Rosemary, Part 2

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Rosemary plant

Rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) has been a common ingredient in cosmetic and cosmeceutical products for the last few decades. Used as a spice in various, particularly Mediterranean, cuisines and in traditional medicine for hundreds of years, this aromatic shrub has been the focus of substantial research this century to clarify its roles in skin care. It is used broadly in cosmetic formulations, particularly to preserve the product, and acts as a skin conditioner and fragrance in safe concentrations.¹ Rosemary essential oil is also a popular choice frequently used in aromatherapy.^2,3 This column focuses on recent promising results supporting the antioxidant and anti-photoaging activities, especially, of rosemary.

UV Protection and Rosemary in Combination

A 2021 study in mice authored by Auh and Madhavan showed that a mixture of marigold and rosemary extracts yielded anti-photoaging effects, with the botanical formula suppressing UV-induced damage.⁴

Seven years earlier, Pérez-Sánchez et al. combined rosemary and citrus extracts and found that they exerted protective effects against UV damage in human HaCaT keratinocytes as well as human volunteers after oral consumption. Significant increases in minimal erythema dose (MED) were seen in participants, with daily intake of 250 mg of botanical combination, at 8 weeks (34%) and 12 weeks (56%). The investigators attributed the photoprotective effects of the formula to rosemary polyphenols and diterpenes as well as citrus flavonoids.⁵

Evaluation of a human skin cell model by Sánchez-Marzo et al. in 2020 revealed that rosemary diterpenes were instrumental in an herbal extract that combined citrus, olive, and rosemary in conferring genoprotection against UV-induced DNA damage. The authors note that human trials are needed to overcome the limitations of the cellular model in ascertaining whether the tested herbal formulations can yield oral and/or topical photoprotection.⁶

Anti-Photoaging and Anti-Pollution

In 2022, Ibrahim et al. assessed a hexane extract of rosemary leaves for anti-photoaging activity. Their evaluation showed an abundance of triterpenoids, monoterpenoids, and phenolic diterpenes in rosemary, with in vitro assays verifying the anti-aging, antioxidant, and wound healing functions of the extract. Further, topical rosemary hexane extract–loaded lipid nanocapsules protected rat skin from UV radiation, as epidermal and dermal histological parameters improved, antioxidant biochemical balance was restored, and inflammatory markers and wrinkling were diminished. The researchers concluded that the use of rosemary hexane extract represents a safe, efficient, and cost-effective way to deliver anti-aging, photoprotective functions to cosmeceutical formulations.⁷

In March 2021, Nobile et al. published a report on their randomized, double-blind, placebo-controlled parallel group study to investigate the efficacy of a marketed polyphenol-enriched dietary supplement (Zeropollution, which contains four standardized herbal extracts: Olea europaea leaf, Lippia citriodora, S. rosmarinus, and Sophora japonica) in diminishing pollution-induced oxidative stress and in improving skin aging in 100 White and Asian women who were outdoor workers living in a polluted environment (Milan, Italy). Statistically significant improvements in reducing wrinkle depth and hyperpigmentation, enhancing elasticity and firmness, as well as promoting skin moisturization and diminishing transepidermal water loss were noted as early as 2 weeks after product consumption began, with inter-group and intra-group analysis verifying that all skin parameters were ameliorated in Asian and White subjects.⁸

Previously, Nobile et al. conducted a randomized, parallel-group study on 90 subjects to evaluate the photoprotective effects of a combination of rosemary and grapefruit (Citrus paradisi) extracts (Nutroxsun). The investigators also performed a pilot, randomized crossover study on five participants. Both studies included only females with Fitzpatrick skin phototypes I-III who manifested mild to moderate chronological aging or photoaging. Within as little as 2 weeks, treated individuals exhibited reductions in UVA- and UVB-induced skin changes. Skin elasticity improved in this group, with wrinkles diminishing along with skin redness and lipoperoxides. The investigators concluded that the oral blend of rosemary and grapefruit consumed long term merits consideration as an adjuvant approach to preventing the deleterious effects of solar exposure.⁹

In 2021, Hoskin et al. used ex vivo human biopsies exposed to diesel engine exhaust to study the impact of spray-dried algae-rosemary particles against pollution-induced damage. The spirulina-rosemary gel that was developed lowered levels of 4-hydroxynonenal protein adducts (4HNE-PA) as well as matrix metalloproteinase-9 (MMP-9) and reduced the loss of filaggrin. The researchers concluded that their topically applied spirulina-rosemary gel was effective in mitigating or preventing skin aging and cutaneous damage caused by diesel air pollution.¹⁰