Informant Consensus Factors and Antibacterial Activity of Ethnomedicinal Plants of Brahmanbaria, Bangladesh

Abstract

In spite of the constantly increasing need for new antibacterial agents, antibiotic drug discovery and development seem to have greatly decelerated in recent years. Presented with the significant problem of advancing antibacterial resistance, the global scientific community has attempted to find alternative solutions. One of the most promising ones is to find new sources of antibiotic agents from ethnomedicinal plants those used by local people since first for the treatment diseases caused by bacteria. The present research focuses the consensus of local people of Brahmanbaria district in the use of ethnomedicinal plants to treat different ailments in their daily life and to evaluate the antibacterial properties of most cited ethnomedicinal plant species. Ethnomedicinal data were collected in between June 2015 to June 2017 from 467 local people using mainly key informant’s interviews and also followed by plant interviews, field interviews, checklist interviews, group discussions and market surveys. In order to identify the most important ethnomedicinal plants in the study area, Factor of informant consensus (Fic), Fidelity level (Fl), Citation frequency (Cf), Relative frequency of citation (RFC) and Use values (UV) of medicinal plants have been calculated. Plant species with high Cf, RCF, UV, F ic and Fl values can be subjected to further ethno-pharmacology studies to find active compounds for the new drug candidates. To validate the knowledge of local people for the treatment of bacterial diseases, most cited ethno-medicinal plant species have been subjected to determine antibacterial activity. After collection of plant samples, aqueous and ethanol extractions of leaves were made. Both the aqueous and ethanol extracts of leaves were screened for antibacterial activity through disc diffusion assays against eight clinical strains belonging to gram-positive Staphylococcus aureus, Bacillus subtilis, Bacillus cereus bacteria and gram-negative Escherichia coli, Pseudomonas aeruginosa, Salmonella paratyphi, Shigella dysenteriae and Shigella boydii bacteria. The extracts showed antibacterial activity further tested for Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) which were determined through serial dilution assays and serial dilution plate method respectively. In the present study, a total of 247 ethnomedicinal plants under 89 families have been recorded. These plants have been used to treat 73 ailments through 485 formularies. Among 247 ethnomedicinal plants species, four species viz. Achyranthes bidentata, Kalanchoe serrata, Echinopsis peruviana and Lippia alba are recorded as new ethnomedicinal plant for Bangladesh. Among the 485 formularies, 96 formularies using 77 species appear to be new for Bangladesh. The highest number of medicinal plants species were found to be Fabaceae, Euphorbiaceae and Asteraceae family. Among formularies 77% have been administered orally and rest 23% used externally. Out of 247 ethnomedicinal plants, 18413 species were found to grow wild and 59 species were cultivated. The major modes of remedy preparations were making juice (47%) followed by decoction (16%), paste (13%), tablet (6%), fruit (4%), cooked (4%), powder (4%), plaster (4%), gurgling and brush (3%), Chewed (1%), and others 5% including; tied up with respective organ, oil, and rubbing. The most commonly used ethnomedicinal plants based on use values (UV) were found to be Centella asiatica, Litsea glutinosa, Coccinea grandis, Ocimum sanctum, Azadirachta indica, Cynodon dactylon, Cissus quandrangularis, Leucas lavandulaefolia, Acyranthes aspera, Mimosa pudica and Kalanchoe pinnata. Among the ailment categories high informant consensus factor (Fic) was found in case of diarrhoea and dysentery followed by respiratory tract disorder, diabetes, gynecological, dermatological, sexual problem, gastrointestinal, musculoskeletal, helmenthiasis, mental disorder, cardiovascular, fever and pain, dental problem, jaundice and others. Most cited species for the treatment of such ailment categories are Centella asiatica, Litsea glutinosa, Scoparia dulcis, Dalbergia sissoo, Clerodendrum viscosum, Kalanchoe pinnata, Ocimum sanctum, Abroma augusta, Alternanthera sessilis, Aloe vera, Cissus quandrangularis, Azadirachta indica, Achyranthes aspera, Coccinia grandis, Andrographis paniculata, Ananas sativus, Hyptis sauveolens, Terminalia arjuna, Eclipta alba, Asparagus racemosus, Kalanchoe serrata, Commelina benghalensis, Holarrhena antidysenterica and Echinopsis peruviana. From the most cited plant species, 20 plant species were showed 100% Fidelity level (Fl) values. These are Adhatoda zeylanica, Ananas sativus, Aerva sanguinolenta, Butea monosperma, Calotropis procera, Catharanthus roseus, Dalbergia sissoo, Echinopsis peruviana, Ficus racemosa, Holarrhena antidysenterica, Jatropha gossypifolia, Kalanchoe serrata, Mikania cordata, Momordica indica, Paederia foetida, Syzygium cumini, Thevetia peruviana, Scoparia dulcis, Vitex nigundo and Zingiber officinale. Maximum Ficvalue was found in case of diarrhoea and dysentery category. This disease category was treated by 51 ethnomedicinal plant species by the local people of Brahmanbaria district. Among 51 ethnomedicinal plant species, most cited species were Litsea glutinosa, Scoparia dulcis, Dalbergia sissoo, Clerodendrum viscosum, Holarrhena antidysenterica, Phyllanthus reticulatus, Paederia foetida and Stephania japonica. The results of antibacterial activity revealed that maximum plant extracts (85%) were potentially effective in suppressing microbial growth of pathogenic bacteria with variable potency. Litsea glutinosa was the most effective plant species retarding microbial growth of five tested pathogenic bacteria followed by Dalbergia sissoo, Scoparia dulcis, Holarrhena antidysenterica, Clerodendrum viscosum, Paederia foetida and Phyllanthus reticulatus. The tested plant Stephania japonica did not show any activity in retarding microbial growth. Maximum zone of inhibition was found for aqueous leaf extract from Litsea glutinosa against E. coli (21.6 ± 0.33mm) at 10mg per disc with MIC value 4mg/ml and MBC value 16mg/ml. The Second highest zone of inhibition was found for leaf extract of Dalbergia sissoo with a MIC value 4mg/ml and MBC value 32mg/ml. Among the eight tested ethnomedicinal plant14 species, five species showed more antibacterial activity than others on which maximum local people rely to treat bacterial diseases as recorded during data collection. Therefore, the results validate the traditional use of ethnomedicinal plant species for the treatment diseases caused by bacteria in Brahmanbaria district. The present research was the first attempt in Bangladesh to established link between field data and scientific evaluation in the laboratory. Based on current findings, conclusion can be drawn that Litsea glutinosa, Dalbergia sissoo, Scoparia dulcis, Holarrhena antidysenterica and Clerodendrum viscosum could be the potential source of new antibacterial agents. Further long term studies are needed to isolate, evaluate, characterize and screen out pure compounds to mitigate bacterial diseases.