Quantitative Ethnobotany of Medicinal Plants from Darjeeling District of West Bengal, India, along with Phytochemistry and Toxicity Study of Betula alnoides Buch.-Ham. ex D.Don bark

Abstract

This study offers considerable information on plant wealth of therapeutic importance used traditionally by the residents of 11 villages under three subdivisions of Kurseong, Darjeeling Sadar, and Mirik in the Darjeeling District, West Bengal. For the acquisition of ethnomedicinal information, semi-structured interviews were conducted with 47 informants, of whom 11 persons were herbalists and 36 were knowledgeable persons. Free prior informed consent was obtained from each participant prior to the collection of field data. A total of 115 species were documented, which spread over 65 families and 104 genera. From the informants, a total of 101 monoherbal and 21 polyherbal formulations were recorded for treating 50 types of health conditions. The collected ethnobotanical data have been evaluated to measure the utilitarian significance of remedies using three quantitative tools, informant consensus factor (F_ic), use value (UV), and fidelity level (FL%). A statistical analysis revealed that among 11 disease categories, the highest F_ic value was estimated for the category of digestive diseases. The plant Hellenia speciosa (J.Koenig) S.R.Dutta scored the highest use value among all the recorded plant species. In the case of the FL% analysis, the highest score (97%) was observed in Betula alnoides Buch-Ham. ex D.Don, which is used for snake bites, among the recorded 115 plant species. In addition, the present study embodies the quantitative estimation of phenolics and flavonoids, along with an HPLC analysis of the B. alnoides bark to endorse this most important and underexplored plant as a potential source of therapeutically important chemical compounds. The bark extract contains significant amounts of phenolics (87.8 mg GAE/g dry tissue) and flavonoids (30.1 mg CE/g dry tissue). An HPLC analysis unveiled a captivating ensemble of six phenolic compounds, namely, chlorogenic acid, sinapic acid, caffeic acid, coumarin, p-coumaric acid, and gallic acid. Among the identified phenolics, chlorogenic acid scored the highest amount of 117.5 mg/g of dry tissue. The present study also explored the moderate cytotoxic nature of the bark extract through an in vitro cytotoxicity assay on the L929 mouse fibroblast cell line. Our study not only documents the statistically analyzed information about ethnomedicinal practices that prevailed in the rural communities of the Darjeeling District but also highlights the profound therapeutic capabilities and non-toxic nature of B. alnoides bark.

Keywords: Darjeeling Himalaya; HPLC; MTT assay; bark extract; ethnobotanical indices; ethnomedicine.

Figure 1

Number of plant species in respective families.

Figure 2

Habits of medicinal plants in the study area.

Figure 3

Plants parts used in herbal preparations.

Figure 4

Methods of preparation of ethnomedicine.

Figure 5

Route of administration of ethnomedicine.

Figure 6

HPLC chromatogram obtained from methanolic bark extract of B. alnoides.

Figure 7

Micrographs showing the morphological changes in the L929 mouse fibroblast cells before and after 24 h exposure to different concentrations (50–300 mg/L) of B. alnoides bark extract, along with negative control.

Figure 8

Map (a–d). (a) Map showing the geographical location of West Bengal in India. (b) Geographical location of Darjeeling District in West Bengal. (c) The map of surveyed area. (d) Map depicting the various villages visited during the present study in Darjeeling District, West Bengal. (The map is created using Qgis software 3.10. and Google Earth Pro 7.3).