In Vitro Propagation, Genetic Assessment, and Medium-Term Conservation of the Coastal Endangered Species Tetraclinis Articulata (Vahl) Masters (Cupressaceae) from Adult Trees

Tetraclinis articulata (Vahl) Masters is an endangered tree growing in coastal and arid environments that is widely exploited by the timber and resin industry, among other applications. In this context, the use of in vitro techniques is highly encouraged for its propagation. We present a protocol for micropropagation using twigs from adult trees as a source of explants. The Schenk and Hildebrandt basal medium (SH) supplemented with 30 g L−1 sucrose, 6.5 g L−1 plant agar, 4.0 mg L−1 6-benzyladenine (BA), and 0.05 mg L−1 1-naphthaleneacetic acid (NAA) provided the optimum multiplication rate (90.48 ± 9.52 explants with basal shoots and 2.58 ± 0.29 basal shoots per explant). Application of activated charcoal (AC) or ½ Knop solution in a liquid overlay produced significantly longer shoots. Supplementation of solid media with indole-3-butyric acid (IBA) or NAA gave low rooting percentages (<17%). Addition of 0.9 g L−1 AC improved rooting (40%) but rooting performance was optimal (66.7%) after a pulse treatment consisting of 4 h immersion in liquid SH medium without growth regulators, followed by 8 weeks of cultivation. Rooted microplants were successfully acclimatized (93.33%) in a peat moss and vermiculite mixture (1:1 v/v ratio). The genetic stability of the in vitro regenerated plantlets was confirmed using the randomly amplified polymorphic DNA (RAPD) technique. Explant survival and growth remained higher than 90% after 28 weeks of cold storage at both 4 °C and 10 °C. The protocol presented here allows for largescale T. articulata production and could be applied for both ex situ conservation strategies and industrial purposes.

Screening for Selective Anticancer Activity of 65 Extracts of Plants Collected in Western Andalusia, Spain

Finding cytotoxic drugs with a high selectivity towards cancer cells is crucial to improve the low survival rates of patients diagnosed with metastatic cancers. Since plants are an important source of anticancer drugs, we have screened 65 extracts from 45 plants collected in several areas of Western Andalusia (Spain) for cytotoxic activity on lung cancer cells versus lung normal cells. An extract from the leaves of Tetraclinis articulata (Vahl) Mast. (Cupressaceae) showed a marked cytotoxicity (IC50 = 0.37 ± 0.03 μg/mL) and selectivity (selectivity index = 378.3) against the lung cancer cells; cisplatin, 5-fluorouracil, and an extract from the leaves of Taxus baccata L. (Taxaceae) were less cytotoxic and selective. Extracts from Cascabela thevetia (L.) Lippold (Apocynaceae), Frangula alnus Mill. (Rhamnaceae), Iberis ciliata subsp. contracta (Pers.) Moreno (Brassicaceae), Juniperus macrocarpa Sm (Cupressaceae), and Pancratium maritimum L. (Amaryllidaceae) also showed selective cytotoxicity (selectivity index > 10). Active extracts were also tested against a panel of cancer cell lines from a variety tissues. The plants identified in this work are potential sources of natural compounds with selective toxicity towards cancer cells.

Enhancing the Resilience of a Mediterranean Forest to Extreme Drought Events and Climate Change: Pinus—Tetraclinis Forests in Europe

The southeast Iberian Peninsula is the only place in the European Community where Tetraclinis articulata (Vahl) Masters populations are native. In this area, the optimal ecological niche for this species is occupied by Pinus halepensis (Miller). The increasing intensity of extreme drought events induced by climate change causes severe declines in pine forests, while providing expansion opportunities for established Tetraclinis populations. Within the framework of the LIFE-TETRACLINIS project, a study has been designed to simulate the pine forest decline effects on the population dynamics of this protected species. This work investigates the effects of decreasing competition on T. articulata specimens with limited reproductive activity. To induce the reproductive activity of these specimens through increasing the availability of light, the surrounding pines were removed within a 15 m radius. Increased light availability was modelled using “Light Detection And Ranging” (LiDAR) data, and changes in the main reproductive parameters were registered throughout the study period. A significant increase in the reproductive population was achieved, as well as the cones produced per specimen and the recruitment. Findings obtained are promising for the habitat management in continental Europe and enhancing this forest system’s resilience to extreme drought events and climate change.

Chemical Composition and Cytotoxic Activity of the Fractionated Trunk Bark Essential Oil from Tetraclinis articulata (Vahl) Mast. Growing in Tunisia

The aim of the present research was to determine the chemical composition and the cytotoxic effects of Tetraclinis articulata trunk bark essential oil (HEE) obtained by steam distillation and five fractions obtained by normal phase silica chromatographic separation. Chemical analysis allowed the identification of 54 known compounds. Relatively high amounts of oxygenated sesquiterpenes (44.4–70.2%) were detected, mainly consisting of caryophyllene oxide (13.1–26.6%), carotol (9.2–21.2%),14-hydroxy-9-epi-(E)-caryophyllene (3.2–15.5%) and humulene epoxide II (2.6–7.2%). The cytotoxic activity against human mammary carcinoma cell lines (MDA-MB-231) and colorectal carcinoma cell lines (SW620) of the essential oil and its fractions were assessed. All the samples displayed moderate to weak activity compared to 5-fluorouracil. The colorectal carcinoma cell line was relatively more sensitive to the essential oil and its fractions compared to the breast cancer cell line, showing IC50 values from 25.7 to 96.5 μg/mL. In addition, the essential oil and its fraction E.2 revealed a cytotoxic activity against colorectal carcinoma cell line, with IC50 values lower than 30 μg/mL. This is the first report on the chemical composition and cytotoxic activity of the trunk bark essential oil of T. articulata.