Two new compounds from the roots of Ilex pubescens

Botany, traditional uses, phytochemistry, pharmacology and toxicology of Ilex pubescens Hook et Arn

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex pubescens (I. pubescens), which is well known in Chinese as Mao-Dong-Qing, is widely used in traditional Chinese medicine. This plant is distributed in the wild in southern China, and the roots and stems are used for clearing heat, detoxifying, activating blood circulation and dispelling stasis. Moreover, it is used for treating wind-heat cold, lung-heat asthma, swelling and pain of pharynxes and gingivae, thoracic obstruction and cardiodynia with pungent, stroke, hemiplegia, thromboangiitis obliterans, burn, scald and central retinitis.

AIMS OF THE REVIEW

This paper aims to provide a critical summary of the current studies on I. pubescens. The progress in research on the botany, traditional uses, phytochemistry, pharmacology and toxicology of the plant is discussed. We mainly focus on the phytochemical and pharmacological investigations of I. pubescens. Furthermore, perspectives for possible future studies on I. pubescens are also discussed.

MATERIALS AND METHODS

A systematic review was conducted on the studies of I. pubescens performed during the past 40 years with resources including the Chinese Pharmacopoeia and literature databases such as PubMed, Science Direct, Wiley, CNKI (China National Knowledge Infrastructure), SciFinder, Web of Science, Google Scholar and Baidu Scholar.

RESULTS

To date, more than 200 compounds have been isolated and identified from the plant, a substantial proportion of which were reported to be triterpenes. Biological effects such as protective effects against cardio-cerebrovascular diseases, anti-thrombosis, anti-inflammatory and anti-tumour activities were also investigated in in vitro and in vivo research. Therapeutic effects are attributed to the bioactivities of the naturally occurring compounds in this herb. Furthermore, toxicological studies on I. pubescens are relatively scarce, and it is worthy of further research.

CONCLUSIONS

This review summarizes the results from current studies of I. pubescens, which is one of the valuable medicinal sources from traditional herbs. Some conventional uses have been evaluated by pharmacological investigation. In addition, unresolved issues include molecular mechanisms underlying bioactivities, pharmacokinetics, toxicology and efficacy, which are still being studied and explored before achieving integration into clinical medicines.

Ilexsaponin A attenuates ischemia-reperfusion-induced myocardial injury through anti-apoptotic pathway

The protective effects of ilexsaponin A on ischemia-reperfusion-induced myocardial injury were investigated. Myocardial ischemia/reperfusion model was established in male Sprague–Dawley rats. Myocardial injury was evaluated by TTC staining and myocardial marker enzyme leakage. The in vitro protective potential of Ilexsaponin A was assessed on hypoxia/reoxygenation cellular model in neonatal rat cardiomyocytes. Cellular viability and apoptosis were evaluated by MTT and TUNEL assay. Caspase-3, cleaved caspase-3, bax, bcl-2, p-Akt and Akt protein expression levels were detected by western-blot. Ilexsaponin A treatment was able to attenuate the myocardial injury in ischemia/reperfusion model by reducing myocardial infarct size and lower the serum levels of LDH, AST and CK-MB. The in vitro study also showed that ilexsaponin A treatment could increase cellular viability and inhibit apoptosis in hypoxia/reoxygenation cardiomyocytes. Proapoptotic proteins including caspase-3, cleaved caspase-3 and bax were significantly reduced and anti-apoptotic protein bcl-2 was significantly increased by ilexsaponin A treatment in hypoxia/reoxygenation cardiomyocytes. Moreover, Ilexsaponin A treatment was able to increase the expression levels of p-Akt in hypoxia/reoxygenation cellular model and myocardial ischemia/reperfusion animal model. Coupled results from both in vivo and in vitro experiments indicate that Ilexsaponin A attenuates ischemia-reperfusion-induced myocardial injury through anti-apoptotic pathway.

Triterpenoid saponins with anti-inflammatory activities from Ilex pubescens roots

Seven triterpenoid saponins, named ilexsaponin I-O, along with twelve known ones, were isolated from the roots of Ilex pubescens. The structures of all compounds were elucidated by use of extensive spectroscopic methods (IR, HR-ESI-MS, and 1D and 2D NMR). Sugar residues obtained after acid hydrolysis were identified by TLC and HPLC. The in vitro anti-inflammatory effects of the triterpenoid saponins were also evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Among the isolated saponins, seven compounds were shown to inhibit LPS-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production by suppressing the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively, in LPS-stimulated RAW 264.7 cells. Ilexsaponin I and β-d-glucopyranosyl 3-β-[β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranosyloxy]-olea-12-en-28-oate exerted more potent anti-inflammatory effects than the other compounds tested.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids reported during 2012 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 348 references are cited.