically sebum. This compatibility makes squalene an effective emolient and skin conditioner. When applied topically, squalene helps hydrate and nourish the skin, sealing in moisture and preventing water loss. This not only enhances skin hydration, but also improves its softness and elasticity. These properties make squalene a valuable ingredient in various skincare products, including moisturizers, serums, creams, and lotions [58]. Squalene's ability to penetrate the skin's barrier allows it the ability to deliver other beneficial compounds, such as vitamins and antioxidants, deeper into the skin, maximizing its effectiveness. This makes it an essential component in many anti-ageing and repairing skincare formulations.  
Squalene also has a crucial role in vaccine development as an adjuvant studied by [PERSON] et al. [59]. Adjuvants are added to vaccines to enhance the body's immune response to the target antigen (e.g., a virus or bacteria). Squalene's immunological properties make it an ideal candidate for vaccine adjuvants [60]. When introduced into a vaccine formulation, squalene stimulates a more potent and more effective immune response. It achieves this by increasing the persistence of the antigen at the injection site, recruiting immune cells, and promoting the production of antibodies. Squalene-based adjuvants have been utilized in influenza vaccines and have shown promise in enhancing the body's defense against viral infections described by [PERSON] et al. [61]. They are particularly beneficial in vaccines for vulnerable populations, such as the elderly, where a robust immune response is critical. Importantly, squalene-based adjuvants have demonstrated a high level of safety and efficacy in vaccine formulations, contributing to developing protective and well-tolerated vaccines.  
In conclusion, squalene, a natural hydrocarbon in rubber seed oil, exhibits diverse and valuable applications. In the cosmetics industry, it is a potent moisturizing agent and skin conditioner, enhancing skin hydration and promoting health and appearance. In the realm of vaccines, squalene is an adjuvant, bolstering the immune response to antigens and contributing to the development of effective and safe vaccines. This versatility underscores the importance of squalene as a natural resource with many applications, from skincare to public health.