5-Alkylresorcinol Derivatives from the Bryozoan Schizomavella mamillata: Isolation, Synthesis, and Antioxidant Activity

Abstract

The chemical study of the bryozoan Schizomavella mamillata has led to the isolation of six new 5-alkylresorcinol derivatives, schizols A–F (1–6), whose structures were established by spectrocospic means. Schizol A (1) exhibits a (E)-6-phenylnon-5-enyl moiety linked to the C-5 of a resorcinol ring, while in schizol B (2) the substituent at C-5 contains an unusual 1,2-dihydrocyclobutabenzene moiety. Schizols C (3) and D (4) have been characterized as the 1-sulfate derivatives of 1 and 2, respectively, and schizols E (5) and F (6) are the corresponding 1,3-disulfates. Schizol A (1) has been synthetized from 3,5-dimethoxybenzaldehyde through a sequence involving a Wittig reaction for the construction of the C-1′,C-2′ bond and a Julia–Kocienski olefination for the synthesis of the C-5′,C-6′ double bond. In the ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) antioxidant assay, the natural compounds schizol A (1) and schizol B (2) showed higher radical scavenging activity than the Trolox standard.

Autofluorescence mediated red spherulocyte sorting provides insights into the source of spinochromes in sea urchins

“…Sulphate esters are common in marine natural products (sulphate esters within Marinlit marine natural products database: n = 1098) 50 . A number of studies have demonstrated various changes in biological activities of natural products due to variations in the number of sulphate esters [51][52][53][54][55][56][57] . At least one study comparing a class of marine natural products demonstrated a correlation between sulphate groups and reduced biological activity 49 , representing a detoxifying effect.…”

“…At least one study comparing a class of marine natural products demonstrated a correlation between sulphate groups and reduced biological activity 49 , representing a detoxifying effect. Other studies have also demonstrated significant differences between sulphated and de-sulphated analogues of natural products, with many showing a decrease in biological activity for sulphate analogues [53][54][55] . Although a decrease in activity is common for sulphated derivatives, one study has described an increase in biological activity 57 , and another described an increase in activity for a disulphated analogue compared to its monosulphated counterpart 52 .…”

Marine natural products

“…Schizol A 1379 was synthesised from 3,5-dimethoxybenzaldehyde. 613 The Arctic species Securiustra securifrons yielded a number of halogenated alkaloids including securidine A 1385 (ref. 614) and securamines H 1386 and I 1387.…”

Marine Pharmacology in 2016–2017: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

“…NH-F6 polyketides perylenequinones (294,295) [316]; sponge Petrosia alfiani xestoquinone derivatives petroquinones A and B (296, 297) [317]; fungus Peyronellaea glomerata isocoumarin derivatives peyroisocoumarins B and D (298,299) [318]; fungus Phoma sp. NTOU4195 polyketide phomaketide A (300) [319]; ascidian Sidnyum elegans phosphorylated polyketide phosphoeleganin (301) [320]; soft coral Pseudopterogorgia rigida sesquiterpenes (302, 303) [321]; sponge Spongia ceylonensis diterpene ent-13-norisocopalen-15-al-18-oic acid (304) [322]; bryozoan Schizomavella mamillata 5-alkylresorcinol derivatives schizols A and B (305, 306) [323]; fungus Stachybotrys longispora FG216 isoindolinone derivatives FGFC6 and FGFC7 (307,308) [324]; sponge Spongia pertusa Esper sesquiterpene (309) [325]; sponge Psammocinia sp. furanosesterterpene tetronic acid sulawesin A (310) [326]; cyanobacterium Okeania sp.…”