Objectives: Costaceae family comprises many ornamental and medicinal plants used for different diseases. This investigation includes the phytochemical, histochemical, and in vitro antimicrobial study of Costus speciosus (J. Koenig) Sm. and C. pictus D. Don.
Materials and methods: Solvents such as methanol, ethyl acetate, and hexane were used to extract the leaves and rhizomes of both plants. The antibacterial study was executed using the agar well diffusion technique.
Results: Phytochemical study confirmed that alkaloids, flavonoids, quinones, and saponins were present in solvent extracts of both plants. The macromorphological studies including size, shape, texture, surface characters, and color, were analyzed. Salmonella typhi, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were used for the antibacterial study. Agar well diffusion and agar disk diffusion methods were performed to determine the susceptibility of bacterial strains to various extracts of these plants.
Conclusion: Histochemical analysis revealed alkaloids, proteins, and phenols in the vascular bundles, the cortex, and epidermis of stem, root, and leaves of the plants. Inhibition zones caused by the methanol and hexane extracts showed better antibacterial activity compared to those of other extracts. Future work on the isolation, purification, and characterization of the active constituents and the elucidation of possible mechanisms can be executed.
Keywords: Costaceae; Costus pictus; Costus speciosus; antibacterial activity; histochemical.