Latha Rangan

Ethnomedical uses of Zingiberaceous plants of Northeast India

AIM OF THE STUDY Family Zingiberaceae consists of large number of medicinal plants and is well known for its use in ethnomedicine. The objective of this study is to systematically analyse and document the traditional knowledge regarding the use of Zingiberaceous plants for the treatment of various human ailments from NE India, adding information to the valuation of biodiversity and, to forward suggestions for its sustainable use, conservation and for future pharmacological studies. MATERIALS AND METHODS A survey on the utilization of medicinal plants belonging to Zingibereceae of North-eastern states was carried out by interviewing herbalists followed by collecting plant specimens and identifying the specimen. Ethnobotanical information on traditional plants was catalogued through structured questionnaires in consultations with traditional healers. RESULTS A total of 34 species were documented belonging to 9 genera of Zingiberaceae for about 25 types of ailments, 67.6% of which were used in curing multiple disorders. Arunachal Pradesh hosts maximum number of Zingiberaceous plant (88%). Rhizomes were found to be the primary plant material as a source for medication and poultices as the predominant mode of preparation. Gastrointestinal conditions (58%) and chest and lungs (41%) related ailments were the main categories for which these plants are used. CONCLUSIONS The study establishes Zingiberaceae as a medicinal family since 41% of all the available Zingiberaceous plant species in NE were found to possess medicinal value. Some new use of herbs also appeared in this study for the first time.

Plant regeneration in Curcuma species and assessment of genetic stability of regenerated plants.

An efficient plant regeneration protocol was developed from rhizomes of two Curcuma species C. longa and C. amada. Response was highly dependent on the season, with above 69 % of culture developing adventitious shoots during spring. Greatest regeneration and multiplication was observed in modified Murashige and Skoog (MS) medium supplemented with 13.31 μM benzyladenine and 2.68 μM α-naphthalene acetic acid (NAA) in C. longa or 2.46 μM indolebutyric acid in C. amada. Effect of sugars and agar at different concentrations were also studied and 2 % maltose and 0.7 % agar were found optimum for shoot multiplication and regeneration. Most plantlets developed roots simultaneously but others formed roots when subcultured in ½ MS medium supplemented with 2.68 μM NAA. Plants were successfully hardened in greenhouse with 80 % survival. The genetic purity of micropropagated plantlets was analyzed using RAPD and protein profiles.

Development of Pongamia pinnata as an alternative biofuel crop — current status and scope of plantations in India

Pongamia pinnata is a leguminous tree known for its multipurpose benefits and as a potential source of biodiesel crop. Its added benefits to grow on marginal lands make it a suitable candidate in agro-forestry. These properties support the suitability of this plant for large-scale production required by a sustainable biodiesel industry. While utilizing these species as a source of biodiesel, there is a further need for research and extensive knowledge generation into various areas of production and utilization. The future success of P. pinnata as a sustainable source of biodiesel will heavily depend on an unlimited feed stock supply. This will call for large-scale plantations of clonal stocks of elite genotypes to encourage afforestation programs coordinated both at the central and state levels to cater to the needs of the biodiesel industry. The success rate will rely on the elite planting stock, propagation techniques, and plantation practices and models in making Pongamia cultivation an economically viable proposition.

Unveiling the mode of action of antibacterial labdane diterpenes from Alpinia nigra (Gaertn.) B. L. Burtt seeds.

The labdane diterpene, (E)-labda-8(17), 12-diene-15, 16-dial (compound A) and its epoxide analogue, (E)-8β, 17-Epoxylabd-12-ene-15, 16-dial (compound B) were isolated from the seeds of Alpinia nigra for the first time. The antibacterial activities of both compounds were evaluated against three Gram-positive and four Gram-negative bacteria, and flow cytometric analysis revealed that these compounds caused significant damage to the bacterial cell membranes. Further, field emission scanning electron microscope imaging and cell leakage analysis confirmed that the labdane diterpenes were responsible for bacterial cell membrane damage and disintegration. Our findings provide new insight into the broad-spectrum effects of two natural labdane diterpenes that may be useful in the future development of herbal antibiotic products.

Molecular marker-based characterization in candidate plus trees of Pongamia pinnata, a potential biodiesel legume.

Molecular marker studies provide valid guidelines for collection, characterization and selective cultivation of elite Pongamia germplasm that can be exploited further for its improvement through breeding and marker assisted selection for improved characters and oil yield towards biodiesel production.

Rhizobium pongamiae sp. nov. from root nodules of Pongamia pinnata.

Pongamia pinnata has an added advantage of N2-fixing ability and tolerance to stress conditions as compared with other biodiesel crops. It harbours “rhizobia” as an endophytic bacterial community on its root nodules. A gram-negative, nonmotile, fast-growing, rod-shaped, bacterial strain VKLR-01T was isolated from root nodules of Pongamia that grew optimal at 28°C, pH 7.0 in presence of 2% NaCl. Isolate VKLR-01 exhibits higher tolerance to the prevailing adverse conditions, for example, salt stress, elevated temperatures and alkalinity. Strain VKLR-01T has the major cellular fatty acid as C18:1   ω7c (65.92%). Strain VKLR-01T was found to be a nitrogen fixer using the acetylene reduction assay and PCR detection of a nifH gene. On the basis of phenotypic, phylogenetic distinctiveness and molecular data (16S rRNA, recA, and atpD gene sequences, G + C content, DNA-DNA hybridization etc.), strain VKLR-01T = (MTCC 10513T = MSCL 1015T) is considered to represent a novel species of the genus Rhizobium for which the name Rhizobium pongamiae sp. nov. is proposed. Rhizobium pongamiae may possess specific traits that can be transferred to other rhizobia through biotechnological tools and can be directly used as inoculants for reclamation of wasteland; hence, they are very important from both economic and environmental prospects.

Genetic diversity in ecotypes of the scarce wild medicinal crop Zingiber moran revealed by ISSR and AFLP marker analysis and chromosome number assessment

Zingiber moran, a rare ginger found only in a few parts of northeast India, faces the threat of extinction due to its exploitation as an important medicinal plant. In this study, the chromosome number of wild ecotypes of Z. moran was determined and the genetic analysis was carried out using two kinds of molecular markers: inter simple sequence repeats (ISSR) and amplified fragment length polymorphism (AFLP). A chromosome number of 2n = 22 was confirmed for all 10 ecotypes investigated. AFLP analysis revealed a greater amount of genetic polymorphism (95.06%), with a strong resolving power in detecting intraspecific variation, compared to ISSR analysis (34.61%). Genetic diversity parameters, such as number of observed alleles (na), mean number of effective alleles (ne), mean Neis gene diversity index (h), and Shannon index (I) for ISSR and AFLP were in the range 1.34–1.95, 1.25–1.60, 1.44–0.33, and 0.20–0.49, respectively. Marker indices and polymorphic information content varied from 0.5–19.3 and 0.03–0.27 for ISSR, and 28.2–39 and 0.3–0.39 for AFLP, respectively. Dendrograms derived by unweighted pair group method of arithmetic averages cluster analysis based on molecular data classified the ecotypes into two major clusters. The Mantel test cophenetic correlation coefficient (r) for ISSR (0.85) and AFLP (0.91) showed a good degree of confidence in the association with 10 ecotypes. Clustering was further supported by principle component analysis which demarcated individuals of hilly topography from the ones of plain land.

Molecular Docking and Inhibition Kinetics of α-glucosidase Activity by Labdane Diterpenes Isolated from Tora Seeds (Alpinia nigra B.L. Burtt.)

Current approach against type 2 diabetes involves α-glucosidase inhibitors like acarbose associated with many side effects. Therefore, as an alternative to the existing drug, many natural products mainly from plant sources have been investigated which inhibit α-glucosidase. Here, we have selected medicinally important Alpinia nigra to explore its α-glucosidase inhibitory activity. Organic extracts of seeds and two purified natural diterpenes I: (E)-labda-8(17), 12-diene-15, 16-dial and II: (E)-8β, 17-epoxylabd-12-ene-15, 16-dial from A. nigra were investigated towards inhibition of α-glucosidase activity. Dose-dependant inhibition pattern were observed for seed extracts and both the compounds. Further, inhibition kinetics studies of the diterpenes indicated a non-competitive type of inhibition against α-glucosidase. Docking studies were carried out which revealed that both the diterpenes interacted within the active site of N-terminal and C-terminal domain of human maltase-glucoamylase enzyme, respectively. This is the first report of α-glucosidase inhibitory activity of these isolated diterpenes and their higher inhibitory potential than any terpenoids studied till date against α-glucosidase.

Genetic diversity and relationship of Hedychium from Northeast India as dissected using PCA analysis and hierarchical clustering

Molecular genetic fingerprints of eleven Hedychium species from Northeast India were developed using PCR based markers. Fifteen inter-simple sequence repeats (ISSRs) and five amplified fragment length polymorphism (AFLP) primers produced 547 polymorphic fragments. Positive correlation (r = 0.46) was observed between the mean genetic similarity and genetic diversity parameters at the inter-species level. AFLP and ISSR markers were able to group the species according to its altitude and intensity of flower aroma. Cophenetic correlation coefficients between the dendrogram and the original similarity matrix were significant for ISSR (r = 0.89) compared to AFLP (r = 0.83) markers. This genetic characterization of Hedychium from Northeast India contributes to the knowledge of genetic structure of the species and can be used to define strategies for their conservation and management.

Exploration of ‘Hot-Spots’ of Methane and Nitrous Oxide Emission from the Agriculture Fields of Assam, India

BackgroundAgricultural soils contribute towards the emission of CH4 (mainly from paddy fields) and N2O (from N-fertilizer application), the two important greenhouse gases causing global warming. Most studies had developed the inventories of CH4 and N2O emission at the country level (larger scale) for India, but not many studies are available at the local scale (e.g. district level) on these greenhouse gases (GHGs). Assam is an important state in the North Eastern region of India. In addition to being the regional economic hub for the entire region, agriculture is the major contributor to the state’s gross domestic product. In Assam about three-fourths of the area is under paddy cultivation and rice is the staple food. With this background, a district wise inventory of CH4 and N2O emission in the North Eastern state of Assam, India was carried out using different emission factors, viz., IPCC, Indian factors and others, to highlight the discrepancies that arose in the emission estimation of these important GHGs while used at the smaller scale i.e. district level. This study emphasizes the need for better methodologies at the local level for GHGs inventories. This study also reiterates the fact that no emission factor is universally applicable across all regions. The GHGs like CH4 and N2O are highly site and crop specific and the factors required for their inventory are driven by cultural practices, agronomic management, soil resources and socio-economic drivers.Material and methodsIn this study, Intergovernmental Panel on Climate Change (IPCC) methodology was used for the estimation of CH4 and N2O emission. In case of N2O emission, both direct and indirect emission from agricultural soil was estimated for the various districts of Assam.ResultsThe CH4 (base year 2000–2001) and N2O (base year 2001–2002) emission was estimated to be 121 Gg and 1.36 Gg from rice paddy and agricultural fields of Assam state respectively.ConclusionsThis study is the first report on the estimation of the GHG emission at the district level from the entire state of Assam, agriculturally one very important state of North Eastern India. This state is also considered as remote due to its geographical location. The study clearly elucidates that there is large variation in the emission inventory of CH4 and N2O at the district level (local scale) when different emission factors are used. This calls for detailed and comprehensive data collection and mapping at the micro level for accurate inventory of greenhouse gases in future from agriculture fields.