Combination of 1H and 13C NMR for quantitative analysis of the orange pigments produced by Monascus kaoliang KB9

Color and functionality construction of cellulose towels with biological Monascus pigment based on a nano-suspension system

As a sanitary textile that directly contacts sensitive parts of the human body, such as mouth, nose and eyes, towel is very important for our daily life and health. However, the colored cellulose towels we use daily are dyed with synthetic dyes. This can be a problem for people with sensitive skin, particularly babies. In this research, cellulose towel fabric was dyed using a nano-level Monascus pigment dyeing solution, which eliminated the need for organic solvent to dissolve the pigment, making it an environmentally friendly dyeing scheme. After 90 °C pre-mordanting treatment and 80 °C dyeing for 30 min respectively, the K/S value of towel fabric could reach 9. In addition, the washing fastness of dyed towel fabric was 3-4, the dry/wet friction fastness was 4-5 and 3-4, and the K/S value remained high even after 20 washing times, and also demonstrated a certain level of UV resistance and antibacterial properties. In conclusion, the application of the dyeing method for cellulose towel fabric with biological Monascus pigment based on a nano-suspension system was found to be both efficient and environmentally friendly, which was anticipated to replace certain traditional synthetic dyes in the future.

Absolute configuration of azaphilones from Monascus kaoliang KB9 and solvent effects on their keto and enol forms

Monascus fermented rice, also known as red yeast rice, exhibits a broad spectrum of biological activities due to its chemical constituents, such as monacolins and azaphilone pigments. Here, we cultured Monascus kaoliang KB9 in a liquid malt medium instead of on rice as a carbon source. Eleven known compounds (1-11) containing azaphilones and their early intermediate were isolated and identified. However, this was the first time that angular tricyclic azaphilones, monasfluols A (4) and B (7), acetyl-monasfluol A (5) and monasfluore A (6), were isolated from this species. Interestingly, all isolated tricyclic azaphilones existed exclusively in enol form in CD₃OD, as evidenced by NMR spectroscopy. The absolute configuration of compounds 4-7 was also first experimentally identified based on ECD spectroscopy combined with conformational analyses using computational techniques. The assigned stereochemistry of Monascus azaphilones in this work provides essential structural information that will benefit future biological and pharmaceutical investigations.