In Vitro Anticancer Activity of Staphyloxanthin Pigment Extracted from Staphylococcus gallinarum KX912244, a Gut Microbe of Bombyx mori

Abstract

The present study reports the in vitro biological nature of the pigment produced by Staphylococcus gallinarum KX912244, isolated as the gut microflora bacterium of the insect Bombyx mori. The purified pigment was characterized as Staphyloxanthin based on bio-physical characterization techniques like Fourier transform infrared spectroscopy, high performance liquid chromatography, Proton nuclear magnetic resonance spectroscopy (¹H NMR), Liquid chromatography-Mass spectroscopy and Gas chromatography-Mass spectroscopy. The Staphyloxanthin pigment presented considerable biological properties including in vitro antimicrobial activity against pathogens Staphylococcus aureus, Escherichia coli and Candida albicans; in vitro antioxidant activity by % DPPH free radical scavenging activity showing IC₅₀ value of 54.22 µg/mL; DNA damage protection activity against reactive oxygen species and anticancer activity evaluated by cytotoxicity assay against 4 different cancer cell lines like the Dalton's lymphoma ascites with IC₅₀ value 6.20 ± 0.02 µg/mL, Ehrlich ascites carcinoma having IC₅₀ value 6.48 ± 0.15 µg/mL, Adenocarcinomic human alveolar basal epithelial cells (A549 Lung carcinoma) bearing IC₅₀ value 7.23 ± 0.11 µg/mL and Mus mucus skin melanoma (B16F10) showing IC₅₀ value 6.58 ± 0.38 µg/mL and less cytotoxicity towards non-cancerous human fibroblast cell lines (NIH3T3) with IC₅₀ value of 52.24 µg/mL. The present study results suggest that Staphyloxanthin acts as a potential therapeutic agent especially due to its anticancer property.

Keywords: Bombyx mori; Cancer; Free radicals; Staphylococcus gallinarum; Staphyloxanthin.

Fig. 1

Isolation of microflora of silkworm midgut by crowded plate technique

Fig. 2

Secondary screening of antimicrobial property of the isolated bacterial colony by giant colony technique

Fig. 3

Gram positive cocci in clusters on gram staining

Fig. 4

Phylogenetic tree representing evolutionary relationship of Staphylococcus gallinarum DSBM5.1 (GenBank accession no: KX912244) with other closely related Staphylococcus strains

Fig. 5

FTIR chromatogram of extracted Staphyloxanthin pigment

Fig. 6

HPLC chromatogram of the extracted Staphyloxanthin pigment

Fig. 7

¹H NMR spectrum of the extracted Staphyloxanthin pigment

Fig. 8

LC-MS chromatogram showing mass peak and m/z values for the extracted Staphyloxanthin pigment

Fig. 9

GC-MS chromatogram showing Staphyloxanthin m/z value

Fig. 10

Graph showing antioxidant activity of Staphyloxanthin pigment

Fig. 11

DNA damage protection activity of the extracted Staphyloxanthin pigment. Lane 1: pBR322 DNA. Lane 2: pBR322 DNA + Fenton’s reagent. Lane 3: pBR322 DNA + Fenton’s reagent + Staphyloxanthin pigment

Fig. 12

Antimicrobial activity of the extracted Staphyloxanthin pigment against pathogens A) E. coli, B) S. aureus and C) C. albicans