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Infections by microbes (viruses, bacteria, and fungi) and parasites can cause serious diseases in both humans and animals. Heavy use of antimicrobials has created selective pressure and caused resistance to currently available antibiotics, hence the need for finding new and better antibiotics. Natural products, especially from plants, are known for their medicinal properties, including antimicrobial and anthelmintic activities. Geoclimatic variation, together with diversity in ethnomedicinal traditions, has made the Himalayas of Nepal an invaluable repository of traditional medicinal plants. We studied antiviral, antibacterial, antifungal, and anthelmintic activities of medicinal plants, selected based upon ethnobotanical evidence.

Eighteen plant species were collected for evaluation of their antibacterial, antifungal, antiviral, and anthelmintic activity based on their uses in the scientific literature and indigenous knowledge. The collected plant materials were washed thoroughly with tap water and shade-dried at ambient temperature. Dried samples were ground to a powder with an electric blender and subjected to Soxhlet extraction using polar solvents (ethanol and methanol). The extracts were evaporated on a rotary evaporator under reduced pressure till a solid mass was obtained.The effects of these plant extracts on the motility of the L4 stage of C. elegans were evaluated. The anthelmintic assay was carried out in a 96-well microplate with flat-bottom wells in a WMicrotracker device. The movement of worms in each well was measured every 30 minutes for 16 h at 20°C and recorded by the WMicrotracker. The percentage of the average movement within 16 hours of worms exposed to samples, compared to a DMSO control, was used to calculate the relative anthelmintic activity. Levamisole (50 μM) was used on every plate as a positive control, and DMSO was used as solvent control.

Interestingly, four plants were found to be active out of 18 plants tested: A. tomentosa, B. albiflora, K. pinnata, and D. integrifolia. These four plants significantly reduced C. elegans motility, comparable to the positive control (>50%) (Figure 1). Moreover, plants such as B. diffusa, P. polyphylla, and T. chebula showed moderate inhibition using the WMicrotracker, but under the microscope, these extracts showed clear paralytic activity. The average inhibition was lower; however, very good activity was seen during the last four hours of WMicrotracker movement recordings, revealing that many extracts appear to have a slow onset of action.

Evid Based Complement Alternat Med. 2020 Apr 22;2020:1043471. doi: 10.1155/2020/1043471. eCollection 2020.

Bishnu Joshi, Sujogya Kumar Panda, Ramin Saleh Jouneghani, Maoxuan Liu, Niranjan Parajuli, Pieter Leyssen, Johan Neyts, Walter Luyten.