The following statements are made regarding phenolic biosynthesis in plants.
A. The lignans and flavonoids have abundant methylated carboxyl groups, compared to methylated hydroxyl groups.
B. Cells producing lignans and flavonoids have a very high demand for S-adenosylmethionine.
C. The majority of methylation reactions involved in the formation of phenolics are catalyzed by O-methyltransferases.
D. The catechol-O-methyltransferase (COMT) has strict substrate specificity.
Which one of the following options represents the combination of all correct statements?

Correct option is B

Correct Answer
(b) B and C
Explanation
Phenolic biosynthesis involves extensive methylation reactions, creating a high demand for S-adenosylmethionine, making statement B correct. Most methylation steps in phenolic metabolism occur on hydroxyl groups and are catalyzed by O-methyltransferases, validating statement C. Statement A is incorrect because phenolics are rich in hydroxyl groups rather than methylated carboxyl groups. Statement D is incorrect since COMT shows broad substrate specificity.
Information Booster
• Phenolics are characterized by aromatic rings with hydroxyl substitutions
• S-adenosylmethionine is the universal methyl donor in plant metabolism
• O-methylation increases stability and diversity of phenolic compounds
• Methylation plays a key role in plant defense and lignin formation
Additional Knowledge
Statement A is incorrect because lignans and flavonoids predominantly contain hydroxyl groups, not methylated carboxyl groups. Statement D is incorrect as COMT can act on multiple phenolic substrates and is not highly substrate-specific.