Variation in phenolic constituents and antioxidant capacities of plant organs of three Cuban species of Pluchea Cass. (Asteraceae) under ex vitro and in vitro growth conditions.

The phenolic content and antioxidant capacity of Cuban Pluchea species extracts were measured by polar extraction technique with the aim to optimize antioxidant-rich extracts. Our results highlighted the variability of the phenolic content and antioxidant potential in the genus Pluchea according to the species and plant organs. The antioxidant capacity and phenolics were additionally examined in P. carolinensis under various growth conditions, ex vitro (location, age, and harvest time) and in vitro (amount of added cytokinin). Some specific phenolic compounds were monitored during the harvest time. Leaves proved to be richest in antioxidants, followed by inflorescences. The antioxidant capacity of P. carolinensis (DPPH: 103.2 ±1.3 mg TE/g DW; ORAC: 254.4 ±14.2 mg TE/g DW) and P. rosea (DPPH: 97.2 ±5.9 mg TE/g DW ORAC: 286.7 ±23.7 mg TE/g DW) leaf extracts were higher than that measured in material from various plant species, including fruits, vegetables and condiments. adult P. carolinensis grown in a natural environment and harvested in winter showed the highest phenolic content and antioxidant activity. A micropropagation protocol was developed for P. carolinensis. The presence of cytokinin in the in vitro culture medium increased the antioxidant capacity in leaves, but the level remained lower than in natural plants.