Related Experiment Video

Updated: Aug 29, 2026

Screening and Isolation of C-Glycoside-Cleaving Intestinal Bacteria
06:38

Screening and Isolation of C-Glycoside-Cleaving Intestinal Bacteria

Published on: February 28, 2025

Phenylpropanoid glycosides from Orobanche caerulescens

Lie-Chwen Lin1, Wen-Fei Chiou, Cheng-Jen Chou

  • 1National Research Institute of Chinese Medicine, Taipei, Taiwan, ROC. lclin@cma23.nricm.edu.tw

Planta Medica
|February 7, 2004
PubMed

More Related Videos

High-resolution Tandem Mass Spectrometry for Studying Chemical Constituents of Gynura bicolor DC07:16

High-resolution Tandem Mass Spectrometry for Studying Chemical Constituents of Gynura bicolor DC

Published on: February 2, 2024

Related Concept Videos

Adrenergic Agonists: Direct-Acting Agents01:30

Adrenergic Agonists: Direct-Acting Agents

Drugs that mimic the action of endogenous catecholamines like noradrenaline and adrenaline are called adrenergic agonists or sympathomimetics. Based on their mechanism of action, sympathomimetics can be classified as direct-, indirect-, or mixed-acting sympathomimetics. Direct-acting adrenergic agonists activate adrenoceptors without affecting presynaptic neurons, making them independent of neuronal catecholamine-depleting agents like reserpine and guanethidine.
These agents can be classified...
Adrenergic Agonists: Chemistry and Structure-Activity Relationship01:16

Adrenergic Agonists: Chemistry and Structure-Activity Relationship

Adrenergic agonists' structure-activity relationship (SAR) determines their selectivity and efficacy. These agonists comprise a phenylethylamine moiety with an aromatic ring and an ethylamine side chain.
Aromatic ring substitutions: Substituting the aromatic ring with –OH groups at positions 3 and 4 yields catecholamines (e.g., epinephrine), which have a high affinity for adrenoceptors. Hydrogen bonding between –OH groups and receptors enhances adrenergic activity.
Separation of the aromatic...
Preparation of Diols and Pinacol Rearrangement01:57

Preparation of Diols and Pinacol Rearrangement

Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers01:17

Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers

Adrenergic antagonists, or sympatholytics, inhibit adrenoceptor activation driven by catecholamines or agonists. Based on their adrenoceptor specificity, adrenergic blockers can be categorized into two primary groups: α-adrenergic blockers (α-blockers) and β-adrenergic blockers (β-blockers). α-blockers interact with α1 and α2 subtypes of α-adrenoceptors.
Nonselective α-blockers: Nonselective α-blockers contain haloalkylamine or imidazoline moieties. Phenoxybenzamine, with a haloalkylamine...
Adrenergic Agonists: Mixed-Action Agents01:28

Adrenergic Agonists: Mixed-Action Agents

Mixed-action adrenergic agonists, like ephedrine and pseudoephedrine, directly and indirectly affect adrenergic receptors. These agents stimulate adrenoceptors and indirectly release stored neurotransmitters, amplifying the adrenergic response.
Ephedrine and pseudoephedrine lack a catecholamine group, making them less susceptible to degradation by metabolic enzymes. They have increased oral bioavailability and lipophilicity, resulting in a longer duration of action. Their response is reduced by...
Antiasthma Drugs: Methylxanthines01:24

Antiasthma Drugs: Methylxanthines

Theophylline, a member of the methylxanthine class of bronchodilators, has long been used in asthma management. While its exact mechanism of action is not fully understood, it is believed to have multiple effects on various cellular processes.
Theophylline is thought to inhibit phosphodiesterase enzymes, increasing intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). This rise in cAMP and cGMP concentrations stimulates cardiac function,...