Rosemary (Rosmarinus officinalis), a Mediterranean herb with a long history of traditional use, has long been associated with beneficial effects on memory, skin health, and antimicrobial activity. Modern scientific research is increasingly exploring these traditional claims. A study published in the International Journal of Molecular Sciences in April 2025 reported that a combination extract of rosemary and grapefruit (Nutroxsun, Nx) may help mitigate ultraviolet radiation (UVR)-induced photoaging by reducing oxidative stress, inflammation, and collagen degradation. This article summarizes the findings of that study and reviews the broader biological activities of rosemary and grapefruit. Both plants contain a variety of bioactive compounds—including polyphenols, diterpenes, flavonoids, and terpenoids—that may contribute to antioxidant, anti-inflammatory, and metabolic health benefits. While current evidence from in vitro models and animal studies is promising, further clinical research is required to fully confirm their potential roles in supporting skin health and overall well-being.
Rosemary and Grapefruit Extracts May Help Delay Skin Aging
The herb Rosmarinus officinalis, commonly known as rosemary, derives its English name “rosemary” from a phrase meaning “the rose of Mary,” referring to the Virgin Mary. It has been used for thousands of years. According to legend, rosemary flowers were originally pure white. During the flight to Egypt, when the Virgin Mary was carrying the infant Jesus, she laid her purple cloak over a rosemary bush, and the flowers were said to have turned the same color as her cloak. In addition to its distinctive fragrance, rosemary was also believed to possess powerful abilities such as enhancing memory, supporting skin health, and resisting bacteria.
In April 2025, a paper published in the journal International Journal of Molecular Sciences appeared to “validate” some of the properties mentioned in these legends. The study reported that a combination extract of rosemary and grapefruit (Nutroxsun, Nx) can alleviate photoaging by reducing oxidative stress, inflammation, and collagen degradation caused by ultraviolet radiation (UVR), thereby helping delay skin aging.
Photoaging is a process that accelerates the development of wrinkles, loss of skin elasticity, and excessive pigmentation. UVR is a key factor driving photoaging because it penetrates the skin and induces the production of reactive oxygen species (ROS), which play a central role in photodamage mechanisms. ROS can induce DNA damage and alter cellular signaling pathways, disrupting the skin’s antioxidant defense system and accelerating photoaging.
Fibroblasts produce elastin and collagen, which are critical for maintaining skin firmness and elasticity. Type I collagen accounts for approximately 80–90% of total skin collagen. Matrix metalloproteinases MMP-1 and MMP-3 are also present in human dermal fibroblasts and are capable of degrading collagen and elastin fibers. Experimental results showed that Nx significantly inhibited the UVR-induced increase in the secretion of MMP-1 and MMP-3, while enhancing elastin and type I collagen activity.
The researchers also evaluated the effects of Nx on ROS production and interleukin generation in UVR-induced keratinocytes. Compared with the UVB group, the groups treated with 0.01% Nx + UVB and 0.02% Nx + UVB showed significantly reduced production of ROS, IL-1α, IL-6, and IL-8, with a dose-dependent effect.
This study was based on a previous investigation published in 2014 titled Protective effects of citrus and rosemary extracts on UV-induced damage in skin cell model and human volunteers. That study found that a mixture of rosemary and grapefruit extracts can act synergistically to eliminate free radicals generated by solar radiation. After UVB irradiation, the survival rate of HaCaT cells was higher with the combined extract than with either extract alone. The primary active components responsible for these effects include rosemary polyphenols and diterpenes as well as flavonoids present in grapefruit.
Rosemary: A Plant Spice with Multiple Bioactive Properties
Rosemary originated in the Mediterranean region but is now cultivated worldwide due to its strong adaptability. Modern research indicates that rosemary contains numerous biologically active phytochemicals, particularly polyphenols. Natural rosemary extracts have demonstrated antibacterial, antioxidant, and anti-inflammatory properties.
Rosemary has shown notable clinical effects in improving mood, cognition, learning, memory, pain, and sleep. In addition, it may help support skin health, improve diabetes-related conditions, and exhibit antidepressant-like effects.
1) Mood Relief
A total of 49 volatile aroma compounds have been identified in rosemary. Terpenes (45.79%), ketones (17.79%), and alcohols (8.2%) are the most prominent aromatic components. Some studies have shown that after participants were exposed to rosemary aroma, both blood pressure and heart rate decreased significantly. In addition, scores on the Self-Rating Anxiety Scale (SAS) dropped by 11%, and anxiety symptoms improved in 78% of participants.
2) Improvement of Cognitive Impairment
Cognitive impairment significantly affects learning, memory, and the psychological well-being of pregnant women, and individuals with cognitive impairment may struggle to adapt to time and spatial orientation. Numerous experimental results suggest that rosmarinic acid can improve motor dysfunction, cognition, and spatial memory, while also enhancing sleep quality and psychological activity.
3) Support for Skin Health
Both endogenous and exogenous glycation stress and reactive oxygen species can lead to the accumulation of advanced glycation end products (AGEs), accelerating skin aging. Rosemary extracts and their active polyphenol rosmarinic acid possess anti-glycation and antioxidant properties, which may help block AGE formation and protein crosslinking, thereby supporting skin health and improving signs of skin aging.
4) Improvement of Diabetes
Rosemary has antioxidant properties and has been shown to significantly reduce malondialdehyde levels in diabetic rats while increasing glutathione and superoxide dismutase levels. Additionally, insulin and glucose levels improved significantly in diabetic rats treated with rosemary.
Grapefruit: A Nutrient-Rich Citrus Fruit
Grapefruit belongs to the citrus family Rutaceae and is a cultivated group related to citrus sour orange. The fruit has a slightly aromatic scent, a sweet-sour taste, and a distinctive flavor. Compared with other citrus fruits, grapefruit is rich in nutrients such as protein, vitamins, fiber, pectin, and folic acid. It also contains numerous bioactive compounds, including vitamin C, carotenoids, terpenoids, and flavonoids—primarily hesperidin and naringin—which provide multiple potential health benefits.
1) Support for Skin Health
The grapefruit-derived sesquiterpene compound Nootkatone (NK) can suppress UVB-induced photoaging and skin damage by regulating the NRF2-HO-1 and AhR-CYP1A1 signaling pathways in HaCaT cells. Grapefruit can also help repair skin inflammation caused by Staphylococcus aureus by reducing ROS production and inhibiting the upregulation of IL-1 and COX-2.
2) Prevention of Diabetes
Insulin resistance refers to the reduced physiological action of insulin in the body and is one of the major contributors to diabetes development. The bioactive compound naringin found in grapefruit can lower blood glucose and improve insulin tolerance. Some studies have shown that the glucose-lowering effect of clarified grapefruit juice is similar to that of the commonly used antidiabetic drug Metformin, and that insulin sensitivity improved in high-fat-fed mice that consumed grapefruit juice.
3) Weight Management
The prevalence of obesity has reached epidemic levels and requires multiple intervention strategies. Grapefruit extracts—particularly hesperidin—can inhibit pancreatic lipase and regulate weight gain and triglyceride elevation induced by saturated fats.
Grapefruit can be consumed fresh or processed into canned products and juice. It is also widely used as a flavoring ingredient in frozen desserts, baked foods, carbonated beverages, and alcoholic drinks. In addition, grapefruit is used as an aromatic component in cosmetics, detergents, and soaps.