Pyranonaphthoquinones (PNQs) are important structural scaffolds found in numerous natural products. Research interest in these specialized metabolites lies in their natural occurrence and therapeutic activities. Nonetheless, research progress has thus far been hindered by the lack of analytical standards and analytical methods for both qualitative and quantitative analysis. We report here that various parts of Ventilago harmandiana are rich sources of PNQs. We developed an ultraperformance liquid chromatography–electrospray ionization multiple reaction monitoring/mass spectrometry method to quantitatively determine six PNQs from leaves, root, bark, wood, and heartwood. The addition of standards in combination with a stable isotope of salicylic acid-D6 was used to overcome the matrix effect with average recovery of 82% ± 1% (n = 15). The highest concentration of the total PNQs was found in the root (11,902 μg/g dry weight), whereas the lowest concentration was found in the leaves (28 μg/g dry weight). Except for the root, PNQ-332 was found to be the major compound in all parts of V. harmandiana, accounting for ∼48% of the total PNQs quantified in this study. However, PNQ-318A was the most abundant PNQ in the root sample, accounting for 27% of the total PNQs. Finally, we provide novel MS/MS spectra of the PNQs at different collision induction energies: 10, 20, and 40 eV (POS and NEG). For structural elucidation purposes, we propose complete MS/MS fragmentation pathways of PNQs using MS/MS spectra at collision energies of 20 and 40 eV. The MS/MS spectra along with our discussion on structural elucidation of these PNQs should be very useful to the natural products community to further exploring PNQs in V. harmandiana and various other sources.
For the first time, total phytochemical profiles of methanol crude extracts of Cuscuta reflexa grown on three different hosts, Coccinia grandis, Ficus racemosa and Samanea saman, that were cultivated in northern Thailand were examined, along with their antidiabetic and antioxidant activities. The highest level of total flavonoids (114.4 mg QE/ g extract) and total phenolic content (90.8 mg GAE/ g extract) were observed in the extract of Cu. reflexa that was grown on Co. grandis. The GC-MS results showed that various types of phenolic compounds, hydrocarbons, saturated fatty acids and methyl ester of fatty acids, unsaturated fatty acids and methyl ester of fatty acids, vitamin E, terpenes and sterol contained in the extracts of Cu. reflexa were capable of being grown on three hosts. Moreover, the HPLC results showed the presence of gallic acid, catechin, vanillic acid, rutin and quercetin in all Cu. reflexa samples. The extract of Cu. reflexa that was grown on Co. grandis represented the highest antidiabetic activity with a percent inhibition of 51.2. Moreover, the extract also possessed the greatest antioxidant activity (DPPH; IC 50 168.6 µg/mL, FRAP; 40.5 mg GAE/ g extract).
Protein glycation and oxidative stress caused by chronic hyperglycemia play vital role in diabetic complications. This study focused on the evaluation of the antiglycation effect of four Lamiaceae plants (Ocimum sanctum, O. basilicum, O. americanum and Metha cordifolia opiz.). Among the ethanolic extracts, O. sanctum extract exhibited high content of phenolic compounds and strong antioxidant activity. Chemical composition analyzed by HPLC revealing two major phenolic conpounds in O. sanctum extracts as rosmarinic acid (4.43 mg/g) and luteolin (0.96 mg/g). In the antiglycation assays, bovine serum albumin (BSA) and histone which were used as model proteins for investigation in the presence of methylglyoxal (MGO) with or without the extracts comparing with the authentic phenolic compounds. The results showed that O. sanctum extract possessed a potent antiglycation activity in both BSA and histone models with 23.4% and 43.0 % inhibition at the concentration of 500 and 250µg/mL, respectively. The results indicated that O. sanctum which contained high phenolic compounds has potential to prevent protein glycation caused by oxidative stress.
The accurate quantification
of triterpenoids in Ganoderma
lucidum mushroom in the mycelium stage is challenging due
to their low concentrations, interference from other possible isomers,
and the complex matrix. Here, a high-resolution quadrupole-time-of-flight
mass spectrometry “multiple reaction monitoring” with
target enhancement (HR-QTOF-MRM) method was developed to quantify
seven target triterpenoids in G. lucidum. The performance
of this method was compared against an optimized QQQ-MRM method. The
HR-QTOF-MRM was shown to be capable of distinguishing target triterpenoids
from interferent peaks in the presence of matrices. The HR-QTOF-MRM
LOD and LLOQ values were found to be one to two times lower than those
derived from the QQQ-MRM method. Intraday and interday variabilities
of the HR-QTOF-MRM demonstrated better reproducibility than the QQQ-MRM.
In addition, excellent recoveries of the analytes ranging from 80
to 117% were achieved. Spiking experiments were carried out to verify
and compare the quantitative accuracy of the two methods. The HR-QTOF-MRM
method provided better percent accuracy, ranging from 84% to 99% (<3%
RSD), compared with the range of 69 to 114% (<4%RSD) given by the
QQQ-MRM method. These results demonstrate that the new HR-QTOF-MRM
mode is able to improve sensitivity, reproducibility, and accuracy
of trace level analysis of triterpenoids in the complex biological
samples. The triterpenoid concentrations were in the range of nondetect
to 0.06–6.72 mg/g of dried weight in fruiting body and to 0.0009–0.01
mg/g of dried weight in mycelium.
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