| This study documented the information on significant ethnomedicinal plant usage,which was dictated from the traditional healers of four indigenous communities of Bangladesh.It is the first time of documentation of this kind of data with quantitative analysis from this area.It was aimed to record ethnomedicinal information from both the traditional healers and also the elderly men and women of the community,in order to compile and document all available information concerning plant use,and preserve it for coming generations.A goal of this study is to compare how already known species are used compared to elsewhere,and particularly to highlight new ethnomedicinal plant species alongside their therapeutic use(s).All ethnomedicinal information was collected following established techniques.Open-ended and semi-structured techniques were primarily utilized.The benefits,importance and scope of ethnomedicine use were exhibited through several quantitative indices,including Informant Consensus Factor(ICF),Use Value(UV),Frequency of Citation(FC),Relative Frequency of Citation(RFC)and Relative Importance Index(RI).The degree of homogeneity both between this and previous studies and among the various indigenous communities was evaluated using the Jaccard Index(JI).All recorded plant species are presented in tabular format,alongside corresponding ethnomedicinal usage information.This investigation revealed the traditional use of 276 ethnomedicinal plant species,which were distributed in 236 genera under 116 families,were documented from 292 informants.Of a majority of documented species,herbs and leaves were the most utilized plant parts for the preparation of ethnomedicines whereas pastes and decoctions were the most popular formulations.Among the documented species,the dominant families were the Asteraceae and Fabaceae.The highest ICF value was for digestive system disorders.Importantly,28 species were reported with new therapeutic uses and to our knowledge,13 species described herein have never been phytochemically and pharmacologically studied.This study showed that the indigenous communities still depend substantially on ethnomedicinal plants for the treatment of various ailments and diseases,and that several of these plants are used in novel ways or represent their first instances of use for medicinal applications.Documentation of new ethnomedicinal species with their therapeutic uses shall promote further phytochemical and pharmacological investigations and possibly,lead to the development of new drugs.In order to investigate the potential antimicrobial activity of Bangladeshi medicinal plants and identify their bioactive metabolites,we studied those medicinal plants utilized by the indigenous communities of Bangladesh for the treatment of microbial diseases.Among the documented species,22 were used for microbial diseases.Of these,5 species had little or no formal investigations of either their antimicrobial properties or phytochemical composition,including Congea tomentosa(CT).The extracts of leaves,stems and flowers of CT were tested for antimicrobial activity using the agar well diffusion and micro-dilution methods.Compared to leaf and flower extracts,the crude stem extract was the most effective against the tested microorganisms.Therefore,the crude stem extract was further subjected to sequential fractionation,with the petroleum ether and ethyl acetate extracts proved the most active against tested microorganisms.Using gas chromatography-mass spectra(GC-MS)analysis,10 compounds were identified from the petroleum ether extract,all of which are known to the literature,and some/all of which may have contributed to the observed antimicrobial properties.Additionally,two compounds(β-amyrin and stigmasterol)were isolated and identified from the ethyl acetate fraction using mass spectrometry and NMR spectroscopy.Compound-2(stigmasterol)displayed promising antimicrobial activity against tested microorganisms.Despite the ethnobotanical importance of CT,no chemical or biological studies have been published to date,supporting either its traditional applications or its sustainable use in Bangladesh.However,our study demonstrates that both the stem extract of this ethnomedicinal plant and the isolated compound 2(stigmasterol)of this ethnomedicinal plant may offer potential as antimicrobials.The traditional healers of indigenous communities of Bangladesh use several plants/plant parts,with often unknown ingredients,for the treatment of cancer/tumors,often with promising anecdotal results,and which have never been screened.To investigate such traditional treatments,we selected three ethnomedicinal plants for in-vitro studies.We performed the MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)assay on a panel of cancer cell lines to evaluate cytotoxicity of the hydroethanolic leaf/stem/flower extracts at six different concentrations.Preliminary screening results showed that the extent of inhibition varied between the types of cell lines and also the types of extract used.Out of five plant parts of the three species tested,only the stem extract of Congea tomentosa showed > 50 % cytotoxic activity against the different cancerous cell lines.The plant crude hydroethanolic extract and its subsequent fractions,namely n-butanol,petroleum ether,ethyl acetate and aqueous fractions at different concentrations were tested for cytotoxic activities.Among all fractions,the aqueous fraction was dominant in activity against U-251 cell lines(IC50-26.81μg/m L),while the ethyl acetate extract gave an IC50 value of 39.13μg/m L.To the best of our knowledge,the antitumor/anticancer activity of this species is reported herein for the first time.The aqueous fraction was further purified by HPLC(high performance liquid chromatography),and within it we identified three compounds by NMR and Mass spectral analysis.Among the isolated compounds,compound-2 concentration-dependently inhibited U-251 cell proliferation without inducing cytotoxic effects in a normal cell line.Hence,we performed several in-vitro experiments to further explore the mechanism of action of compound-2 against U-251 cell proliferation.This study first monitored cell morphology and Annexin-V FITC/PI staining,which confirmed the efficiency of compound-2 in inducing apoptosis.We also investigated the expression of Bcl-2/Bax,Stat3,Akt,caspase-9 and-3 proteins.Our results showed that compound-2 significantly decreased the ratio of Bcl-2/Bax and increased the expression level of cleaved caspase-9 and-3 in a concentration-dependent manner.Together,these results proved that compound-2 had the potential to induce apoptosis in U-251 cells by activation of the intrinsic/mitochondrial pathway.In addition,compound-2 also suppressed the activity of Stat3 and Akt,postulating that compound-2 induced apoptosis might be triggered by the inhibition of Stat3 and Akt expression.The results of this study support the possible use of this ethnomedicinal plant in the treatment of tumors/cancers,and support its traditional use. |
