Boosting summer sun protection and promoting skin repair

Boosting summer sun protection and promoting skin repair

Boosting summer sun protection and promoting skin repair with DU NORD SKIN CARE

A highlight of some of the secondary metabolites in Northern plant-based ingredients in DU NORD SKIN CARE in terms of their possible photoprotective actions. 



For many of us, the return of spring sunlight, and the promise of summer’s, brings immense joy, but also a more heightened concern about it less joyful aspects. Chronic exposure to the sun’s UV radiation is the greatest contributor to the visible signs of aging.

Climate change and depletion of stratospheric ozone may increase our risk for UV-induced skin damage. As the report from 2020 update from the UNEP Environmental Effects Assessment Panel notes: “In the Arctic, springtime episodes of stratospheric ozone depletion, identified first in the early 2010s, continue to occur. The last episode in the spring of 2020 led to the largest ozone loss measured to date and resulted in UV indices that were twice as high as typical at several Arctic locations.”*

About 7% of the radiation that reaches us is ultraviolet (90% of which is UVA, 10% UVB); the other 93% consists of visible and infrared radiation (IR).


Radiation penetration into skin


Although UVB makes up a small fraction of total UV radiation, it is the immediately more dangerous because it is the “sunburn radiation.” The risk due to UVB is related to heat intensity, which is why a sunscreen with high SPF (sun protection factor—a marker relevant only to protection against UVB) is especially recommended if we are outside during the mid-day hours. It is directly absorbed by DNA in keratinocytes, the skin cells found in the epidermis. Absorption leads to modification of the DNA strands that detrimentally alters their structure. The damage blocks replication and transcription of new DNA. The cells’ repair machinery replaces the damaged region with newly synthesized DNA, but as we age our cellular repair machinery itself becomes damaged, rendering it less effective.**

Notably, UVB cannot not penetrate glass. UVA can, however, and its intensity is fairly constant throughout the day; that is, UVA intensity is related to the number of daylight hours. UVA penetrates beyond the skin’s upper epidermal layers, deep into the epidermis and dermis. Longer wavelength UVA (UVA1, 340-400 nm) damages DNA indirectly via generation of reactive oxygen species (ROS). The shorter wavelengths (UV2, 320-340 nm) act indirectly through ROS generation and directly because it is also absorbed by DNA with consequent adverse modifications that need to be excised and repaired.

An important point to note: The extent of UV exposure is thus determined not just by the UV index but the length of time spent outdoors.  

This is why sunscreen products claiming “broad-spectrum” sun protection (that is, protection against both UVA and UVB) are considered superior to those just claiming a high SPF. An SPF >30 doesn’t offer significantly more protection: An SPF30 shields approximately 97% of UVB; >SPF50 about 98%, according to a recent article in the New York Times (20 May 2021), and no sunscreen offers 100% protection. Some of the issues around sunscreen use are that it requires a thick application and frequent reapplication and aquatic safety.  Quoting from one of the experts interviewed for the NYT article: The average adult needs about one ounce of sunscreen to cover all exposed skin. “We often say a shot glass of sunscreen for the whole body…but I tell my patients to fill the shot glass up to the brim and use even more if needed so you don’t miss any spots.” According to another NYT article (18 May 2021), no sunscreen has been proven safe for aquatic life, but there is some consensus that the least damaging to coral reefs may be non-nano zinc oxide formulations. Other ingredients these sunscreens contain may be problematic.

It seems it is not just UV that is harmful, but solar radiation in toto.

One interesting study suggests that the sun’s visible and IR radiation magnifies the degree of skin cell damage caused by UV radiation. The researchers exposed two types of skin cells obtained from human donors—epidermal keratinocytes and dermal fibroblasts—to solar radiation under conditions that were equivalent to spending one hour in noon sunlight in the Mediterranean, during the month of June. Further, they used filters to isolate the effects of UV only and then combinations of UV, visible and IR radiation. A key result was that whereas taking into account the effects of visible and IR did not significantly add to the damage in keratinocytes already caused by UV, this was not the case for fibroblasts. Allowing visible and IR radiation to pass unblocked along with the UV caused further damage to these cells than UV alone, and the effect was synergistic. The experiment was repeated in human cell lines of keratinocytes and fibroblasts with the same result. Other studies have shown that visible light and IR can induce ROS generation; both have been linked to hyperpigmentation disorders. UV sunscreens alone don’t protect against this damage, so products with robust antioxidants may be useful.

As discussed above and shown in the figure, UVB only reaches the upper layers of skin—the epidermis, but UVA, visible and infrared penetrate deep into the dermis—where the extracellular matrix (with the proteins elastin and collagen) gives the skin its structure. Frequently one will hear UVB referred to as the “sunburn radiation” and UVA as more significant for photoaging. Given the results above, it seems more appropriate just to say that chronic exposure to solar radiation, without sufficient protection, increases our risk for premature skin aging.   

In addition, there has been growing alarm about harmful effects to skin (and eyes) from exposure to artificial sources of high-energy visible light. This radiation—generally referred to as blue light because it lies in the 400 -500 nm region of the visible light spectrum—is emitted primarily from digital screens (cell phones, computers, tv, etc), LEDs and fluorescents. Artificial sources of light of these wavelengths, just like their solar equivalent, can penetrate to the dermal layers.

Although the skin's defence and repair mechanisms are complex and powerful, chronic low-grade exposure to the sun’s radiation can eventually lead to alteration of cellular homeostasis, irreversible DNA damage (which can lead to mutations and neoplasia); protein, connective tissue and cell-membrane degradation; and cell death.   

All this said, it must also be noted that UV, visible and IR radiation have also been used specifically to treat various skin conditions with significant positive benefit.  

The sensorial and visible effects on skin of UV radiation damage may include dry and rough texture, deep wrinkles, loss of elasticity, areas of hyperpigmentation and impaired wound healing.   


photo damage image



Northern Plant Phytochemicals: Potential to Provide Photoprotection for Human Skin?

Of course, plants are subject to the sun’s damaging rays as well and have evolved to protect themselves with molecules (secondary metabolites) that absorb radiation and dissipate the energy, act as antioxidants, and as anti-inflammatory, immunomodulatory and anti-tumorigenic agents. Their cellular machinery also processes and removes damaged material. These molecules are broadly multifunctional, as they also function to ward off herbivores and pathogens. Many belong to a class of organic compounds called polyphenols.  


Plant cytoprotective molecules that are found in Northern plants relevant to Du Nord Skin Care have been studied for their activity particularly in the context of UV radiation and photoprotection. Some are briefly reviewed below, along with two purified molecules caffeine and niacinamide, which are used in MOUNTAIN Gel Cream and BOREAL Emulsion, respectively.


One thing you will notice is that they all contain a ring structure of five or six carbons; this structure plays a role in their photoprotective properties. The 6-carbon ring with an OH (hydroxyl) group is a phenol. Phenolic acids contain one hydroxyl group; polyphenols, as the name indicates, have several. Many polyphenols are pigmented, and these give rise to the colours we see in Northern berries. They absorb UV radiation, as well as function as powerful antioxidants, neutralizing ROS, and they can reduce the extent of ROS formation.

Caffeine structure


 A number of animal studies have demonstrated that both consumption and topical application of caffeine had a protective effect against exposure to UV radiation. Caffeine is a strong antioxidant. Clinical studies have been conducted also, mostly with respect to consumption. One of the largest involved subjects enrolled in the Women’s Health Initiative Observational Study (93,676 participants). It showed that Caucasian women who regularly consumed caffeinated coffee had nearly an 11% lower incidence of non-melanoma skin cancer compared with non-consumers, and those who consumed six or more cups per day had an even lower risk—30%. (This result is not a recommendation to drink cups of coffee a day!)

Caffeic acid structure

Caffeic acid

This phenolic acid is not related to caffeine and is a ubiquitous phytochemical. Apples, bogbean and elderberries are just some examples of Northern plants that contain caffeic acid. It protects against UVA-induced photo damage.

Beta carotene structure 


Carotenoids are well established as photoprotective. Black currant, blueberry/bilberry, cloudberry, cranberry, raspberry and sea buckthorn are examples of Northern berries that contain carotenoids.

 Chlorogenic acid structure

Chlorogenic acid

Another phenolic acid, chlorogenic acid (it does not contain chlorine!) is found in edelweiss, apple, Arctic roseroot, bogbean, and elderberries for example. It has been shown to protect human dermal fibroblasts and keratinocytes cell lines exposed to UV radiation.

Ellagic acid

Ellagic acid

This phenolic acid has been shown to prevent UV-induced toxicity in a human epithelial cell line, human dermal fibroblasts and in mice. The researchers conducting this study also report that it prevented collagen destruction and inflammatory responses. So, in principle, ellagic acid may help to prevent wrinkling. A few examples of Northern plants that contain significant concentrations of ellagic acid are cloudberry, raspberry, cranberry, and sea buckthorn.



Epigallocatechin, catechins  

These belong to the proanthocyanidin family of polyphenols (see below). The “green tea molecule” much studied for its photo-protectivity is also found in cranberry, lingonberry and sea buckthorn. The red maple bark extract, among others used in DU NORD SKIN CARE, contains catechin.


Leontopodic acid 

Leontopodic acid

Leontopodic acid, found in edelweiss, has been shown to inhibit inflammatory responses induced by UVA/B radiation. Edelweiss has a long history of traditional use as an anti-inflammatory.

 mycosporine-like amino acids

Mycosporine-like amino acids

These small molecules are thought to have evolved specifically to protect marine species from UVA which penetrates the water column as deep as 47 metres, depending on the water turbidity. Shoreline seaweeds are particularly vulnerable to excessive UV exposure. The red alga Porphyra umibilicalis contains the MMAs, shinorine and porphyra-334, both of which absorb in the UVA region of the spectrum. They also have antioxidant activity.




Portulacanone A/Portulacanon D

These two molecules, found in purslane, were identified in a laboratory study of UVB-stressed keratinocytes to provide photoprotection in part by suppressing the breakdown of procollagen.




These are the molecules that give fruits and flowers their red-blue (pH-dependent) colours. Grape seed proanthocyanidin has been shown in laboratory studies to be photoprotective. Northern tree barks and Northern berries, apples and Arctic roseroot are considered important sources of these polyphenols for phytochemical-based photoprotection.  



Laboratory and animal studies have demonstrated that resveratrol in grape extracts protects against UVAB-induced toxicity. The more active biological isomer, trans-resveratrol shown above, is found in lingonberry and black spruce among other plants. The black spruce extract used in DU NORD SKIN CARE is particularly enriched in trans-resveratrol. The manufacturer reports that it contains >10 more resveratrol than some common sources of white and grape (skin and/or seed) extracts. (The cis-resveratrol isomer has the carbon link between the two rings in an arc (bent) formation).


This polyphenol, found in Arctic roseroot, has been shown to be photoprotective against UVB in human dermal fibroblasts, a human keratinocyte cell line and guinea pig skin.



This is a significant bioactive molecule in alpine rose leaves. Taxifolin has been shown in laboratory and animal studies to be protective against UVB radiation.

 Ursolic acid

Ursolic acid

In a recent study, ursolic acid (found in bilberry/blueberry, cranberry, apple, Labrador tea) was shown to inhibit ultraviolet B radiation-induced oxidative stress and proinflammatory response-mediated senescence in human skin dermal fibroblasts.

 Vitamins A, C, E


Vitamins A, C and E

Finally, vitamins A, C and E are found in many of the Northern plant extracts used in DU NORD SKIN CARE. They are all powerful antioxidants. Black currant, cloudberry, lingonberry, and sea buckthorn have high levels of vitamin C. The firming bogbean extract used in DU NORD SKIN CARE was shown in to preserve vitamin C in a manufacturer-led study. Vitamin E is a component of many plant oils, including those used in DU NORD SKIN CARE. The bilberry seed oil in particular is documented by the manufacturer as being a source of pro-retinol (Vitamin A) and has standardized levels of carotenoids.

DU NORD SKIN CARE plants table

Some of the more specialized plant-derived ingredients in DU NORD SKIN CARE products also have been shown in manufacturer-led laboratory and clinical studies to help protect against radiation damage specifically and repair components of skin. Just to mention some: the upcycled bilberry seed extract absorbs in the high-energy visible light region; the stem cell extract of lingonberry absorbs in the UVB and IR regions and has antioxidant activity. In addition to laboratory studies, this lingonberry extract was shown in two small manufacturer-led clinical studies to help prevent and repair oxidative damage to skin, respectively, as a result of sun exposure. The upcycled black spruce bark extract strongly absorbs in the UVB region, moderately in the higher frequency end of the UVA, and has antioxidant activity; the algae-derived silica has been shown in preliminary manufacturer-led in vitro studies to boost SPF. Clinical studies are underway. I await the results!

DU NORD SKIN CARE also uses raspberry and meadowfoam seed oils. Raspberry seed oil absorbs mostly in the UVB region, although one study suggests it may also help protect against UVA damage by scattering the radiation. A study on an extract of meadowfoam seeds suggest it may prevent UVB-induced damage, and this may extend to an oil extract. Sea buckthorn oil has also been shown in laboratory studies to protect skin proteins and lipids from UV damage.



DU NORD SKIN CARE products with possible solar protection


Although it is reasonable to conclude that the Northern plant-based extracts in DU NORD SKIN CARE contain the powerful bioactive molecules here reviewed, what are the exact concentrations, I do not know. I cannot make a true substantive claim that DU NORD SKIN CARE products will indeed help to protect against the harms of solar radiation. But the formulation for each has been specifically designed to provide for some degree of protection. ****


Nature + Science + Art DU NORD SKIN CARE

The take-home message: Take proper precaution when enjoying the outdoor sunshine! A long-standing recommendation to boost our protection against the damaging effects of solar radiation is to consume plenty of fruits and vegetables high in these bioactive molecules. In addition, of course, the general smarts: limiting exposure (especially between 10 am – 4 pm), wearing protective clothing and sunglasses, and using a broad-spectrum sunscreen properly. DU NORD SKIN CARE products may be useful as an underlying base before application of a product containing mineral- or chemical-based sunscreens with proven efficacy, and as after-sun care.


DU NORD SKIN CARE products in the summer sun!




* This report also notes the following estimates based on a health effects model: “The largest effects on incidence of skin cancer are estimated to occur in people born between 1960 and 1980 since these birth cohorts experienced the full period of stratospheric ozone depletion, and will also have received the largest cumulative lifetime dose of UV radiation. The model estimates that cohorts born in 2040 or later will not experience any excess incidence of skin cancer caused by the effects of ozone depletion.” (Neale et al, 2021, see references)


** Dr. Luigi Ferrucci, the scientific director of the National Institute on Aging (USA): “ … over millions of years we have developed mechanisms that allow us to repair [DNA damage}…And when we cannot repair it … we eliminate the DNA, and we create new DNA...The ratio between damage accumulation and compensatory mechanisms gives us the rate of aging...But this same accumulation also occurs in the molecules that take care of the damage, and so slowly and progressively, this compensation becomes less effective, more and more damage escapes from compensatory control, and, phenotypically, this manifests as aging.” Thuault, S. Reflections on aging research from within the National Institute on Aging. Nat Aging 1, 14–18 (2021). https://doi.org/10.1038/s43587-020-00009-z


***Topical caffeine has other benefits, as do all the other molecules discussed, but here I am considering effects in the context of UV radiation.


**** MARITIME Cleanser and STREAM Mist also contain some of the ingredients mentioned, but these products are not specifically formulated to enhance their photoprotective benefit.




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Image citations


  1. Alpine rose: By Martin Quandt ©2017 Martin Quandt.


  1. Anthocyanin: By NEUROtiker (talk) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4507478


  1. Bilberry By Anneli Salo - File:Vaccinium myrtillus Mustikka IMG 1100 C.JPG, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=74706669


  1. Caffeic acid: By Rhododendronbusch - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1452815


  1. Caffeine: By Vaccinationist - Own work, based on PubChem, Public Domain, https://commons.wikimedia.org/w/index.php?curid=54417143


  1. Carotenoid: By NEUROtiker - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2330317


  1. Catechin: By Edgar181 - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=7761803


  1. Chlorogenic acid: By Hbf878 - Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=74344002


  1. Edelweiss: By Martin Quandt ©2017 Martin Quandt.


  1. Ellagic acid: By Yikrazuul - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4189082


  1. Epidermis: By Normal_Epidermis_and_Dermis_with_Intradermal_Nevus_10x.JPG: KilbadCropped and labeled by Fama Clamosa (talk) and Mikael Häggström, respectively - Normal_Epidermis_and_Dermis_with_Intradermal_Nevus_10x.JPG (Public Domain)Scale at lower left was created from the an estimation of mean epidermal cell nuclei of 8.6 μm according to the following study:(2011). "Automated identification of epidermal keratinocytes in reflectance confocal microscopy". Journal of Biomedical Optics 16 (3): 030502. DOI:10.1117/1.3552639. ISSN 10833668., Public Domain, https://commons.wikimedia.org/w/index.php?curid=10759481


  1. Epidermis and UV: Modification by U. Snyder of above figure


  1. Epigallocatechin: Public Domain, https://commons.wikimedia.org/w/index.php?curid=1571704


  1. Leontopodic acid: PubChem https://pubchem.ncbi.nlm.nih.gov/compound/Leontopodic-acid#section=2D-Structure


  1. Mycosporine-like amino acids: Gacesa R, et al. Public domain.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214812/figure/fig2/


  1. Porphyra umbilicalis: By Annelise Chapman ©2017 Annelise Chapman.


  1. Purslane images from: Oh JH, et al. https://onlinelibrary.wiley.com/doi/abs/10.1111/jfbc.12814


  1. Proanthocyanadin: By Ed (Edgar181) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17693458


  1. Resveratrol: By Fvasconcellos 23:21, 9 December 2007 (UTC) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3206004


  1. Salidroside: By Meodipt at en.wikipedia - I drew this anyone can use it. Transferred from en.wikipedia to Commons by User:Quadell using CommonsHelper., Public Domain, https://commons.wikimedia.org/w/index.php?curid=16468977


  1. Taxifolin: By Ed (Edgar181) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17906801


  1. Ursolic acid: By Yikrazuul - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=8906909


  1. Vitamin A: By NEUROtiker (talk) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4351709


  1. Vitamin C: By Yikrazuul - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5886009


  1. Vitamin E: By Calvero. - Selfmade with ChemDraw., Public Domain, https://commons.wikimedia.org/w/index.php?curid=1556458


  1. All text and other photos, diagrams, graphics: By Ursula Snyder. ©2017 – 2021 Ursula Snyder, DU NORD SKIN CARE.