Influence of altitudinal variation on the anti-oxidant capacity of essential oil of Syzygium densiflorum from Southern Western Ghats, India

Background: Syzygium densiflorum is a vulnerable tree species belonging to the Myrtaceae family. Objective: To investigate the influence of altitudinal variation on the anti-oxidant potential of leaf essential oil of Syzygium densiflorum. Materials and Methods: The leaf essential oil has been isolated using hydrodistillation process and their scavenging ability was determined using five in vitro assays such as 2, 2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing anti-oxidant power (FRAP), 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), hydrogen peroxide (H 2 O 2 ) and hydroxyl radical scavenging assays. Statistical analysis: The results were analysed statistically using one-way analysis of variance (ANOVA) following Duncan′s multiple range test. Results: Leaves from lower altitude showed higher activity against hydrogen peroxide, hydroxyl radical and ferric ion and moderate activity against DPPH and ABTS free radicals. Leaves from higher altitude essential oil exhibits potent activity against hydrogen peroxide and hydroxyl radical compared with the standard. Conclusions: Comparatively lower altitude leaf essential oil showed potent anti-oxidant activity confirming the fact that altitudinal variations have profound effect on the anti-oxidant potential of Syzygium densiflorum

Metabolomic insights into the mechanisms underlying tolerance to salinity in different halophytes

Salinity is among the most detrimental and diffuse environmental stresses. Halophytes are plants that developed the ability to complete their life cycle under high salinity. In this work, a mass spectrometric metabolomic approach was applied to comparatively investigate the secondary metabolism processes involved in tolerance to salinity in three halophytes, namely S. brachiata, S. maritima and S. portulacastrum. Regarding osmolytes, the level of proline was increased with NaCl concentration in S. portulacastrum and roots of S. maritima, whereas glycine betaine and polyols were accumulated in S. maritima and S. brachiata. Important differences between species were also found regarding oxidative stress balance. In S. brachiata, the amount of flavonoids and other phenolic compounds increased in presence of NaCl, whereas these metabolites were down regulated in S. portulacastrum, who accumulated carotenoids. Furthermore, distinct impairment of membrane lipids, hormones, alkaloids and terpenes was observed in our species under salinity. Finally, several other nitrogen containing compounds were involved in response to salinity, including amino acids, serotonin and polyamine conjugates. In conclusion, metabolomics highlighted that the specific mechanism each species adopted to achieve acclimation to salinity differed in the three halophytes considered, although response osmotic stress and oxidative imbalance have been confirmed as the key processes underlying NaCl tolerance