twitter

Tuesday, 12 May 2015

Steroidal saponins from the leaves of Cordyline fruticosa (L.) A. Chev. and their cytotoxic and antimicrobial activity

Volume 7, February 2014, Pages 62–68

Steroidal saponins from the leaves of Cordyline fruticosa (L.) A. Chev. and their cytotoxic and antimicrobial activity


Highlights

Three new steroidal saponins were isolated from the leaves of Cordyline fruticosa.
The new compounds were tested for cytotoxic and antimicrobial activity.
Two of the compounds showed cytotoxicity against three human tumour cell lines.
One compound showed a moderate antibacterial activity against Enterococcus faecalis.

Abstract

Three new steroidal saponins, spirosta-5,25(27)-diene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranoside (fruticoside H) 1, 5α-spirost-25(27)-ene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-(4-O-sulfo)-β-d-fucopyranoside (fruticoside I) 2, and (22S)-cholest-5-ene-1β,3β,16β,22-tetrol 1-O-β-galactopyranosyl-16-O-α-l-rhamnopyranoside (fruticoside J) 3, together with the known quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-[6-trans-p-coumaroyl]-β-d-glucopyranoside, quercetin 3-rutinoside, apigenin 8-C-β-d-glucopyranoside and farrerol, were isolated from the leaves of Cordyline fruticosa. Their structures were elucidated by spectroscopic techniques (1H NMR, 13C NMR, HSQC, 1H–1H COSY, HMBC, TOCSY, NOESY), mass spectrometry (HRESIMS, Tandem MS–MS), chemical methods and by comparison with published data. Compounds 1 and 2 showed moderate cytotoxic activity against MDA-MB 231 human breast adenocarcinoma cell line, HCT 116 human colon carcinoma cell line, and A375 human malignant melanoma cell line, while compound 3 was not active. Compound 2 also showed a moderate antibacterial activity against the Gram-positive Enterococcus faecalis.

Graphical abstract

Keywords

  • Cordyline fruticosa; 
  • Agavaceae; 
  • Steroidal saponins; 
  • Biological activity

1. Introduction

Cordyline fruticosa (L.) A. Chev. (syn. C. terminalis (L.) Kunth) belongs to the family Agavaceae ( IPNI, 2012), which comprises more than 480 species distributed in tropical and subtropical regions of the World (Yokosuka et al., 2000). The plant is widely used in both everyday life and traditional medicine. A hedge ofC. fruticosa around the house was believed to ward off evil spirits and bring good luck ( Elbert and Roger, 1989). The leaves have been used for costumes, decorations, clothing, sandals, packaging, and cooking. The rhizomes can be baked into a molasses-like food product and eaten ( Hinkle, 2007). In addition, the plant is traditionally used for the treatment of various diseases: the leaves are used to treat sore throat and neck pain ( Whistler, 1985), as haemostatic ( Buttner, 2001 and Dalimartha, 2007), and to induce abortion (Nugent, 2006); the roots are used for toothache, laryngitis and infections of mammary glands ( Dalimartha, 2007 and Nombo and Leach, 2010).
The plants of the genus Cordyline are very well known as source of steroidal saponins and cholestane glycosides ( Simmons-Boyce and Tinto, 2007, Challinor and De Voss, 2013, Yang et al., 1989, Mimaki et al., 1997 and Mimaki et al., 1998). Saponins possessing a steroidal (C27) skeleton are commonly found in monocotyledonous angiosperms, especially plants of the yam (Dioscoreaceae), asparagus (Asparagaceae), solanum (Solanaceae), lily (Liliaceae), onion (Amaryllidaceae), and agave (Agavaceae) families ( Challinor and De Voss, 2013 and Simmons-Boyce and Tinto, 2007). Steroidal saponins can be divided into three structural subclasses, spirostane-, furostane- and cholestane-type (open chain) glycosides ( Challinor and De Voss, 2013) and, over the years, have attracted attention for the wide spectrum of their biological actions, particularly cytotoxic, antimicrobial, antifungal and in vivo antitumoral activities ( Sautour et al., 2007 and Li et al., 2012). Cytotoxic activity of spirostane and open-chain saponins isolated from C. fruticosa has been recently reported ( Yokosuka et al., 2012 and Bogoriani et al., 2007).
In our continuous search of potentially interesting bioactive saponins from Cameroonian medicinal plants (Nzowa et al., 2010, Ponou et al., 2010 and Tapondjou et al., 2011), we have examined the methanol extract from the leaves of C. fruticosa growing in the western highlands of Cameroon. In the present paper we report the isolation and structure elucidation of three new steroidal saponins: fruticosides H (1) and I (2), having a spirostane-type aglycone, and the open chain (alliosterol-type) fruticoside J (3) ( Fig. 1). The known quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-[6-trans-p-coumaroyl]-β-d-glucopyranoside, quercetin 3-rutinoside, apigenin 8-C-β-d-glucopyranoside (vitexin) and farrerol were also isolated.
Full-size image (11 K)
Fig. 1. 
Structures of compounds 13.
Since, as stated above, steroidal saponins are known to possess cytotoxic and antimicrobial properties, compounds 13 were investigated for their cytotoxic activity against three tumour cell lines namely the MDA-MB 231 human breast adenocarcinoma cell line, HCT 116 human colon carcinoma cell line, and A375 human malignant melanoma cell line, and for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans.

2. Results and discussion