Anti-diabetic compounds from Uvaria dulcis Dunal.

Medicinal plants have long been a source of lead compounds for drug discovery. Among these, the Annonaceae family has gained recognition for its potential to yield novel compounds, particularly those that can be used in the development of drugs targeting chronic diseases like diabetes mellitus (DM). We employed various chromatographic methods to isolate bioactive compounds from the roots, leaves, and twigs of Uvaria dulcis Dunal. We used spectroscopic methods to determine the chemical structures of these compounds. We successfully identified twelve known compounds from various parts of U. dulcis: patchoulenon, polygochalcone, 2'3'-dihydroxy-4',6'-dimethoxydihydrochalcone, 2',3'-dihydroxy-4',6'-dimethoxychalcone, chrysin, techochrysin, 8-hydroxy-5,7-dimethoxyflavanone, pinocembrin, 3-farnesylindole, onysilin, cinchonain la, and cinchonain lb. Interestingly, cinchonain la and cinchonain lb exhibited more potent anti-α-glucosidase activity than acarbose (standard drug), with IC50 values of 11.88 ± 1.41 µg/mL and 15.18 ± 1.19 µg/mL, respectively. Cinchonain la inhibited the DPP-IV enzyme, with IC50 value lower than the standard compound (diprotin A) at 81.78 ± 1.42 µg/mL. While 2',3'-dihydroxy-4',6'-dimethoxychalcone show more potent inhibitory effect than standard drug with IC50 value of 8.62 ± 1.19 µg/mL. Additionally, at a concentration of 10 µg/mL, cinchonain lb and 2',3'-dihydroxy-4',6'-dimethoxychalcone promoted glucose uptake in L6 myotubes cells to the same extent as 100 nM insulin. These findings suggest that cinchonain la, cinchonain lb, and 2',3'-dihydroxy-4',6'-dimethoxychalcone are the U. dulcis-derived bioactive compounds that hold promise as potential structures to use in the development of anti-diabetic drugs.

Aporphine alkaloids and a naphthoquinone derivative from the leaves of Phaeanthus lucidus Oliv. and their α-glucosidase inhibitory activity.

Three previously undescribed aporphine alkaloids, phaeanthuslucidines E-G, one previously undescribed naphthoquinone derivative, phaeanthusnaphthoquinone, and three known compounds were isolated from an EtOAc extract of the leaves of Phaeanthus lucidus Oliv. The structures of all previously undescribed compounds were established through extensive spectroscopic investigations and high-resolution mass spectroscopy. The 6aR configuration of phaeanthuslucidines E-G was assigned by comparing their ECD spectra and specific rotation values with the reported known compounds. Some isolated compounds were evaluated for their α-glucosidase inhibitory activity. Among these compounds, phaeanthuslucidine E showed the highest α-glucosidase inhibitory activity with an IC50 value of 17.9 ± 0.4 µM. The molecular docking of phaeanthuslucidine E was further studied.

Styryl lactone derivatives and aristolactam alkaloids from Goniothalamus tapis Miq. and their α-glucosidase inhibitory activity.

Two new styryl lactone derivatives, goniothapic acids A (1) and B (2), and 18 known compounds, were isolated from the twig and leaf extracts of Goniothalamus tapis Miq. The structures of new compounds were characterised by spectroscopic methods and HRESITOFMS. Their absolute configuration was established by comparing the experimental and calculated ECD spectra. Eleven compounds were evaluated for their α-glucosidase inhibitory activity. Of these, (-)-goniothalamin (5) and oldhamactam (16) showed the best α-glucosidase inhibitory activity with IC50 values of 54.8 and 57.9 µM, respectively.

Phaeanthuslucidines A-D, dimeric aporphine alkaloid derivatives from Phaeanthus lucidus Oliv.

The first phytochemical investigation of the twigs of Phaeanthus lucidus Oliv. resulted in the isolation and identification of four undescribed alkaloids, including two aporphine dimers, phaeanthuslucidines A and B, a hybrid of aristolactam-aporphine, phaeanthuslucidine C, and a C-N linked aporphine dimer, phaeanthuslucidine D, together with two known compounds. Their structures were determined by extensive analysis of spectroscopic data, and by comparison of their spectroscopic and physical data with previous reports. Phaeanthuslucidines A-C and bidebiline E were analysed and resolved by chiral HPLC to yield the (Ra) and (Sa) atropisomers, whose absolute configurations were respectively determined by ECD calculations. Phaeanthuslucidines A and B, bidebiline E, and lanuginosine showed α-glucosidase inhibitory activities with IC50 values in the range of 6.7-29.2 µM. Moreover, molecular docking simulations of α-glucosidase inhibition of active compounds were studied.

Alkaloids and Styryl lactones from Goniothalamus ridleyi King and Their α-Glucosidase Inhibitory Activity.

Gonioridleylactam (1), a new compound, is a unique dimeric aristolactam isolated from the EtOAc extract of the twigs of Goniothalamus ridleyi King. The structure of gonioridleylactam (1) consists of two different aristolactams linked together with two methylenedioxy bridges at C-3/C-3' and C-4/C-4', generating a ten-membered ring of [1,3,6,8]tetraoxecine. A new natural product, gonioridleyindole (3-hydroxymethyl-1-methyl-1H-benz[f]indole-4,9-dione, 2), together with eight known compounds (3-10) were also isolated from this plant. Their structures were extensively characterized by spectroscopic methods and comparisons were made with the literature. Compounds 1-4, 7, and 9 were evaluated for their α-glucosidase inhibitory activity. Of these, 3,5-demethoxypiperolide (7) displayed the highest α-glucosidase inhibitory activity, with an IC50 value of 1.25 µM.

Dimeric aporphine alkaloids from the twigs of Trivalvaria costata (Hook.f. & Thomson) I.M.Turner.

A phytochemical investigation of the twig extract of Trivalvaria costata (Hook.f. & Thomson) I.M.Turner has identified ten undescribed dimeric aporphine alkaloids, trivalcostatines A-J, one undescribed isoquinoline alkaloid, trivalcostaisoquinoline, and four known aporphine alkaloids. Their structures were elucidated by detailed analysis of NMR and HRESITOFMS data. Three of the dimeric aporphine structures were confirmed by single crystal X-ray diffraction analysis. All of the dimeric aporphine alkaloids were isolated as mixtures of atropisomers. Several of them were resolved by chiral-phase HPLC and the absolute configurations of the pure atropisomers were assigned by calculated and experimental ECD analysis. Bidebilines A and B, heteropsine, and urabaine showed α-glucosidase inhibitory activities with IC50 values in the range of 4.1-11 µM.

Rotenoids and isoflavones from the leaf and pod extracts of Millettia brandisiana Kurz.

Phytochemical investigations of the leaf and pod extracts of Millettia brandisiana Kurz led to the isolation and identification of four previously undescribed rotenoids, (-)-(6aS,12aS)-millettiabrandisins A-C and (-)-(6aS,12aS)-6-deoxyclitoriacetal, two previously undescribed isoflavones, millettiabrandisins D and E, and 20 known compounds. The structures of previously undescribed compounds were determined on the basis of NMR and MS data. The absolute configurations of (-)-(6aS,12aS)-millettiabrandisins A-C were determined from the comparison of their experimental and calculated ECD spectra. (-)-(6aR,12aR)-12a-Hydroxy-α-toxicarol was also confirmed by X-ray crystallographic data. Some isolated compounds were evaluated for their cytotoxicity against three cancer cell lines, including lung cancer (A549), colorectal cancer (SW480), and leukemic cells (K562). Of these, α-toxicarol displayed the best cytotoxicity against lung cancer (A549) and leukemic cells (K562) with the IC50 values of 104.4 and 67.5 µM, respectively. 6″,6″-Dimethylchromene-[2″,3″:7,8]-flavone showed the highest cytotoxicity against colorectal cancer (SW480) with an IC50 value of 97.2 µM.

α-Glucosidase inhibitory and α-amylase inhibitory activities of compounds isolated from Uvaria rufa Blume.

A new C-benzylated flavone, uvariaruflavone (1), along with 13 known compounds (2-14) were isolated from the twig and leaf extracts of Uvaria rufa Blume. Their structures were established by extensive spectroscopic methods. Flavones (5-8) and cyclohexene (10) were isolated from U. rufa for the first time. Most of the isolated compounds were evaluated for their α-glucosidase and α-amylase inhibitory activities. Of these, uvariaruflavone (1) showed the highest α-glucosidase inhibitory activity with an IC50 value of 44.3 µM, while ferrudiol (12) displayed the highest α-amylase inhibitory activity with an IC50 value of 73.5 µM.