The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services, functions, disturbance, and ...resilience that lead to the development of integrated areas such as ecological niche modeling and contribute to identifying the valuable bio-indicators which can be used in framing conservation and management planning.
B. utilis
is one of the most dominant tree species of treeline ecotone in the Himalayan Region. The species is also considered as indicator species for monitoring the past and recent climate change impact. The current study was carried out in the natural populations of
B. utilis
from the sub-alpine zone of North-western Indian Himalaya. The birch dominated forest harbors a total of 305 plant species comprising Angiosperms (51 families, 160 genera and 277 species), Gymnosperms (03 families, 05 genera and 07 species) and Pteridophytes (07 families, 11 genera and 21 species) with Asteraceae, Ranunculaceae and Rosaceae as dominant family. Birch forests are found dominant in shady moist habitat and North West aspect. Geographical characteristics, anthropogenic and developmental activities affect the population structure of
B. utilis
and associated species. However, the species has fair regeneration status in the study area. The acidic nature of soil pH and spatial variation in edaphic characteristics may be due to geographical differences, rooting patterns and litter accumulation of below and above-ground vegetation. Biomass estimation of a representative population of
B. utilis
from each site showed that TAGBD, TCD and TBD were found maximum in ST3 (Hamta Pass II site). The CCA analysis determined that environmental variables such as altitude, organic matter, available phosphorous, organic carbon, available nitrogen, and electrical conductivity played a significant role in determining tree species composition and distribution in
B. utilis
dominated forests.
•Present study identified 295 plant species into 8 different rarity classes.•Tree diversity decreased and its endemic subset increased along the gradients.•At all altitudes, some species with narrow ...distributions and others with wide ranges.•The study found 16 most rare species in the studied region.•Rarity analysis species has highlighted conservation priorities at local to regional scale.
The assessment of plant rarity patterns and mapping of endemic species is a challenging task, however, this kind of assessment having great conservation significance. In the present study, a classification system of rarity, considering biogeographical, ecological and abundance of species was developed along with assessing the vegetation composition. Following systematic random approach of vegetation sampling, three altitude transects were sampled within each 100 m interval in three possible aspects (North-West, North-East and South-West) in the high-altitude forested zone (2000–3300 m asl) of Kedarnath Wildlife Sanctuary (KWS). The study identified a total of 295 plant species (191 genera and 70 families) in the studied region. Considering different attributes of rarity, 8- rarity groups were used for identification of rare and endemic plants. Altogether, most of the species exhibited wide geographical distribution an attribute of commonness, and few of these have narrow distributions due to habitat specificity. The lower altitudinal zone exhibited the maximum floristic diversity (184 spp.; 62.4 %), and minimum in the higher zone (134 spp.; 45.4 %). Tree species richness decreases, and its endemic subset increased along the altitudinal gradient due to remoteness, habitat heterogeneity, isolation of the areas and other environmental factors. A sharp decline was observed in the tree species richness from lower (33 spp.; 84.6 %) to higher altitude (8 spp.; 20.51 %). The species to genera ratio in the entire altitudinal range was 1.2 for trees and 1.6 for shrubs and herbs. Rarity analysis of these native and endemic species has highlighted conservation priorities at local and regional scale.
The assumption of the pineal hormone melatonin as a therapeutic use for COVID-19-affected people seems promising. Its intake has shown significant improvement in the patients’ conditions. Higher ...melatonin titers in children may provide a protective shield against this disease. The hormone melatonin works as an anti-inflammatory, antioxidant, immunomodulator, and strategically slows down the cytokine release which is observed in the COVID-19 disease, thereby improving the overall health of afflicted patients. The medical community is expected shortly to use remedial attributes like anti-inflammatory, antioxidant, antivirals, etc., of melatonin in the successful prevention and cure of COVID-19 morbidity. Thus, the administration of melatonin seems auspicious in the cure and prevention of this COVID-19 fatality. Moreover, melatonin does not seem to reduce the efficiency of approved vaccines against the SARS-CoV-2 virus. Melatonin increases the production of inflammatory cytokines and Th1 and enhances both humoral and cell-mediated responses. Through the enhanced humoral immunity, melatonin exhibits antiviral activities by suppressing multiple inflammatory products such as IL-6, IL1β, and tumor necrosis factor α, which are immediately released during lung injury of severe COVID-19. Hence, the novel use of melatonin along with other antivirals as an early treatment option against COVID-19 infection is suggested. Here, we have chalked out the invasion mechanisms and appropriate implications of the latest findings concerned with melatonin against the virus SARS-CoV-2. Nevertheless, within the setting of a clinical intervention, the promising compounds must go through a series of studies before their recommendation. In the clinical field, this is done in a time-ordered sequence, in line with the phase label affixed to proper protocol of trials: phase I–phase II and the final phase III. Nevertheless, while medical recommendations can only be made on the basis of reassuring evidence, there are still three issues worth considering before implementation: representativeness, validity, and lastly generalizability.
Polygonatum verticillatum
(L.) All. is one among eight species of Astavarga group of plants known for its vitality strengthening properties and used in different herbal formulations. However, ...systematic investigation on morphology and antioxidant phytochemicals in relation to different environmental variables like altitude and habitat conditions is poorly available. The present study reveals significant (
p
< 0.05) differences in structural and functional attributes among sixteen different populations of
P
.
verticillatum
in West Himalaya. Among the different populations, plants growing in moist habitat and oak forest exhibited maximum plant height, leaf number, biomass and phytochemical content (total phenolics, tannin, and flavonol). Antioxidant activity using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) positively (
p
< 0.05) correlated with altitude. Presence of strong antioxidant and DNA damage prevention activity of the species validate its use as vitality strengthening and anti-aging properties. Identified suitable altitude, habitat conditions, and forest types can be utilized for reintroduction of species in to suitable agro-climatic condition. This will also help in obtaining higher quality produce and management practices for conservation of this species.
In this study, we report about the suitability of thin-GaN (~ 200 nm) for AlGaN/GaN HEMT (High Electron Mobility Transistor) material and device. These HEMT structures are grown on SiC substrate ...using MOVPE (Metal Organic Vapor Phase Epitaxy). The morphological, structural, and electrical characteristics of two kinds of grown HEMT structures are studied. The HEMT structures with thin-GaN epi-layer, grown by using different AlN NL (Nucleation Layer) resulted in dislocation density of thin-GaN epi-layer comparable to ~ 2.2 µm thick GaN epi-layer used in conventional-GaN HEMT structure. X-ray Rocking Curve broadening along the symmetric (002) and skew-symmetric (102) planes for conventional-GaN/optimized thin-GaN epi-layer of HEMT structure are found to be ~ 145/135 arc-sec and ~ 350/310 arc-sec respectively. Material characteristics such as structural quality, surface morphology, and 2DEG (Two-Dimensional Electron Gas) properties of the optimized thin-GaN HEMT structure are comparable with conventional-GaN HEMT structure. HEMT devices are fabricated on optimized thin-GaN and conventional-GaN based HEMT structures. The important device attributes viz. drain-source saturation current at zero gate bias (~ 1 A·mm
−1
), transconductance (~ 210 mS·mm
−1
), and pinch-off voltage (~ −5 Volt) measured from DC characteristics are found to be comparable in both the devices. The mesa leakage is significantly improved in thin-GaN compared to conventional-GaN HEMT device to ~ 10 nA·mm
−1
from ~ 350 nA·mm
−1
.
Graphical abstract
Polygonatum verticillatum
(L.) All. is an important medicinal herb that belongs to the family
Asparagaceae
. The rhizome of the species is used in Chyavanprash preparation and several other ayurvedic ...formulations. Numerous active constituents like saponins, alkaloids, phytohormones, flavonoids, antioxidants, lysine, serine, aspartic acid, diosgenin, β-sitosterol, etc. have been reported from this species. In this study, morphological, phytochemical, antioxidant and genetic variations of 11 distant populations of
P. verticillatum
were measured. Considerably (
P
< 0.05) higher variations were recorded among different populations of
P. verticillatum
using morphological, phytochemical and genetic diversity parameters. AGFW (above ground fresh weights); flavonols, FRAP (Ferric ion reducing antioxidant power) and NO (Nitric Oxide scavenging activity) were recorded maximum in Kafni population. Similarly, a significantly higher above and below ground dry weight was recorded in Mayawati and Surmoli populations respectively. Maximum phenolic content, tannins, and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity were recorded in Milam population. A total of 165 individuals from 11 populations were assessed for genetic diversity using inter-simple sequence repeats (ISSR) marker. High genetic diversity (He = 0.35) was recorded in Himkhola and Surmoli populations while it was observed minimum (0.28) in the Mayawati population. Altitude showed a significant positive correlation with tannins (r = 0.674;
P
< 005) and DPPH (r = 0.820;
P
< 0.01). Phenol content exhibited a considerably positive relationship with He (r = 0.606;
P
< 0.05) and BGFW (r = 0.620;
P
< 0.05), flavonol displayed a positive correlation with Pp% (r = 0.606;
P
< 0.05). The population structure of
P. verticillatum,
exhibited that the optimal value of the K was 3 for its populations as determined by the ΔK statistic structure. Among populations, the amount of gene flow is higher (Nm = 1.717) among all sites. Hence, it can be concluded that
P. verticillatum
populations possess considerable variability in the collected populations. Likewise, the populations from Kafni, Satbunga and Himkhola with higher morphological, phytochemicals and genetic variability were prioritized and therefore recommended for cultivation and mass multiplication to meet the industrial demand for target species.
Polygonatum cirrhifolium
(Wall.) Royle is an important medicinal herb of the family Asparagaceae used to cure several ailments. The rhizome of the species forms an important ingredient of ...“Chyavanprash” which is identified for its rejuvenating properties. However,
P. cirrhifolium
is least explored scientifically and systematically till date. Therefore, in this study genetic diversity and phytochemical variations along with antimutagenic activity of
P. cirrhifolium
populations were evaluated. Antimutagenic activity varied remarkably (p < 0.05) among population and Gagar population with significantly (p < 0.05) higher DNA recovery (84.95%) percentage. Higher genetic diversity (He) was recorded among populations using RAPD (He, 0.30–0.36) and ISSR (0.25–0.38) markers. High intra and low inter population variations were recorded in the species using both kinds of markers. Phenolics (p < 0.05; r = 0.924); tannins (p < 0.05; r = 0.897) and DNA damage inhibition efficiency displayed a highly positive correlation with genetic diversity (estimated using ISSR markers). The population structure analysis of
P. cirrhifolium
revealed that the greatest value of the K was 3 for studied populations. Gene flow among studied populations was found sufficient to encounter genetic erosion in the species. Therefore, it is recommended that the populations with higher ingredient and genetic diversity can be utilized for conservation priority and management plan of this species.
•Variation in bioactive content of Ashtvarga species was observed.•Ashtvarga species showed a total of 13 phenolic compounds.•Potential of antiageing properties in Ashtvarga species was ...assessed.•Antioxidant activity validated the antiageing and vitality strengthening properties.
Ashtvarga is a popular Ayurvedic group comprises of eight herbs used in various rejuvenating Ayurvedic tonics like Chyvanprash. Considering the importance of Ashtvarga group in various preparations, the phenolic composition, antioxidant and antimutagenic activities of all eight species extracts were evaluated. Total phenolic content measured by Folin- Ciocalteu assay of Ashtvarga species showed the highest value in Polygonatum cirrhifolium and minimum was recorded in Roscoea procera. However, R. procera showed significantly higher tannin and flavonoid content as compared to other Ashtvarga species. Total fifteen phenolic compounds were quantified using HPLC analysis, and maximum 11 phenolic compounds were detected in Malaxis acuminata extract. Antioxidant activities using in vitro assay like 2,2-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging (ABTS), 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH), Ferric reducing antioxidant power (FRAP) and Superoxide scavenging activity were also determined. The results showed all the Ashtvarga plants possess strong ability to protect DNA and therefore, these species could be a potential source of natural antioxidant.
Mahonia jaunsarensis
(
Family
Berberidaceae) is an endemic species of the Himalaya narrowly distributed in Chakrata hills of Uttarakhand. Considering that the species is traditionally used by local ...inhabitants for various purposes, this study was made to explore its biochemical attributes using diverse solvent systems, i.e., ethanol, methanol and distilled water. Results revealed a varied range of total phenolics (1.00–1.39 mg GAE/g); tannins (1.01–1.11 mg TAE/g); flavonoids (1.07–1.22 mg QE/g); and flavonols (0.71–1.04 mg QE/g) across solvent extractions. Likewise, in vitro antioxidant activity (i.e., ABTS 0.82–1.09; DPPH 0.94–1.16; and FRAP 0.81–1.05 mM AAE/100 g fresh weight) varied. Results are indicative that the species possess higher bioactive attributes and a good source of natural antioxidant. A solvent system with moderate polarity, such as methanol, was found best for harnessing the maximum potential. The study provides baseline information on biochemical attributes of the species, which can, with due R&D interventions, be extended for the industrial applications.
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