Natural Products & Green Chemistry
Nepal, at an altitude ranging from 1000 to 2500 meters, is home to a vast array of plant species, including over 2000 medicinal plants. The Department of Natural Products and Green Chemistry has been delving into various aspects of plants, plant extracts, and essential oils, applying their findings in fields such as medical treatment, food preservation, and cosmeceuticals.
The department began its research journey by studying high-altitude lichens and their endophytes to uncover their antimicrobial, antioxidant, and anticancer properties, as well as their bioactive compounds. Additionally, we have investigated the mushroom diversity in the forests around the Kathmandu Valley, focusing on both morphology and molecular identification. With a plant extracts library at the institute, the department welcomes scientists interested in exploring these extracts to advance their research in natural products and green chemistry-related projects and could be a starting point for innovative ideas.
With the growing interest in promoting sustainability and reducing waste, recent research projects at the Department have focused towards a green chemistry approach. One initiative, funded by the OWSD Early Career Fellowship, is the citrus fruit waste project, which highlights the department’s commitment to green chemistry principles. This research aimed to enhance citrus fruit waste through green extraction methods, utilizing the active compounds as value-added products. Additionally, we have investigated the medicinal potential of Pterocarpus marsupium (Bijaysal) sawdust using green extraction techniques. The study examined the phytochemicals in sawdust waste after producing tumblers from the Bijaysal tree, which is significant in traditional Ayurvedic medicine and renowned for its antidiabetic properties. Furthermore, our ongoing project, “Guava leaves as natural preservatives for smallholder farmers of Nepal,” focuses on promoting safer food, green solvents, and local, natural alternatives to chemicals. Funded by The Elsevier Foundation, this project uses local guava leaf water extracts to create edible coatings for agricultural produce. With such innovative research initiatives, the Department of Natural Products and Green Chemistry supports the UN Sustainable Development goals and encourages young minds to pursue sustainable and eco-friendly missions.
Investigation of antimicrobial, anticancer and antioxidant secondary novel metabolites from lichens and their endophytes from high altitude regions of Nepal.
International Foundation of Science (IFS), Sweden
Link: http://ifs.se/
Lichens are reported to produce various biologically active compounds. Lichens from extreme environments such as high altitudes, regions with high UV exposure, extremes of drought and cold are believed to synthesize unique types of secondary metabolites. Similarly, endophytic fungi or bacteria isolated from lichens from extreme environments are also believed to produce unique as well as novel secondary metabolites in terms of molecular structure and biological activity. Several human pathogenic bacteria and fungi have evolved into drug resistant strains. Various synthetic antioxidants have been found to show accelerated carcinogenic effects. These phenomena point out the need for further research to produce effective drugs.
A total of 84 lichen specimens were collected and identified from Annapurna Conservation Area (ACA) Nepal. The specimens were identified as belonging to 19 genera and 47 species. Methanol fractions of 16 specimens and dichloromethane (DCM) fractions of 21 lichens specimens showed antioxidant activities comparable with commercial standards (BHA, Butylated hydroxyanisole, IC50=4.9±0.9 μg/mL) even at crude extract level. Similarly, the DCM fraction of 17 lichens showed potential antimicrobial activity against a Gram-positive bacterium (Staphylococcus aureus KCTC3881) and DCM fractions of 45 lichens showed antimicrobial activity against a Gram-negative bacterium (Klebsiella pneumoniae KCTC2242). DCM fractions of three lichens showed antifungal activity against the yeast, Candida albicans KCTC 7965. Likewise, methanol fractions of 39 lichens and DCM fractions of 74 lichens showed strong toxicity against brine shrimp nauplii with more than 80% mortality. Such biological activity-rich lichen specimens warrant further research on exploration of natural products with antioxidant, antimicrobial and anti cancer (toxic) potential.
Exploration of novel antibiotics, antioxidants and anticancer compounds from microorganisms (bacteria, fungi, lichens) collected from extreme environments of mountainous regions of Nepal.
Alexander von Humboldt Foundation, Germany
Several lichens are traditionally used as medicines against pathogenic bacteria and fungi infections, asthma and stomach disorder. The bioactive natural compounds of various chemical classes were characterized from the different species of lichens. Because of the loose tissue of the lichen thallus, several bacteria and fungi remain on their body as endophytes. These endophytic species could be the potential sources of novel natural products with various biological activities. In search of novel bioactive natural products from the lichens-endophytes, Preussia sp. was isolated from the mountainous lichen, Canoparmelia sp., collected from the Annapurna Conservation Area region of Nepal. The voucher specimen was deposited in the lichen collection center of the Research Institute for Bioscience and Biotechnology. The identification of Preussia sp. was performed by 16S rDNA sequencing analysis and data comparison with the National Center for Biotechnology Information. Two compounds, compounds 1 and 2, were isolated from Preussia sp. The molecular structures of both compounds were elucidated by analyzing one dimensional (1D) and 2D nuclear magnetic resonance data along with high-resolution mass spectrometry data. Compound 1 was obtained as novel in structure, and compound 2 was recently reported elsewhere. Compound 1 did not show antioxidant and antimicrobial activities and brine shrimp toxicity, while compound 2 showed strong antioxidant activity (DPPH reduction capacity; IC50 = 3 μg/mL) and brine shrimp toxicity (LD50 = 50 μg/mL).
Guava (Psidium guajava Linn) leaves as natural preservatives for smallholders farmers of Nepal.
Elsevier Foundation, the Netherlands
A large number of fruits and vegetables are transported from terai and mountain regions of Nepal to different parts of the country especially for farmers and local vendors. During the process, there is significant loss of food, around 8 – 33% which is very surprising and problematic for a developing country like Nepal whose major economy relies on agriculture. Due to lack of good refrigeration facilities, the agricultural produce in Nepal has been affected. Political strikes and instability in power supply are some of the major issues which exacerbate the problem. Food spoilage is prominent when these situations elongate and degrades the quality of food. Ultimately, it creates loss of nutritional value, texture and flavor of food. To minimize the situation, application of fungicides and chemical preservatives are common practice to preserve post harvested food in Nepal. This helps extend shelf life and maintain food quality. But due to greater consumer awareness towards the negative impact of chemicals there is increasing demand of natural preservatives as an alternative. Our concept is to formulate water based leaf extract of guava plants which possess antioxidant and antimicrobial properties making it a potential natural preservative to extend the shelf life of food. This will eventually help achieve the UN sustainable development goal of reducing poverty and minimize hunger problems.
The phenolic and total flavonoid content was found to be higher in ethanol extract (331.84 mg GAE/g dry extract) and methanol extract (95.53 mg QE/g dry extract) from Kuleshwor respectively. Water extract of guava leaves from Kuleshwor (WGK) did not show significantly different antioxidant activity when compared to methanol and ethanol extracts. Fisetin and quercetin were higher in WGK (1.176 mg/100 g) and (10.967 mg/100 g) dry extract weight respectively. Antibacterial activity against food spoilage bacteria was dose-dependent and found to be highest for all the extracts from different solvents and altitudes at higher concentrations (80 mg/ml). Similarly, methanol and ethanol guava extracts from all locations showed antifungal activity against Geotrichum candidum RIBB-SCM43 and Geotrichum candidum RIBB-SCM44. WGK was found to be non-toxic. Our study concludes that the antioxidant and antimicrobial activity of WGK was found to be similar statistically to that of methanol and ethanol extracts of Bishnupur Katti and Mahajidiya. These results suggest the possibility of using water as a sustainable solvent to extract natural antioxidant and antimicrobial compounds which can further be used as natural preservatives to extend the shelf life of fruits and vegetables.
Functional enhancement of abundantly available citrus fruits waste via green extraction and solid-state fermentation methods to utilize the obtained bioactive compounds as key ingredients in nutraceuticals, preservatives, and cosmeceuticals
Organization for Women in Science for the Developing World (OWSD), Italy
Food waste is an alarming global economic, environmental, and food security issue with 1.3 billion tons of food wasted every year (45% from fruits and vegetables) as per FAO 2011 report. Among fruits and vegetable waste, citrus fruits contribute to a significant portion of waste globally. In fact, Nepal has high production of citrus fruits, but 10-15% of them are wasted resulting in adverse economic and environmental impacts. This study aims to formulate a sustainable scientific approach to reduce, reuse and add value to these wastes. The present study focuses on addressing citrus waste related issues, from lime (Citrus aurantifolia) and orange (Citrus reticulata), by obtaining highly valuable extracts containing bioactive compounds that can be used as key ingredients in pharmaceutical, nutraceutical, and cosmeceutical industries. This study employs green, cost-effective, and energy-efficient extraction methods by using abundantly available citrus fruits waste as substrates, and water and ethanol as green solvents at room temperature. Therefore, the proposed method for value addition can replace generally used tedious processes involving high temperature, toxic solvents and expensive equipment, thus making this method accessible and implementable in rural areas as well. Phytochemical and antioxidant analyses of extracts exhibit high amounts of phenols and flavonoids, and impressive free radical scavenging activities. Likewise, these extracts exhibit good antimicrobial properties against common gram-positive and gram-negative bacteria. Overall, this study provides evidence that these extracts obtained from waste citrus fruit peels can be potentially used as therapeutic agents in various applications.
Investigating water as a green solvent for phytochemical extraction from sawdust of Pterocarpus marsupium, and exploring its medicinal properties.
N/A
Pterocarpus marsupium, commonly known as Bijaysal in Nepal, is significant in traditional ayurvedic medicine due to its various phytoconstituents. This plant’s heartwood has been used for ages for its anti-diabetic properties. However, the phytoconstituents of discarded sawdust during wooden tumbler manufacturing are unexplored. The neglected sawdust was collected from the factory of the Bijaysal tumbler and its crude extract was prepared using solvents ie; aqueous and ethanol that varies in terms of their polarity index. Water extraction consisted of normal, microwave-assisted, hot water and tumbler extraction and for ethanol extraction; 12% and 75% ethanol was utilized. The yield percentage was calculated. Anti-diabetic activity, Antioxidant activity, Total Phenolic content, and Total flavonoid content, were determined by α-amylase enzyme inhibition assay, DPPH (2,2-Diphenyl-1- picrylhydrazyl) assay, Folin-Ciocalteu method and Aluminium chloride colorimetric method respectively. The anti-inflammatory activity was determined by preparing a diclofenac solution. The antimicrobial activity was tested against 3 gram positive and 3 gram negative bacteria and Brine Shrimp Lethality Assay (BSLA) was used to test the extracts’ toxicity.
The extract was analyzed for saponins, terpenoids, flavonoids, tannins, phenols, and alkaloids, confirming their presence by preliminary phytochemical analysis. Microwave-assisted aqueous extraction exhibited the highest antioxidant activity (IC50 ~200µg/ml). Both normal and microwave-assisted extraction demonstrated good antidiabetic activity (IC50 ~165 µg/ml) and anti-inflammatory effect (80-90% inhibition). Normal aqueous extraction yielded higher phenolic content (260 GAE mg/g) compared to microwave and hot water processes and in ethanol extraction, 12% ethanol extraction possessed higher phenolic content (240 GAE mg/g) than 75% ethanol (150 GAE mg/g). The flavonoid content was consistent between normal and microwave extraction, with tumbler extraction yielding higher content (160 QE mg/g). The extract exhibited low toxicity (LC50 ﹤1000 µg/ml) except with 75% ethanol (LC50 ﹥1000 µg/ml). However, all samples showed negative antibacterial activity against bacterial strains (3-gram positive bacteria: Bacillus subtilis, Micrococcus, Staphylococcus aureus and 3-gram negative bacteria: Escherichia coli, Klebsiella, and Enterobacter). Our study concluded that the aqueous extract of sawdust is a possible candidate for ayurvedic treatment of various diseases as it could contain various possible polyphenolic compounds, flavonoids, and antioxidant compounds that exhibited good antidiabetic and anti-inflammatory activity and were safe for human consumption. The study outcomes indicated that water serves as the superior solvent for extracting natural antioxidant and anti-diabetic compounds. economic growth while alleviating environmental and food security concerns.
Assessment of Mushroom Diversity in Forests around Kathmandu Valley through Molecular Characterization of Nuclear ITS region.
Nepal Academy of Science and Technology (NAST), Nepal
Link: http://www.nast.gov.np
The aim of this project is to perform molecular identification of mushroom specimens found in Kathmandu valley and establish an online database incorporating both morphological and genetic information. As such, the project aims to raise awareness towards mushroom diversity and the consequences of habitat loss resulting from human intrusions into forests areas of Kathmandu.
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Responsible Department Members
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Responsible Department Members
