Berberine

Berberine is a quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids found in such plants as Berberis (e.g. Berberis vulgaris – barberry, Berberis aristata – tree turmeric, Mahonia aquifolium – Oregon-grape, Hydrastis canadensis – goldenseal, Xanthorhiza simplicissima – yellowroot, Phellodendron amurense – Amur cork tree, Coptis chinensis – Chinese goldthread, Tinospora cordifolia, Argemone mexicana – prickly poppy, and Eschscholzia californica – Californian poppy). Berberine is usually found in the roots, rhizomes, stems, and bark. Berberine is a quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids found in such plants as Berberis (e.g. Berberis vulgaris – barberry, Berberis aristata – tree turmeric, Mahonia aquifolium – Oregon-grape, Hydrastis canadensis – goldenseal, Xanthorhiza simplicissima – yellowroot, Phellodendron amurense – Amur cork tree, Coptis chinensis – Chinese goldthread, Tinospora cordifolia, Argemone mexicana – prickly poppy, and Eschscholzia californica – Californian poppy). Berberine is usually found in the roots, rhizomes, stems, and bark. Due to berberine's strong yellow color, Berberis species were used to dye wool, leather, and wood. Wool is still dyed with berberine today in northern India. Under ultraviolet light, berberine shows a strong yellow fluorescence, so it is useful in histology for staining heparin in mast cells. As a natural dye, berberine has a color index of 75160. Berberine was supposedly used in China as a folk medicine by Shennong around 3000 BC. This first recorded use of berberine is described in the ancient Chinese medical book The Divine Farmer's Herb-Root Classic. The hydrocloride salt of berberine, listed as an oral antibacterial in Pharmacopoeia of the People's Republic of China, is a common over-the-counter medication for gastrointestinal infection. It is usually made into round tablets of 0.1 g each and taken 1-3 pills three times a day. Colliqually it is known as huánglián sù (Chinese: 黄连素; literally: 'the essence of Chinese goldthread'). Although the clinical research has been low in quality, studies have been conducted to determine if berberine may affect diabetes or blood lipids. As of 2018, there is insufficient evidence to conclude that berberine is safe or effective for any condition. The oral bioavailability of berberine is low. Berberine is tentatively considered an antibiotic. Some research has been undertaken into possible use against methicillin-resistant Staphylococcus aureus (MRSA) infection. A small randomized controlled trial shows that it is effective in diahhrea caused by Enterotoxigenic E. coli but not in cholera. Although berberine is used mainly as an antibacterial in China, this aspect of berberine for human use is poorly-reviewed in English literature as of July 2019. The alkaloid berberine has a tetracyclic skeleton derived from a benzyltetrahydroisoquinoline system with the incorporation of an extra carbon atom provided by S-adenosyl methionine via an N-methyl group. Formation of the berberine bridge is readily rationalized as an oxidative process in which the N-methyl group is oxidized to an iminium ion, and a cyclization to the aromatic ring occurs by virtue of the phenolic group. Reticuline is known as the immediate precursor of protoberberine alkaloids in plants. Berberine is an alkaloid derived from tyrosine. L-DOPA and 4-hydroxypyruvic acid both come from L-tyrosine. Although two tyrosine molecules are used in the biosynthetic pathway, only the phenylethylamine fragment of the tetrahydroisoquinoline ring system is formed via DOPA, the remaining carbon atoms come from tyrosine via 4-hydroxyphenylacetaldehyde. L-DOPA loses carbon dioxide to form dopamine 1. Likewise, 4-hydroxypyruvic acid also loses carbon dioxide to form 4-hydroxyphenylacetaldehyde 2. Dopamine 1 then reacts with 4-hydroxy-phenylacetaldehyde 2 to form (S)-norcolaurine 3 in a reaction similar to the Mannich reaction. After oxidation and methylation by SAM, (S)-reticuline 4 is formed. (S)-reticuline serves as a pivotal intermediate to other alkaloids. Oxidation of the tertiary amine then occurs and an iminium ion is formed 5. In a Mannich-like reaction the ortho position to the phenol is nucleophilic, and electrons are pushed to form 6. Product 6 then undergoes keto-enol tautomerism to form (S)-scoulerine, which is then methylated by SAM to form (S)-tetrahydrocolumbamine 7. Product 7 is then oxidized to form the methylenedioxy ring from the ortho-methoxyphenol, via an O2-, NADPH- and cytochrome P-450-dependent enzyme, giving (S)-canadine 8. (S)-canadine is then oxidized to give the quaternary isoquinolinium system of berberine. This happens in two separate oxidation steps, both requiring molecular oxygen, with H2O2 and H2O produced in the successive processes.