Inga vitro

Heng, Ming Yuan, Thuerig, Barbara, Danton, Ombeline, Ramseyer, Justine, Gupta, Mahabir P., Tamm, Lucius, Hamburger, Matthias & Potterat, Olivier, 2022, Ingadosides A-C, acacic acid-type saponins from Inga sapindoides with potent inhibitory activity against downy mildew, Phytochemistry (113183) 199, pp. 1-8 : 7

4.6. In vitro Plasmopara viticola inhibition assay

Bioassays were conducted using a previously published protocol ( Thuerig et al., 2016). Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni was maintained on grapevine ( Vitis vinifera L.) seedlings ‘Chasselas’ by weekly reinoculation. P. viticola sporangia suspensions were prepared from previously infected plants by washing freshly sporulating grapevine leaves with water and filtering through cheese cloth.

Samples were dissolved in DMSO (10 mg /mL for extracts and fractions, or 5 mg /mL for pure compounds) and serially diluted in water in 96 well plates before adding sporangial suspension (20 μL, approx. 200 ′ 000 sporangia/mL), resulting in a final volume of 120 μL per well. Final concentrations of serial dilutions ranged from 100 to 0.1 ppm for extracts and fractions, while serial dilutions from 50 ppm to 0.05 ppm were used for pure compounds. DMSO alone was tested as negative control in at least two replicates in all relevant concentrations. The release and activity of zoospores was assessed 2–3 h after setup of the experiment. MIC 100 values correspond to the concentration needed to completely inhibit the release and/or the activity of zoospores. The experiment was repeated four times with independent serial dilutions.