The benefits of calendula for the skin.

Theinflammation is triggered by numerous pathophysiological conditions in response to an infection or tissue injury. In the early stages of this process, the first line of defence is provided by macrophages which, in the presence of a stimulus, produce several pro-inflammatory mediators, including nitric oxide, cytokines, and prostaglandins. Under normal conditions, the release of these molecules is of paramount importance, manifesting severely, rapidly, and only for a short period until the resolution of harmful stimuli. However, abnormal production of these pro-inflammatory mediators over a long period can evolve into chronic diseases related to inflammation.

The Calendula officinalis L. is often prescribed for its anti-inflammatory potential, documented in numerous experimental and clinical studies. The presence of terpenoids (faradiol, lupeol, faradiol monoester, bisabolol, β-amyrin) and flavonoids (quercetin, isorhamnetin, kaempferol) in marigold would confer this activity with a dose-dependent effect. For instance, one study revealed that the reduction in inflammation observed was greater the higher the concentration of faradiol monoester that the botanical preparations contained. Another study also showed that a lipophilic extract of calendula flowers is capable of reducing oedema due to the action of faradiol esters.

It has been suggested that calendula extract works by inhibiting pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IFN-γ), cyclooxygenase-2 (COX-2) and the synthesis of prostaglandins. Calendula, through the action of certain bioactive constituents, would also cause a decrease in the level of nitric oxide (NO), a pro-inflammatory mediator produced by macrophages associated with several conditions (inflammatory skin diseases, hyper-proliferative diseases, autoimmune diseases and skin cancer). Therefore, the extract of calendula flowers can thus be used in topical formulations for inflamed and injured skin to soothe acute and chronic inflammations caused by skin conditions, such as rosacea, allergic contact dermatitis, theeczema, sunburn or nappy rash, as a complementary skin care.

Thanks to its content of flavonoids, polyphenols, and carotenoids, calendula is believed to be capable of protecting the skin from oxidative stress, a general term that describes the damage that occurs when the skin is exposed to free radicals. Without intervention, these can alter cellular DNA, which ultimately damages structural compounds such as collagen and elastin, and causes lipid peroxidation.

Several studies have shown that calendula protects the skin from oxidative damage and reduces the symptoms of skin ageing. The results indicate that calendula flower extract has proven capable of trapping superoxide radicals and hydroxyls, inhibiting lipid peroxidation and increasing the levels of catalase, glutathione, superoxide dismutase and ascorbic acid, limiting the effects they can have on the skin. It thus helps to limit the appearance of signs of skin ageing.

It has been reported that calendula may be effective in the healing of wounds and skin ulcers. This healing property of calendula can be attributed to its pro-angiogenic, fibroplastic and keratoplastic effects. Thus, calendula could help to prevent wound complications as a complementary treatment.

An animal study has demonstrated that calendula has a positive effect on angiogenesis, characterised by the induction of neovascularisation, which promotes the diffusion of necessary nutrients and oxygen for faster healing (increase in fibroblast metabolism and production of the extracellular matrix).

Similarly, calendula flowers, rich in flavonoids, would activate the PI3K metabolic pathways in fibroblasts and the NF-kB pathway in keratinocytes, thereby stimulating their proliferation and migration to increase the production of granulation tissue and accelerate the regeneration of damaged skin tissue.

Phenolic compounds, such as flavonoids and phenolic acids, along with saponins, are believed to give calendula bactericidal properties against both Gram-positive and Gram-negative bacteria, as well as antifungal properties. It is thought to have the ability to inhibit the growth in vitro of Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Calendula is also believed to have potential fungicidal effects against various isolated yeast strains (Candida albicans, Candida parapsilosis, Candida tropicalis, etc.). As a result, this property of calendula could help prevent certain skin infections such as acne. However, further studies are needed for a full understanding.

The UV rays from the sun can wreak havoc on the skin, potentially leading to premature signs of ageing and even skin cancers. Studies have been undertaken to investigate the sun protection activity of the essential oil of Calendula officinalis. According to the studies, calendula essential oil would have a sun protection factor (SPF) in vitro between 8 and 14. These results would suggest that calendula may have a photoprotective effect or increase the additional value of a sun protection formula. However, calendula has a low SPF value, not providing sufficient sun protection when used alone. Further experiments are needed to consolidate these initial data and determine the types of phytoconstituents responsible for this property. The application of a sunscreen containing UV filters remains the most effective approach to prevent photoaging, sunburn, wrinkles, age spots, immunosuppression and other skin damage.

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