Officinalioside,a new lignan glucoside from Borago officinalis L.

A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC₅₀: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC₅₀ > 100 μM).     

Simultaneous determination of naphthoquinone derivatives in Boraginaceous herbs by high-performance liquid chromatography

A high-performance liquid chromatographic method using diode-array detection (HPLC-DAD) has been developed for the simultaneous quantification of eight naphthoquinone derivatives namely shikonin, acetylshikonin, deoxyshikonin, β-acetoxyisovalerylshikonin, isobutylshikonin, β,β-dimethylacrylshikonin, 2-methyl-n-butyrylshikonin and isovalerylshikonin in nine species of the Boraginaceae family. These species, coming from different areas of China, are all used as interchangeable sourcing plants for the Chinese Materia Medica known as “Zicao”, and are Arnebia euchroma (Royle) Johnston., A. guttata Bunge, Lithospermum erythrorhizon Sieb. et Zucc., Onosma paniculatum Bur. et Franch., O. exsertum Hemsl., O. confertum W.W. Smith, O. hookerii Clarke var. longiflorum Duthie, O. hookerii Clarke and O. waltonii Duthic. Quantification of the eight naphthoquinones in all the Zicao samples are reported and compared with each other. Furthermore, two positional isomers, 2-methyl-n-butyrylshikonin and isovalerylshikonin, were successfully separated and quantified for the first time in the present study. The results showed that, besides the three officially used species (namely, A. euchroma, A. guttata and L. erythrorhizon) that were listed in Chinese pharmacopoeia as interchangeable sourcing plants for Zicao, other six species of Onosma used by native peoples in Tibet and Yunnan Province also contain various types and considerable amounts of naphthoquinones and that O. waltonii contains the most. Therefore, these species of Onosma could be developed as new sources of naphthoquinones. The entire analytical procedure is reproducible and suitable for the quantification of naphthoquinones in all related Boraginaceous plants for quality assessment purposes.     

1H and 13C NMR assignments for two new cordiaquinones from roots of Cordia leucocephala

From the roots of Cordia leucocephala (Boraginaceae), two new meroterpenoid naphthoquinones, 6‐[10‐(12,12‐dimethyl‐13α‐hydroxy‐16‐methenyl‐cyclohexyl)ethyl]‐1,4‐naphthalenedione (cordiaquinone L) and 5‐methyl‐6‐[10‐(12,12‐dimethyl‐13β‐hydroxy‐16‐methenyl‐cyclohexyl)methyl‐1,4‐naphthalenedione (cordiaquinone M) were isolated. Their structures were elucidated after detailed 1D and 2D NMR (COSY, HSQC, HMBC and NOESY) data analyses and comparison with literature data for analogous compounds. Copyright © 2008 John Wiley & Sons, Ltd.     

Comparative study on enantiomeric excess of main akannin/shikonin derivatives isolated from the roots of three endemic Boraginaceae plants in China

This work systematically investigated the enantiomeric excess (e.e.) of main components isolated from the roots of three endemic Boraginaceae plants distributed extensively in China, named Arnebia euchroma (Royle) Johnst (A.e.), Lithospermum erythrorhizon Sieb. et Zucc. (L.e.) and Onosma confertum W. W. Smith (O.c.), and the optical purity of their hydrolysis products separately, by means of three different approaches. The influence of HCl on the e.e. values of the major constituents was also studied. Analysis of the absolute configurations and e.e. values of all the derivatives acquired was performed by CD and chiral-HPLC respectively. The results of the main constituents demonstrated that A.e. mainly yields S-form naphthoquinone derivatives, while the R-form is predominant in the derivatives of L.e. and O.c. The optical purity of alkannin and shikonin and their derivatives was not influenced by acid treatment in the course of separation and hydrolysis. Additionally, it was found that 100% e.e. of shikinon could be acquired from a specific shikinon ester derivative, β,β-dimethylacrylshikonin occurring in the roots of O.c., as did 100% e.e. of alkannin from β,β-dimethylacrylalkannin contained in the roots of A.e.     

A new flavanone glycoside isolated from Tournefortia sibirica

A new flavanone glycoside, (2S)-dihydrooroxylin A 7-O-[β-D-apiosyl(1→2)]-β-D-glucoside (1), and four known compounds (2–5) were isolated from Tournefortia sibirica L. The chemical structures of these compounds were determined by 1?D and 2?D NMR and HR-ESI-MS spectra, and results were compared with data from the literature. These five compounds (1–5) were isolated from the family Boraginaceae for the first time. Anti-inflammatory effects of compounds (1–5) were evaluated in terms of inhibition of production of NO, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells.     

Cytotoxic naphthoquinones from Arnebia densiflora (Nordm.) Ledeb and determining new apoptosis inducers

Abstract

In this study, phytochemical composition of Arnebia densiflora (AD) was determined and cytotoxic effects of the n-hexane extract and compounds isolated from this species on various cell lines were investigated. By means of serial chromatographic studies, 6 naphthoquinone derivatives were yielded, which are isovalerylalkannin, α-methyl-n-butyl alkannin, acetylalkannin, β-acetoxy isovalerylalkannin, alkannin and a new compound: 4-hydroxy 4-methyl valeryl alkannin. Structures of the isolated compounds were elucidated using UV, IR, 1D-2D NMR, MS and CD methods. Cytotoxic effects of the extract and isolated alkannins were investigated on L929, HeLa, HEp-2 cells. AD and the isolated compounds demonstrated moderate to strong cytotoxic effects (IC₅₀ range: 4.92-172.35?µg/ml). The results of DNA fragmentation and caspase-3 activity studies on HeLa cells exhibited that AD and the naphthoquinones isolated from it caused cytotoxicity through induction of apoptosis.

     

A Novel Terpenoid from Lappula anocarpa

A novel terpenoid, named lappulanocarpine A 1 was isolated from the alcoholic extract of the whole plant of Lappula anocarpa. Its structure was characterized by I D-, 2D-NMR and HR-ESIMS.     

Quantitative determination of alkannins and shikonins in endemic Mediterranean Alkanna species

The optical antipodes alkannin/shikonin (A/S) and their esters are potent pharmaceutical substances found in the roots of 150 Boraginaceous species. This study estimated and compared total and free A/S content and A/S enantiomeric ratio in roots of 11 Alkanna species (A. corcyrensis, A. tinctoria, A. pindicola, A. orientalis, A. methanaea, A. calliensis, A. graeca, A. primuliflora, A. stribrnyi, A. sieberi and A. noneiformis) growing wild in various Greek regions, to compare with cultivated species. It also re‐characterized the chirality of A/S commercial samples, since most of them were misnamed by the providers. Several Alkanna species were collected (groups 1 and 3) and botanically identified, whereas some Alkanna species were cultivated from collected seeds (group 2). Free A/S and derivatives were extracted from the dried roots of Alkanna species and analyzed by high performance liquid chromatography‐diode array detection (HPLC‐DAD). For total A/S content the hexane extracts of Alkanna roots were hydrolyzed and analyzed by HPLC‐DAD. Chirality determination and A/S enantiomeric ratio estimation was performed for several commercial samples by polarimetry,chiral LC‐DAD and circular dichroism studies. Quantitative analysis revealed that A/S content varied from one region to another even within the same species. Most of the cultivated samples contained greater amounts of free and total A/S compared with the wild ones, wheras no difference was observed in A/S enantiomeric ratio. All the Alkanna samples tested contain mainly alkannin derivatives. Some of the examined Alkanna species of the Greek flora that are endemic to the Mediterranean area could serve as alternative sources for medicinally valuable A/S derivatives. Most of the commercial A/S samples tested were misnamed in terms of chirality and re‐characterized. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of alkannin derivatives from Alkanna species by high-performance liquid chromatography/photodiode array/mass spectrometry

Alkannin, shikonin (A/S) and their derivatives are enantiomeric hydroxynaphthoquinone red pigments found in the roots of almost 150 species of the Boraginaceae family. A/S have been shown to exhibit strong wound healing, antimicrobial, anti-inflammatory and antioxidant activities and recent extensive research has well established their antitumor properties. A/S and their derivatives comprise the active ingredients of several pharmaceutical and cosmetic preparations. Although A/S have been efficiently synthesized and have been produced by cell tissue cultures in high yield, most of the pharmaceutical preparations worldwide contain A/S extracted from the roots of Boraginaceous species, found in nature. In the present study, a high-performance liquid chromatography/photodiode array/mass spectrometry (HPLC/PDA/MS) method was established to identify monomeric hydroxynaphthoquinones of the alkannin series and other metabolites from Boraginaceous root extracts. This method can be applied for the identification of alkannin derivatives and other metabolites from Boraginaceous cell cultures, and also to determine active ingredients in pharmaceutical preparations containing A/S derivatives. A phytochemical investigation of the Alkanna genus grown in Greece was also performed. Fifty-three root samples belonging to 10 species of the genus Alkanna (A. calliensis, A. corcyrensis, A. graeca, A. methanaea, A. orientalis, A. pindicola, A. primuliflora, A. sieberi, A. stribrnyi and A. tinctoria) were collected from several regions of the Greek flora and analyzed for their constituent hydroxynaphthoquinones and other metabolites. In most of the above Alkanna samples tested, the main hydroxynaphthoquinones were determined to be beta,beta-dimethylacrylalkannin, isovalerylalkannin + alpha-methyl-n-butylalkannin and acetylalkannin. The hydroxynaphthoquinone constituents and their proportions were found to vary among Alkanna species. Unknown metabolites (not monomeric hydroxynaphthoquinones) were detected by HPLC-PDA-MS, while in several Alkanna species hydroxynaphthoquinones were detected for the first time.