Unveiling the apoptotic potential of antioxidant-rich Bangladeshi medicinal plant extractives and computational modeling to identify antitumor compounds

Abstract

Nowadays, there has been a significant surge in the exploration of anticancer compounds derived from medicinal plants due to their perceived safety and efficacy. Therefore, our objective was to investigate the antioxidant and antiproliferative properties, along with the phytoconstituents, of methanol extracts from various parts of 15 selected Bangladeshi medicinal plants. Standard spectrophotometric methods and confocal microscopy were utilized to assess the antioxidant and antiproliferative potential of these extracts. Additionally, phytochemical profiling was executed through gas chromatography-mass spectrometry (GC-MS) analysis. Among the extractives, Bombax ceiba bark exhibited the highest scavenging capacity against DPPH (IC₅₀: 10.3 ± 0.7 μg/mL) and hydroxyl (IC₅₀: 3.9 ± 0.1 μg/mL) free radicals. Furthermore, the total antioxidants, reducing power, and polyphenols of B. ceiba bark were higher than those of other extracts. B. ceiba bark also showed significant antiproliferative capacity against MCF-7 cells (86.67 %) in the MTT assay, followed by Cocos nucifera roots (83.92 %), Bixa orellana leaves (44.09 %), and Leea macrophylla roots (25 %). Moreover, B. ceiba bark, L. macrophylla roots, C. nucifera roots, and B. orellana leaves-treated Ehrlich ascites carcinoma (EAC) cells demonstrated growth inhibition rates of 87.27 %, 80.45 %, 42.9 %, and 37.27 %, respectively. Fluorescence microscopic analysis of EAC cells treated with these extracts revealed apoptotic features such as condensed chromatin, cell shrinkage, nucleus fragmentation, and membrane blebbing compared to untreated EAC cells. The GC-MS analysis of B. ceiba bark identified 18 compounds, including various alcohols, alkenes, and esters. Additionally, a molecular docking study revealed oxalic acid, cyclohexyl dodecyl ester as the most potent compound (-6.5) active against breast cancer. In summary, our results demonstrate that B. ceiba bark possesses robust antioxidant and antiproliferative properties, along with potent antitumor compounds, which could be utilized in the treatment of carcinoma.

Keywords: Antioxidants; Antitumor compounds; Apoptosis; Bangladeshi medicinal plants; Oxidative stress.

Fig. 1

Antiproliferative capacity of antioxidant-rich Bangladeshi medicinal plant extractives (A) Growth inhibition of MCF-7 cells after treatment with plant extractives using MTT assay, (B) IC₅₀ of plant extractives, (C) Antiproliferative capacity of extractives against EAC cell in mouse model, (D) RBC level of control and extractives-treated EAC cell (E) WBC level of control and extractives-treated EAC cell, (F) Hemoglobin content of control and extractives-treated EAC cell. Data are showed as mean ± SEM, n = 6. Where significant values are ∗p < 0.05, ∗∗p < 0.01 and ∗∗∗p < 0.001. LMR: Leea macrophylla roots, BCB: Bombax ceiba bark, CNR: Cocos nucifera roots, CGB: Cassia grandis bark, BOL: Bixa orellana leaves, BL: Bleomycin sulfate.

Fig. 2

Tumor growth inhibition capacity of antioxidant-rich Bangladeshi medicinal plant extractives and standard anticancer drug bleomycin sulfate. EAC-cell-bearing mice were treated with plant extracts (10 mg/kg body weight) and bleomycin sulfate (0.3 mg/kg body weight). Tumor weight was recorded for up to 20 days. Data are presented as mean ± SEM, n = 6. Statistical significance is indicated as follows: ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001. LMR - Leea macrophylla roots, BCB - Bombax ceiba bark, CNR - Cocos nucifera roots, CGB - Cassia grandis bark, BOL - Bixa orellana leaves, BL - Bleomycin sulfate.

Fig. 3

Morphological observation of control and extractives-treated EAC cell by fluorescence microscopy (Olympus IX71). (A, B) indicate control and bleomycin-treated cells; (C–G) represent L. macrophylla roots, B. ceiba bark, C. nucifera roots, B. orellana leaves, and C. grandis bark-treated cells, respectively. Arrows indicate cells undergoing an apoptosis.

Fig. 4

GC-MS spectrum of Bombax ceiba bark extractive. An equipment gas chromatograph (GC-2010 Plus Shimadzu, Japan) combined with a mass spectrometer (GCMS-QP2020 Shimadzu, Japan) was used.

Fig. 5

Molecular docking and interaction close view of HER2 protein (PDB ID: 7PCD) with (A) Carboplatin (Standard Drug); (B) Oxalic acid, cyclohexyl dodecyl ester; (C) Undecylcyclohexane; and (D) 1,5-Diethyl-2,3-dimethylcyclohexane.