Flavonol glycosides from Aconitum vulparia

A review on efforts for improvement in medicinally important chemical constituents inAconitum through biotechnological interventions

The genus Aconitum belongs to the family Ranunculaceae, is endowed with more than 350 species on the earth. Medicinally important aconitine type of diterpenoid alkaloids are the characteristic compounds in most of the Aconitum species. The present review endeavored the major research carried out in the field of genetic resource characterization, pharmacological properties, phytochemistry, major factors influencing quantity, biosynthetic pathways and processing methods for recovery of active ingredients, variety improvement, propagation methods, and important metabolite production through cell/organ culture of various Aconitum species. More than 450 derivatives of aconitine-type C19 and C20-diterpenoid alkaloids along with a few other non-alkaloidal compounds, such as phenylpropanoids, flavonoids, terpenoids, and fatty acids, have been identified in the genus. A few Aconitum species and their common diterpenoid alkaloid compounds are also well characterized for analgesic, inflammatory and cytotoxic properties. However, the different isolated compound needs to be validated for supporting other traditional therapeutical uses of the plant species. Aconitine alkaloids shared common biosynthesis pathway, but their diversification mechanism remains unexplored in the genus. Furthermore, the process needs to be developed on secondary metabolite recovery, mass-scale propagation methods, and agro-technologies for maintaining the quality of products. Many species are losing their existence in nature due to over-exploitation or anthropogenic factors; thus, temporal monitoring of the population status in its habitat, and suitable management programs for ascertaining conservation needs to be developed.

Protein tyrosine phosphatase 1B inhibitory activity of compounds from Justicia spicigera (Acanthaceae)

An infusion from the aerial parts of Justicia spicigera Schltdl., an herb commonly used to treat diabetes, inhibited the activity of protein tyrosine phosphatase 1B (PTP1B). Two undescribed compounds, 2-N-(p-coumaroyl)-3H-phenoxazin-3-one, and 3″-O-acetyl-kaempferitrin, along with kaempferitrin, kaempferol 7-O-α-L-rhamnopyranoside, perisbivalvine B and 2,5-dimethoxy-p-benzoquinone were isolated from the active extract. Their structures were elucidated by a combination of spectroscopic and spectrometric methods. The isolates were evaluated for their inhibitory activity against PTP1B; the most active compounds were 2-N-(p-coumaroyl)-3H-phenoxazin-3-one, and perisbivalvine B with IC₅₀ values of 159.1 ± 0.02 μM and 106.6 ± 0.01 μM, respectively. However, perisbivalvine B was unstable. Kinetic analysis of 2-N-(p-coumaroyl)-3H-phenoxazin-3-one and 2,5-dimethoxy-p-benzoquinone (obtained in good amounts) indicated that both compounds behaved as parabolic competitive inhibitors and bind to the enzyme forming complexes with 1:1 and 1:2 stoichiometry. Docking of 2-N-(p-coumaroyl)-3H-phenoxazin-3-one and 2,5-dimethoxy-p-benzoquinone to PTP1B_1-400 predicted a good affinity of these compounds for PTP1B catalytic site and demonstrated that the binding of a second ligand is sterically possible. The 1:2 complex was also supported by the second docking analysis, which predicted an important contribution of π-stacking interactions to the stability of these 1:2 complexes. Finally, an UHPLC-MS method was developed and validated to quantify the content of kaempferitrin in the infusion of the plant.

Non-alkaloidal constituents from the genus Aconitum: a review

Multiple non-alkaloidal constituents from Aconitum showed great research significance for their novel structures, broad bioactivities and chemotaxonomical significance.

Antioxidant activities of ethanolic extracts from the twigs of Cinnamomum osmophloeum

Cinnamomum osmophloeum Kaneh. is an indigenous tree species in Taiwan. In this study, phytochemical characteristics and antioxidant activities of ethanolic extracts from the twigs of C. osmophloeum were investigated for the first time. The extracts were obtained successively using liquid-liquid partition to yield n-hexane (Hex), ethyl acetate (EtOAc), n-butanol (BuOH) and water fractions. The antioxidant activities of C. osmophloeum twig extracts were examined using various antioxidant assays, such as DPPH, NBT, reducing power, lipid peroxidation using mouse brain homogenates, metal chelating ability, and photochemiluminescence (PCL). In addition, total phenolic contents were also determined. Results revealed that the BuOH fraction exhibited the best performance in DPPH assay, NBT assay, reducing power assay and lipid peroxidation using mouse brain homogenates assay. Furthermore, the BuOH fraction has the highest total phenolic contents (496.7 mg of GAE/g). Consequently, kaempferol-7-O-rhamnoside was also isolated from the antioxidative BuOH fraction and its activity was also confirmed. These results demonstrated that ethanolic extracts of C. osmophloeum twigs have excellent antioxidant activities and thus it has great potential as a source for natural health products.