Blue light and skin: what is the intriguing link?

Blue light has garnered attention because of its ability to penetrate more deeply into the skin layers, and induce cellular dysfunction and DNA damage. Photoageing, hyperpigmentation and melasma are some of the cutaneous changes that develop on exposure to blue light. To date, the therapeutic roles of blue light have been evaluated in dermatological conditions like psoriasis, eczema, acne vulgaris, actinic keratosis and cutaneous malignancies, among others. In this review, we have attempted to present an evidence-based compilation of the effects of blue light on the skin.

Dermatological adverse drug reactions to tyrosine kinase inhibitors: a narrative review.

Tyrosine kinase inhibitors (TKIs) target the signal transduction pathways of protein kinases by several modes of inhibition. Adverse effects are generally dose dependent, with certain side-effects unique to each drug. However, due to similarities in target sites, different classes of TKIs may have identical or overlapping side-effect profiles. This narrative review is an attempt to summarize the common and uncommon adverse effects of different classes of TKIs.

Chronic venous disease. Part 1: pathophysiology and clinical features.

Chronic venous disease (CVD) is a commonly encountered condition in the dermatology outpatient department. If untreated, CVD may progress to chronic leg ulcer causing serious morbidity to the patient. It also affects the quality of life of the affected patient and contributes to loss of work productivity. The spectrum of clinical manifestations for CVD is myriad, ranging from asymptomatic varicose veins and pigmentation to ulceration and scarring. Awareness of spectrum of clinical presentations is required to identify, diagnose and manage CVD. Long-standing cases may develop ankle joint stiffness, fixed flexion deformity, periostitis and even Marjolin ulcer. Increased venous hypertension, thought to result from valve incompetence and failure of the calf muscle pump, is central to the pathophysiology of the development of CVD. Tissue oedema, hypoxia and subsequent fibrosis are major immediate contributing factors responsible for the clinical manifestations of CVD. Localized, chronic inflammation is now increasingly being recognized as a key player, directly responsible for stasis dermatitis and hypercoagulable state. The complete ramifications of persistent inflammation in CVD are yet to be understood and serious systemic morbidities such as arterial and cardiac disease are increasingly being recognized in association with CVD.

Photo-assisted inactivation of highly drug resistant bacteria and DPPH scavenging activities of zinc oxide graphted Pd-MCM-41 synthesized by new hydrothermal method.

A major current biomedical challenge is to find materials that are specific, have high efficiency and with long lasting stability to serve as antimicrobial agents. In this contribution we examined new bifunctional nanostructural materials (ZnO/Pd-MCM-41) which were synthesized by a new hydrothermal procedure. To deposit active cites i.e. ZnO, a new protocol was followed in which catechol was used as a precipitating agent. Results indicated that nanostructures comprising palladium nanocrystals of a small size dispersed consistently within the hexagonal pores of the MCM-41 and also ZnO was successfully coated on mesoporous Pd-MCM-41 and that the mesoporous Pd-MCM-41 structure has been well-maintained upon modification of ZnO. The ZnO/Pd-MCM-41 is promising antibacterial agent and have efficient light inhibition activity towards Escherichia coli (E. coli), Psedomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The inhibition zone of irradiated ZnO/Pd-MCM-41 nanostructure against E. coli, P. aeruginosa and S. aureus were (17 ± 0.4) mm, 18 (±0.4) mm and 22 (±0.2) mm respectively while that in dark were (9 ± 0.5) mm, 11 (±0.3) mm and 13 (±0.4) mm respectively. The production of reactive oxygen species and hemolytic assay were also analyzed. Different parameters affecting the photo-inhibition efficiency of ZnO/Pd-MCM-41 were also studied. Likewise, the antioxidant activity of these nanostructures was studied against DPPH stabilization. Results indicated that the synthesized nanostructures are highly active and stabilized 99 % DPPH at very low concentration i.e. 1.4 mg/mL.

Enantioselective, Noncovalent, Substrate-Directable Heck-Matsuda and Oxidative Heck Arylations of Unactivated Five-Membered Carbocyclic Olefins.

Highly diastereo- and enantioselective, noncovalent, substrate-directable Heck desymmetrizations of cyclopentenyl olefins containing hydroxymethyl and carboxylate functional groups are presented. These conformationally unbiased cyclic olefins underwent effective arylations in yields of up to 97 %, diastereoselectivity up to >20:1, and enantiomeric excesses of up to 99 %. Noncovalent directing effects were shown to be prevalent in both Heck-Matsuda and oxidative Heck reactions, allowing the preferential formation of cis-substituted aryl cyclopentenes containing two stereocenters, including quaternary stereocenters. These results further validate the internal out-of-coordination-sphere ion-dipole interaction concept directing the reaction diastereoselectivity to the cis-Heck product. This approach is complementary to existing methods using bis-phosphine monoxide ligands to give the opposite trans-diastereoisomer. The applicability of the method is showcased by the straightforward synthesis of a potent phosphodiesterase 4 inhibitor in a diastereo- and enantioselective manner. The reaction is operationally simple and has broad scope with regard to the nature of the arenediazonium salt and boronic acid employed. The mechanism and origin of stereoselectivity were investigated with control experiments and DFT calculations that fully supported the stabilizing internal out-of-coordination-sphere ion-dipole interaction between the resident functional group and cationic palladium.

Enantioselective total synthesis of the highly selective sphingosine-1-receptor VPC01091 by the Heck desymmetrization of a non-activated cyclopentene-fused spiro-pyrrolidinone.

A novel, efficient and enantioselective Heck-Matsuda desymmetrization of non-activated cyclopentene-fused spiro-pyrrolidinones was developed. The reaction provided the Heck products in good to excellent yields and selectivities and tolerated a variety of functional groups in arenediazonium tetrafluoroborates (12 examples) with respect to its electronics and substitution patterns. This methodology was successfully applied in the concise enantioselective total synthesis of VPC01091 (2b), a drug candidate for the treatment of multiple sclerosis.

Enantioselective and Regiodivergent Functionalization of N-Allylcarbamates by Mechanistically Divergent Multicatalysis.

A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel-catalyzed isomerization of N-allylcarbamates and subsequent phosphoric-acid-catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene-carbamates are mechanistically partitioned to yield opposing functionalized products. Formal α-functionalization to give protected α-arylamines is achieved upon enantioselective Friedel-Crafts reaction with arene nucleophiles, whereas formal ß-functionalization is achieved upon reaction with diarylimine electrophiles in an enantioselective Povarov-[4+2] cycloaddition.