ProShield® Propolis and ProShield® Mustard: Sealing the Absorption "Leakage"

A photo of honey and honeycomb on the left and black mustard seeds on the right.

Absorption “leakage” is an unavoidable phenomenon associated with the interactions between UV filters and light. The ideal transmission spectrum of a sunscreen is shown on the left side of Figure 1, while the best possible transmission spectrum is shown on the right side. The difference between the ideal spectrum and the best possible spectrum is the area of absorption “leakage” on the best possible spectrum.

A step graph on the left shows transmission going from 0% to 100% at 400 nm. The same graph is on the right but with a shaded area at from around 380 nm to 400 nm labeled as 'Leakage.''
Figure 1: Ideal transmission spectrum (left) and best possible transmission spectrum (right) of a sunscreen.

Our ProShield® Aline products enable uniform sunscreen coverage while further preventing oxidative leakage by positioning potent antioxidants in the sunscreen layer. This combination achieves the highest sun protection performance (SPF) using minimum levels of UV filters; however, we knew we could do more.

To completely prevent all oxidative stresses and totally seal off the damages caused by the absorption “leakage,” we developed ProShield® Propolis and ProShield® Mustard. Based on Proscien’s patent pending extraction technology and its implementation on local French agricultural processes, both products contain powerful, antioxidative natural molecules that are concentrated and delivered in a formulation-friendly matrix.

ProShield® Propolis (propolis extract, Theobroma cacao (cocoa) seed butter) is derived from the extraction of local honeybee propolis. Propolis is generally known as “bee glue,” referring to the resinous substance accumulated by the bees; it is used to seal holes and cracks in the construction of the beehive. It also smooths the inner surface of the beehive, allowing the hive to maintain its internal temperature and prevent weather damage or predator invasions. Upon heating, propolis becomes soft and sticky, and it possesses a pleasant smell.

Propolis and its extracts have been used to treat various diseases due to its antiseptic, anti-inflammatory, antioxidant, antibacterial, antimycotic, antifungal, antiulcer, anticancer, and immunomodulatory properties. Naturally, propolis has also been used in dermatological products such as creams and ointments. Having a promotive action on collagen synthesis, propolis also displays positive collagen metabolism in wounds during the healing process, since it increases the collagen content of tissues.

Using Proscien’s proprietary technology, the extract from the local propolis is particularly rich in caffeic acid phenethyl ester (CAPE, Figure 2), a bioactive compound with proven antimicrobial, antioxidant, and anti-inflammatory properties. As such, when used in sunscreen formulation, ProShield® Propolis helps eliminate leaked oxidative stresses and improve sunscreen performance.

The chemical structure of caffeic acid phenethyl ester
Figure 2: Caffeic acid phenethyl ester (CAPE).

We studied the inhibitory effect of ProShield® Propolis against ultraviolet (UV) irradiation-induced matrix metalloproteinase 1 (MMP-1) expression and its underlying molecular mechanism. ProShield® Propolis treatment suppressed UV-induced MMP-1 levels in both human dermal fibroblasts (HDF) and foreskin fibroblasts (Hs68) (Figure 3). ProShield® Propolis also suppressed UV-induced acetyl-histone H3 (Lys9) and total lysine acetylation in HDF cells and attenuated UV-induced lysine acetylations in human skin tissues. The working mechanism is displayed by the dose-dependent attenuation ProShield® Propolis impacted on UV-induced histone acetyltransferase (HAT) activity in HDF (Figure 4).

A bar graph on the left showing Proshield Propolis suppressing MMP-1 levels in HDF, and a bar graph on the right showing Proshield Propolis suppressing MMP-1 levels in Hs68.
Figure 3: Effects of ProShield® Propolis on UV-induced MMP-1 concentration. HDF and Hs68 cells were pre-treated with ProShield® Propolis for 1 hour before being exposed to UV.
A bar graph showing increasing amounts of Proshield Propolis increasingly decreasing HAT activity.
Figure 4. Effect of ProShield® Propolis on HAT activity assessed using a colorimetric HAT assay kit. The kit uses active Nuclear Extract (NE) as a positive control.

ProShield® Mustard (Lactobecillus/Brassica nigra seed ferment extract and glycerin) is based on Proscien’s patent-pending extraction method using local mustard seed products. It is derived from the valorization of mustard seed byproducts generated by local mustard producers in the Drôme region of the south of France. These byproducts are an interesting and readily available renewable material that contains highly valuable sinapic acid (Figure 5) and its derivatives. Repurposing these byproducts can provide financial support to cultivate the crops in the region.

The chemical structure of sinapic acid.
Figure 5: Sinapic acid.

We studied the protective effects of ProShield® Mustard against the photoaging in human skin fibroblasts induced by UVB irradiation (30 mJ/cm2). Exposure to this amount of UVB irradiation reduced cell viability by approximately 33% compared to the non‐UVB irradiated control. ProShield® Mustard significantly reduced the UVB irradiation‐induced cytotoxicity (Figure 6). ProShield® Mustard also inhibited the release of MMP‐1 and reduced the expression of MMP‐1 mRNA in UVB‐irradiated Hs68 cells (Figure 7). Furthermore, ProShield® Mustard reduced UVB‐induced production of reactive oxygen species (ROS) in Hs68 cells, (Figure 8).

A bar graph showing Proshield Mustard increasing cell viability.
Figure 6. Effects of ProShield® Mustard on cell viability in UVB irradiated Hs68 cells. Hs68 cells were treated with 300 μM ProShield® Mustard for 24 hours. The cells exposed to UVB light (30 mJ/cm2) were cultured with 300 μM ProShield® Mustard for a further 24 hours.
A bar graph on the left showing Proshield Mustard suppressing MMP-1 levels in Hs68, and a bar graph on the right showing Proshield Mustard suppressing MMP-1 mRNA expression levels in Hs68.
Figure 7: Effects of ProShield® Mustard on UVB‐induced MMP‐1 secretion and mRNA expression in Hs68 cells. Hs68 cells were pretreated with ProShield® Mustard (300 μM) for 24 hours. The cells exposed to UVB light (30 mJ/cm2) were cultured with ProShield® Mustard (300 μM) for a further 24 hours. MMP‐1 secretion was determined in the cell culture medium using an ELISA kit. MMP‐1 mRNA expression levels were determined in cell lysates by quantitative real‐time polymerase chain reaction (qRT‐PCR).
A bar graph showing Proshield Mustard decreasing DCF fluorescence in Hs68, which corresponds to decreasing ROS production in Hs68.
Figure 8: Effects of ProShield® Mustard on UVB‐induced ROS production in Hs68 cells. Hs68 cells were pretreated with ProShield® Mustard (300 μM) for 24 hours. The cells exposed to UVB light (30 mJ/cm2) were cultured with ProShield® Mustard for a further 24 hours. Cellular ROS production was measured by fluorescence analysis using 2′,7′‐dichlorofluorescein diacetate (DCF).