A histological analysis was performed with the aim of elucidating the spontaneous regeneration process of the hairy root lines LRT 2.3 and LRT 6.4, derived from Lopezia racemosa leaf explants and genetically transformed with the Agrobacterium rhizogenes strain ATCC15834/pTDT. The analysis showed both lines regenerate via indirect somatic embryogenesis; LRT 6.4 also regenerated by direct organogenesis. The morphogenic characteristics of the regenerated plantlets from both lines showed the typical characteristics, described previously, including a higher number of axillary shoot formation, short internodes, and plagiotropic roots compared with wild-type seedlings. The regeneration process occurred without the addition of plant growth regulators and was linked to the sucrose concentration in the culture medium. Reducing the sucrose concentration from 3% to 2%, 1%, and 0.5% increased the regeneration rate in LRT 6.4; the effect was less pronounced in LRT 2.3. The cytotoxic activity of different organic extracts obtained from roots and shoots were evaluated in the cancer cell lines HeLa (cervical carcinoma), HCT-15 (colon adenocarcinoma), and OVCAR (ovary carcinoma). The hexane and dichloromethane extracts from roots of both lines showed cytotoxic activity against the HeLa cell line. Only the dichloromethane extract from the roots of PLRT 2.3 showed cytotoxic activity against the OVCAR cell line. None of the methanol extracts showed cytotoxic activity, nor the shoot extracts from any solvent.

Lopezia racemosa Cav., commonly known as “cancer herb” in indigenous communities, has long been used for its medicinal properties. The biotechnological production of its bioactive compounds through genetic transformation represents a valuable approach for obtaining pharmacologically relevant substances. The initial focus of this study was to identify compounds previously reported in the species; however, phytochemical analysis by HPLC and NMR led to the isolation and identification of two pentacyclic triterpene esters not previously described in L. racemosa: 3-O-[(E)-feruloyl]-maslinic acid (1) and 3-O-[(E)-feruloyl]-corosolic acid (2), identified as constituents of fraction 33. The LRTC3.1 callus line was obtained from hairy roots generated by infecting L. racemosa leaf explants with Agrobacterium rhizogenes strain ATCC15834/pTDT. The crude extract, specific fractions, and the mixture of these compounds demonstrated significant anti-inflammatory and cytotoxic activities. Anti-inflammatory activity was evaluated using the carrageenan-induced mouse paw edema model, where the crude extract achieved 51.02% inhibition of inflammation compared to meloxicam (30.86%). Cytotoxicity was assessed against three human cancer cell lines: breast carcinoma (MCF7), cervical carcinoma (SiHa), and colon carcinoma (HCT-15). Fractions FD (28–29) and 33 exhibited potent cytotoxic effects, with IC₅₀ values of 0.508 and 1.345 µg/mL against SiHa cells, and 0.053 and 2.693 µg/mL against MCF-7 cells, respectively. These findings suggest that transformed L. racemosa cultures represent a promising source of bioactive compounds for potential therapeutic development.

Hydrogen peroxide (H₂O₂) regulates plant metabolism. This study examined its effect on the biosynthesis of specialized metabolites in Baccharis conferta, a medicinal plant rich in phenolics and terpenes. Plants were elicited with 25 µM and 250 µM H₂O₂. Phenolic changes were evaluated by total phenolic content (TPC), total flavonoid content (TFC), phenylalanine ammonia-lyase (PAL) activity, and LC-MS analysis of flavonoids and hydroxycinnamic acids. Meanwhile, terpene changes were evaluated by HPTLC, total terpene content (TTC), and expression of the 1-deoxy-D-xylulose-5-phosphate synthase (Bco-DXS1) gene. H₂O₂ markedly modulated both pathways. Phenolic metabolism was activated, particularly under 25 µM H₂O₂, with PAL activity increasing by 52%, TPC by 42%, and TFC by 50% relative to the control. Chemical analysis revealed that five compounds, including chlorogenic acid, differed significantly across treatments. Gene expression analysis showed that 25 µM H₂O₂ upregulated Bco-DXS1 and increased TTC, whereas 250 µM H₂O₂ repressed gene expression but still enhanced terpene accumulation. Overall, these results suggest that moderate H₂O₂ levels function as a signaling molecule in B. conferta, simultaneously boosting phenolic and terpene pathways. This highlights controlled H₂O₂ elicitation as an effective biotechnological approach to increase the production of valuable metabolites in medicinal plant cultures.