A Novel Biochemical Study of Anti-Ageing Potential of Eucalyptus Camaldulensis Bark Waste Standardized Extract and Silver Nanoparticles.

• Egyptian Eucalyptus camaldulensis Dehnh bark is considered waste. • UPLC-ESI-MS/MS analysis of extract showed twenty compounds and Rutin was major. • Extract was formulated into AgNps through green synthesis. • Extract and AgNPs inhibited apoptosis, senescence and prevented wrinkles formation. • In spite of being considered waste, extract and AgNPs are anti-ageing candidates. Eucalyptus camaldulensis Dehnh belongs to family Myrtaceae. They are massive in Egypt. Although reputed for high phenolic content, barks are considered waste. Ageing is a natural phenomenon caused by apoptosis and senescence resulting in wrinkles. The phytochemical analysis of the 70% ethanolic Eucalyptus camaldulensis bark extract (EBE) and evaluation of its anti-ageing potential and as silver nanoparticles (AgNPs) were conducted in this study. Ultra performance liquid chromatography / electrospray ionization mass spectrometry of EBE fingerprint revealed twenty compounds, where Rutin was major. EBE was standardized to contain 1.26 % Rutin. AgNPs synthesized by green synthesis, were characterized by transmission electron microscope and zeta potential measurement. Both EBE and AgNPs were subjected to MTT assay in HFB4 cells and cell cycle arrest. Flow cytometry was used to assess apoptosis and p16 INK4a. Genetic expression of p53 and p21 and telomerase level were determined. Anti-wrinkle enzyme assays were done. AgNps were spherical, 468.7 nm in size and with Poly dispersity index of 0.817 ± 0.129. EBE and AgNPs with IC 50 0.156 mg/mL ± 0.05 and 2.315 ± 0.07 μg/mL expressed significant difference in % of cells (DNA content) at G2/M, apoptotic cells numbers, p53 and p21expression and p16INK4a vs aged cells (P < 0.0001). Both expressed significant increase in telomerase (P < 0.0001). They exhibited elastase, collagenase and tyrosinase inhibition (75 ± 4.3 and 75.9 ± 6.8 % at 300 μg/mL, 58 ± 4.8 and 63 ± 2.3, at 500 μg/mL, 51 ± 4.8 and 65 ± 5.87, at 500 μg/mL, respectively. Although it is considered waste, EBE and Ag NPs are anti-ageing candidates as they inhibit apoptosis, senescence and prevent wrinkles formation. [ABSTRACT FROM AUTHOR]