Rosmarinic acid, scutellarein 4′-methyl ether 7- O-glucuronide and (16S)-coleon E are the main compounds responsible for the antiacetylcholinesterase and antioxidant activity in herbal tea of Plectranthus barbatus (“falso boldo”)

• Published in: Food chemistry 2009-06, Vol.114 (3), p.798-805
• Main Authors: Falé, Pedro L., Borges, Carlos, Madeira, Paulo J. Amorim, Ascensão, Lia, Araújo, Maria Eduarda M., Florêncio, Maria Helena, Serralheiro, Maria Luísa M.
• Format: Article
• Language: English
• Subjects: (16S)-coleon E; Acetylcholinesterase; Antioxidant activity; chemical constituents of plants; enzymatic hydrolysis; enzyme activity; enzyme inhibition; enzyme inhibitors; food analysis; food composition; herbal tea; leaves; medicinal plants; plant extracts; Plectranthus barbatus; Rosmarinic acid; Scutellarein 4′-methyl ether 7- O-glucuronide
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2008.10.015

Plectranthus barbatus, known as “falso boldo” in Brazil, is used in herbal tea or cooked as a vegetable. Infusions and decoctions of leaves from P. barbatus were analysed for their inhibition of acetylcholinesterase and their antioxidant activity. The decoction showed high inhibition activity (31% inhibition with 0.5 mg of extract/ml) and also high antioxidant activity (IC 50 = 45.8 ± 0.5 μg of dry extract/ml in the DPPH test; IC 50 = 69.8 ± 3.1 μg of dry extract/ml in the β-carotene–linoleic acid test). Rosmarinic acid, scutellarein 4′-methyl ether 7- O-glucuronide and (16S)-coleon E were the main constituents identified. These compounds have antiacetylcholinesterase activity. Rosmarinic acid and the scutellarein derivative have IC 50 = 440 μg/ml and 1 mg/ml, respectively. One milligram per millilitre of (16S)-coleon E showed 61% inhibition of the enzyme. Other Plectranthus species, P. ecklonii, P. fructicosus, P. lanuginosus and P. verticillatus, were also analysed and the results obtained correlated with the content in rosmarinic acid.