Chemical Constituent Profiling of Phyllostachys heterocycla var. Pubescens with Selective Cytotoxic Polar Fraction through EGFR Inhibition in HepG2 Cells

Abstract

Different extracts of the Bamboo shoot skin Phyllostachys heterocycla var. pubescens were screened against panel of cancer cell lines and normal one. The cell viability results exhibited that the ethyl acetate extract showed the least vitality percentage of 2.14% of HepG2 cells. Accordingly, it was subjected to chromatographic separation, which resulted in the isolation of a new natural product; 7-hydroxy, 5-methoxy, methyl cinnamate (1), together with four known compounds. The structures of the pure isolated compounds were deduced based on different spectroscopic data. The new compound (1) was screened against the HepG2 and MCF-7 cells and showed IC₅₀ values of 7.43 and 10.65 µM, respectively. It induced apoptotic cell death in HepG2 with total apoptotic cell death of 58.6% (12.44-fold) compared to 4.71% in control by arresting cell cycle progression at the G1 phase. Finally, compound 1 was validated as EGFR tyrosine kinase inhibitor in both enzymatic levels (IC₅₀ = 98.65 nM compared to Erlotinib (IC₅₀ = 78.65 nM). Finally, in silico studies of compound 1 through the molecular docking indicated its high binding affinity towards EGFR protein and the ADME pharmacokinetics indicated it as a drug-like.

Keywords: EGFR activity; Phyllostachys heterocycla; apoptosis; cytotoxic activity; polar fraction.

Figure 1

Selected COSY and HMBC correlations of compound 1.

Figure 2

Chemical structures of the isolated compounds.

Figure 3

Cytograms annexin-V/propidium iodide stained HepG2 cells showing induction of apoptosis in cancer cells by compound 1 (IC50 = 7.43 µM, 48 h) compared to untreated cells. “Quadrant charts show Q-UL (intermediate, AV–/PI+), Q-UR (late apoptotic cells, AV+/PI+), Q-LL (normal cells, AV–/PI–), and Q-LR (early apoptotic cells, AV+/PI–).”

Figure 4

(A) Cytogram of the cell cycle distribution of untreated and treated HepG2 cells with. compound 1 (7.43 µM, 48 h); (B) bar chart representation of the percentage of cell population in different HepG2 cell cycle phases.

Figure 5

Representative of superimposition and binding mode of compound 1 (Orange) and the cocrystalized ligand (Green) inside the epidermal growth factor receptor tyrosine kinase (EGFR)-binding site (PDB 1M17) in 2D and 3D.

Figure 6

(A) BOILED-Egg model for compound 7 using SwissADME: “points located in the BOILED-Egg‘s yolk are molecules predicted to passively permeate through the blood–brain barrier (BBB), while points located in the BOILED-Egg‘s white are molecules predicted to be passively absorbed by gastrointestinal (GI) tract” and (B) drug likeness score of compound 1 using MolSoft: “The green color means nondrug-like behavior, and those fall under blue color area are considered as drug-like. Those compounds having negative or zero value should not be considered as drug like.”