Acne vulgaris is a common chronic inflammatory skin disease. In the present study, we reported the anti-acne vulgaris effect of the Mesua ferrea (M. ferrea) flower extract. The extract was evaluated for three anti-acne-causing bacteria properties including Cutibacterium acnes (C. acnes), Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus). The results indicated that the M. ferrea flower extract could be considered as the bactericidal agent against S. epidermidis and S. aureus with MIC values of 0.78 and 6.25 mg mL⁻¹ and MBC values of 1.56 and 12.50 mg mL⁻¹ and the bacteriostatic agent against C. acnes with MIC and MBC values of 3.12 and 25.00 mg mL⁻¹, respectively. The extract at a concentration of 25 µg mL⁻¹ also presented potent anti-inflammatory activity with a significant decrease of nitric oxide (NO) and tumor necrosis factor (TNF)-α productions in RAW 264.7 macrophage cells stimulated by LPS. In addition, the extract showed moderate to weak anti-oxidative capacities against DPPH, ABTS, FRAP and NO assays and also showed weak anti-tyrosinase activity. M. ferrea flower extract may serve as the alternative natural anti-acne formulations.

Natural tyrosinase inhibitors from herbal plants are promising therapeutic agents for skincare and cosmetic products. Natural curcuminoids exhibit weak antityrosinase properties. The structural modification of curcumin, the major curcuminoid from Curcuma longa, gave 14 analogues. The tyrosinase inhibitory activity of the natural curcuminoids and the modified analogues on both L-tyrosine and DOPA substrates were evaluated. The inhibition kinetics were also undertaken. For analogues with potent activity on the L-tyrosine substrate, the isoxazole analogue 12 and two reduced analogues, hexahydrocurcumin (16) and the α,β-unsaturated analogue 17, showed IC₅₀ values of 8.3, 14.6 and 9.4 µM, and were 20.9-, 11.9- and 18.4-fold more active, respectively, than kojic acid, the reference compound. For the analogues with potent antityrosinase on DOPA substrate, the dimethylated analogue 5 exhibited the strongest antityrosinase activity against the DOPA substrate, with the IC₅₀ value of 8.0 µM, which was 16.6-fold more active than kojic acid. The inhibition kinetics revealed that curcuminoid 5 could bind with both free enzyme and with the enzyme–substrate complex. It acted as a competitive–uncompetitive mixed-II type inhibitor. Curcuminoid 17 could bind with both free enzyme and the enzyme–substrate complex. The results indicated that 17 acted as a competitive–uncompetitive mixed-I type inhibitor, while curcuminoid 12 was a noncompetitive inhibitor which bound with both free enzymes and the enzyme–substrate complex. These potent analogues might serve as new potential tyrosinase inhibitors for the prevention and treatment of skin pigmentation disorders.

Eight new alkaloids, which are four new tetrahydroprotoberberine alkaloids, stephapierrines A–D (1–4), and four new aporphine alkaloids, stephapierrines E–H (5–8), together with three new naturally occurring alkaloids (9–11) and thirty-four known alkaloids (12–45) were isolated from the tubers of Stephania pierrei Diels. The structures of the new compounds were elucidated by spectroscopic analysis and physical properties. The structures of the known compounds were characterized by comparison of their spectroscopic data with those previously reported. Compound 42 exhibited the strongest acetylcholinesterase (AChE) inhibitory activity, which was more active than galanthamine, the reference drug. Compound 23 showed the highest butyrylcholinesterase (BuChE) inhibitory activity, which was also more active than galanthamine. Molecular docking studies are in good agreement with the experimental results.

Ultraviolet-B (UVB) exposure is one of the primary extrinsic factors causing skin photoaging. It stimulates inflammatory responses and arrests the cell cycle. Matrix metalloproteinase-1 (MMP-1) secreted by keratinocytes is one of the important extracellular matrixes to attenuate UVB-induced skin aging via collagen degradation. Curcuma aromatica (CA) and Curcuma comosa (CC), the herbaceous plants in the Zingiberaceae family, are commonly used in Thai traditional women’s medicines. The present work was aimed to investigate the potential of the CA and CC extracts and their isolated compounds to attenuate UVB-induced MMP-1 and cell cycle arrest in HaCaT keratinocytes. Total phenolic contents and antioxidant capacities of the extracts were determined. CC extract contains more phenolic components and provides more potent antioxidant activities than CA extract. HaCaTs were pretreated with the extracts or their isolated constituents 1–4 for 24 h and then repeatedly exposed to UVB at 100 mJ/cm² 10 times. Both extracts and compounds 1–4 effectively reduce UVB-induced MMP-1 levels in HaCaT cells and restore cell cycle arrest. This is the first report on the potential of CA and CC extracts in reducing UVB-induced MMP-1 expression and regulating cell proliferation in HaCaT cells. Thus, CA and CC extracts might be used as alternative natural agents to prevent UVB-induced skin photoaging.