Use of Exotic Plant Oils for Skin Aging

Exotic plant oils are a prime example of topical skincare products retaining a deep and rich historical tradition of use across various regions and cultures. Their benefits are now being rediscovered and more firmly established through studies into their cutaneous effects. Many exotic oils are found to offer the dual benefit of skin hydration effects alongside being a source of antioxidants which help mitigate against the skin-aging processes.

Amid the plethora of emerging topical products for skin health and beauty, a particular segment exists which is rooted in a deep historical tradition, that of exotic plant oils. Although these oils seem to attain less attention as compared to more heavily marketed cosmeceuticals like retinol, peptides, and various antioxidants, there has been a growing interest in both research and incorporation of these agents into the topical beauty landscape. Our focus for this article will be to explain how topical oils have been used in aesthetics medicine. We will explore their use for reducing the appearance of the signs of skin aging, and as part of this, in fortifying the skin barrier and maximizing skin hydration.

Skin Aging

Rebuilding the Structures

One of the primary means by which topical cosmeceuticals function in countering the signs of skin aging is to limit the net loss of collagen, elastin, and glycosaminoglycans which make up the firmness and elasticity of the skin. Numerous exotic plant oils have been studied for their ability to positively impact these components. To best appreciate their mode of action, we will briefly review key elements of the skin-aging process. Signs of skin aging are influenced by intrinsic factors, including chronological and oxidative metabolism changes, and extrinsic factors, primarily owing to the effects of UV-light exposure from the sun.¹². A common denominator for both intrinsic and extrinsic skin aging is the increased production of reactive oxygen species (ROS) which, in turn, stimulate the production of transcription factor AP‑1 and nuclear factor kappa‑B (NF‑κB). These agents have a direct impact on skin aging through their influence over various structures in the skin. For example, transcription factor AP‑1 simultaneously activates collagen-degrading enzymes, such as matrix metalloproteinases (MMPs), while also suppressing factors leading to the synthesis of new collagen. A vicious cycle can ensue whereby NF‑κB further induces inflammation, augments ROS production, and thus, continues stimulation of AP‑1.² Additionally, UV radiation can deplete the ROS‑countering antioxidant network already present in skin while also negatively influence the proper metabolism of elastin.² Together, these changes lead to the common signs of skin aging, including skin thinning, wrinkle formation, loss of elasticity, dry skin and skin-barrier impairment, roughness, and pigmentary changes of age-spot formation and uneven skin tone.¹ We will highlight some of the exotic oils for their use in this context, including a description of research studies to this end.

Argan Oil

Native to Morocco and sourced from the seeds of Argania spinosa, argan oil retains a rich history of topical use for general skin health, hair health, and cosmetic benefits such as the reduction of facial pigmentation. It contains a high level of monounsaturated fatty acids, alongside various antioxidant sources including polyphenols (such as ferulic acid), tocopherols (vitamin E), and triterpenes.¹³⁴ Interest has surrounded the ability of argan oil to influence skin elasticity. In a 60-day, randomized, controlled trial of 60 postmenopausal women,⁴ 10 drops of argan oil (equating to approximately 240 mg) were applied to the left volar (inner) forearm each night. Instrument-based assessments of skin elasticity were obtained at the baseline as well as after 30 and 60 days. The research team measured parameters such as gross and net elasticity of skin as well as biological elasticity, which incorporates the ratio of immediate skin retraction to final distension. Compared to the control group, researchers found that use of argan oil for 60 days led to significant improvements in such elasticity measures. Specifically, those of increased gross elasticity (p < 0.001), net elasticity (p < 0.001), biological elasticity (p < 0.001), and reduced resonance running time (p = 0.022), a measure of shear-wave propagation whose decrease signifies an increase in skin elasticity.⁴ In explaining these observed effects, the authors speculated how the antioxidant content of argan oil likely mitigated against the skin-aging processes. As part of this, the elevated amount of vitamin E in argan oil was postulated as an agent that can down-regulate transforming growth factor beta (TGF‑β), and as such, augment fibroblasts in the skin to produce more collagen and elastin.⁴

Pomegranate Seed Oil

Much of the research involving topical pomegranate (Punica granatum) has explored benefits derived from its extracts. As a rich source of various antioxidants like anthocyanins, vitamin C, niacinamide, and polyphenols (like ellagic acid), it is not surprising how animal and human trials have shown benefit toward skin aging and hyperpigmentation. Such effects have been by way of reduced activation of NF‑κB, anti‑inflammatory effects, and reduced production of melanin via tyrosinase inhibition by ellagic acid.³ In a study using human keratinocytes obtained from a skin biopsy, pomegranate seed oil stimulated keratinocyte proliferation, leading to epidermal thickening, but showed no effect on dermal fibroblast functioning. The impact on keratinocytes, however, may help counter the epidermal thinning seen as part of skin aging. Interestingly, the same study found pomegranate peel extract to inhibit the production of MMP‑1, possibly allowing for an increase in net collagen production.⁵

Sea Buckthorn Oil

The oil from sea buckthorn (Hippophae rhamnoides), naturally found in Northern and Central Europe as well as parts of Asia, can be obtained from either its fruit pulp or seeds. Both sources are rich in various forms of vitamin E and other lipid-soluble vitamins as well as sterols, while the fruit pulp offers a higher concentration of carotenoids and a rarer omega‑7 lipid known as palmitoleic acid.⁶ The unique variety of constituents in sea buckthorn oil are believed to impart beneficial effects on the skin-aging process. For example, its content of omega‑3 and ‑6 fatty acids, alongside antioxidants like carotenoids and vitamin E, may help limit reactive oxygen species (ROS) production and lipid peroxidation, reduce inflammation, stimulate fibroblast proliferation, and, by consequence, collagen formation.⁶⁷ The presence of the omega‑7 palmitoleic acid is noted for its ability to promote epidermal regeneration as part of the wound-healing process, whose features overlap greatly with mechanisms relating to the slowing of the skin-aging process.⁶

Optimizing Hydration

Augmenting epidermal skin hydration is the second means by which cosmeceuticals reduce the appearance of fine lines, deeper wrinkles, and both skin dryness and roughness. As a complement to their antioxidant content, where exotic plant oils likely shine most is through their rich amount of fatty acids, which offer various methods of hydration and skin-barrier support.

Exotic Oils Rich in Linoleic Acid and Other Unsaturated Fatty Acids

Unsaturated fatty acids (UFAs) as a group work to improve skin structure, tone, and appearance. Improving local circulation and oxygen delivery to skin are among effects contributing to these benefits.⁶ Among UFAs, linoleic acid deserves a noted mention. It is directly incorporated into the lipid structure of the skin and stimulates keratinocyte differentiation, which then maintains production of skin-barrier components. The skin barrier is crucial in preventing water loss through the skin and maintaining adequate long-term skin hydration. Other common UFAs in exotic oils include alpha‑linolenic acid, gamma‑linolenic acid, and oleic acid.⁶⁸ Exotic Oils Retaining a Rich Content of Linoleic Acid :

• Sea buckthorn oil (Hippophae rhamnoides);⁶
• Argan oil (Argania spinosa);⁸⁹
• Kalahari melon seed oil (Citrullus lanatus);¹⁰
• Rosehip seed oil (Rosa canina, Rosa moschata);⁹¹¹
• Baobab oil (Adansonia digitata);¹²
• Safflower seed oil (Carthamus tinctorius);¹
• Avocado oil (Persea americana);¹
• Jojoba oil (Buxus chinensis, Simmondsia chinensis);¹³ and
• Pomegranate seed oil (Punica granatum).¹

Exotic Oils Rich in Saturated Fatty Acids

The presence of saturated fatty acids (SFAs) in exotic oils has been found to impart the characteristics of skin turgor, firmness, smoothening, and softening. A primary mechanism by which this occurs is through their acting as occlusive moisturizers, essentially creating a barrier over the top of the epidermis, helping lock moisture below.⁶ Examples of SFAs common in exotic oils include lauric acid, myristic acid, palmitic acid, and stearic acid.⁶ Exotic Oils Retaining a Rich Content of Saturated Fatty Acids:

• Sea buckthorn (Hippophae rhamnoides);⁶
• Baobab oil (Adansonia digitata);¹²
• Coconut oil (Cocos nucifera);¹
• Argan oil (Argania spinosa);¹⁴ and
• Avocado oil (Persea americana).¹⁴

Exotic Oils Rich in Sterols

Certain exotic oils uniquely feature an elevated content of sterols. The cosmetic benefits they can provide to the skin include incorporation and contribution to the sterol components of the skin barrier’s lipid matrix, thus increasing hydration; protection of the skin from external irritation; and improvement of skin firmness and elasticity.⁶ Examples of sterols present in exotic oils include beta‑sitosterol, campesterol, stigmasterol, citrostadienol, and avenasterol.⁶  Exotic Oils Retaining a Rich Content of Sterols:

• Sea buckthorn (Hippophae rhamnoides);⁶
• Rosehip seed oil (Rosa canina);¹¹
• Avocado oil (Persea americana);¹
• Moringa oil (Moringa oleifera);¹⁵ and
• Avocado oil (Persea americana).¹⁴

General Precautions

Exotic plant oils can be a beneficial addition to one’s skincare and beauty regimen. As with any topical agent, however, it is always recommended to take certain precautions. First, it is important to follow the manufacturer directions concerning proper usage of exotic oils. Some may be able to be applied directly onto skin, while others may be recommended instead to be first blended into other topical products ahead of skin applications. Second, prior to using any topical for the first time, including exotic oils, it is essential to have your patients perform a simple patch test to determine irritancy. An example of this would be to apply a small amount of the product over an area of skin on the inner forearm, to be left for 24 hours. The product should not be used if that area develops any signs of irritation during this time, including itching, reddening, or burning.

Exotic plant oils occupy a unique position within the topical skincare and beauty realm. This is especially beneficial given their content of both saturated and unsaturated fatty acids, which offer various benefits for skin conditioning and hydration support, alongside antioxidant compounds, which provide activity countering the skin-aging process. Further research will continue to explore and establish how the historical use of these oils can transfer into their role among current-day cosmeceuticals. Their simplicity and purity will satisfy the simplest to the most demanding needs!

Disclaimer: The information presented in this article is for general information purposes only and does not constitute medical advice. Please first review with your personal health-care provider what therapeutic approaches and products would be best for your case.