Vincamine and 14-epi-vincamine indole alkaloids from Ambelania occidentalis

Chemical composition and antioxidant activity of the Amazonian fruit Ambelania acida Aubl

Aqueous and hydroalcoholic extracts from the pulp of Ambelania acida Aubl. (Apocynaceae) fruits were subjected to analysis through UHPLC-HRMS and antioxidant potential using the TPC, DPPH, ABTS, FRAP, and ORAC assays. A putative identification of the compounds carried out by comparison of the fragmentation spectra revealed the predominance of the monoterpene indole alkaloids tabersonine, pseudocopsinine, ajmalicine, and strictosidine. Additionally, gallic acid, caffeic acid, citric acid, 3-O-p-coumaroylquinic acid, chlorogenic acid, catechin, ellagic acid, eschweilenol C (ellagic acid deoxyhexoside), and sucrose were identified. In face of the phenolic compounds observed, hydroalcoholic extract showed a higher antioxidant activity compared to the aqueous extract, observed at TPC (108.85 mg GAE/100g), FRAP (0.73 µmol Fe2SO4/g), DPPH (1221.76 µmol TE/g), ABTS (3460.00 µmol TE/g), and ORAC assays (120.47 µmol TE/g). These findings underscore the abundant presence of bioactive compounds, including phenolics and alkaloids, in an edible Amazonian fruit.

Vincamine, from an antioxidant and a cerebral vasodilator to its anticancer potential

Vincamine is a naturally occurring indole alkaloid showing antioxidant activity and has been used clinically for the prevention and treatment of cerebrovascular disorders and insufficiencies. It has been well documented that antioxidants may contribute to cancer treatment, and thus, vincamine has been investigated recently for its potential antitumor activity. Vincamine was found to show cancer cell cytotoxicity and to modulate several important proteins involved in tumor growth, including acetylcholinesterase (AChE), mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and T-box 3 (TBX3). Several bisindole alkaloids, including vinblastine and vincristine and their synthetic derivatives, vindesine, vinflunine, and vinorelbine, have been used as clinically effective cancer chemotherapeutic agents. In the present review, the discovery and development of vincamine as a useful therapeutic agent and its antioxidant and antitumor activity are summarized, with its antioxidant-related mechanisms of anticancer potential being described. Also, discussed herein are the design of the potential vincamine-based oncolytic agents, which could contribute to the discovery of further new agents for cancer treatment.

Evaluation of the Amazonian fruit Ambelania acida: Chemical and nutritional studies

Ambelania acida is native to the Amazon region, with few published studies of its fruits. We examined the proximate composition of its fruits, including minerals, fatty acids, volatile organic compounds (VOCs), as well as its antioxidant capacity. The protein contents (2.61%) of the pulp and seeds (13.6%) were higher than observed in other taxa of the family or in other tropical fruits. Peel and pulp showed high contents of potassium, calcium, and magnesium, and the potassium content in the pulp was 1125 mg/100 g. The peel had higher contents of total phenolics, tannins, and ortho-diphenols than the pulp, as well as better antioxidant activity as evidenced by 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), Ferric Reducing Antioxidant Power (FRAP), and Fe²⁺ chelating activity assays. GC-MS analyses identified 42 VOCs in the peel and pulp, with more than 90% being classified as terpenes. Eleven types of fatty acids were identified in the lipid fractions of the peel, pulp, and seeds. Linoleic acid, an essential fatty acid for humans, was the principal fatty acid in the edible portion of the fruit, therefore, evidencing its nutritionally significant profile for the fruits when considering the relationship among polyunsaturated, saturated, and monounsaturated fatty acids. The information gathered here indicates that this native fruit is a healthy food source and its cultivation and consumption should be stimulated.

Chemical and nutritional characterization of Ambelania duckei (Apocynaceae) an unexplored fruit from the Amazon region

Ambelania duckei Markgr is a species of the Apocynaceae family, native to the Amazon region that is unexplored from a nutritional point of view and studied in relation to its chemical constituents. This work presents an unprecedented study of the proximate composition, lipid profile, a chromatographic analysis, and the antioxidant activity of extracts obtained from the pulp, peel and seeds of the fruit. The results showed that potassium, calcium, and magnesium stood out as the most abundant key minerals in the fruit peel and pulp, with an emphasis on the potassium present in the fruit pulp at 1750.0 mg/100 g. The peel had the highest content of total phenolics (374.86 mg/g), flavonoids (15.54 mg/g), tannins (27.45 mg/g) and O-diphenols (379.36 mg/g; 645.71 mg/g). The antioxidant activity (AA) was highest in the peel compared to the pulp in the DPPH, ABTS, and ORAC tests showing: IC₅₀ of 29.82; 43.67; and 407.13 µg/mL, respectively but a lower activity for the Fe²⁺ chelator. The analysis of the lipid fractions from the peel, pulp, and seeds of the A. duckei fruit resulted in 14 types of fatty acids. The major fatty acids found in the three parts of the fruit were oleic acid (peel, 22.52 %), palmitic acid (pulp, 17.34 %), and linoleic acid (seeds, 47.99 %). The lipid profile and nutritional aspects had a PUFA/SFA ratio (0.4-1.8) in the different parts of the A. duckei fruit; the atherogenic and thrombogenic indexes were higher in the peel (1.23) and pulp (0.62), respectively. The ratio between the hypocholesterolemic and hypercholesterolemic fatty acids (0.5 - 3.8) calculated for the fruit are within the desirable range for a nutritious food. The chromatographic analysis of the volatile organic compounds (VOCs) from the peel and pulp of the fruit, identified 74 VOCs, of which 60.9 % are related to terpenes, and emit notes such as cucumber, green, fatty, floral, and mint, due to the presence of substances with OAVs > 10, especially α-ionone, 1,8-cineole, 2,4-decadienal, and dodecanal. The analysis of the MS and MS/MS spectra of the chromatograms obtained by LC- QTOF-HRMS led to the identification of 26 compounds in the peel, seeds and pulp of A. duckei, such as fatty acids, phenolic acid, flavonoids, proanthocyanidins, alkaloids, and terpenoids. The results show that the pulp of A. duckei has potential as nourishing food and the nutritional and chemical aspects of the peel can be applied to commercial applications.

Analysis of alkaloids from different chemical groups by different liquid chromatography methods

Alkaloids are biologically active compounds widely used as pharmaceuticals and synthesised as secondary methabolites in plants. Many of these compounds are strongly toxic. Therefore, they are often subject of scientific interests and analysis. Since alkaloids — basic compounds appear in aqueous solutions as ionized and unionized forms, they are difficult for chromatographic separation for peak tailing, poor systems efficiency, poor separation and poor column-to-column reproducibility. For this reason it is necessity searching of more suitable chromatographic systems for analysis of the compounds. In this article we present an overview on the separation of selected alkaloids from different chemical groups by liquid chromatography thus indicating the range of useful methods now available for alkaloid analysis. Different selectivity, system efficiency and peaks shape may be achieved in different LC methods separations by use of alternative stationary phases: silica, alumina, chemically bonded stationary phases, cation exchange phases, or by varying nonaqueous or aqueous mobile phase (containing different modifier, different buffers at different pH, ion-pairing or silanol blocker reagents). Developments in TLC (NP and RP systems), HPLC (NP, RP, HILIC, ion-exchange) are presented and the advantages of each method for alkaloids analysis are discussed.