Cyanine–flavonol hybrids as NIR-light activatable carbon monoxide donors in methanol and aqueous solutions

Abstract

Carbon monoxide release from biocompatible heptamethine cyanine–flavonol hybrids is activated by NIR light. Excellent release yields and uncaging cross sections, enhanced water solubilities, and a host–guest approach using cucurbit[7]uril are shown.

Strategies toward Metal‐Free Carbon Monoxide Prodrugs: An Update

“…In a follow-up study, Klán and co-workers fused 3-HF scaffold with the heptamethine cyanine moiety, yielding a series of NIR (770 nm) activated water-soluble CO prodrugs. [78] Upon irradiation with a 770 nm light, these compounds exhibited constant CO release with good chemical (50-78 %) and quantum yields (2-8 × 10 À 4 ). The addition of a large excess of 1 O 2 scavenger only led to a slight decrease in CO release yield, indicating that CO release mainly resulted from the reaction between 3 O 2 and the excited CO prodrugs.…”

“…Although photo-responsive CO prodrugs present the advantages of on-demand activation with a high temporospatial resolution, some inherent limitations associated with external light irradiation should not be overlooked, such as phototoxicity and poor light accessibility of deep tissues. Although a handful of NIR-activated metal-free CO prodrugs have been developed and achieved localized CO delivery in vivo, [54,75,78] NIR photons possess relatively low energy and thus the in vivo activation efficiency will be compromised. Consequently, the development of metal-free and light-free CO prodrugs is highly desirable for in vivo applications.…”

“…Importantly, the intraperitoneal injection of 24 plus 2 h NIR light (780 nm) irradiation resulted in a very pronounced increase in serum carbonyl hemoglobin (COHb) level and CO content in liver and heart tissue, indicating a promising application potential for localized CO delivery. In a follow‐up study, Klán and co‐workers fused 3‐HF scaffold with the heptamethine cyanine moiety, yielding a series of NIR (770 nm) activated water‐soluble CO prodrugs [78] . Upon irradiation with a 770 nm light, these compounds exhibited constant CO release with good chemical (50–78 %) and quantum yields (2–8×10 −4 ).…”

Exactly controlled linear CO liberation: an A- and B-ring simultaneously extended flavonol-based red fluorescent photoCORM

“…So far, the efforts for red-shifting of visible light absorption of flavonol-based photoCORMs have mainly concentrated on the extension of π-conjugation or substituent introduction on the A-ring or/and B-ring. 20–35 However, visible/sun-light triggered red fluorescent photoCORMs are very rare. In addition, the main obstacle hindering the practical application of photoCORMs is the shortage of a reliable way to exactly and spatiotemporally control the photo-released CO amounts within the safe and therapeutic dose range.…”

Proton-Coupled Triplet-Triplet Energy Transfer: Carbon Monoxide Photorelease from Porphyrin-Flavonol Hybrids

“…30 Our laboratory used an alternative approach of combining an established cyanine 7 scaffold with the flavonol moiety, pushing the absorption of the resulting cyanine-flavonol hybrids to the near-infrared (NIR) region (λ max = 750-790 nm). [31][32] More recently, 3,4'dihydroxyflavone derivatives have been embedded in a polymer matrix with 5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin used as a 1 O 2 generator to trigger CO release. 33 Still, the combined requirements for a successful biological application of a photoCORM, such as water solubility, absorption near or within the phototherapeutic window, high quantum efficiency of CO release, and very low or no toxicity, remain a challenge.…”