Curcuma longa (C. longa) is widely known for its medicinal properties. However, the potential overexploitation of this plant raises doubts about its long-term survival on Rapa Nui. Micropropagation using a temporary immersion system (TIS) could be the basis for developing a cost-effective and highly productive method of large-scale cultivation of this plant. Our objective was to develop and refine the in vitro multiplication system for mass propagation of C. longa, and thus help restore the fragile ecosystem of Rapa Nui. Three parameters were evaluated: number of explants per flask, flask capacity, and LEDs spectrum. For each parameter evaluated, four aspects were analyzed: fresh weight per plant, number of shoots, percentage of non-sprouting explants, and the proliferation rate. The use of 30 explants per two-liter flask results in more plants with high fresh biomass than other configurations. In addition, LEDs with a red:blue ratio of 2:1 provided the best lighting conditions for in vitro propagation and positively affected C. longa proliferation and rooting. Therefore, our results show that 30 explants per two-liter flask and an LED source with a red:blue ratio of 2:1 allow a higher number of C. longa plants to be obtained using TIS.

Curcuma longa (C. longa), an herbaceous plant used for medicinal purposes by the indigenous people of Easter Island, has been overexploited in its natural habitat, leading to its conservation status being designated as a vulnerable species. We have recently reported on the use of light-emitting diodes (LEDs) to improve the productivity of C. longa in vitro cultures under a temporary immersion system (TIS), but the effects of light quality on plant growth, phytochemical composition, and antioxidant capacity remained unexplored. Here, we set out to study these three aspects as observed at the end of TIS culture (day 0) and after 30 days of greenhouse acclimation (day 30). Thus, we evaluated plant morphological characteristics, phytochemical profile (polyphenols, tannins, flavonoids, reducing sugars, and curcumin), and radical scavenging activity by DPPH, ORAC, and FRAP assays. The results showed that, during in vitro cultivation under TIS, the red:blue (RB) LED light spectrum promoted C. longa shoot proliferation, with the resulting seedlings exhibiting greater fresh weight and no signs of etiolation. In the acclimation phase, the RB spectrum increased phytochemicals, such as polyphenols, flavonoids, and reducing sugars, and boosted curcumin synthesis. Nevertheless, the antioxidant activity of the plants under the RB light spectrum did not intensify. We surmise that this may be due to the premature intraplant allocation of metabolites to alternative pathways (e.g., curcumin synthesis) under RB light.

Microsorum scolopendia (MS), which grows on the Chilean island of Rapa Nui, is a medicinal fern used to treat several diseases. Despite being widely used, this fern has not been deeply investigated. The aim of this study was to perform a characterization of the polyphenolic and flavonoid identity, radical scavenging, antimicrobial, and anti-inflammatory properties of MS rhizome and leaf extracts (RAE and HAE). The compound identity was analyzed through the reversed-phase high-performance liquid chromatography (RP-HPLC) method coupled with mass spectrometry. The radical scavenging and anti-inflammatory activities were evaluated for DPPH, ORAC, ROS formation, and COX inhibition activity assay. The antimicrobial properties were evaluated using an infection model on Human Dermal Fibroblast adult (HDFa) cell lines incubated with Staphylococcus aureus and Staphylococcus epidermidis. The most abundant compounds were phenolic acids between 46% to 57% in rhizome and leaf extracts, respectively; followed by flavonoids such as protocatechic acid 4-O-glucoside, cirsimaritin, and isoxanthohumol, among others. MS extract inhibited and disaggregated the biofilm bacterial formed and showed an anti-inflammatory selective property against COX-2 enzyme. RAE generated a 64% reduction of ROS formation in the presence of S. aureus and 87.35% less ROS in the presence of S. epidermidis on HDFa cells. MS has great therapeutic potential and possesses several biological properties that should be evaluated.

Endemic medicinal plants that grow at altitudes in northern Chile have been traditionally used for therapeutic applications by Aymara doctors. Several studies have analyzed the biological properties of these plants for therapeutic purposes. The aim was to characterize at molecular and biochemical levels the bacteria that live in the rhizosphere and roots from endemic medicinal plants that grow between 3681–5104 m.a.s.l. in the province of Parinacota. Thirty-nine bacteria were isolated from nine medicinal plants under our laboratory conditions. These bacteria were characterized by Gram stain, hydrolase production, plant-growth promotion, anti-fungal and antibacterial activities, and 16S rDNA sequencing. A phylogenetic study revealed the presence of three major phyla, Actinomycetota (46.2%), Bacillota (43.6%), and Pseudomonadota (10.3%). The rhizobacteria strains associated with the Aymara medicinal plant exhibited several interesting biological activities, such as hydrolytic enzymes, plant-growth-promoting traits, and antibacterial and antifungal properties, indicating their potential for developing new bio-based products for agricultural or clinical applications. These results are promising and highlight the need to point toward the search for explanations of the bio-molecular basis of the therapeutic effects of medicinal plants.