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

Two orange pigments, rubropunctatin (1) and monascorubrin (2), along with the yellow pigments, monascin (3) and ankaflavin (4), were isolated from M. kaoliang KB9-fermented rice, also known as red yeast rice. The orange pigments exhibit a broad spectrum of biological activities and appeared to be the major components of this fermented rice. In this work, quantitative 1H NMR (qHNMR) and 13C NMR experiments were used to determine the amounts of the two orange pigments in a crude extract in which most of the 1H NMR signals of the two compounds were indistinguishable. The quantitative values obtained by NMR techniques were found to be similar to those obtained by HPLC. Thus, the combined qHNMR with 13C experiment described in this work could be further developed to quantifying Monascus pigments or other invaluable natural products when qHNMR alone is insufficient for quantitative analysis.

Variation in the Antibacterial and Antioxidant Activities of Essential Oils of Five New Eucalyptus urophylla S.T. Blake Clones in Thailand.

Eucalyptus oils are widely used for a variety of purposes. This study investigates the terpenoid compositions and antibacterial and antioxidant activities of eucalypt leaf oils extracted from four E. urophylla clones and one E. urophylla × E. camaldulensis hybrid clone grown in Thailand. According to GC/MS analysis, the E. urophylla oils were mainly composed of 1,8-cineole, α-terpinyl acetate, ß-caryophyllene, and spathulenol, while 1,8-cineole, α-terpinyl acetate, p-cymene, and γ-terpinene were mostly identified in the hybrid oil. All eucalypt oils exhibited a significant bacteriostatic effect against Gram-positive bacteria, Streptococcus pyogenes, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. Only the hybrid oil had an effect on all Gram-negative bacteria tested, including Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes. These oils have antibacterial properties that vary according to their terpenoid content. Only the hybrid oil had a potent antioxidant effect, with an IC50 value of 4.21 ± 0.35 mg/mL for free radical (DPPH) scavenging. This oil's antioxidant effect may be a result of the phenolic terpenoids, thymol and carvacrol. As a result, these oils may be a novel source of antibacterial and antioxidant agents. Additionally, the antibacterial and antioxidant capabilities of the E. urophylla × E. camaldulensis hybrid essential oil are reported for the first time.