Alkaloids from leaves of Annona salzmannii and Annona vepretorum (Annonaceae)

Aporphine and amide alkaloids from Illigera parviflora

Three undescribed alkaloids (+)-9-hydroxy-N-acetylnordicentrine (1), illigeparvinine (2), and deca-(2E,4Z)-2,4-dienoic acid 4-hydroxy-2-phenethyl amide (3), along with 19 known analogues (4-22), were isolated from the ethnic medicinal plant Illigera parviflora. Their structures were established using NMR, MS, and other spectroscopic analyses as well as X-ray diffraction. Moderate inhibition of human gastric carcinoma (MGC-803) and breast adenocarcinoma (T-47D) cell lines proliferation was observed for actinodaphnine (4) with IC50 values of 28.74 and 11.65 μM, respectively. These findings contribute new anticancer potential compounds and expand the chemical diversity known from the valuable traditional medicinal plant I. parviflora.

New ent-kaurene-type nor-diterpene and other compounds isolated from Annona vepretorum Mart. (Annonaceae)

A new nor-ent-kaurene diterpene and ten other compounds were isolated from Annona vepretorum stems, including four kaurene diterpenes, three alkamides, one sesquiterpene and two steroids. Their chemical structures were elucidated using spectroscopic methods, including 1D-, 2D-NMR, and HRESIMS. The absolute configuration of compounds 1, 5, 8, 9 and 10 was confirmed by CD experiments. Compounds 1-5 and 8-10 were evaluated for cytotoxic activity using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT method, against three human carcinoma cell lines: human colon (HCT-116), glioblastoma (SF295) and prostate (PC3). However, all isolated compounds exhibited low cytotoxic activity.

Anti-cancer activity of new benzyl isoquinoline alkaloid from Saudi plant Annona squamosa

Two alkaloids, belonging to benzylisoquinoline alkaloids, were isolated from Annona squamosa. One of these alkaloids, 6, 7-dimethoxy-1-(α-hydroxy-4-methoxybenzyl)-2-methyl-1, 2, 3, 4-tetrahydroisoquinoline, was isolated for the first time from natural sources, while, the alkaloid, Coclaurine was known in Annona squamosa L. Moreover, the isolated alkaloids tested for the anti-cancer activities on various cell lines (HepG-2, MCF-7, and HCT-116).

Total content of kaurene diterpenes in Annona vepretorum stems via 1 H qNMR: A method for speeding the identification of bioactive extracts

INTRODUCTION

Kaurene diterpenes (KDs) constitute a chemical class often found in the genus Annona with interesting biological activities. To date, chromatographic tools have been mostly used to determine KDs. Quantitative nuclear magnetic resonance (qNMR) has distinguished itself in quantitative estimation of natural products and is an interesting choice to assess total KD contents.

OBJECTIVE

To establish a ¹ H qNMR method for determining the total KD contents in extracts and fractions obtained from Annona vepretorum stems.

METHODOLOGY

Stems were extracted with hexane and methanol, resulting in the hexane extract (HEX-E) and the methanol extract (MeOH-E). The former was partitioned with the acid-base method to obtain the total alkaloid fraction (TA-F) and the neutral dichloromethane fraction (NDM-F). ¹ H qNMR measurements were performed on 400 MHz with samples solubilized in deuterated dimethyl sulfoxide. Quantification was carried out using the signals at 4.71 and 4.78 ppm related to hydrogens of the exocyclic double bond of the basic skeleton of KDs and gallic acid as the standard reference. The selectivity, intra- and inter-day precision, reproducibility, limit of detection, limit of quantification, and robustness of the methodology were evaluated.

RESULTS

Using the newly developed method, the total KD contents (in μg/mg) were 653.80 ± 12.15 (HEX-E), 458.90 ± 25.94 (NDM-F), 375.60 ± 27.52 (TA-F), and 315.10 ± 19.20 (MeOH-E). For determining the most promising bioactive sample, the KD contents and the sample discriminations obtained by principal component analysis were correlated to the antibacterial activity. Such approach pointed out HEX-E as a potential source of KDs.

CONCLUSION

The developed method offers a fast and simple way of determining total KD contents.

Antitumour Activity of the Microencapsulation of Annona vepretorum Essential Oil

Annona vepretorum Mart. (Annonaceae), popularly known as 'bruteira', has nutritional and medicinal uses. This study investigated the chemical composition and antitumour potential of the essential oil of A. vepretorum leaf alone and complexed with β-cyclodextrin in a microencapsulation. The essential oil was obtained by hydrodistillation using a Clevenger-type apparatus and analysed using GC-MS and GC-FID. In vitro cytotoxicity of the essential oil and some of its major constituents in tumour cell lines from different histotypes was evaluated using the alamar blue assay. Furthermore, the in vivo efficacy of essential oil was demonstrated in mice inoculated with B16-F10 mouse melanoma. The essential oil included bicyclogermacrene (35.71%), spathulenol (18.89%), (E)-β-ocimene (12.46%), α-phellandrene (8.08%), o-cymene (6.24%), germacrene D (3.27%) and α-pinene (2.18%) as major constituents. The essential oil and spathulenol exhibited promising cytotoxicity. In vivo tumour growth was inhibited by the treatment with the essential oil (inhibition of 34.46%). Importantly, microencapsulation of the essential oil increased in vivo tumour growth inhibition (inhibition of 62.66%).