Unlocking Nature: The Secrets of Effective Botanical Extracts

In 2019, Procter and Gamble (P&G) with Royal Botanic Gardens, Kew (RGB Kew) in London wrote an article about the importance of understanding the chemistry that supports the functional benefits of botanical extracts that are used in hair care products.  This was written as part of our journey to identify extracts that deliver meaningful benefits, and we noted some of the important watch-outs for using these materials. These included regulatory restrictions, safety considerations, adulterations with other botanical materials and the need to evaluate a range of extracts from any given species of plants.      

We learned a lot during the past six years, especially the importance of understanding the phytochemistry of a selected extract and its participation in the chosen mechanism of action. In this follow-up article we share what we have learned and how we have used these insights to ensure we use high quality extracts moving forward.

Looking Back: Important Considerations for Botanicals

The first area we covered in our original article was the importance of ensuring compliance with regulatory requirements and only using sustainable sources for our extracts.  An important part of this is CITES (Convention of International Trade in Endangered Species of Wild Fauna and Flora) regulations that help in the protection of plants that are threatened by non-sustainable cultivation practices. This resource has lists of species that are covered by Appendix I (highly threatened), Appendix II (threatened, but manageable trade) and Appendix III (threatened in specific countries).  

It is critical when reviewing this database to have the correct Latin scientific name for the plant.  For example, the majority of the 592 species of Aloe (POWO, 2026)¹ are included in Appendix II, which means international trade is permitted but it is regulated to ensure its trade is sustainable.  There are also several Aloe species included in Appendix I which means no trade is permitted (Aloe albida, Aloe polyphylla, Aloe suzannae, and Aloe helenae). However, Aloe vera (synonym Aloe barbadensis) is the most common form of aloe used in cosmetics. It is now grown commercially and is specifically excluded from the CITES appendices and is not subject to these trade restrictions.  

The other important consideration we discovered was a clear understanding of where the plant was grown and whether it was considered to be an indigenous plant from a specific country (i.e., a species that occurs naturally in a specific country or region and has evolved there over thousands of years). Depending on the country in question, a Prior Informed Consent (PIC) agreement might be needed before any research or commercialization of a plant starts as well as Access & Benefit Sharing (ABS) considerations. These agreements are governed by the Convention of Biological Diversity and Nagoya Protocol International treaties that create the legal frameworks that ensure the fair and equitable sharing of benefits from the use of genetic and associated traditional knowledge. These laws vary by country and cover the use of these genetic materials in both research and commercialization and may involve payments for use of these plants in products.  

Due to the variation in laws between countries, P&G had to understand sources of all our botanicals and make sure we were compliant with all ABS laws. An example was the inclusion of pequi oil in Herbal Essences products, where P&G worked with the Brazilian authorities to ensure Herbal Essences complied with ABS laws, as pequi (Caryocar brasiliense) is an indigenous plant from the Cerrado region of Brazil.

The second important consideration is a safety assessment of botanicals, and we shared our assessment protocol where we consider a tiered approach based on the concentration of phytochemical constituents of concern found in plants.²  This approach proved to be successful as we have qualified new botanicals for use in our products.  A related concern was the possibility of product alteration which would not only impact performance but could also introduce materials with very different safety profiles.  For our high volume botanicals, we also initiated regular analyses using LC-MS/MS methods to compare ongoing extract quality.     

The third part of the previous article was concerned with the question of functionality – how we can ensure that we select the best extract to deliver the desired benefit.  This is the space where we had the most learning.  As we qualified more materials, it became a requirement to correlate in detail the phytochemical composition of our botanicals with their performance.   Without this understanding we could not identify the best extracts and ensure we have on-going quality to deliver the required benefits.

Testing Tea Extracts and Antioxidants

P&G’s first research project with RGB Kew in this area was on Camillia sinensis i.e.  tea extracts. Tea is known to have high antioxidation benefits driven by its composition of polyphenols including catechins and proanthocyanidins.³  Many companies supply tea extracts to the cosmetics industry, and we easily gathered sixteen tea extracts from various suppliers to test, including both green and white tea extracts.       

The phytochemistry of tea can vary among cultivars and varieties, the season the leaves are picked and how the leaves have been processed. White tea is minimally processed (withered/sun-dried) from young leaves and buds, whereas green tea is heat-treated (steamed/pan-fired) from mature leaves.  Differences in the processing methods influence      the phytochemistry composition are also observed.⁴  These differences can alter the antioxidant properties of the extracts. Another difference in the suppliers extracts was the extracts themselves – whether they were diluted or concentrated extracts.  As we compared the extract efficacy to scavenge a peroxyl radical via use of the ORAC assay (Oxygen Radical Absorbance Capacity) we saw a clear delineation between concentrated and dilute extracts (see Figure 1).⁵  This difference makes sense, as most of the extracts contained a similar profile of phytochemistry, but the concentration of the phytochemicals was lowered in the diluted extracts. In our following projects we tried to target concentrated extracts as a priority.

Figure 1 - ORAC Scores (Trolox Equivalents µM/100g) for 16 White & Green Tea ExtractsCourtesy of P&G

Once we had identified the concentrated extracts, we screened the extracts against relevant hair care endpoints.  Our initial tea project was focused on antioxidants, which is why we used ORAC testing as a fast initial screening protocol.  In parallel, work was ongoing to understand the oxidation mechanism relevant to hair and how to measure these changes.  This mechanism involved creating model systems and measurements on hair.⁶  For example, P&G demonstrated that radical damage to hair proteins in the presence of UV is significantly higher in high humidity when the free radicals are more mobile.⁷ This then informed future testing.  

In the tea work we used a hair biomarker fragment of the cuticle S100A3 protein (m/z = 1278) to screen protection of protein oxidation by the tea extracts. This enabled us to measure performance of the tea extract in the presence of UV.  To correlate the benefit with individual phytochemistry in the extracts and understand why a specific extract has superiority, we then needed to create data identifying all the different phytochemistry in each tea extract. RBG Kew used their analytical expertise in natural product chemistry to detect all the individual chemistries in the extracts. The majority of compounds were then identified based on mass spectrometry analysis and standards available in RBG Kew’s mass spectral library. 

Each of the tea extracts contained more than 40 molecules that were identified along with their relative abundance.  Multivariate analyses (heatmap and correlation analysis) were performed to determine which molecules are responsible for driving the measured benefit data.  (−)-Epicatechin and procyanidin B had the greatest correlation coefficients, which suggest that the catechin and procyanidin cluster, especially (−)-epicatechin (with coefficient 0.94), contains the key antioxidant compounds in the tea samples that contribute to the ORAC scores. In fact, most catechins in the tea samples significantly correlate (p < 0.001) with the ORAC scores. In contrast, other chemistries in tea such as theobromine and theogallin showed lower correlations to the ORAC scores and 3-O-(E)-caffeoylquinic acid showed no correlation to ORAC scores.

Superiority of the lead tea extract was shown in UV testing, and ORAC antioxidant testing confirmed we can link fundamental mechanisms of action with specific phytochemistry in botanical extracts and ultimately to consumer relevant benefit spaces.

Testing Grapeseed Extracts and Color Fade

We repeated this type of study with Grapeseed extracts but in this case our defined benefit space was color fade.⁸  Again, we defined the mechanism of action and correlated performance with phytochemistry composition of six grapeseed extracts.  Only concentrated extracts were chosen in this work and we investigated another key variable observed within botanical extracts. The differences in performance were also detected between batches of material from the same supplier.  

It is well known in the literature that plant phytochemistry will vary according to the climate and environmental conditions during plant growth. It is important to understand this variability so we can ensure that extract quality and performance is maintained.  

In this study, we looked at five batches of the same grapeseed extract and analyzed their phytochemicals and quantified their abundance using the same method as for the tea extracts.  In addition, we measured the UV color fade benefit.  This allowed us to analyze which of the extract components are critical for the measured hair benefit and to understand the variability of these critical components in each of the received batches.  The key chemicals responsible for the benefit were the procyanidins and catechins (similar to chemistries we identified in the tea extracts) and these were highly correlated between the six extracts (R² > 90%).  However, when this same correlation was performed with all the chemicals identified in the extracts, this correlation was only moderately high (R² = 50-60%).  This suggests that some of the phytochemicals do not contribute to the hair benefits of the grapeseed extracts.  These analyses gave us confidence that across batches from different grape harvests, the key phytochemical responsible for the color fade benefit was consistent, even if the overall phytochemistry profile changed.  This was confirmed when the ORAC scores and color fade benefit data showed high coherence across all the extracts.

Testing Extraction Processes and Performance

In our third botanical extract project, we investigated how the extraction process can determine extract composition and performance. For this project we investigated rosemary, another botanical well known for its antioxidant and hair and scalp benefits.⁹  In this case, we were studying solvent extracts of the dried rosemary plant leaves using either polar or non-polar solvents to access well-documented chemistries such as rosmarinic acid, carnosic acid and carnosol.¹⁰  Very different phytochemicals would be accessed from rosemary if we had used steam distillation as an extraction protocol (e.g. essential oil monoterpenes and terpenoids).  As in the tea and grapeseed projects we identified high concentration rosemary extracts and used LC-MS/MS to identify components that made up the 10 extracts studied (see Table 1). It was clear when we ordered the phytochemicals by their hydrophobicity (see Figure 2) and created a heat map based on the peak intensities of each of the 33 phytochemicals in the rosemary extract that each extract had a very different phytochemical profile.  

Figure 2 - Heat map showing the abundance of 33 phytochemicals in 10 rosemary extracts. Mostabundant compounds are dark to light green. N=3Courtesy of P&G

We tracked this difference to different solvent systems used for extraction.  Extracts 01, 02, 03, 09 and 10 were extracted by more polar solvents, such as water, to concentrate the extract in the more hydrophilic chemistries.  In several of the extracts, additional analytical manipulation was also used to standardize specific chemistry, as was done in this case with rosemarinic acid (see Figure 3).  Extracts 05 and 09 were extracted with more non-polar solvents, such as ethanol, to extract the phytochemicals such as carnosic acid and carnosol that are more hydrophobic.  Both of these extracts were also standardized in carnosic acid.  Extracts 04 and 07 have both hydrophilic and hydrophobic components and have used super critical fluid extraction methods to get these profiles. This extraction method involves using a fluid (usually CO₂) above its critical temperature and pressure, giving it solvent-like properties to extract compounds from solids or liquids. It can often solubilize a wider range of materials than typical solvents such as water or ethanol typically used to extract botanical ingredients.  

Figure 3 - Structures of rosmarinic acid, carnosic acid and carnosol in rosemary extracts.Courtesy of P&G

Several of these extracts were standardized by the suppliers in either rosmarinic acid or carnosic acid, which are well known as key antioxidants in rosemary.  Choosing one of these extracts is very attractive as a lead material because it helps us ensure high activity from every batch we receive.  We also tested both rosmarinic acid and carnosic acid in our ORAC antioxidant and hair testing and compared these individual materials to the botanical extracts.  In addition, we confirmed the mechanism by which these materials act as antioxidants in model system studies as we did for the tea and grapeseed extracts.¹¹

These three examples share how the expertise in hair science at P&G and that of natural product chemistry at RBG Kew enables us, as a team, to identify high-quality, high-performing botanical extracts with antioxidant benefits.  We have learned how to control for batch-to-batch variability based on different growing conditions and how to take advantage of different extraction protocols to maximize concentration of specific chemistries and optimize performance.  

We have also demonstrated similar benefits from this approach in understanding the detailed composition of triglyceride oils. These oils like shea butter, coconut, argan and almond oil are widely used in the hair industry and, as with the antioxidant extracts, we want to make sure we understand their compositions in detail and use this to choose the optimum oil for the benefit we require.  Most analysis completed on oils look just at the fatty acid composition profile of the oils, but we wanted to understand the full complex di- and triglyceride composition. RBG Kew developed a method in which LC-MS was used to detect the oil components, where each triglyceride is fragmented to its MS2 spectra featuring constituent fatty acids. This information can then be used to identify the triglyceride structure (see Figure 4).

Figure 4 - Workflow of triglycerides analysis for shea butter using LC-MS/MS method.Courtesy of P&G

With this analysis we could more accurately characterize the oil composition of the different botanical oil options and correlate this with performance in the areas of lubrication and strength.¹²  It was also very useful to compare oils that have similar compositions so that they could potentially be used interchangeably in formulations to deliver the same benefit. 

Conclusion

In closing, we have learned a lot in the past five years and more importantly developed the knowledge that allows us to identify high quality and high performing botanicals to deliver benefits to our product users.

References

1. POWO (2026). "Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; https://powo.science.kew.org/
   Retrieved 02 January 2026.
2. Roe, A.L., McMillan, D.A, Mahony, C, (2018).  A tiered approach for the evaluation of the safety of botanicals used as dietary supplements: an industrial strategy, Clin Pharm Ther 104(3) 446-457
3. Cabrera C, Gimearez R, Pez MCL. Determination of tea components with antioxidant activity. J Agric Food Chem. 2003;51(15):4427-4435.
4. Fang R, Redfern SP, Kirkup D, et al. Variation of theanine, phenolic, and methylxanthine compounds in 21 cultivars of Camellia sinensis harvested in different seasons. Food Chem. 2017;220:517-526.
5. Stephanie L. Davis, Jennifer M. Marsh, Casey P. Kelly, Lijuan Li, Cheryl S. Tansky, Rui Fang, Monique S. J. Simmonds, Protection of hair from damage induced by ultraviolet irradiation using tea (Camellia sinensis) extracts, J Cosmet Derm, 2021,14387
6. Jennifer M Marsh, Stephanie L Davis, Rui Fang, Monique SJ Simmonds, Phillip Groves, Victor Chechik, UV oxidation: mechanistic insights using a model system, J Cosmetic Sci, 2021, 72, 697-710
7. Philip Groves, Jennifer M Marsh, Yiping Sun, Tanuja Chaudhary, Victor Chechik, “Effect of humidity on photoinduced radicals in human hair” Free Radic. Med. Biol., 2018, 121, 20-25
8. Sonja L Knowles, Wei Sheng, Stephanie Davis, Vincent P Sica, Christopher J Pulliam, Timothy R Baker, Lijuan Li, Jennifer M Marsh, Rui Fang, Guillermo F Padilla-Gonzalez, Monique SJ Simmonds, Color Protection from UV irradiation of artificial dyes with grape seed (Vitis vinifera) extract, Journal of Photochemistry and Photobiology, 2022, 10, 100113
9. Marsh JM, Li L, Knowles S, Locker KC, Pearson K, Bacon R, Kozak K, Laughlin T, Schwartz JR. Scalp condition improvement with botanical extracts possessing chemical and physical antioxidant activity. International Journal of Cosmetic Science. 2025 Apr;47(2):297-304.
10. Jennifer M. Marsh, Shane Whitaker, Lijuan Li, Rui Fang, Monique S. J. Simmonds, Nikolaos Vagkidis, Victor Chechik, The key phytochemistry of rosemary (Salvia rosmarinus) contributing to hair protection against UV, Int J Cosmet Sci. 2023, 45(6) 749-760
11. Vagkidis, Nikolaos, Jennifer Marsh, and Victor Chechik. "The role of polyphenolic antioxidants from tea and rosemary in the hydroxyl radical oxidation of N-acetyl alanine." Molecules 28.22 (2023): 7514.
12. Jennifer M Marsh, Shane Whitaker, Tim Felts, Chris Cowans, Shikhar Gupta, Srdan Masirevic, Rui Fang, Monique SJ Simmonds, Gu Chen, Haibo Jiang, Penetration of oils into hair, Int J Cosmet Sci., 2024, 46(6), 905-917