The concentration of carbon dioxide (CO2) has risen continuously in atmosphere due to human induced activities, and has been considered the predominant cause of global climate change. Paulowina tomentosa Steud. (P. tomentosa), a multipurpose tree is popular around global market for its timber and its potential role in CO2 sequestration. In this study, the total biomass carbon of five years old and newly planted P. tomentosa has been estimated. The results indicated that the average total biomass carbon of five years old plant was found to be 4.52±0.53Kg C Year-1 per tree i.e. 9.04±1.06-ton C ha-1 Year-1 (assuming 2000 plants per hector). Likewise, the average total biomass carbon of newly planted P. tomentosa within 4 months was found to be 6.07±0.38 Kg in remote village area in Nepal. The estimated biomass carbon in one year of newly planted plants was found to be 18.21±1.14 Kg Year-1 i.e. 0.36-ton C ha-1 Year-1. These findings reveled that short rotational trees like P. tomentosa can be implemented in agroforestry system to reduce the green house emission in cities and emphasizes the carbon storage potential of agroforestry. In vitro micro propagation technique could be implemented to produce genetically uniform clone of P. tomentosa and can be applied in agroforestry system for the adaptation and to mitigate global climate change.Int. J. Appl. Sci. Biotechnol. Vol 6(3): 220-226

Background:Nepal is very rich in biodiversity, and no extensive effort has yet been carried out to screen plants that are used by traditional healers against parasitic diseases. The aim of this study was to evaluate the in vitro antileishmanial and antimalarial activity of crude methanolic or ethanolic extracts of 29 plant species that are currently used by local people of Nepal for treating different ailments.Methods:Crude extracts of leaves, twigs, aerial parts, and/or roots of the selected plants were evaluated for in vitro inhibitory activity against intracellular amastigotes of Leishmania infantum and against erythrocytic stages of Plasmodium falciparum. To determine the selectivity index (SI), cytotoxicity was assessed on MRC-5 cells in parallel.Results:Three plant species, namely Phragmites vallatoria and Ampelocissus tomentosa, for which no antiprotozoal activity has previously been reported, and Terminalia chebula revealed antiprotozoal activity. The extract of A. tomentosa exhibited moderate activity against L. infantum with an inhibitory concentration 50% (IC50) of 13.2 ± 4.3 µg/ml and SI >3, while T. chebula exhibited fairly good antiplasmodial activity with IC50 values of 4.5 ± 2.4 µg/ml and SI values >5.Conclusion:In countries like Nepal, where the current health system is unable to combat the burden of endemic parasitic diseases, evaluation of local plants as a potential source of the drug can help in expanding the treatment options. The extent of untapped resources available in these countries provides an opportunity for future bioprospecting.

Paulownia tomentosa Steud is a fast growing multipurpose tree. In vitro propagation using nodal explants of P. tomentosa was performed by manipulating amount of cytokinin and auxin in culture media. Shoot bud proliferation from explants were assessed in Murashige and Skoog (MS) medium supplemented with various amounts of hormones such as a) 0.5-2.5 mg/l benzylaminopurine (BAP) and 0.1 mg/l naphthalene acetic acid (NAA), b) 0.5-2.5 mg/l BAP and 0.5-2.5 mg/l kinetin (KN) and c) 0.5-2.5 mg/l BAP and 0.1 mg/l indole-3-acetic acid (IAA). In the present study, we found that hormone combination of BAP and NAA gave optimum growth results. MS medium enriched with 2.0 mg/l BAP and 0.1 mg/l IAA resulted a similar outcome but took 3-4 weeks with respect to the same medium enriched with 1.0 mg/ml BAP and 0.1 mg/ml NAA, which showed response within 2-3 weeks. Shoot length of 2.5-3.5 cm with 3-4 nodes and 8-12 leaves were obtained on MS medium supplemented with 1.0 mg/l BAP and 0.1 mg/l NAA. The acclimatization of explants was done in a polyhouse at 20±5 o C for 2-6 weeks. Rooting was induced in sterile sand. Rooted plants were transferred to plastic bags containing mixture of soil, sand and compost in the ratio of 1:1:1.Besides aforementioned issues, there are several other challenges associated with in vitro propagation of P. tomentosa. Tissue culturing of the plant was established (90%) on MS medium enriched with BAP and NAA and adapted ex vitro with surviving up to 80%. People received an opportunity with this plant because it grows fast and can generate income in 10 years in comparison with others, but at the same time people also have been facing the challenges for plantation of P. tomentosa as government of Nepal does not formulate necessary national policies, legislations and regulatory frameworks in its favor. Thus, system should be developed to set royalty rate of P. tomentosa recognizing its lifetime value.

Aldose reductase has received extensive research as a key enzyme in the development of long-term problems linked to diabetes mellitus. Overexpression of this enzyme or with exceeded glucose concentration in the blood increases sorbitol on the retina leading to retinopathy, which is the adverse effect of type II diabetes. Approximately 100 million people are suffering from diabetic retinopathy globally. This research is focused on studying the total phenolic content (TPC), total flavonoid content (TFC), antioxidant potential, and aldose reductase inhibiting properties of selected medicinal plants such as Anacyclus pyrethrum, Bergenia ciliata, Rhododendron arboreum, and Swertia chirayita. In addition, ADMET analysis and molecular docking of seven previously identified compounds from the chosen medicinal plants were carried out against human aldose reductase (PDB ID: 4JIR). The ethanol extract of S. chirayita exhibited the highest TPC (4.63 ± 0.16 mg GAE/g) and TFC (0.90 ± 0.06 mg QE/g). Analysis of 2,2-diphenyl-1-picrylhydrazyl (DPPH)-based antioxidant assay showed that IC50 of the ethanolic extract of B. cilata and R. arboreum showed a significant antioxidant activity with IC50 value of 0.05 mg/mL. The percentage inhibition of AR by extract of B. ciliata (94.74 ± 0.01%) was higher than other plant extracts. A molecular docking study showed that morin isolated from B. ciliata showed a good binding interaction with AR. This study showed that the extracts of A. pyrethrum, B. ciliata, and R. arboreum could be potential sources of inhibitors against AR to treat retinopathy.