congresos y reuniones científicas
Polyphenol-rich Larrea divaricata Cav extracts as skin and hair care agents against oxidative stress and melanomas
Congreso; International Conference on Polyphenols and Health; 2017
Skin constitutes an organ that protects the body from the external environment such as microorganisms, chemicals and UV radiation, moreover acts regulating the temperature and maintaining the fluid balance.UV irradiation and oxidative stress are the main causes of extrinsic ageing and cutaneous damages and diseases as skin cancer. Oxidative stress is provoked by an excess of reactive oxygen species (ROS). Under normal conditions, the endogenic antioxidant system of the skin is very effective as it contains non-enzymatic compounds and enzymes. The enzymes are glutathione peroxidase, glutathione reductase, catalase and superoxide dismutase, which degrade hydrogen peroxide, lipid hydroperoxides and superoxide. But when the organism is exposed to oxidative stress, the effectiveness of the endogenic antioxidant system is diminished. For example, after irradiation of skin fibroblasts with UVA, the activity of catalase and superoxide dismutase decreases. Under these situations skin care agents are needed, instead of synthetic substances that may cause seriously adverse effects plant extracts which are rich in vitamins, essential oils, and antioxidants, such as polyphenols, can be used with less toxic effects. Larrea divaricata is an autochthonous South American plant widely used in Argentina popular medicine for treatment of inflammatory diseases and cancer. The leaves are covered by a resin rich in polyphenols such as lignans (NDGA (nor-dihydroguaiaretic acid)) and flavonoids. The aqueous extract (Aq) of the leaves is an active component of ECOHAIR  lotion that induces hair growth and diminishes hair loose in humans. Also, an acethyl acetate fraction (AE) from Aq was shown to exert antiproliferative action on a lymphoma cell line EL-4, flavonoid quercetin 3 methyl eter (Q3ME) was one of the active compound identified but the effect on melanoma cell line has not been determined before.The objective of this work, to complete the action on hair, was to analyze the participation of polyphenols, especially flavonoids, in the protection of the skin exerted by Aq, analyzing the effect of Aq and AE on: proliferation of melanoma cell line B16F10, normal lymphocytes and fibroblasts and on viability of hydrogen peroxide stressed fibroblasts. Moreover the sun protection factor (SPF) ?in vitro?, the simil peroxidase (Px) and superoxide dismutase (SOD) activities and the phytochemical composition were determined. Aq was fractionated by liquid/liquid extraction first in dichloromethane (DM) and then in acethyl acetate to obtain AE. Total polyphenols, total flavonoids were quantified by spectroscopy techniques; NDGA and Q3ME were quantified by high performance liquid chromatography (HPLC) in both Aq and AE. The effect on cell proliferation was determined through tritiated tymidine uptake after the incubation of cells 24 h (tumoral and fibroblasts) and 48-72 h (normal lymphocytes). Cell viability was determined by MTT assay. Simil Px and SOD activities were determined by kinetic spectrophotometric assays. Results represent mean ± SEM of three experiments made by triplicate.Results: Phytochemical studies: AE was concentrated in flavonoids and presented less NDGA content, which was extracted in DM. Proliferation studies: tumoral cells: Aq, AE, Q3ME and NDGA presented antiproliferative action on Melanoma B16F10: (effective concentration 50) EC50 Aq: 316 ± 30 µg/ml; EC50 AE < 0.1 µg/ml; EC50 Q-3ME < 0.1 µg/ml; EC50 NDGA: 2.3± 0.2 µg/ml. Normal lymphocytes: Both AE and Q3ME stimulated cell proliferation: Basal (CPM): 530± 89; AE 1µg/ml: 10277± 2500; Q3-ME: 22767 ± 4000. Fibroblasts: Aq stimulated cell proliferation: Basal (CPM): 5403± 467; Aq 1µg/ml: 14596± 261.Antioxidant activity: SOD simil activity EC50 (µg/ml): Aq: 170; AE: 10.96. Px simil activity EC50 (µg/ml):Aq: 436; AE: 251.Sun protection factor: AE 1.5 mg/ml (SPF) = 30 %Conclusions: Aq extract of Larrea divaricata especially the fraction AE rich in plyphenols exerted a potent antiproliferative action on melanoma cell line, induced normal lymphocytes and fibroblast cell proliferation, protected fibroblast against hydrogen peroxide induced damage and presented simil antioxidant SOD and PX activities as well as UVB protection. All these actions turn the extracts into good candidates to be used as skin and hair care cosmeceutical or phytomedicine agents.