Problem 62 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following statements is true? (1) some disinfectants can be used as antiseptics in lower concentrations (2) sulphadiazine is a synthetic antibacterial (3) ampicillin is a natural antibiotic (4) aspirin is an analgesic and an antipyretic (a) 1,2 and 3 (b) 1,2 and 4 (c) 2,3 and 4 (d) 1,3 and 4

Step-by-Step Solution

Answer

The correct answer is (b) 1, 2 and 4.

Step 1: Evaluate Statement 1

Statement 1 reads: "Some disinfectants can be used as antiseptics in lower concentrations." This statement is true because certain disinfectants, such as alcohol-based solutions, can serve as antiseptics when diluted to lower concentrations.

Step 2: Evaluate Statement 2

Statement 2 states: "Sulphadiazine is a synthetic antibacterial." This statement is true. Sulphadiazine is a synthetic antibiotic that belongs to the class of sulfonamides, which are used to treat bacterial infections.

Step 3: Evaluate Statement 3

Statement 3 mentions: "Ampicillin is a natural antibiotic." This statement is false. Ampicillin is a semi-synthetic derivative of penicillin, not a natural antibiotic.

Step 4: Evaluate Statement 4

Statement 4 says: "Aspirin is an analgesic and an antipyretic." This statement is true as aspirin is widely used to relieve pain (analgesic) and reduce fever (antipyretic).

Step 5: Determine the Correct Answer

Based on the evaluation of the statements, Statements 1, 2, and 4 are true. Therefore, option (b), which includes 1, 2, and 4, is the correct answer.

Key Concepts

Disinfectants vs Antiseptics

Understanding the distinction between disinfectants and antiseptics is crucial when it comes to maintaining hygiene and preventing infections. Both are used to kill or inhibit harmful microorganisms, but their application and concentration differ.

• Disinfectants are chemical agents applied to inanimate surfaces to eliminate or reduce bacteria, viruses, and fungi. They are typically potent and can be harmful if applied to the skin due to their high concentration and strong chemical composition. Common examples include bleach solutions and phenolic compounds.
• Antiseptics, on the other hand, are used on living tissues, such as skin, to prevent infection. They are milder than disinfectants and specially formulated for safe contact with the human body. Examples include hydrogen peroxide and iodine solutions.

Interestingly, some disinfectants, when diluted, can serve as antiseptics. For instance, alcohol-based disinfectants can be used on the skin at lower concentrations, making them versatile for both applications.
This adaptability highlights the importance of understanding product labels and knowing the correct concentration for safe usage to ensure effective disinfection while avoiding potential harm.

Sulphonamides

Sulphonamides, often referred to as sulfa drugs, were the first class of antibiotics used in medical treatment of bacterial infections. They mark a significant milestone in medicinal chemistry due to their synthetic origin. These drugs function by hindering the bacterial synthesis of folic acid, which is essential for bacterial growth and reproduction.

• Synthetic Origin: Unlike antibiotics derived from natural sources, sulphonamides are wholly synthesized in laboratories. This synthetic nature allows for tailored modifications to enhance their antibacterial efficiency.
• Mechanism of Action: By mimicking a component of folic acid, sulphonamides competitively inhibit the enzyme dihydropteroate synthase in bacteria. This inhibition prevents the bacteria from producing folic acid, a nutrient they need for DNA synthesis and cell division.

A well-known example is sulphadiazine, which underscores the utility of sulphonamides in treating urinary tract infections and other bacterial diseases.
This ability to chemically control and strategically combat bacteria has played a vital role in modern medicine, particularly before the widespread use of penicillin and other related antibiotics.

Antibiotics

Antibiotics are powerful medicines that fight bacterial infections, either by killing bacteria or inhibiting their growth. The discovery of antibiotics heralded a new era in medical treatment, enabling doctors to treat previously life-threatening infections.

• Natural vs. Synthetic: Antibiotics can be derived from natural sources, like penicillin from mold, or they can be semi-synthetic or fully synthetic. Penicillin was one of the first naturally occurring antibiotics, whereas others, like ampicillin, are semi-synthetic, undergoing chemical modifications to enhance their efficacy.
• Mechanism: These drugs work by targeting specific bacterial processes, such as cell wall synthesis, protein production, or DNA replication. This selectivity is crucial, as it allows antibiotics to target bacteria without harming host cells.

However, the misuse and overuse of antibiotics can lead to antibiotic resistance, a threat to public health where bacteria evolve to resist the effects of medicines.
Thus, antibiotics must be used judiciously, monitored by healthcare professionals to remain effective in managing bacterial infections, preserving their benefits for future generations.