Phytochemical and Pharmacological Investigations on Himalayan Poplar Populus ciliata Wall ex Royle from Western Himalaya

Abstract

newline xiii newlineABSTRACT newlineHimalayan poplar (Populus ciliata Wall. ex Royle) of family Salicaceae is a fast-growing, multipurpose native tree of the Himalayas. Traditionally, the bark of the tree is used for the purification of blood and treatment of rheumatism, fatigue, and pain of menstrual cramps. The present study first time deals with the screening of crude methanolic extracts and various fractions (n-hexane, chloroform, ethyl acetate, and n-butanol) of P. ciliata bark and leaves for total polyphenolic contents, antioxidant, antimicrobial, anti-inflammatory, and cytotoxic activities. Further bioactive molecules were isolated from the most bioactive fraction of P. ciliata. The results showed that among all crude extracts (CE) and fractions, the bark ethyl acetate fraction (EF) had the highest polyphenolic contents (317±2.61 mg/g GAE; 271.26±2.16 mg/g QUE) and strong antioxidant potential (DPPH-25.75±2.60 and#956;g/mL; ABTS-33.55±2.96 and#956;g/mL; FRAP-70.39±1.75 and#956;M of Fe equivalents). Similarly, EF of bark also revealed higher antibacterial and antifungal activities against Pseudomonas aeruginosa (MIC-0.02 mg/mL), Klebsiella pneumoniae and Staphylococcus aureus (MIC-0.03 mg/mL), Bacillus subtilis and Escherichia coli (MIC-0.06 mg/mL), and Fusarium oxysporum (MIC-0.13 mg/mL), respectively, whereas butanol fraction of bark showed maximum antifungal activity against Candida auris (MIC-1.25 mg/mL). The anti-inflammatory activity was also recorded maximum in EF of bark (IC50-0.11±0.017 mg/mL for egg s albumin and 0.16±0.01 mg/mL for bovine serum assay). However, cytotoxic activity was observed higher in CE and EF of bark in comparison with other fractions. The most bioactive fraction (EF) of bark was further used for the extraction of compounds. newlineA total of four flavonoids (EF01-4) were isolated first time from EF of P. ciliata bark and characterized as kaempferol-7-O-glucoside, apigenin, quercetin, and naringin, respectively through UV, FTIR, NMR, and MS spectroscopy. All compounds were further screened for different biological activities. The results showed that among all compounds, the highest antioxidant potential (IC50) was recorded with quercetin (DPPH assay-8.47±0.60 and#956;M; ABTS assay-12.30±0.56 and#956;M; FRAP assay-14±0.15 and#956;M) followed by kaempferol-7-O-glucoside, apigenin, and naringin. Similarly, antimicrobial activity (MIC) [P. aeruginosa, K. pneumoniae, and S. aureus, (2.57 and#956;M) and E. coli, and B. subtilis (5.14 and#956;M) and F. oxysporum (0.005 mM)] and anti-inflammatory activity (IC50) (egg s albumin assay-19.01±0.25 and#956;M; bovine serum albumin assay-22.76±0.31 and#956;M) were also observed maximum in quercetin. However, naringin was found most active (MIC-0.06 mM) against C. auris whereas quercetin (MIC-0.049 newlinexiv newlinemM) showed maximum antifungal activity against C. glabrata. All these flavonoids were first time extracted from the P. ciliata tree bark. The present study concludes that P. ciliata tree parts (bark and leaves) are rich in polyphenolic content responsible for different biological activities. In comparison to both plant parts (bark and leaves), the bark has higher biological potential than leaves, therefore, reveals its traditional medicinal use. In the wood and paper industries, the P. ciliata bark was release as waste or either used for cellulose production therefore recommends the P. ciliata bark as a renewable source for the extraction of bioactive compounds of medicinal use. newlineKeywords: Anti-inflammatory activity, biological activity, ethano-medicinal use, cytotoxic activity, polyphenolic content, spectroscopy,