Sechium compositum (Cucurbitaceae) is a wild species that is distributed in the Soconusco region, Chiapas, Mexico, and the border with Guatemala. This species has an intangible biochemical value resulting from the pharmacological relevance of its secondary metabolites. However, as a consequence of the lack of knowledge about its importance, it is being displaced from its habitat at an accelerated rate, incurring the risk of genetic loss. Therefore, an in vitro culture protocol with two experimental phases was evaluated to propagate, conserve, and regenerate this species. The first phases considered the multiplication of seedlings, adding seven concentrations (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mg mL-1) of 6-benzylaminopurine (BA) and thidiazuron (TDZ) and evaluating the number of buds, shoots, and seedling height. The best multiplication response was recorded with 0.1, 0.2, 0.4, and 1.0 mg L-1 of BA and 0.1 mg L-1 of TDZ, as well as the MS base culture medium. With 0.1 mg L-1 of BA, 52-mm height, 1.36 shoots, and 9.22 buds were obtained, surpassing the MS control (MS culture medium alone); likewise, twice more roots (80%) and a 14% reduction in the bud structure were packed in 50 repetitions. The second phase consisted of inducing callus formation from stem and leaf explants through the addition of 0.5, 1.0, and 2.0 mg L-1 of TDZ and 2,4-Dichlorophenoxyacetic acid (2,4-D) to the medium. The results demonstrated that the induction of callogenesis in S. compositum has a better start from the stem in a medium with 2.0 mg L-1 of 2,4-D, whose value was 4.89 —equivalent to 97.8% callus formation around the explant. The addition of 500 mg L-1 of polyvinylpyrrolidone (PVP) is also suggested to reduce oxidation. This protocol represents a significant advance in the conservation, multiplication, and callogenesis of S. compositum and contributes to its rescue and revaluation in the face of the danger of extinction.

The aim was to determine the effect of Sechium edule var. nigrum spinosum (chayote) on gene ex-pression related to antioxidant protection mechanisms and the inflammatory process in older adults with metabolic syndrome (MetS). A quasi-experimental study was carried out in a con-venience sample of 46 older adults diagnosed with MetS: (i) placebo group (PG; n=20), (ii) ex-perimental group (EG; n=26). Clinical, biochemical, and anthropometric parameters, SOD, GPx, and CAT enzyme activity, total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), cytokines (IL-6, IL-8 and TNF-α) and mRNA expression of (SOD, GPx, CAT, IL-6, IL-8, TNF-α, Nrf2, NFkB p50 and NFkB p65), were measured at baseline and 6 months post-intervention. A statistically significant decrease was observed in TOS (baseline, 28.9 ± 3.6 vs. post, 23.7 ± 3.4, p < 0.01) and OSI (baseline, 24.1 ± 3.8 vs. post, 17.7 ± 4). As well as the increase in IL-6 (baseline, 10.7 ± 1.1 vs. post, 12.3 ± 2, p = 0.03), SOD activity (baseline, 167.1 ± 11.9 vs. post, 180.6 ± 7.6, p < 0.05), CAT activity (baseline, 1.0 ± 0.2 vs. post, 1.3 ± 0.2, p < 0.01) and TAS (baseline, 1.1 ± 0.1 vs. post, 1.4 ± 0.1, p < 0.01) in the EG compared to the PG. Regarding the expression of Nrf2, SOD and IL-6, the EG showed a significant increase vs basal levels (47%, 44% and 43%, re-spectively). Our findings suggest that Sechium edule supplementation promotes the antioxidant response and decreases oxidative stress via Nrf2.