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

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 . 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 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 p16 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.