Effect of Ducrosia flabellifolia and Savignya parviflora Extracts on Inhibition of Human Colon and Prostate Cancer Cell Lines

The goal of this study was to investigate whether Ducrosia flabellifolia and Savignya parviflora methanol extract the have effect on colon and prostate cancer cell lines. Analysis of total content of phenolics and flavonoids of each plant extract was carried out. Cytotoxic effect, cell cycle analysis, induction of apoptosis and gene expression of Bcl-2 and Bax genes were studied. Obtained results indicated that, the plant extracts exhibit growth inhibition of used cancer cell lines and induced apoptosis as well as arresting of cell cycle. At the molecular level, changes in gene expression were detected via qPCR and confirmed by western blotting. The exhibited anticancer potentialities of plant extracts against utilized cancer cell lines are due to its containing bioactive compounds. Further detailed isolation, fractionation and characterization of bioactive compounds are needed.     

A morpho-anatomical characterisation of Myrothamnus moschatus (Myrothamnaceae) under the aspect of desiccation tolerance

Morpho-anatomical traits of the rarely studied dicotyledonous desiccation-tolerant shrub Myrothamnus moschatus were examined and compared for the first time to Myrothamnus flabellifolius under the aspect of desiccation tolerance. Both species almost exclusively occur on rock outcrops and differ mainly in their geographic range and leaf morphology (fan-shaped in M. flabellifolius, lanceolate in M. moschatus) but have a very similar leaf and wood anatomy, except for the lack of hydathodes in M. moschatus. Both species adopt the parallel leaf venation of monocots, although this is more pronounced in M. moschatus. This provides a mechanical and protective advantage over the net venation pattern of most dicots and facilitates the reversible, drought-induced, accordion-like leaf contraction. The sclerenchyma, as a stabilising tissue, is mainly confined to vascular bundles in leaves of both species. Here, mechanical support seems to be less crucial for survival in long periods of drought than other morpho-anatomical traits (e.g. parallel leaf venation).     

A novel cold-inducible gene from Arabidopsis,RCI3, encodes a peroxidase that constitutes a component for stress tolerance

Myrothamnus flabellifolia, a short woody shrub from southern Africa, can survive severe desiccation of its vegetative organs. We studied mechanisms protecting this plant from oxidative damage during desiccation for 2 weeks, 4 and 8 months, and also during subsequent rehydration. This plant retains high concentrations of chlorophyll during desiccation, and these chlorophyll molecules are probably a source for potentially harmful singlet oxygen production. Desiccation triggered substantial increases in zeaxanthin and redox shifts of the antioxidants glutathione and ascorbate towards their oxidised forms. Simultaneously, the concentrations of violaxanthin, beta-carotene, ascorbate, alpha-tocopherol, and glutathione reductase activity progressively decreased. Antheraxanthin, gamma-tocopherol, lutein, neoxanthin and glucose-6-phosphate dehydrogenase displayed less pronounced changes in response to desiccation. Even after 4 months of desiccation, Myrothamnus flabellifolia recovered rapidly upon rehydration. Re-watering induced formation of ascorbate and glutathione, simultaneous reduction of their oxidised forms, and rapid production of alpha-tocopherol and of various carotenoids. Only after 8 months of desiccation did the antioxidant system of M. flabellifolia break down; 3 weeks after the onset of rehydration, these plants abscised their leaves, but even then they were still able to recover and develop new ones. Ascorbate, beta-carotene and alpha-tocopherol were totally depleted after 8 months of desiccation and did not recover upon rehydration; glutathione was partly maintained, but only in the oxidised form. We present a model demonstrating which parts of antioxidant pathways break down as oxidative stress becomes detrimental and we discuss some potential implications of our results for the genetic modification of crop plants to improve their drought tolerance.     

The unusual sugar composition in leaves of the resurrection plant Myrothamnus flabellifolia

To understand mechanisms of osmoprotection, the composition of sugars and related compounds were analyzed in extracts of fully hydrated and desiccated leaves of the desiccation-tolerant resurrection plant Myrothamnus flabellifolia . During the dehydration process the concentrations of fructose and glucose decrease, whereas sucrose, arbutin and glucopyranosyl-β-glycerol increase. The substances were identified by GC-MS and NMR-analyses. This is the first report of large amounts of glucopyranosyl-β-glycerol in higher plants which may act as an osmoprotectant. Significant levels of the nonreducing sugar trehalose were present in all samples tested.     

Marginal and laminar hydathode-like structures in the leaves of the desiccation-tolerant angiosperm Myrothamnus flabellifolius Welw.

The fan-shaped leaves of the resurrection plant Myrothamnus flabellifolius Welw. fold during episodes of drought and consequent desiccation of the tissue. The leaf teeth of M. flabellifolius have several features characteristic of hydathodes. Tracheary elements from the three vein endings that converge in each leaf tooth subtend and extend into a cluster of cells significantly smaller than those of the adjacent mesophyll. The stomata overlying this putative epithem are larger than the other stomata on the leaf surface. Crystal violet is absorbed via these stomata in non-transpiring leaves, suggesting that they are water pores. Two to four such water pores occur per hydathode and are readily distinguished in desiccated leaves. Laminar hydathodes apparently also occur in the leaves of M. flabellifolius. Branched vein endings that terminate in short, wide tracheary elements subtend the outer edges of the abaxial leaf ridge, which otherwise lack stomata, and coincide with regions of crystal violet uptake. Guttation could not be induced in M. flabellifolius. However, desiccated leaves readily absorb liquid water through the leaf surface. The use of Calcafluor White to trace the pathway of apoplastic water movement suggests a role for both types of hydathode in foliar water uptake during rehydration while the accumulation of Sulphorhodamine G (indicating solute retrieval from the apoplast) in the epithem of transpiring plants suggests the hydathodes may be a pathway of water loss in the desiccating leaf.     

Essential‐Oil Polymorphism in the ‘Resurrection Plant’ Myrothamnus moschatus and Associated Ethnobotanical Knowledge

Gas chromatography/mass spectroscopy analysis (GC/MS) of essential oils obtained from populations of the resurrection plant Myrothamnus moschatus, growing in different areas of Madagascar, allowed identification of three main chemotypes in the species. The first one was provided by plants with a high content of trans‐pinocarveol and pinocarvone; the second one involved plants with high percentages of limonene, cis‐ and trans‐p‐mentha‐1(7),8‐dien‐2‐ol, and β‐selinene; and the third chemotype was characterized by plants with high levels of oxygenated sesquiterpenes such as caryophyllene oxide and α‐ and β‐isomers of caryophylla‐4(12),8(13)‐dien‐5‐ol. Chemical data were supported by chemometric technique as the principal component analysis. Furthermore, the relationship between the dioecy and phytochemistry within one population was also considered. Finally, correlations between chemical variations and ethnobotanical data were assessed.