Locally crystallized PCN is prone to form *OCCHO groups rather than *CH ₂ O groups, regulating the endoergic C–C coupling step to a simultaneous exoergic reaction and changing the reaction pathway towards CH ₃ CHO (selectivity of 98.3%) instead of HCHO.

Psoriasis is considered as a common chronic immune-mediated skin disorder characterized by abnormal keratinocyte proliferation. Luteolin, an anti-inflammatory natural flavonoid with well-accepted inhibition effect against keratinocyte proliferation, was hypothesized to have a potential therapeutic effect for psoriasis. In this paper, we investigated the relieving effect of luteolin against imiquimod-induced psoriasis-like lesions on BALB/c mice and its possible anti-inflammatory mechanisms in lipopolysaccharide-stimulated macrophages (RAW264.7 cells). We found that luteolin ameliorated psoriasis-like skin lesions, suppressed the cutaneous infiltration of macrophages, T cells and neutrophils, and downregulated the expression of cytokines like IL-6, IL-1β, TNF-α, IL-17A and IL-23 in both skin lesions and eyeball blood of model mice. In vitro, we observed luteolin significantly suppressed the levels of psoriasis-related pro-inflammatory cytokines, such as IL-17A, IL-6, TNF-α and IL-23, and inflammatory mediators like nitric oxide NO, inducible NOS, COX-2 in RAW264.7 cells. The anti-inflammatory activity was accomplished by inhibiting NF-κB expression and activation. This study demonstrates luteolin is effective in alleviating psoriasis-like skin lesions and downregulating inflammatory response via NF-κB pathway, suggesting luteolin as a potential molecule for further therapeutic research of inflammation-related skin diseases like psoriasis.

Volatile compounds in flowers of Rhododendron delavayi, R. agastum, R. annae, and R. irroratum were analyzed using comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC) coupled with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS). A significantly increased number of compounds was separated by GC×GC compared to conventional one-dimensional GC (1DGC), allowing more comprehensive understanding of the volatile composition of Rhododendron flowers. In total, 129 volatile compounds were detected and quantified. Among them, hexanal, limonene, benzeneacetaldehyde, 2-nonen-1-ol, phenylethyl alcohol, citronellal, isopulegol, 3,5-dimethoxytoluene, and pyridine are the main compounds with different content levels in all flower samples. 1,2,3-trimethoxy-5-methyl-benzene exhibits significantly higher content in R. irroratum compared to in the other three species, while isopulegol is only found in R. irroratum and R. agastum.