“Tiger grass”: the next rising star of skincare or folklore?

By Jeslyn Kho 

Centella asiatica is an aquatic plant indigenous to Asia and goes by many names: Gotu kola, Asiatic pennywort, or (most famously) “tiger grass”. It was named after the supposed Laotian legend whereby villagers spotted tigers rolling in it to heal their wounds leading to the discovery of its healing properties. It has been popularised as a skincare ingredient by Korean skincare brands which boast of its amazing hydration, anti-inflammatory, anti-aging and wound healing properties. This unassuming plant seems to bear the key to youthful, healthy skin but does it really match up to its claims or is it just another marketing tool? This article aims to explore the credibility of each of these claims and whether C.asiatica is a worthy addition in formulations.

C.asiatica’s properties can be attributed to their active chemical compounds, which consist of pentacyclic triterpenes (a compound consisting of six isoprene units), produced by all animals, plants and fungi as precursors to steroids. (Eberhard Breitmaier, 2006). The most notable constituents due to their pharmacological activity being asiaticoside, madecassoside, asiatic acid and madecassic acid. 

In a large number of scientific reports, C.asiatica extracts, consisting of individual and a mixture of triterpene compounds, have shown promising results in wound healing. Terpenoids (which are derived from isoprenes) aid in wound healing by stimulating the production of type I collagen, reducing the inflammatory reaction and myofibroblast production (Bylka, Wiesława et al., 2014).  

In one clinical study, carried out on 106 post-operative patients, over the span of 6-months, a 2% purified extract of C.asiatica was applied topically as a cream on the surface of a microporous tape. It proved extremely successful with stimulating maturation of scars as well as a more favourable scar appearance. Furthermore, in vitro studies have proven that C.asiatica stimulates fibroblast development and activates the SMAD pathway – a family of proteins that are the main receptors for the transforming growth factor beta (TGF-B) superfamily, which are imperative for regulating cell development and growth. It has also been found to increase collagen synthesis and reduce metalloproteinase activity thereby increasing collagen deposition. (Tenni et al.,1988) C.asiatica’s ability to stimulate type I collagen synthesis (which decreases with age) has also been exploited in anti-aging treatments.

C.asiatica has also been used for the treatment of cellulite or liposclerosis. Cellulite is the herniation of subcutaneous fat within the fibrous connective tissue as a result of an increase in the volume of fat cells or by increased division of connective tissue thereby causing constriction of small blood vessels. C.asiatica has been used in a few clinical studies with different methodologies-;C.asiatica was either taken orally or applied topically. In a randomised, double-blind, placebo-controlled trial of a cream containing C.asiatica extract, hydrolyzed collagen and elastin, the cream was tested on 100 pregnant women. The cream was applied over a duration of 30 months in areas where cellulite was typically found- the breasts, buttocks, abdomen and hips. Out of the 50 women who were not given placebos, only 14 women had striae, proving that it was very effective in preventing striae during pregnancy. (J Mallol et al., 1991)

A great number of studies and clinical trials have demonstrated a largely positive effect of C.asiatica’s wound healing properties. It is however, worth noting that while it has shown great results in the treatment of post-op scars and hypertrophic scars, it proved ineffective in patients with progressive disease and for those with diffuse skin lesions (F Bonte et al., 1994). Current knowledge is also insufficient to determine the best route and dosage or formulation of C.asiatica extract. 

C.asiatica has also been found to increase the skin’s hydration state by decreasing transepidermal water loss. This is primarily due to the presence of tritepene saponins – a hydrophilic sugar chain that has the ability to bind water within an occlusive layer (James & Dubery, 2009).  A stratum corneum hydration test using a corneometer showed a significant increase of 25% in hydration with a 5% C.asiatica extract emulsion. However, this experiment was only carried out on a small sample size of 25 individuals over a four week duration. (Ratz-Lyko, A., Arct, J. & Pytkowska, K., 2016). Another experiment used C.asiatica extract in conjunction with hyaluronic acid and glycerin to create a moisturising fluid and found that skin hydration after 24 hours was significantly higher in comparison with the control site. C.asiatica shows great promise in its ability to reduce transepidermal water loss, especially when used in conjunction with other compounds known to improve hydration like hyaluronic acid and glycerin (M.Milani & A. Sparavigna, 2017). 

C.asiatica shows especially promising activities for wound healing and there are a large number of scientific reports which support this claim. However, as mentioned previously, the most effective route and formulation of C.asiatica is undetermined. Furthermore, it should also be mentioned that the proangiogenic activity of topically applied agents has been linked to neoplasm formation. This should always be taken into consideration and caution should be exercised during clinical trials (A W Griffioen & G Molema, 2000). While C.asiatica shows much promise in its anti-inflammatory and hydrating properties, there simply have not been enough studies to come to a credible, concrete conclusion. Though investigating the properties of plants used in traditional medicine such as C.asiatica proves to be an arduous journey, examples such as Tu Youyou’s breakthrough discovery in using artemisinin from sweet wormwood to inhibit the malaria parasite proves that it is a worthy one indeed (Youyou Tu, 1979) 

References:

A. Ratz-Łyko, J. Arct, & K. Pytkowska, 2016. Moisturizing and Antiinflammatory Properties of Cosmetic Formulations Containing Centella asiatica Extract. Indian J Pharm Sci. 2016;78(1):27-33. doi:10.4103/0250-474x.180247

Eberhard Breitmaier, 2006 Terpenes: Flavors, Fragrances, Pharmaca, Pheromones. https://doi.org/10.1002/9783527609949.ch6

F Bonte, M Dumas, C Chaudagne & A Meybeck, 1994. Influence of asiatic acid, madecassic acid, and asiaticoside on human collagen I synthesis. Planta Med. 1994 Apr;60(2):133-5. doi: 10.1055/s-2006-959434. PMID: 8202564.

Griffioen AW, Molema G., 2000. Angiogenesis: potentials for pharmacologic intervention in the treatment of cancer, cardiovascular diseases, and chronic inflammation. Pharmacol Rev. 2000 Jun;52(2):237-68. PMID: 10835101.

Jacinda T James & Ian A Dubery, 2009. Pentacyclic triterpenoids from the medicinal herb, Centella asiatica (L.) Urban. Molecules. 2009 Oct 9;14(10):3922-41. doi: 10.3390/molecules14103922. PMID: 19924039; PMCID: PMC6255425.

J Mallol, M A Belda, D Costa, A Noval & M Sola, 1991. Prophylaxis of Striae gravidarum with a topical formulation. A double blind trial. Int J Cosmet Sci. 1991 Feb;13(1):51-7. 

doi: 10.1111/j.1467-2494.1991.tb00547.x. PMID: 19291041.

Massimo Milani & Adele Sparavigna, 2017. The 24-hour skin hydration and barrier function effects of a hyaluronic 1%, glycerin 5%, and Centella asiatica stem cells extract moisturizing fluid: an intra-subject, randomized, assessor-blinded study. Clin Cosmet Investig Dermatol. 2017;10:311-315. Published 2017 Aug 11. doi:10.2147/CCID.S144180

R Tenni, G Zanaboni, M P De Agostini, A Rossi, C Bendotti & G Cetta, 1988. Effect of the triterpenoid fraction of Centella asiatica on macromolecules of the connective matrix in human skin fibroblast cultures. Ital J Biochem. 1988 Mar-Apr;37(2):69-77. PMID: 3042688.

Tu Y. Artemisinin, 2016. A Gift from Traditional Chinese Medicine to the World (Nobel Lecture). Angew Chem Int Ed Engl. 2016 Aug 22;55(35):10210-26. doi: 10.1002/anie.201601967. Epub 2016 Aug 4. PMID: 27488942. 

Wiesława Bylka, Paulina Znajdek-Awiżeń, Elżbieta Studzińska-Sroka & Małgorzata Brzezińska, 2014. Centella asiatica in cosmetology. doi: 10.5114/pdia.2013.33378

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