Antioxidant and anti-inflammatory caffeoyl phenylpropanoid and secoiridoid glycosides from Jasminum nervosum stems, a Chinese folk medicine

Highlights

• Jasnervosides A–H, were isolated from Jasminum nervosum.

• Jasnervosides A, B, D and G displayed potent antioxidant activities.

• Jasnervosides B and C showed good anti-inflammatory activities.

Abstract

Eight compounds including four caffeoyl phenylpropanoid glycosides, jasnervosides A–D (1–4), one monoterpenoid glycoside, jasnervoside E (5), and three secoiridoid glycosides, jasnervosides F–H (10–12), were isolated from the stems of Jasminum nervosum Lour. (Oleaceae), along with four known compounds, poliumoside (6), verbascoside (7), α-l-rhamnopyranosyl-(1→3)-O-(α-l-rhamnopyranosyl(1→6)-1-O-E-caffeoyl-β-d-glucopyranoside (8), and jaspolyanthoside (9). Their structures were elucidated on the basis of their physicochemical and spectroscopic properties. Compounds 1, 2, 4 and 11 displayed potent antioxidant activities in the DPPH assay, while 2 and 3 displayed good activities against LPS-induced TNF-α and IL-1β production in BV2 cells. Compounds 1–5 and 10–12 were evaluated for their cytotoxic activities against three human cancer cell lines (A-549, Bel-7402, and HCT-8), but none displayed significant activity.

Introduction

Jasminum nervosum Lour. is commonly used in folk medicinal in many Asian countries (Chang et al., 1996). Jasminum is the largest genus in the Oleaceae family, including more than 200 species, and which are mainly distributed in tropical and sub-tropical regions of Asia and Africa. There are about 50 species in China and some of them have been cultivated as ornamental, medicinal or aromatic plants (Chang et al., 1996). In China, J. nervosum stems are used as a traditional Zhuang folk medicinal herb called qingtengzi for treating a number of disorders, including rheumatoid arthritis and wound-healing in southwest China (Zhan, 1994, Editorial Committee of the National Chinese Medicine Administrative Bureau, 2005). The Zhuang ethnic group is the largest minority of the 55 officially recognized minority groups in the People’s Republic of China, and many live in the southern subtropical area known as Five Ridges, where plant resources are abundant. Zhuang medicine has developed distinctly from other forms of Traditional Chinese medicine (TCM) due in part to the rugged and subtropical environment this minority group live. The Zhuang pharmacopeia is especially rich in treatments for diseases prevalent in subtropical areas, including insect and snake bites, wounds, and rheumatoid arthritis (Huang, 2001). More than 700 Zhuang medicines have been developed, some have become well-known throughout China (Huang, 2001).

The Zhuang celebration of the Dragon Boat Festival in late spring is a good time to collect fresh plant material, particularly in the most well-known Jingxi County, Guangxi Autonomous Region, which has carried on this tradition for over a thousand years. Studies have shown that the Dragon Boat Festival drug market range up to 476 kinds, these local ethnomedicines have a remarkable curative effect for certain diseases (Lin et al., 2012).

An ethnobotanical survey on the Dragon Boat Festival drug market in Jingxi County over a four-year period found that J. nervosum is extensively and frequently used as a medicine, for treating rheumatoid arthritis and wound-healing, among other conditions. The Zhuang people have validated its efficacy clinically within their own culture, and therefore it was selected here for further phytochemical and biological activity studies.

Few studies had been reported on the constituents of J. nervosum. One study examined the antioxidant potential of J. nervosum stems using free radical scavenging reducing assays, but they did not report purifying or identifying any of the antioxidant constituents (Huo et al., 2011a). A second study by the same group used GC–MS to identify 68 volatile constituents from the leaves of J. nervosum, and they found that β-linalool was the major volatile comprising about 26% of the total volatiles (Huo et al., 2011b). There have been numerous phytochemical studies on other species of Jasminum, and many natural products have been reported. For example, the iridoid and secoiridoid glycosides have been studied extensively as chemotaxonomic markers for this genus (Jensen et al., 2002). Others have investigated alkaloids (Hart et al., 1968, Hart et al., 1969), phenylpropanoid glycosides (Andary et al., 1992, Huong et al., 2008) and flavonoid glycosides (Tanahashi et al., 1997).

The current research was carried out to investigate the bioactive constituents of J. nervosum that may help to explain its use in Zhuang folk medicine. Eight new compounds and four known compounds were isolated, identified, and tested for biological activity in antioxidant and anti-inflammatory assays.