COSMETICS & PERSONAL CARE can suffer from xerosis or dry skin . Conversely , when it exceeds 1.5 mg / 10 cm 2 , it is considered excessive and results in seborrhea or oily skin . 6 , 7 Differences in sebum secretion at different stages of life are associated with concomitant changes in endogenous androgen production . While the number of sebaceous glands remains the same during life , sebum secretion rates are highest in 15 to 35-year-olds and decline continuously throughout the adult age range . 8
At any age range , the mean sebum values in men exceed those of women . African American women secrete larger amounts of sebum than Asian American and Caucasian American women . 9
A plant-based approach
In the course of our research into plant-based actives for personal care products , a novel ingredient called Epispot ** was developed . This is derived from Epilobium angustifolium ( pictured ), a perennial herb of the Onagraceae family . The plant has a rich history and has been valued for a variety of purposes , including medicinal uses .
Epilobium angustifolium , also known as fireweed or willow herb , is a glabrous-stemmed plant that can grow from 20 to 200 cm tall . Seed set is generally very high and seeds remain viable for about 18 months . It thrives in temperate regions of the Northern Hemisphere and typically flowers from July to September . A sunny environment and welldrained , moist soil create the best growing conditions . 9
During the Second World War , fireweed gained prominence in Europe , particularly in the UK , where its rapid growth on bombsites earned it the nicknames ‘ bombweed ’ and ‘ phoenix plant ’. 10 Its resilience and the speed with which it colonised these landscapes served as a symbol of nature ’ s resilience and recovery after the devastation of war , much like the mythical phoenix that rises from its ashes .
Epilobium angustifolium is better known as fireweed or the phoenix plant
Sebaceous lipid balance
Oily skin occurs when oversized sebaceous glands produce excessive amounts of sebum , giving the skin a shiny appearance that is often associated with enlarged visible pores and sometimes with blemishes and pimples . Androgen hormones and growth factors , which are particularly prevalent during puberty , play an important role in the development of these skin conditions . 4
The aim of our study was to evaluate the efficacy of Epispot in regulating the proliferation rate and lipid synthesis in human sebocytes when stimulated with human serum ( HS ) containing androgen and growth factors . Tests were carried out in vitro and in vivo on sebocytes from different ethnic backgrounds .
Materials & methods
Primary sebocytes derived from normal human donors were initially cultured at a density of 25,00 cells / cm 2 in a standard growth medium , Dulbecco ’ s Modified Eagle ’ s Medium , ( DMEM / HAM F12 ) supplemented with 10 % foetal calf serum ( FCS ). Cultures were maintained for a period of four to five days at 37 ° C in a 5 %
CO 2 environment . This growth medium was then replaced with a standard medium containing 1 % HS , which was either supplemented with extracts of Epilobium angustifolium at concentrations of 0.017 % or 0.034 %, or left untreated as a control . The cells were then incubated for a further five days under the same conditions .
Cell numbers were determined by DNA staining and the resulting fluorescence intensity was measured at 465 nm ( excitation at 356 nm ). Results were expressed as the mean percentage of fluorescence ± standard deviation ( n = 3 ), relative to the HS-stimulated condition , which was standardised to 100 %. Statistical analysis was performed using the Student ’ s t-test , with a predefined significance threshold of 5 % ( p < 0.05 ). The quantity of cellular lipids was determined with Nile red reagent . We used an excitation light at 810 nm ( Femtosecond laser ) and emission fluorescence between 590-654 nm . The fluorescence was recorded at 625 nm ( excitation at 520 nm ). The results were expressed as the mean percentage of fluorescence ± SD ( n = 3 ) compared to HS-stimulated condition standardised to 100 %. The statistical analysis was done using the Student ’ s t-test , with a threshold of significance set at 5 % ( p < 0.05 ).
For each condition and each stack on the Nile Red channel , 3D segmentation was realised to isolate the lipid droplets . The lipid droplets were detected , and their volume quantified in μm 3 using the AMIRA software . The determination of mean volume for each condition was done on a standardised number of the largest droplets equal to the total number of droplets detected in the untreated control ( n = 4 ).
The results are expressed as the mean volume ± SEM in μm 3 . The statistical analysis on the droplet size was done using the Student ’ s t-test versus the HS-stimulated condition , with a threshold of significance set at 5 % ( p < 0.05 ).
Efficacy on different ethnicities
As expected , HS-stimulation of sebocytes resulted in a significant increase in both cell proliferation and lipid synthesis for Caucasian and Asian sebocytes . In Black American sebocytes , lipid staining with Nile
MAR / APR 2024 SPECCHEMONLINE . COM
39