The untapped potential of spermidine alkaloids: Sources, structures, bioactivities and syntheses

Spermidine alkaloids are a kind of natural products possessing an aliphatic triamine structure with three or four methylene groups between two N-atoms. Spermidine alkaloids exist in plants, microorganisms, and marine organisms, which usually form amide structures with cinnamic acid or fatty acid derivatives. Their unique structures showed a wide range of biological activities such as neuroprotective, anti-aging, anti-cancer, antioxidant, anti-inflammatory, and antimicrobial. In order to better understand the research status of spermidine alkaloids and promote their applications in human health, this paper systematically reviewed the biological sources, structures, pharmacological actions, and synthetic processes of spermidine alkaloids over the past two decades. This will help to open up new pharmacological investigation fields and better drug design based on these spermidine alkaloids.

Acute effect of Capparis spinosa root extracts on rat articular pain

ETHNOPHARMACOLOGICAL RELEVANCE

Capparis spinosa L. originates from dry regions of Asia and Mediterranean basin. In traditional medicine of these areas, infusions from caper root are considered to be beneficial for the treatment of rheumatism, gout and against abdominal pains.

AIM OF THE STUDY

To evaluate the pain relieving properties of a Syrian cultivar of Capparis spinosa roots in rat models of osteoarthritis and rheumatoid arthritis.

MATERIALS AND METHODS

Decoction (DEC) and hydroalcoholic extract (EtH₂O) were obtained from powdered roots; the latter was further separated in CH₂Cl₂ and aqueous (H₂O-Res) fractions. The extracts were characterized in terms of spermidine alkaloids by HPLC/DAD/MS and stachydrine by NMR. Different amount of free and glycosilated forms of capparispine and analogues (from 0.5% w/w for DEC up to 7.6% w/w for CH₂Cl₂ fraction) were detected. Rat models of rheumatoid arthritis and osteoarthritis were induced by the intra-articular administration of Complete Freund's Adjuvant (CFA) or monosodium iodoacetate (MIA), respectively.

RESULTS

Fourteenth days after CFA or MIA injection, the different preparations of Capparis spinosa (3, 30, 100 and 300mgkg^-1) were acutely administered p.o.. Powdered roots (300mgkg^-1), DEC (100mgkg^-1), and EtH₂O (300mgkg^-1) significantly reduced hypersensitivity to mechanical noxious stimuli as well as spontaneous pain evaluated as hind limb bearing alterations in both models. The CH₂Cl₂ and the H₂O-Res (30mgkg^-1) were the most potent in reverting pain threshold alterations despite the different content of free alkaloids.

CONCLUSIONS

Capparis spinosa extracts relieved pain related to rheumatoid arthritis and osteoarthritis after single administration. A synergistic effect due to a specific "phytochemical mixture" is suggested.

An insight on the alkaloid content of Capparis spinosa L. root by HPLC-DAD-MS, MS/MS and (1)H qNMR

The Capparis spinosa L. has a wide distribution in the Old World from South Europe, North and East Africa, Madagascar, Southwest and Central Asia to Australia and Oceania. The consolidated traditional use of C. spinosa root as remedy against different pains in human is well known since the antiquity. Various secondary metabolites have been found in caper plant, nevertheless, few studies have been focused to the analysis of root constituents. To date, several free and glycosilated spermidine alkaloids and a more polar alkaloid, the stachydrine, have been isolated from the root of C. spinosa. Aim of this work was to improve the knowledge on the alkaloid content of the root of a Syrian sample of C. spinosa by HPLC-DAD-MS(n) and to propose methods to quantify these molecules in different raw extracts. A decoction, an hydroalcoholic extraction and a fractionation process to selectively recover the spermidine alkaloids were applied. To our knowledge, this is the first HPLC-DAD-MS(n) profile that pointed out the co-presence of stachydrine, several isobaric forms of capparispine and/or capparisine in free and glycosylated forms and some isobars of isocodonocarpine or codonocarpine as monoglycosides in extracts of C. spinosa root. The determination by HPLC/DAD for the spermidine alkaloids expressed as p-OH-coumaric acid gave values up to 3.5mg/g dried root and the stachydrine evaluated by (1)H NMR was close to 12.5mg/g dried root. Overall, the total alkaloids were almost doubled in hydroalcoholic extract with respect to the decoction, and the stachydrine in the cortex was almost double than in the whole root.