Compendium of the most significant studies with reference to properties, intake, effects.

Carini M, Aldini G, Orioli M, Facino RM. Antioxidant and photoprotective activity of a lipophilic extract containing neolignans from Krameria triandra roots. Planta Med. 2002 Mar;68(3):193-7. doi: 10.1055/s-2002-23167.

Abstract. The antioxidant/photoprotective potential of a standardized Krameria triandra (KT) root extract (15% neolignans) has been evaluated in different cell models, rat erythrocytes and human keratinocytes cell lines, exposed to chemical (cumene hydroperoxide, CuOOH) and physical (UVB radiation) free radical inducers. The extract was significantly more active (IC50 0.28 +/- 0.04 microg/ml) than the typical chain-breaking antioxidant alpha-tocopherol (IC50 = 6.37 +/- 0.41 microg/ml) in inhibiting the CuOOH-induced hemolysis in rat blood cells. The KT constituent 2-(2,4-dihydroxyphenyl)-5-(E)-propenylbenzofuran, was the most active (IC50 = 0.03 +/- 0.005 microg/ml), followed by eupomatenoid 6 (IC50 = 0.29 +/- 0.06 microg/ml) and conocarpan (IC50 = 0.77 +/- 0.08 microg/ml). The same order of potency was observed in red blood cells exposed to UVB irradiation in continuo, with IC50 values 0.78 +/- 0.08 microg/ml for KT extract, 0.18 +/- 0.02 microg/ml for 2-(2,4-dihydroxyphenyl)-5-(E)-propenylbenzofuran, 0.95 +/- 0.11 microg/ml for eupomatenoid 6, and 3.8 +/- 0.39 microg/ml for conocarpan. In cultured human keratinocytes exposed to UVB radiation (50 mJ/cm2), KT extract (2.5-20 microg/ml) significantly and dose-dependently restrained the loss in cell viability and the intracellular oxidative damage: glutathione (GSH) depletion and the rise in dichlorofluorescein (DCF), marker of peroxide accumulation, were suppressed by 20 microg/ml KT and in parallel cell morphology maintained. The cytoprotective effect of the extract was confirmed in a more severe model of cell damage: exposure of keratinocytes to higher UVB doses (300 mJ/cm2), which induce a 50% cell death. In keratinocyte cultures supplemented with 10 microg/ml, cell viability was almost completely preserved and more efficiently than with (-)-epigallocatechin 3-gallate and green tea. The results of this study indicate the potential use of Rhatany extracts, standardized in neolignans, as topical antioxidants/radical scavengers against skin photodamage.

Scholz E, Rimpler H. Proanthocyanidins from Krameria triandra root. Planta Med. 1989 Aug;55(4):379-84. doi: 10.1055/s-2006-962032.

Abstract. Oligomeric proanthocyanidins were isolated from rhatany root (Krameria triandra) and characterised by acid hydrolysis, thiolytic degradation, and spectroscopic methods. They consisted of 2-14 flavanol units with mainly 2,3-cis configuration and with a propelagonidin:procyanidin ratio of 65:35. The predominant interflavan linkage was [4,8]. [4,6]-Bonds were present in the higher oligomers, presumably forming branched chain units. The astringency of the drug was mainly due to proanthocyanidins with degrees of polymerization from 5-10, and these were also the astringent compounds of rhatany tea and tincture. A pharmacological screening of the extract revealed a significant antimicrobial effect.

Korać RR, Khambholja KM. Potential of herbs in skin protection from ultraviolet radiation. Pharmacogn Rev. 2011 Jul;5(10):164-73. doi: 10.4103/0973-7847.91114. 

Abstract. Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV) radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxidants such as vitamins (vitamin C, vitamin E), flavonoids, and phenolic acids play the main role in fighting against free radical species that are the main cause of numerous negative skin changes. Although isolated plant compounds have a high potential in protection of the skin, whole herbs extracts showed better potential due to their complex composition. Many studies showed that green and black tea (polyphenols) ameliorate adverse skin reactions following UV exposure. The gel from aloe is believed to stimulate skin and assist in new cell growth. Spectrophotometer testing indicates that as a concentrated extract of Krameria triandra it absorbs 25 to 30% of the amount of UV radiation typically absorbed by octyl methoxycinnamate. Sesame oil resists 30% of UV rays, while coconut, peanut, olive, and cottonseed oils block out about 20%. A "sclerojuglonic" compound which is forming from naphthoquinone and keratin is the reaction product that provides UV protection. Traditional use of plant in medication or beautification is the basis for researches and making new trends in cosmetics. This review covers all essential aspects of potential of herbs as radioprotective agents and its future prospects.

Malinowska, P., & Kiewlicz, J. (2017). Comparison of antioxidant activity of selected commercial cosmetic plant roots extracts. Towaroznawcze Problemy Jakości, (2), 114-121.

Abstract. The aim of this work was to evaluate the total phenolic content and the antioxidant activity of three commercial root extracts used in cosmetic products: Glycyrrhiza glabra (liquorice), Harpagophytum procumbens (devil's claw) and Krameria triandra (rhatany). DPPH radical scavenging activity and Trolox Equivalent Antioxidant Capacity (TEAC) assays were chosen to evaluate the antioxidant activity of extracts. The total phenolic content varied widely in tested extracts and ranged from 75.9 mg/L in rhatany extract to 952.8 mg/L in liquorice extract. DPPH radical scavenging activity, calculated as EC50 value, ranged from 1.56% for rhatany extract to 0.48% for liquorice extract, and calculated as AADPPH, ranged from 0.64 for rhatany extract to 2.08 for liquorice extract. Antioxidant activity, expressed as TEAC values, ranged from 0.51 mmol/L for devil's claw extract to 7.86 mmol/L for liquorice extract. (original abstract)