Bactericidal and In Vitro Cytotoxicity of Moringa oleifera Seed Extract and Its Elemental Analysis Using Laser-Induced Breakdown Spectroscopy

Abstract

In the current study, we present the correlation between the capability of laser-induced breakdown spectroscopy (LIBS) to monitor the elemental compositions of plants and their biological effects. The selected plant, Moringa oleifera, is known to harbor various minerals and vitamins useful for human health and is a potential source for pharmaceutical interventions. From this standpoint, we assessed the antibacterial and in vitro cytotoxicity of the bioactive components present in Moringa oleifera seed (MOS) extract. Detailed elemental analyses of pellets of MOSs were performed via LIBS. Furthermore, the LIBS outcome was validated using gas chromatography-mass spectrometry (GC-MS). The LIBS signal was recorded, and the presence of the essential elements (Na, Ca, Se, K, Mg, Zn, P, S, Fe and Mn) in the MOSs were examined. The bactericidal efficacy of the alcoholic MOS extract was examined against Escherichia coli (E. coli) and Staphylococcus aureus(S. aureus) by agar well diffusion (AWD) assays and scanning electron microscopy (SEM), which depicted greater inhibition against Gram-positive bacteria. The validity and DNA nuclear morphology of human colorectal carcinoma cells (HCT-116) cells were evaluated via an MTT assay and DAPI staining. The MTT assay results manifested a profoundly inhibitory action of MOS extract on HCT116 cell growth. Additionally, MOS extracts produced inhibitory action in colon cancer cells (HCT-116), whereas no inhibitory action was seen using the same concentrations of MOS extract on HEK-293 cells (non-cancerous cells), suggesting that MOS extracts could be non-cytotoxic to normal cells. The antibacterial and anticancer potency of these MOS extracts could be due to the presence of various bioactive chemical complexes, such as ethyl ester and D-allose and hexadecenoic, oleic and palmitic acids, making them an ideal candidate for pharmaceutical research and applications.

Keywords: GC-MS; LIBS; Moringa oleifera; antibacterial; anticancer; seed extract.

Figure 1

LIBS emission line spectra of various elements recorded in the wavelength range of 245–537 nm of MOS. The signature lines for different vital minerals present in MOSs are indicated in the figure.

Figure 2

GC-MS chromatograph of MOS.

Figure 3

Effect of MOS extract on colon cancer cells (HCT-116) after treatment for 48 h with different concentrations. The average cell viability was calculated by MTT assay (** p < 0.01).

Figure 4

Effect of MOS extract on normal cells (HEK-293) after treatment for 48 h treated different concentrations. The average cell viability was calculated by MTT assay.

Figure 5

Confocal staining by DAPI. (A) The HCT-116 cells (non-treated) and (B) HCT-116 cells treated with MOS (66 µg/mL), 200× magnifications.

Figure 6

Agar well diffusion (AWD) plates showing the inhibition zones. (A) S. aureus and (B) E. coli. 1: 50 µg/mL, 2: 100 µg/mL, 3: 150 µg/mL, 4: 200 µg/mL, 5: 250 µg/mL of MOS, 6: Control (DH₂O).

Figure 7

The graphical illustration of the zones of inhibition in millimeters (mm) examined in both S. aureus and E. coli after treatment using different concentrations of MOS extract. Data are the means ± SD of three different experiments.

Figure 8

SEM micrographs for the study of morphogenesis by MOS extract. (a) E. coli cells (non-treated) and (b) treated E. coli cells, (c) S. aureus cells (non-treated) and (d) treated S. aureus cells.

Figure 9

Pictorial view of the pelletization of Moringa oleifera seed samples, showing: (a) as-purchased Moringa oleifera seeds, (b) Moringa oleifera seeds without coat, (c) pelletized seed sample.

Figure 10

Schematic illustration of the LIBSsetup employed for the detection of vital elements present in MOS.