| Popis: |
Simple Summary Most thyme and basil species are characterized by a great chemical diversity. Uses have been developed through centuries in foods, as a source of essential oil, flavors, and antioxidants. The main aim of this study was to produce volatile metabolites using cell suspensions of Thymus vulgaris and Ocimum basilicum from the Al-Ahsa area in the sub-continental region. We surveyed the antifeedant activity of extracted volatile metabolites and the inhibition of extracts against total proteolytic enzyme activity from the red palm weevil Rhynchophorus ferrugineus (Oliver), (Coleoptera: Curculionidae). Thymus vulgaris was the most active extract, characterized not only by feeding inhibition but also by a growing deterrence on R. ferrugineus larvae. The O. basilicum extract also showed a lower range of biological activity; nevertheless, there was potent insecticidal activity. The high insecticidal activity of the T. vulgaris extract could be attributed to the high diversity of its volatile constituents. One of the merits of the current approach is that the outcomes are applicable and have the environmental goal of producing ecofriendly biopesticides. Abstract The current study was designed to investigate the insecticide role of volatile constituents produced from cell suspensions of T. vulgaris and O. basilicum against R. ferrugineus. Constituents were extracted from cell suspension after 40 days. Growth kinetics were measured with an inoculation of Verticillium dahliae and identified by GC-MS. Total volatile phenolic constituents were measured. Insecticidal activity against R. ferrugineus (adult) and proteolytic enzyme activity in larvae were assessed. GC-MS showed that the T. vulgaris extract has higher amounts of thymol, p-cymene, γ-terpinene, β-caryophyllene, and linalool in comparison to the O. basilicum extract, which is rich in estragole, β-terpineol, (E)-β-ocimene, 1,8-cineole, germacrene D, and eugenol. The T. vulgaris extract showed an LC50 of 1032 µg/mL, followed by O. basilicum with an LC50 of 1246 µg/mL. The IC50 values against the total proteases were 110.8 and 119.4 µg/mL for T. vulgaris and O. basilicum, respectively. The IC50 for the trypsin-like serine proteinase assessment was 81.6 and 91 µg/mL for T. vulgaris and O. basilicum, respectively. Cysteine, chymotrypsin, and metalloproteinase assessment showed an IC50 above 5000 µg/mL for both extracts. The study is proposed as a potential approach to use T. vulgaris and O. basilicum extract as a bio-insecticide against R. ferrugineus using an accessible and efficient cell suspension technique. |
