Chemical composition, antimicrobial, and antioxidant activities of the essential oils from stem, leaves, and seeds of Caryopteris foetida (D. don) Thell.

Abstract

Caryopteris foetida (D. Don) Thell. also known as stinking blue beard is an aromatic shrub of family verbenaceae. The essential oils from the leaf, stem, and seeds of C. foetida were extracted and analyzed in search of a novel compound. Over 73 constituents were identified from the essential oils of leaf, seeds, and stem. The major compound identified in the leaf oil was δ-cadinene (15.4%) followed by β-caryophyllene (7.8%), (E)-β-farnesene (8.3%), γ-cadinene (7.5%), spathulenol (7.2%), and τ-muurolol (5.1%). The stem oil predominantly consisted of methyl 7-methylcyclopenta[c]pyran-4-carboxylate (15.8%) along with a significant amount of δ-cadinene (11.6%) and γ-cadinene (5.6%), whereas seed oil was characterized by the presence of β-caryophyllene (14.3%) along with α-humulene (8.6%) and β-bisabolene (9.4%). The essential oils were screened for their in vitro antioxidant potential in terms of radical scavenging, metal chelating and reducing assay. The leaf oil exhibited strong DPPH radical scavenging (IC₅₀ =5.1±0.2 µg/mL) and reducing activity (IC₅₀ =3.6±0.5 µg/mL). The antibacterial potential was tested against Salmonela typhimurium, Escherichia coli, Staphylococcus Aureus, and Bacillus megaterium. Maximum activity was exhibited by the essential oils from the leaf and seed. The essential oils were also analyzed for their in vitro anti-inflammatory activity by the protein denaturation method. Both the leaf and stem essential oils exhibited good anti-inflammatory activity with IC₅₀ value of 12.8±0.0 µg/mL and 17.3±0.0 µg/mL respectively.