Himalayan Blackberry (Rubus discolor) Leaves and Stems: Phytochemical Analysis, Antioxidant, Antimicrobial and Cytotoxic Activities

Background and objectives: The fruits and leaves of Rubus discolor Weihe Nees (Rosaceae) have been used for treatment of diabetes, diarrhea, prostatitis, and wounds and thus were evaluated in this study. Methods: The leaves and stems methanol extracts were prepared by maceration and different fractions were obtained. Total phenolics, tannins, and flavonoids contents were measured. The phenolic profiles were determined by HPLC/DAD analysis. The antioxidant activity was tested. The antiproliferative activity was evaluated against epidermoid carcinoma (A431) and normal (HU02) cells by MTT assay. The zone of inhibition and minimum inhibitory concentration (MIC) were determined against three pathogens. Results: The leaves ethyl acetate fraction showed the strongest antioxidant activity (IC50 25.74±0.07 μg/mL) and the highest content of total phenolics (149.72±1.23 mg GAE/g). The antioxidant activity and phenolic content of leaves methanol extract were close to ethyl acetate fraction (IC50 26.26±0.13 μg/mL and 140.63±1.32 23 mg GAE/g, respectively). The leaves methanol fraction and methanol extract showed the highest flavonoids (58.87±0.71 mg QE/g) and tannins content (314.4±0.11 mg TAE/g), respectively. The leaves and stems methanol extract and methanol fraction exhibited the highest antimicrobial activity against Staphylococcus aureus (MIC 37.5 mg/mL). The most potent cytotoxic effect was for leaves ethyl acetate fraction (369.6±56.1 μg/mL). HPLC analysis proved the presence of gallic acid, vanillic acid, ferulic acid, luteolin and rutin in leaves ethyl acetate fraction, and gallic acid and ferulic acid in leaves methanol fraction. Conclusion: The leaves ethyl acetate and methanol fraction showed potential to be investigated in further studies.