Methylene-bridged dimeric natural products involving one-carbon unit in biosynthesis

Abstract

This review summarizes the methylene-bridged dimeric natural products involving one-carbon unit in biosynthesis, including their structures, biological activities, synthetic methods, and formation mechanisms.

Phaeochromycins I–K, Three Methylene-Bridged Dimeric Polyketides from Streptomyces sp. 166#

“… 12 − 14 The methylene linkages in heterodimer 1 and homodimer 2 were caused by formaldehyde and were presumed to form via the Michael addition between SEK43 and SEK34b or two SEK34, respectively. 15 , 16 High-performance liquid chromatography (HPLC) analysis ( Figure 3 ) confirmed that compound 2 was subjected to intramolecular dehydration to generate compounds 3 and 4 spontaneously via the loss of one and two H 2 O molecules ( Scheme 1 ). Thus, the physico, spectral, and cytotoxic data of compounds 2 and 3 were acquired as soon as possible after they were purified.…”

“…Meanwhile, the three stereoisomers 2a , 2b , and 2c of 2 could spontaneously be converted to each other (Figure A), and so could the two stereoisomers 3a and 3b of 3 (Figure B). SEK34 and SEK43 were reported as the products of the polyketide synthase pathway. − The methylene linkages in heterodimer 1 and homodimer 2 were caused by formaldehyde and were presumed to form via the Michael addition between SEK43 and SEK34b or two SEK34, respectively. , High-performance liquid chromatography (HPLC) analysis (Figure ) confirmed that compound 2 was subjected to intramolecular dehydration to generate compounds 3 and 4 spontaneously via the loss of one and two H 2 O molecules (Scheme ). Thus, the physico, spectral, and cytotoxic data of compounds 2 and 3 were acquired as soon as possible after they were purified.…”

Tricrilactones A–H, Potent Antiosteoporosis Macrolides with Distinctive Ring Skeletons fromTrichocladium crispatum, an Alpine Moss‐Associated Fungus

“…Methylene‐bridged dimers are infrequently encountered in natural products. However, more than 100 natural compounds with such a feature have been characterized from plants and microorganisms [22] . Tricrilactones B–D ( 2 – 4 ) comprise a bridging methylene carbon atom (C21), which is unaccountable for in the monomeric unit, indicating that a one‐carbon (C1) building block is involved in the molecule.…”

“…Tricrilactones B–D ( 2 – 4 ) comprise a bridging methylene carbon atom (C21), which is unaccountable for in the monomeric unit, indicating that a one‐carbon (C1) building block is involved in the molecule. To our knowledge, S ‐adenosyl methionine and formaldehyde are the two most common C1 units in nature [22, 23] . Thus, it is likely that S ‐adenosyl methionine or formaldehyde could be the source of methylene carbon atom (C21) in compounds 2 – 4 .…”

Rare Carbon-Bridged Citrinin Dimers from the Starfish-Derived Symbiotic Fungus Penicillium sp. GGF16-1-2

“…Dimeric natural products are a group of structurally diverse, biologically active, and biosynthetically complex metabolites. Among them, the methylene-bridged ones are a small but unique class that tend to be formed through the dimerization of two monomeric units with a methylene [ 1 ]. To date, approximately 131 natural dimers with a methylene linker were reported, including dimeric xanthones, dimeric steroids, and dimeric bioflavonoids [ 2 , 3 ].…”