Abstract
This study aimed to investigate the phytochemical screening, total phenolic content, antioxidant and antimicrobial activities of Coleus forskohlii L. stem extract in Al-Baha area, Saudi Arabia. Stem samples were collected from Al-Baha area and air-dried followed by extraction with ethanol, petroleum ether, chloroform, ethyl acetate, and n-butanol. The extracts were then subjected to phytochemical screening, determination of total phenolic content, antioxidant and antimicrobial activities. Results showed the presence of flavonoids, alkaloids, tannins, terpenoids, steroids, saponins, and reducing sugars. Total phenolic content was significantly (P<0.001) higher in n-butanol extract (274.33±3.29 mg GAE/gm), followed by ethyl acetate extract (182.94±1.82 mg GAE/gm), ethanol extract (79.63±2.02 mg GAE/gm) and petroleum ether extract (73.38±3.07 mg GAE/gm), while the lowest content was in chloroform extract (60.06±2.12 mg GAE/gm). The antioxidant activity was significantly (P<0.001) higher in n-butanol extract (67.68±1.55%), followed by ethyl acetate extract (43.38±1.27%), ethanol extract (36.02±1.29%), petroleum ether extract (20.71±0.59%) and chloroform extract (19.73±0.74%). The antimicrobial activity showed that all microorganisms tested were resistant at the concentration of 25 and 50 mg/ml of plant extracts, whereas the concentrations of 100, 150 and 200 mg/ml showed varying activities against gram-negative (Escherichia coli, Pseudomonas aeruginosa), gram-positive (Staphylococcus aureus, Bacillus cereus) and Candida albicans. The study concluded that the stem extracts of C. forskohlli have promising pharmacological and biological activities that could be beneficial in pharmaceutical as well as food and medicinal industries.
Highlights
There is a growing interest in using natural antibacterial compounds such as plant extracts of herbs and spices for the preservation of foods because these extracts possess a characteristic flavour and sometimes show antioxidant and antimicrobial activities [1]
The phytochemical screening revealed the presence of all phytochemicals in the stem extracts except flavonoids and saponins which were absent in petroleum ether and chloroform extracts, terpenoids were absent in ethyl acetate extract, and tannins and saponins were absent in n-butanol extract (Table 1)
Phytochemical-screening results of C. forskohlii water, hexane, chloroform, methanol, and 80% methanol extracts showed the presence of all the constituents in aqueous and methanol extracts, while proteins, carbohydrates, and cardiac glycosides were found in chloroform extract, and cardiac glycosides were found in hexane extracts, indicating that water and methanol were able to extract most of the phytochemicals present in the shoot [19]
Summary
There is a growing interest in using natural antibacterial compounds such as plant extracts of herbs and spices for the preservation of foods because these extracts possess a characteristic flavour and sometimes show antioxidant and antimicrobial activities [1]. Plants are the major source of medicines and foods which play a vital role in the conservation of human health. The importance of plants in medicine is of significance with the current global trends to obtain drugs from plant sources [2]. Medicinal plants are important for pharmacological research and drug development, when constituents are used directly as therapeutic agents, and as starting materials for the synthesis of drugs or as models for pharmacologically active compounds [3]. Ninety percent of the world’s population relies on conventional as well as traditional medicines for their primary health care, the majority of which involves the use of plant extract drugs and secondary metabolites [5].
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