Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to –3.98 mV, compared to untreated cells (–5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.
Methods: The price of different brands of the same anticancer medicines available in the hospital pharmacies of two cancer hospitals was assessed. Prices of different dosage forms such as a single tablet, capsule and vial were calculated. The difference in the maximum and minimum price of the same drug manufactured by different pharmaceutical industries was determined, and the percentage variation in price was calculated. The prices of medicines (brands) were also compared with the price determined by the government where available.
Results: Price variation was assessed for 31 anticancer medicines belonging to six broad categories. Prices were found to vary maximally among the following medicines, each belonging to separate categories: among alkylating agents, the price of temozolomide 100 mg capsule varied 308%; among antimetabolite agents, the price of pemetrexed 500 mg injection varied 134%; among hormonal drugs, the price of letrozole 2.5 mg tablet varied 200%; among antibody class, the price of trastuzumab 440 mg injection varied 73%; among natural products, the price of irinotecan 100 mg injection varied 590%; and among miscellaneous agents, the price of bortezomib 2 mg injection varied 241%. There was a significant difference in the mean MRP of the alkylating agents with the antimetabolites (p-value 0.006) and the monoclonal antibody (p-value