Increasing salinity leads to differential growth and H2O2 homeostasis in plants produced from heteromorphic seeds of the succulent halophyte Arthrocnemum indicum.

Information about responses of plants grown from heteromorphic seeds is limited and inconclusive. This is especially true of subtropical halophytes where such studies have yet to be published. Therefore, growth, water-relations, and oxidative stress mitigation of plants germinated from the heteromorphic seeds of the succulent halophyte Arthrocnemum indicum under increasing (0, 300, and 900 mM NaCl) salinity were studied. Growth of plants from only small seeds was stimulated in moderate (300 mM NaCl) salinity. High (900 mM NaCl) salinity inhibited the growth of plants emerged from both small and large sized seeds. Plants germinating from both seed sizes demonstrated similar patterns of osmotic adjustment and did not develop signs of oxidative damage under increasing salinity. However, the magnitude of hydrogen peroxide and antioxidant responses differed between plant types. Under moderate salinity, plants from small seeds showed constitutive activities of most antioxidant enzymes (except superoxide dismutase) and levels of non-enzymatic antioxidants (except ascorbate). Conversely, a decline in activities of most antioxidant enzymes and levels of most non-enzymatic antioxidants occurred in plants from large seeds. While under high salinity, increased ascorbate peroxidase, glutathione, and polyphenol levels, along with unaffected ascorbate and superoxide dismutase levels, occurred in plants from small seeds. In plants from large seeds, there were increased ascorbate and polyphenol levels, but changes to the ascorbate peroxidase levels were not observed. These results thus indicate differential growth and hydrogen peroxide homeostasis in A. indicum plants emerged from heteromorphic seeds.

RP-HPLC-based phytochemical analysis and diverse pharmacological evaluation of Quercus floribunda Lindl. ex A. Camus nuts extracts.

Quercus floribunda Lindl. ex A. Camus nuts have important folklore uses, assessed for underexplored biological potential. Nuts galls or cores and coats were utilized for the preparation of extracts using 14 solvent systems. Antioxidant, antimicrobial, cytotoxic and enzyme inhibition assays along with phytochemical profiling was carried out. Distilled water cores extract demonstrated maximum percent yield, phenolics content and total antioxidant capacity. Methanol: ethyl acetate cores extract showed maximum flavonoids content, total reducing power and protein kinase inhibition. Highest percentage radical scavenging and brine shrimp lethality was revealed by acetone: distilled water cores extract. Ethyl acetate cores extract indicated maximum α-amylase inhibition. Methanol: water coats extract showed substantial leishmanial growth inhibition. n-Hexane and chloroform coats extracts showed maximum cytotoxicity against HepG2 and THP-1 cell lines, respectively. Polyphenols quantified through RP-HPLC analysis were quercetin, pyrocatechol, gallic acid, catechin and chlorogenic acid ranging from 0.003 ± 0.001 to 1.785 ± 0.5 µg/mg extract.

Salt induced modulations in antioxidative defense system of Desmostachya bipinnata.

This study addressed the interactions between salt stress and the antioxidant responses of a halophytic grass, Desmostachya bipinnata. Plants were grown in a semi-hydroponic system and treated with different NaCl concentrations (0 mM, 100 mM, 400 mM) for a month. ROS degradation enzyme activities were stimulated by addition of NaCl. Synthesis of antioxidant compounds, such as phenols, was enhanced in the presence of NaCl leading to accumulation of these compounds under moderate salinity. However, when the ROS production rate exceeded the capacity of enzyme-controlled degradation, antioxidant compounds were consumed and oxidative damage was indicated by significant levels of hydrogen peroxide at high salinity. The cellular concentration of salicylic acid increased upon salt stress, but since no direct interaction with ROS was detected, a messenger function may be postulated. High salinity treatment caused a significant decrease of plant growth parameters, whereas treatment with moderate salinity resulted in optimal growth. The activity and abundance of superoxide dismutase (SOD) increased with salinity, but the abundance of SOD isoforms was differentially affected, depending on the NaCl concentration applied. Detoxification of hydrogen peroxide (H2O2) was executed by catalase and guaiacol peroxidase at moderate salinity, whereas the enzymes detoxifying H2O2 through the ascorbate/glutathione cycle dominated at high salinity. The redox status of glutathione was impaired at moderate salinity, whereas the levels of both ascorbate and glutathione significantly decreased only at high salinity. Apparently, the maximal activation of enzyme-controlled ROS degradation was insufficient in comparison to the ROS production at high salinity. As a result, ROS-induced damage could not be prevented, if the applied stress exceeded a critical value in D. bipinnata plants.

Polarity based characterization of biologically active extracts of Ajuga bracteosa Wall. ex Benth. and RP-HPLC analysis.

BACKGROUND: The concept of botanical therapeutics has revitalized due to wide importance of plant derived pharmaceuticals. Therefore, the ameliorative characteristics of Ajuga bracteosa were studied. METHODS: Total phenolic content, flavonoid content, antioxidant capacity, reducing power and free-radical scavenging activity were determined colorimetrically. Specific polyphenols were quantified by RP-HPLC analysis. Preliminary cytotoxicity was tested using brine shrimp lethality assay while antiproliferative activity against THP-1 and Hep-G2 cell lines was determined by MTT and SRB protocols respectively. Antileishmanial potential was assessed via MTT colorimetric method. To investigate antidiabetic prospect, α-amylase inhibition assay was adopted whereas disc diffusion method was used to detect likely protein kinase inhibitory, antibacterial and antifungal activities. RESULTS: Among fifteen different extracts, maximum total phenolic content (10.75 ± 0.70 µg GAE/mg DW), total reducing power (23.90 ± 0.70 µg AAE/mg DW) and total antioxidant capacity (11.30 ± 0.80 µg AAE/mg DW) were exhibited by methanol extract with superlative percent extract recovery (17.50 ± 0.80% w/w). Chloroform-methanol extract demonstrated maximum flavonoid content (4.10 ± 0.40 µg QE/mg DW) and ethanol extract exhibited greatest radical scavenging activity (IC50 14.40 ± 0.20 µg/ml). RP-HPLC based quantification confirmed polyphenols such as pyrocatechol, gallic acid, resorcinol, catechin, chlorogenic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, vanillic acid, coumarin, sinapinic acid, trans-cinnamic acid, rutin, quercetin and kaempferol. The brine shrimp lethality assay ranked 78.60% extracts as cytotoxic (LC50 ≤ 250 µg/ml) whereas significant THP-1 inhibition was shown by methanol-acetone extract (IC50 4.70 ± 0.43 µg/ml). The antiproliferative activity against Hep-G2 hepatoma cancer cell line was demonstrated by n-hexane, ethylacetate and methanol-distilled water (IC50 8.65-8.95 µg/ml) extracts. Methanol extract displayed prominent protein kinase inhibitory activity (MIC 12.5 µg/disc) while n-hexane extract revealed remarkable antileishmanial activity (IC50 4.69 ± 0.01 µg/ml). The antidiabetic potential was confirmed by n-hexane extract (44.70 ± 0.30% α-amylase inhibition at 200 µg/ml concentration) while a moderate antibacterial and antifungal activities were unveiled. CONCLUSION: The variation in biological spectrum resulted due to use of multiple solvent systems for extraction. We also deduce that the valuable information gathered can be utilized for discovery of anticancer, antileishmanial, antioxidant and antidiabetic bioactive lead candidates.

Polarity directed optimization of phytochemical and in vitro biological potential of an indigenous folklore: Quercus dilatata Lindl. ex Royle.

BACKGROUND: Plants have served either as a natural templates for the development of new chemicals or a phytomedicine since antiquity. Therefore, the present study was aimed to appraise the polarity directed antioxidant, cytotoxic, protein kinase inhibitory, antileishmanial and glucose modulatory attributes of a Himalayan medicinal plant- Quercus dilatata. METHODS: Total phenolic and flavonoid contents were determined colorimetrically and various polyphenols were identified by RP-HPLC analysis. Brine shrimp lethality, SRB and MTT assays were employed to test cytotoxicity against Artemia salina and human cancer cell lines respectively. Antileishmanial activity was determined using standard MTT protocol. Glucose modulation was assessed by α-amylase inhibition assay while disc diffusion assay was used to establish protein kinase inhibitory and antifungal spectrum. RESULTS: Among 14 extracts of aerial parts, distilled water-acetone extract demonstrated maximum extract recovery (10.52% w/w), phenolic content (21.37 ± 0.21 µg GAE/mg dry weight (DW)), total antioxidant capacity (4.81 ± 0.98 µg AAE/mg DW) and reducing power potential (20.03 ± 2.4 µg/mg DW). On the other hand, Distilled water extract proficiently extracted flavonoid content (4.78 ± 0.51 µg QE/mg DW). RP-HPLC analysis revealed the presence of significant amounts of phenolic metabolites (0.049 to 15.336 µg/mg extract) including, pyrocatechol, gallic acid, catechin, chlorogenic acid, p-coumaric acid, ferulic acid and quercetin. Highest free radical scavenging capacity was found in Methanol-Ethyl acetate extract (IC50 8.1 ± 0.5 µg/ml). In the brine shrimp toxicity assay, most of the tested extracts (57%) showed high cytotoxicity. Among these, Chloroform-Methanol extract had highest cytotoxicity against THP-1 cell line (IC50 3.88 ± 0.53 µg/ml). About 50% of the extracts were found to be moderately antiproliferative against Hep G2 cell line. Methanol extract exhibited considerable protein kinase inhibitory activity against Streptomyces 85E strain (28 ± 0.35 mm bald phenotype at 100 µg/disc; MIC = 12.5 µg/ disc) while, Chloroform extract displayed maximum antidiabetic activity (α-amylase inhibition of 21.61 ± 1.53% at 200 µg/ml concentration). The highest antileishmanial potential was found in Ethyl acetate-Acetone extract (12.91 ± 0.02% at 100 µg/ml concentration), while, Q. dilatata extracts also showed a moderate antifungal activity. CONCLUSION: This study proposes that multiple-solvent system is a crucial variable to elucidate pharmacological potential of Q. dilatata and the results of the present findings prospects its potential as a resource for the discovery of novel anticancer, antidiabetic, antileishmanial and antioxidant agents.

Dormancy and germination responses of halophyte seeds to the application of ethylene.

Ethylene is invariably produced during seed germination but its role in regulating seed dormancy and germination is poorly understood. Seeds of 22 halophytic species having different life forms - salt secreting dicots, salt secreting monocots, stem succulents and leaf succulents were germinated in Petri dishes kept in a growth chamber set at 20/30 degrees C (night/day) temperature and a 12 hr light period. Sodium chloride and ethephon were added to the medium from the beginning of the experiment. Seed germination was recorded every other day for twenty days. Application of ethylene did not have any significant effect on releasing seeds from innate dormancy. However, it appeared to have a role in alleviation of salinity effects which varied from negative in certain species to almost complete alleviation of high salinity effects in others. Our data indicates that ethylene appears to have little role in breaking innate seed dormancy however, in most halophyte seeds studied, application of ethylene alleviate the salinity effect to various degrees. Halophyte seeds which could germinate under saline conditions approaching twice the salinity of seawater may offer clues to understand management of seed germination under highly saline conditions.