Effects of Potentised Substances on Growth Kinetics of Saccharomyces cerevisiae and Schizosaccharomyces pombe

Abstract

Homeopathic potencies are used as specific remedies in complementary medicine. Since the mode of action is unknown, the presumed specificity is discussed controversially. Objective: This study investigated the effects of potentised substances on two yeast species, Saccharomyces cerevisiae and Schizosaccharomyces pombe, in a stable and reliable test system with systematic negative controls. Materials and Methods: Yeast cells were cultivated in either potentised substances or water controls in microplates and their growth kinetics were measured photometrically. Water control runs were performed repeatedly to investigate the stability of the experimental set-up (systematic negative controls). Results: 4 out of 14 screened substances seem to have affected the growth curve parameters slope or yield. Out of these substances, azoxystrobin and phosphorus were chosen for 8 further replication experiments, which partly confirmed the results of the screening. On the average of all experiments, azoxystrobin affected the slope of the growth curve of Saccharomyces cerevisiae (p < 0.05), and phosphorus affected the slope of the growth curve of Schizosaccharomyces pombe (p < 0.05). No effects were seen in the water control runs. In addition, significant interactions between treatment with potentised substances and experiment number were observed in all experiments with potentised substances (p < 0.01), but not in the water control runs. Conclusions: Both yeast species reacted to certain potentised substances by changing their growth kinetics. However, the interactions found point to additional factors of still unknown nature, that modulate the effects of potentised substances. This stable test system with yeasts may be suitable for further studies regarding the efficacy of homeopathic potencies.

Test of a Homeopathic Dilution of Aconitum napellus

“…In opposition to the popularity of homeopathy in several countries, most of the clinical trials and meta-analyses of clinical trials performed so far have indicated either lack of efficacy of homeopathic preparations in healing patients or merely a tendency towards efficacy [6][7][8][9]. At the experimental level, some studies performed with animals [10,11], plants [12] or in vitro [13,14] revealed that homeopathic dilutions may exert biological effects.…”

Models with Plants, Microorganisms and Viruses for Basic Research in Homeopathy

“…the effect that some potentized substances did affect the measured parameters, whilst others did not when tested in the same experimental set-up, was observed for viruses (Glatthaar-Saalmüller et al, 2001), yeast (Scherr et al, 2006) and fungi (Khanna and Chandra, 1992). Another phenomenon was demonstrated in those studies in which several potency levels were tested simultaneously: there were active and inactive potency levels.…”

“…Among the studies with microorganisms most often yeasts have been used as model organisms (Steffen, 1984(Steffen, , 1985Baker and Smith, 1985;Hagelberg, 1987;Koch and Partilla, 1995;Engstler, 2004;Scherr et al, 2006). Some of these works were inspired by the positive results of Jones et al (Jones and Jenkins, 1983a,b) indicating sensitive reactions of Saccharomyces cerevisiae to potencies of Pulsatilla.…”

“…A re-analysis of the data by Baker (Baker et al, 1985) showed similar periodicities with potencies in the work of Steffen et al (Steffen, 1984) and Jones et al (Jones and Jenkins, 1983a, b). In general, the yeast model system was reported to be stable and reliable, however varying sensitivity to homeopathic potencies has been found, depending on the measured parameter and on the substances and potency levels tested (Baker et al, 1985;Engstler, 2004;Scherr et al, 2006). It can be hypothesized that different strains as well as different physiological conditions of the cells at the beginning of the experiment may be important when using microorganisms for investigating effects of potentized substances.…”

“…In the studies named two different yeast species have been used, either Saccharomyces cerevisiae (Steffen, 1984;Koch et al, 1995;Engstler, 2004) or Schizosaccharomyces pombe (Steffen, 1985;Hagelberg, 1987). In one study both species were tested and showed differential reactions in their growth kinetics when treated with homeopathic potencies (Scherr et al, 2006). Engstler (Engstler, 2004) did not come to consistent conclusions because of problems with internal repeatability and sterility.…”