Iboga-type alkaloids with Indolizidino[8,7-b]Indole scaffold and bisindole alkaloids from Tabernaemontana bufalina Lour.

Phytochemical investigation on the aerial parts of Tabernaemontana bufalina Lour. (Apocynaceae) led to the identification of four undescribed monoterpenoid indole alkaloids named taberbufamines A-D, an undescribed natural product, and fourteen known indole alkaloids. The structures of the undescribed alkaloids were established by spectroscopic and computational methods, and their absolute configurations were further determined by quantum chemical TDDFT calculations and the experimental ECD spectra. Taberbufamines A and B possessed an uncommon skeleton incorporating an indolizidino [8,7-b]indole motif with a 2-hydroxymethyl-butyl group attached at the pyrrolidine ring. Biosynthetically, Taberbufamines A and B might be derived from iboga-type alkaloid through rearrangement. Vobatensine C showed significant bioactivity against A-549, Bel-7402, and HCT-116 cells with IC50 values of 2.61, 1.19, and 1.74 µM, respectively. Ervahanine A showed antimicrobial activity against Bacillus subtilis, Mycobacterium smegmatis, and Helicobacter pylori with MIC values of 4, 8, and 16 µg/mL, respectively. 19(S)-hydroxyibogamine was shown as butyrylcholinesterase inhibitor (IC50 of 20.06 µM) and α-glycosidase inhibitor (IC50 of 17.18 µM), while tabernamine, ervahanine B, and ervadivaricatine B only showed α-glycosidase inhibitory activities with IC50 values in the range of 0.95-4.61 µM.

Japonisine A, a fawcettimine-type Lycopodium alkaloid with an unusual skeleton from Lycopodium japonicum Thunb.

Japonisine A, a novel fawcettimine-type Lycopodium alkaloid with an unusual skeleton and two new fawcettimine-type ones, along with 20 known Lycopodium alkaloids, were isolated from the whole plants of Lycopodium japonicum Thunb. Their structures were determined by extensive spectroscopic analysis, including 1D and 2D NMR, and HR-ESIMS, as well as by comparison with the literature data. Notably, japonisine A (1) was the first example of fawcettimine-related Lycopodium alkaloid with a 2-oxopropyl attached at C-6. All the isolates were evaluated for their inhibitory effects on acetylcholinesterase (AChE) and α-glucosidase. Unfortunately, the results indicated that all the compounds were inactive against the acetylcholinesterase (AChE) and α-glucosidase.

[Research progress on chemical compositions and pharmacological action of Drynariae Rhizoma].

Drynariae Rhizoma is warm in nature and bitter in taste, mainly acting on liver and kidney systems. It is a common Chinese herbal medicine for the treatment of fracture and bone injury. The chemical compositions of Drynariae Rhizoma mainly include flavonoids, triterpenoids, phenylpropanoids and lignans. At present, modern pharmacological and clinical studies have shown that Drynariae Rhizoma has the effects of anti osteoporosis, promoting fracture healing, kidney protection, anti-inflammatory, promoting tooth growth, preventing and treating aminoglycoside ototoxicity and lowering blood lipid. In addition, the toxicity evaluation experiment of Drynariae Rhizoma has also shown that it has no obvious toxic and side effects. Naringin is a kind of dihydroflavone in Drynariae Rhizoma. Many studies have shown that naringin and other total flavonoids play an important role in anti-osteoporosis, promoting fracture healing, anti-inflammation, promoting tooth growth and lowering blood lipid. In this study, the research progresses on chemical consti-tuents and pharmacological activities of Drynariae Rhizoma in recent years were reviewed, and some mechanisms of action were summarized, to provide references for the further research and development of Drynariae Rhizoma.