Variation in cultivars can influence plant biological activities. This study aimed to identify superior cultivars while determining the variability in the phytochemical content, antioxidant, alpha-glucosidase inhibitory and antibacterial activities of cladode extracts from selected spineless Burbank cactus pear (Opuntia ficus-indica and Opuntia robusta) cultivars. Total phenolic and flavonoid contents were determined using the Folin-Ciocalteu and aluminum chloride spectrophotometric methods, respectively. Antioxidant activity was investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and β-carotene linoleic acid assays. Alpha-glucosidase inhibition was determined using a spectrophotometric method and antibacterial activity using a non-polar (petroleum ether) and polar (50% methanol) extracts against two Gram-positive and two Gram-negative bacteria. Significant variation in phytochemical content, antioxidant, antidiabetic and antibacterial activities was observed amongst the cultivars. Alpha-glucosidase inhibitory activity varied widely with IC₅₀ values ranging from 0.06 to 1.85 mg/mL. Radical scavenging activity of Polypoly cultivar was about seven fold higher than that recorded in other cultivars with low activity. Turpin and Berg x Mexican cultivars had the highest total phenolic and flavonoid contents, whilst the non-polar extract of Turpin also exhibited higher antibacterial activity against Bacillus subtilis and Escherichia coli. Sicilian Indian Fig was amongst the cultivars with a higher antioxidant activity, whilst also showing a strong inhibition against B. subtilis and E. coli. Polypoly cultivar demonstrated strong antioxidant and antidiabetic activities while its polar extract showed the highest total antibacterial activity against B. subtilis. The cultivar Malta was superior in terms of its antibacterial potency and efficacy against B. subtilis, Staphylococcus aureus and E. coli. The potential of using spineless cactus pear cladodes as a functional food with antioxidant, antidiabetic and antibacterial properties against pathogenic food spoilage bacteria in place of synthetic compounds was established. The significance of cultivar selection to increase this potential was highlighted.

Effective in vitro propagation of medicinal and aromatic plants such as Thymus vulgaris is often limited by the choice of optimal cytokinin sources, which are critical for successful shoot proliferation and overall regeneration. Since their discovery, topolins have been recognized as alternatives to traditional cytokinins (CKs) such as benzyladenine (BA) and kinetin (Kin) in plant tissue culture (PTC). This study investigated the influence of three aromatic CKs (meta-topolin (mT), BA, and Kin), on shoot proliferation of thyme, with the goal of improving current PTC protocols. Of all the tested treatments, the highest shoot proliferation (7.25 ± 0.72 shoots per nodal explant) was observed in the treatment with 1 µM mT, superior to BA and Kin. Increasing mT and BA concentrations from 1 to 15 µM had an inverse effect on shoot production. The addition of indole-3-butyric acid (IBA) at concentrations ranging from 1.0 to 5.0 µM in combination with 0.5 and 1 µM mT did not increase the mean shoot numbers per explant. Regenerated shoots exhibited a strong propensity for root development even in the absence of plant growth regulators with 100% survival ex vitro. This study demonstrated that mT is an effective, sustainable and cost-effective alternative to traditional CKs for in vitro propagation of T. vulgaris, achieving an improved shoot proliferation with 1 μM mT application.