Cactus peptides and extracts in biological studies

Bleogens and antifungal activity

Loo and colleagues described peptides named bleogens. The pB1 studied consists of 36 amino acids and contains six cysteine residues that form disulphide bridges. These bonds stabilise its three-dimensional structure. Analysis of the precursors revealed different arrangements of the sequences from which the plant produces mature peptides [Loo et al. 2017].

pB1 inhibited Candida growth in laboratory tests. This result concerns a specific isolated molecule and the experimental conditions. A later review also covers other microproteins, so the activities of different bleogens need to be attributed to the appropriate compounds. Studying the peptide does not assess the effectiveness of eating leaves or consuming a homemade extract [Loo et al. 2017][Niu et al. 2026].

Purification gives the experiment a shared reference in the form of a recognised peptide sequence and structure. Loo and colleagues assessed pB1 using a diffusion assay and found activity against the two Candida species tested. Selected bacteria examined in the same study showed no activity. The response therefore depended on the microorganism despite use of the same molecule [Loo et al. 2017].

Ionic conditions also changed pB1 activity. Added salt abolished the anti-Candida response in the diffusion assay. This connects peptide structure with the environment of contact with a cell and helps guide further comparisons. Disulphide-stabilised structure and biological activity provide complementary measurements for the same compound [Loo et al. 2017].

Studies of extracts and blood glucose

Afzal and colleagues studied leaf extracts in rats with alloxan-induced diabetes. The experiment involved small groups of animals and administration of preparations over several days. The observed changes in blood glucose constitute a preliminary preclinical result. The study does not investigate treatment in humans, long-term effectiveness or the safety of consuming such extracts [Afzal et al. 2025].

Comparison with the peptide reveals a different organisation of evidence. In the glycaemia study, rats received a solvent-derived mixture and the measured response involved the whole animal. Methanol and chloroform extracts had distinct phytochemical-screening profiles and glycaemic responses. Separating these fractions defines material for further analysis, while assigning the response to a particular molecule requires isolation and testing in the same model [Afzal et al. 2025] [Loo et al. 2017].

Ariocarpus kotschoubeyanus extracts

Under laboratory conditions, a methanolic extract inhibited the growth of organisms including Bacillus cereus, B. subtilis and Microsporum gypseum. The study does not assess treatment effectiveness or the safety of consuming the plant [Rodríguez Garza et al. 2010].

Ariocarpus retusus extracts

A methanolic extract inhibited the growth of Bacillus cereus, B. subtilis and the Microsporum fungi tested. These were in vitro experiments, without assessment of therapeutic effects in humans. They do not confirm the suitability of the plant for consumption [Rodríguez Garza et al. 2010].

The Ariocarpus experiment completes the comparison at the level of mixtures and microbial cultures. Dried whole adult plants were extracted with methanol and the extracts were defatted with hexane. Chemical tests identified component groups, while diffusion assays measured the growth-inhibition zone after applying the mixture [Rodríguez Garza et al. 2010]. This material can be compared with pB1 of known structure. Extract comparisons require control of fraction composition and solvent, while animal experiments also involve administration route and exposure course. These features connect identification of the tested material with the actual endpoint [Loo et al. 2017] [Afzal et al. 2025].