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The leaves of Nyctanthes arbor-tristis L. (Oleaceae) are used in Ayurvedic medicine for the management of a range of diseases, but reports on its phytochemicals and pharmacological properties are inadequate. Herein, we report purification of an antioxidative polysaccharide (F2) extracted from its leaves by water. The presence of a highly branched polysaccharide (75 kDa) containing esterified phenolic acids was revealed by chemical, chromatographic and spectroscopic analyses. Particularly, ESMS analysis of per acetylated oligomeric fragments derived by Smith degradation provides important structural information on a spectrum of glycerol tagged oligosaccharides. This polysaccharide showed dose dependent free radical scavenging capacity as evidenced by DPPH and Ferric reducing power assay. This pharmacologically active compound (F2) formed a water soluble complex with bovine serum albumin over pH 4.0–7.4. Accordingly, traditional aqueous extraction method provides a molecular entity that induces a pharmacological effect: this could epitomize a smart approach in phytotherapeutic management.

The distribution and biosynthesis of iridoid glucosides in the Oleaceae is reviewed and five distinct biosynthetic pathways to iridoids have been identified in the family, deoxyloganic acid apparently being a common intermediate. Likewise, the distributions of caffeoyl phenylethanoid glycosides (CPGs), i.e. verbascoside and its analogues, as well as cornoside are listed. Iridoid glucoside data exist for 17 genera of Oleaceae and the occurrence of iridoids from the different biosynthetic pathways correlate extremely well with the phylogenetic classification inferred from recent chloroplast DNA sequence data. Thus the tribe Fontanesieae (Fontanesia) contains "normal" secoiridoids, Forsythieae (Abeliophyllum, Forsythia) contains cornoside and/or iridoids from the forsythide pathway, Myxopyreae (Myxopyrum, Nyctanthes) have iridoids from the myxopyroside pathway, and finally, the two tribes Jasmineae and Oleeae (the remaining genera) both contain iridoids from the oleoside pathway. Within Jasmineae, one group of Jasminum sp. is characterized by the presence of jasminin or similar compounds, while another group of Jasminum species and Menodora display derivatives of 10-hydroxyoleoside, compounds not present in the other group. CPGs are reported from about half of the species investigated. With regard to taxonomy at the order level, the chemical data might support a position within or close to Lamiales due to the common presence of CPGs, the iridoids being of less significance since they are of a type that are barely found elsewhere.

From the leaves of Nyctanthes arbor-tristis, two new iridoid glycosides, 6,7-di-O-benzoylnyctanthoside and 6-O-trans-cinnamoyl-6β-hydroxyloganin have been isolated along with the previously reported iridoid 7-O-trans-cinnamoyl-6β-hydroxyloganin. Their structures were established by UV, mass and NMR spectroscopy.

A further re-examination of the seeds of Nyctanthes arbor-tristis has led to the isolation and identification of two new minor iridoid glucosides, arbortristoside D and E, together with the previously reported, arbortristoside B. Antiviral activity was observed in the crude alcoholic extract, n-butanol fraction and pure compounds.

Two new iridoid glucosides, arbortristoside A and B have been isolated from the seeds of Nyctanthes arbortristis. The structures of the two new compounds were determined by spectroscopic methods and chemical reactions.

A new iridoid glycoside along with the known compounds, nyctanthic acid, oleanolic acid, friedelin, β-sitosterol glucoside, 6β-hydroxyloganin and arbortristoside A have been isolated from Nyctanthes arbortristis and characterized by spectral and chemical means.