Volatile‐Oils Composition,and Bioactivity of the Essential Oils of Plectranthus barbatus,P. neochilus,and P. ornatus Grown in Portugal |
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Authors: | Luísa Mota A Cristina Figueiredo Luís G Pedro José G Barroso M Graça Miguel M Leonor Faleiro Lia Ascensão |
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Institution: | 1. Universidade de Lisboa, Faculdade de Ciências de Lisboa, Departamento de Biologia Vegetal, Centro de Biotecnologia Vegetal, IBB, Campo Grande, PT‐1749‐016 Lisboa, (phone: +351?21?750?00?00;2. fax: +351?21?750?00?48);3. Universidade do Algarve, Faculdade de Ciências e Tecnologia, Centro de Biotecnologia Vegetal, IBB, Campus de Gambelas, PT‐8005‐139 Faro;4. Universidade do Algarve, Faculdade de Ciências e Tecnologia, Centro de Biomedicina Molecular e Estrutural, IBB, Campus de Gambelas, PT‐8005‐139 Faro |
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Abstract: | Volatile‐oils chemical composition and bioactivity of the essentail oils from Plectranthus barbatus, P. neochilus, and P. ornatus (Lamiaceae) were assessed. Aerial parts from these three related Plectranthus species were collected from cultivated plants grown in Portugal, during vegetative and flowering phases. Volatiles, isolated by distillation? extraction, were analyzed by GC and GC/MS. Monoterpene hydrocarbons (12–74%) and sesquiterpene hydrocarbons (4–45%) constituted the main fractions in all volatiles. α‐Pinene ( 3 ; 12–67%), oct‐1‐en‐3‐ol ( 6 ; traces–28%), β‐pinene ( 7 ; 0.1–22%), and β‐caryophyllene ( 50 ; 7–12%) dominated P. barbatus volatiles. P. neochilus major volatile components were α‐terpenyl acetate ( 41 ; traces–48%), α‐thujone ( 2 ; 2–28%), β‐caryophyllene ( 50 ; 2–28%), β‐pinene ( 7 ; 1–25%), and α‐pinene ( 3 ; 1–19%). Oct‐1‐en‐3‐ol ( 6 ; 13–31%), β‐pinene ( 7 ; 11–24%), α‐pinene ( 3 ; 11–19%), and β‐caryophyllene ( 50 ; traces–11%) were the main constituents from P. ornatus volatiles. These chemical compositions were rather different from those previously found for specimens harvested in Africa and Brazil. Moreover, the volatiles from the flowers are herewith reported for the first time. Essential oils, isolated by hydrodistillation from leaves and stems, showed a yellowish color and unpleasant odor, with yields ranging from 0.08% to 0.84% (v/dry weight). Antioxidant and antimicrobial activities of the essential oils were evaluated by DPPH. and TBARS assays, and agar disc‐diffusion method, respectively. Results showed low or moderate antioxidant capacity and significant antimicrobial activity against Gram‐positive bacteria. |
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Keywords: | Plectranthus species Essential oils Antioxidant activity Antimicrobial activity |
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