Garambullo and the microbiota. What experiments with cactus fruit measure

The fruit and the experimental preparation

The experiment published in January 2026 used ripe, intensely purple fruit collected in June 2021 at Garabatillo near Celaya, in the Mexican state of Guanajuato. After washing, the fruit was freeze-dried, a process that removes water from frozen material, then ground and stored at low temperature. The resulting powder was one of the two materials examined. Retaining information about collection and processing defines the provenance of the sample and the form of the product whose effects were actually compared [Sánchez-Recillas et al. 2026].

The second material was obtained by extracting this powder with a mixture of methanol and water and then separating the liquid portion. The residue contained a fibrous fraction and compounds retained after that procedure. Its composition therefore reflected a laboratory separation. The authors administered both fruit powder and residue at 5 g per kilogram of rat body weight. An equal mass of the two preparations permits comparison of the selected treatments, while the amounts of individual constituents depend on their composition. This detail matters when comparing the results with studies of juice or an extract [Sánchez-Recillas et al. 2026].

Sixteen weeks and four groups of rats

The study included 12 male Sprague-Dawley rats randomly allocated to four groups of three animals. One group served as a control. The others received azoxymethane and dextran sodium sulfate, abbreviated AOM/DSS. This model combines exposure to a DNA-damaging compound with induction of inflammatory changes in the colon. Two groups additionally received either fruit powder or the extraction residue. The AOM/DSS group receiving neither supplement provided a comparison for the differences associated with each preparation within the same model [Sánchez-Recillas et al. 2026].

Faecal samples were collected before the experiment and after 8 and 16 weeks. Extracted DNA was used to analyse the V3 and V4 regions of the gene encoding bacterial 16S ribosomal RNA. Sequence differences allow reads to be assigned to groups of microorganisms and their representation in a sample to be described. Successive sampling times reveal changes in the bacterial community during the experiment. The resulting profile concerns microorganisms detected in faeces, while functional interpretation depends on additional measurements of metabolites and responses in host tissues [Sánchez-Recillas et al. 2026].

Diversity and the representation of individual bacteria

The Shannon and Chao1 indices describe different properties of diversity within a sample. The authors found no significant differences in these indices between the four groups at the same sampling times. In the AOM/DSS group, Chao1 increased over time relative to the beginning of the experiment. Comparing groups in a particular week and comparing one group across successive weeks therefore address distinct questions. The result for a summary index can then be considered alongside changes in particular bacterial genera, which represent a more detailed level of analysis [Sánchez-Recillas et al. 2026].

After 8 weeks, differential abundance analysis found greater representation of Faecalibacterium in both groups receiving fruit material than in the AOM/DSS group. With the extraction residue, increases also included Subdoligranulum, Alloprevotella and Lactobacillus. The pattern changed over time. After 16 weeks, the Escherichia-Shigella taxonomic grouping also occurred among those with increased representation. Taken together, these observations describe a reorganisation of the bacterial community that depended on preparation and sampling time, involving more changes than an increase in a single selected genus [Sánchez-Recillas et al. 2026].

From a DNA profile to microbiota function

The authors related the observations to possible fermentation of fibre and transformation of phenolic compounds. In their proposed explanation, products made by some bacteria can serve as substrates for others, creating feeding relationships within the community. They paid particular attention to short-chain fatty acids, small molecules produced through processes including fermentation. This connection provides a mechanistic hypothesis for the observed profile. These acids were not measured in this publication, and the discussion of their involvement also refers to earlier experiments. Testing the mechanism requires bacterial composition to be linked with measurements of the products of microbial metabolism [Sánchez-Recillas et al. 2026].

Sample structure affects confidence in this interpretation. The methods specify three animals per group and analysis of samples containing DNA pooled from three rats. Pooling limits the ability to recover differences between individuals, and the description of replicates requires caution when assessing their independence. The authors also identified measurement of inflammatory biomarkers as a further stage of the work. Changes in microbiota profile in this small experiment therefore remain the most directly documented result. Their relationship to intestinal barrier function and development of pathological changes requires direct, linked measurements [Sánchez-Recillas et al. 2026].

An earlier study by Sánchez-Recillas and colleagues in 2024 contributes direct measurement of fermentation products. The investigators prepared a fruit fraction remaining after modelled digestion, including an everted rat intestinal-sac stage, and then fermented it with a human faecal inoculum. The inoculum pooled material from two healthy donors. Samples were collected initially and after 6 and 24 hours. This design follows transformation of a defined substrate in a controlled microbial culture [Sánchez-Recillas et al. 2024].

Acetic, propionic and butyric acids were identified by retention-time comparison with standards and quantified using calibration curves in gas chromatography coupled to mass spectrometry. Butyrate increased between six and twenty-four hours. In parallel, the broad volatile-metabolite profile used tentative library-based assignments. Targeted acid measurements with standards and assignment of the wider profile therefore have different levels of analytical certainty [Sánchez-Recillas et al. 2024].

The comparison clarifies the proposed mechanism. The fermentation culture demonstrates production of measured compounds from the fruit fraction. The AOM/DSS experiment’s 16S profile demonstrates changes in bacterial representation within rats. Together, the findings motivate measurement of fermentation products in further animal experiments alongside tissue responses. The pooled inoculum from two people describes a selected microbial community and limits assessment of differences among donors [Sánchez-Recillas et al. 2024] [Sánchez-Recillas et al. 2026].

Juice concentrate in a model of metabolic disturbances

Another 2026 study examined juice concentrate from Myrtillocactus geometrizans in rats receiving a high-fat diet. After 140 days, metabolic indicators and microbiota composition based on the 16S rRNA gene were assessed. Betalains and flavonoid derivatives were identified in the concentrate. The available abstract describes changes in dominant bacterial phyla and selected genera, including Parabacteroides. Analyses of predicted microbial functions suggested links to fatty acid metabolism. This last result comes from functional prediction, whose scope differs from direct measurement of pathway activity [García-Chávez et al. 2026].

At the same time, supplementation did not significantly reverse the main metabolic alterations induced by the diet under the experimental conditions. This result defines the significance of the observed microbiota change. A single study can detect a bacterial community response alongside an absence of significant improvement in selected host parameters. Separating these outcomes permits precise questions about which microbial changes relate to organism function, at what exposure and with what persistence. The abstract supports further investigation of these relationships while retaining the clearly identified scope of the effect observed so far [García-Chávez et al. 2026].

A separate experiment involving the frontal cortex

A 2023 paper extends the range of measurements to the nervous system. It used 25 male Wistar rats divided into five groups. The feeding experiment lasted 24 weeks, with the fruit preparation administered intragastrically during the final four weeks in three treatments described as 150, 300 and 450 mg. The other groups received either a standard or a high-fat diet. Body weight and food consumption were recorded throughout. This arrangement defines the sequence of dietary exposure followed by administration of the preparation and distinguishes it from both experiments analysing microbiota [Sandoval-Salazar et al. 2023].

At the end of the experiment, high-performance liquid chromatography quantified glutamate, glutamine and gamma-aminobutyric acid, abbreviated GABA, in frontal cortex homogenates. A homogenate is a mixture prepared from disrupted tissue and allows compounds present in that tissue to be measured. The measurement therefore concerns the pool of substances in the sampled brain region. The study included this chemical analysis and feeding-related parameters. Assessing memory, behaviour or signalling at an individual synapse would require appropriate additional research methods [Sandoval-Salazar et al. 2023].

The result depends on the chosen measure

Final body weight in the groups receiving 300 and 450 mg of the preparation was lower than in the group receiving the high-fat diet alone. This effect was not demonstrated with the lowest treatment level. This is a comparison between groups at the end of an experiment during which the animals grew and gained weight. The finding can provide a starting point for investigating a mechanism, whose identification requires the contribution of specific constituents to be established. The authors did not examine individual polyphenols or their effects separately. Connecting the observations with antioxidant activity remains a proposed explanation requiring separate testing [Sandoval-Salazar et al. 2023].

Considering the rat experiments together clarifies the scope of the evidence. A microbiota profile, a metabolic indicator and a tissue concentration are separate variables. Here they come from different experiments involving different rats, preparations, treatment periods and methods of inducing alterations. Connecting these results into one sequence leading from fruit through bacteria to the brain would be an additional hypothesis. Testing it would require the relevant stages to be followed together in a planned experiment. Keeping the results distinct identifies concrete research directions for cactus fruit and helps match measurements to the biological question being asked [Sánchez-Recillas et al. 2026] [García-Chávez et al. 2026] [Sandoval-Salazar et al. 2023].

How these observations can be developed

Further experiments can combine a precisely characterised preparation with measurements of microorganisms, fermentation products and tissue responses in the same individuals. Larger independent samples and an explicit distinction between biological and technical replicates would help estimate variability in response. Processing methods and the fractions retained in the product also remain important for these fruits. The rat experiments and fermentation with a human inoculum complement one another by examining different stages of fruit-material transformation. Establishing effects in humans requires separate studies with a specified product and suitable endpoints, meaning concrete measures of the effect being evaluated [Sánchez-Recillas et al. 2026] [García-Chávez et al. 2026] [Sandoval-Salazar et al. 2023].