To prepare various crude extracts using different polarities of solvent and to quantitatively evaluate their total phenol, flavonoids contents and phytochemical screening of Thymus vulgaris collected from Al Jabal Al Akhdar, Nizwa, Sultanate of Oman. The leave sample was extracted with methanol and evaporated. Then it was defatted with water and extracted with different polarities organic solvents with increasing polarities. The prepare hexane, chloroform, ethyl acetate, butanol and methanol crude extracts were used for their evaluation of total phenol, flavonoids contents and phytochemical screening study. The established conventional methods were used for quantitative determination of total phenol, flavonoids contents and phytochemical screening. Phytochemical screening for various crude extracts were tested and shown positive result for flavonoids, saponins and steroids compounds. The result for total phenol content was the highest in butanol and the lowest in methanol crude extract whereas the total flavonoids contents was the highest in methanol and the lowest hexane crude extract. The crude extracts from locally grown Thymus vulgaris showed high concentration of flavonoids and it could be used as antibiotics for different curable and uncurable diseases.

The aim of this work is to investigate and compare the phytochemical screening, antioxidant and antimicrobial activities of different crude extracts from dry and fresh leaves of Datura metel L. Different organic solvents including methanol, chloroform, hexane, ethyl acetate and butanol were used to prepare the crude extracts from the fresh and dry leaves. Antioxidant and antimicrobial activities of different crude extracts from dry and fresh leaves of D. metel were determined by DPPH method and agar disc diffusion method with minor modification. In vitro phytochemical screening for all crude extracts from both dry and fresh leaves was tested and shown positive result for alkaloid, flavonoid, saponin and tannin compounds. However, all the crude extracts did not show positive results for steroids and triterpenoid compounds. The antioxidant activity results of both fresh and dry crude extracts showed that when gradually increasing the samples concentration there was an increase in the absorbance. Therefore the antioxidant activity of dry crude extracts as equivalent to DPPH (2, 2-diphenyl-1-picrylhydrazyl) was in the order of butanol>chloroform>ethyl acetate extract>methanol>hexane extract. However, the order of antioxidant activity for fresh organic crude extracts to DPPH was in order of methanol>hexane>chloroform>ethyl acetate extract>butanol. The methanol crude extract and its derived fractions from dry and fresh leaves showed small and moderate antibacterial potential with one gram positive (Staphylococcus aureus) and three gram negative(Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) bacteria in the range of 0–17%. In conclusion, all organic crude extracts from both fresh and dry leaves could be used as potential sources of new antioxidant and antimicrobial agents

To detect the in vitro total phenolics, flavonoids contents and antioxidant activity of essential oil, various organic extracts from the leaves of tropical medicinal plant Tetrastigma from Sabah. The dry powder leaves of Tetrastigma were extracted with different organic solvent such as hexane, ethyl acetate, chloroform, butanol and aqueous methanol. The total phenolic and total flavonoids contents of the essential oil and various organic extracts such as hexane, ethyl acetate, chloroform, butanol and aqueous ethanol were determined by Folin - Ciocalteu method and the assayed antioxidant activity was determined in vitro models such as antioxidant capacity by radical scavenging activity using α, α-diphenyl- β-picrylhydrazyl (DPPH) method. The total phenolic contents of the essential oil and different extracts as gallic acid equivalents were found to be highest in methanol extract (386.22 mg/g) followed by ethyl acetate (190.89 mg/g), chloroform (175.89 mg/g), hexane (173.44 mg/g), and butanol extract (131.72 mg/g) and the phenolic contents not detected in essential oil. The antioxidant capacity of the essential oil and different extracts as ascorbic acid standard was in the order of methanol extract > ethyl acetate extract >chloroform> butanol > hexane extract also the antioxidant activity was not detected in essential oil. The findings show that the extent of antioxidant activity of the essential oil and all extracts are in accordance with the amount of phenolics present in that extract. Leaves of Tetrastigma being rich in phenolics may provide a good source of antioxidant.

The antibacterial potential of essential oils and methanol extracts of sweet basil Ocimum basilicum L. (Lamiaceae) was evaluated for controlling the growth range of food-borne pathogenic bacteria. Essential oils extracted by hydrodistillation from the leaves and stems were analyzed by GC-MS. Fifty-seven compounds representing 94.9 and 96.1% of the total leaf and stem oils, respectively, were identified, of which methyl chavicol (36.7 and 29.9%), gitoxigenin (9.3 and 10.2%), trimethoquinol (10.3 and 8.4%), β-guaiene (3.7 and 4.1%), aciphyllene (3.4 and 3.0%), alizarin (3.2 and 4.4%), naphthaline (2.2 and 3.8%), (–)-caryophyllene (2.0 and 1.9%), and mequinol (1.6 and 1.8%) were the major compounds. The essential oils (10 μL/disc of 1:5, v/v dilution with methanol) and methanol extracts (300 μg/disc) of O. basilicum displayed a great potential of antibacterial activity against Bacillius cereus, B. subtilis, B. megaterium, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Shigella boydii, S. dysenteriae, Vibrio parahaemolyticus, V. mimicus, and Salmonella typhi with their respective zones of inhibition of 11.2–21.1 mm and MIC values of 62.5–500 μg/mL. The results of this study suggest that the natural products derived from O. basilicum may have potential use in the food and/or pharmaceutical industries as antimicrobial agents.