@article{MasotaVoggOhlsenetal.2021,
  author    = {Masota, Nelson E. and Vogg, Gerd and Ohlsen, Knut and Holzgrabe, Ulrike},
  title     = {Reproducibility challenges in the search for antibacterial compounds from nature},
  series = {PLoS One},
  volume    = {16},
  journal   = {PLoS One},
  number    = {7},
  doi       = {10.1371/journal.pone.0255437},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260239},
  year      = {2021},
  abstract  = {Background Reproducibility of reported antibacterial activities of plant extracts has long remained questionable. Although plant-related factors should be well considered in serious pharmacognostic research, they are often not addressed in many research papers. Here we highlight the challenges in reproducing antibacterial activities of plant extracts. Methods Plants with reported antibacterial activities of interest were obtained from a literature review. Antibacterial activities against Escherichia coli and Klebsiella pneumoniae were tested using extracts' solutions in 10\% DMSO and acetone. Compositions of working solutions from both solvents were established using LC-MS analysis. Moreover, the availability of details likely to affect reproducibility was evaluated in articles which reported antibacterial activities of studied plants. Results Inhibition of bacterial growth at MIC of 256-1024 μg/mL was observed in only 15.4\% of identical plant species. These values were 4-16-fold higher than those reported earlier. Further, 18.2\% of related plant species had MICs of 128-256 μg/mL. Besides, 29.2\% and 95.8\% of the extracts were soluble to sparingly soluble in 10\% DMSO and acetone, respectively. Extracts' solutions in both solvents showed similar qualitative compositions, with differing quantities of corresponding phytochemicals. Details regarding seasons and growth state at collection were missing in 65\% and 95\% of evaluated articles, respectively. Likewise, solvents used to dissolve the extracts were lacking in 30\% of the articles, whereas 40\% of them used unidentified bacterial isolates. Conclusion Reproducibility of previously reported activities from plants' extracts is a multi-factorial aspect. Thus, collective approaches are necessary in addressing the highlighted challenges.},
  language  = {en}
}
@article{MasotaVoggHelleretal.2020,
  author    = {Masota, Nelson E. and Vogg, Gerd and Heller, Eberhard and Holzgrabe, Ulrike},
  title     = {Comparison of extraction efficiency and selectivity between low-temperature pressurized microwave-assisted extraction and prolonged maceration},
  series = {Archiv der Pharmazie},
  volume    = {353},
  journal   = {Archiv der Pharmazie},
  number    = {10},
  doi       = {10.1002/ardp.202000147},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218529},
  year      = {2020},
  abstract  = {Extraction is a key step in studying compounds from plants and other natural sources. The common use of high temperatures in pressurized microwave-assisted extraction (PMAE) makes it unsuitable for the extraction of compounds with low or unknown thermal stability. This study aimed at determining the suitability of low-temperature, short-time PMAE in attaining yields comparable to those of prolonged maceration at room temperature. Additionally, we explored the phytochemical differences of the extracts from both techniques. Maceration at room temperature for 24 hr and PMAE at 40-45°C and 10 bar for 30 min were carried out on 18 samples from 14 plant species at a solvent-to-feeds ratio of 10. The PMAE yields of 16 out of 18 samples were within the proportions of 91-139.2\% as compared with the respective extracts from maceration. Varying numbers of nonmatching peaks were noted in MS chromatograms of five extract pairs, indicating selective extraction of some compounds. Low-temperature PMAE can attain reasonable extraction efficiency with the added value of sparing compounds of low thermal stability. The method can also enable the recovery of compounds distinct from those obtained by maceration.},
  language  = {en}
}
@article{KaiserVoggFuerstetal.2015,
  author    = {Kaiser, Bettina and Vogg, Gerd and F{\"u}rst, Ursula B. and Albert, Markus},
  title     = {Parasitic plants of the genus Cuscuta and their interaction with susceptible and resistant host plants},
  series = {Frontiers in Plant Science},
  volume    = {6},
  journal   = {Frontiers in Plant Science},
  number    = {45},
  doi       = {10.3389/fpls.2015.00045},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144091},
  year      = {2015},
  abstract  = {By comparison with plant microbe interaction, little is known about the interaction of parasitic plants with their hosts. Plants of the genus Cuscuta belong to the family of Cuscutaceae and comprise about 200 species, all of which live as stem holoparasites on other plants. Cuscuta spp. possess no roots nor fully expanded leaves and the vegetative portion appears to be a stem only. The parasite winds around plants and penetrates the host stems via haustoria, forming direct connections to the vascular bundles of their hosts to withdraw water, carbohydrates, and other solutes. Besides susceptible hosts, a few plants exist that exhibit an active resistance against infestation by Cuscuta spp. For example, cultivated tomato (Solanum lycopersicum) fends off Cuscuta reflexa by means of a hypersensitive-type response occurring in the early penetration phase. This report on the plant plant dialog between Cuscuta spp. and its host plants focuses on the incompatible interaction of C. reflexa with tomato.},
  language  = {en}
}