LAUSR

The genus Lonicera is distributed in subtropical and temperate regions of the world. It is widely used against a wide range of diseases like asthma, urinary complaints, feverish conditions, and as anti-inflammatory, anti-spasmodic, and anti-bacterial agent [1, 2]. In Uzbekistan, it has been used by the locals for the treatment of fractures and wounds. It is applied externally on affected area and also given orally. Based on the above important and traditional uses, bioassay guided isolation and characterization was done, resulting in nine known compounds (1–9), reported here for the first time from the plant Lonicera nummulariifolia. Previously only the essential oils of this plant were analyzed by GC and GC/MS [3]. The related species are recognized as a rich source of biologically active and structurally complex diterpenoids, triterpenoids, flavonoids, and swerodides with a wide range of biological activities [2, 4–8]. The aerial parts of plant L. nummulariifolia were repeatedly extracted (five times) with 80% methanol–water mixture at room temperatures. The combined methanolic extract was concentrated under vacuum and separated into different fractions by extracting the aqueous layer with various organic solvents such as n-hexane, diethyl ether, ethyl acetate, and dichloromethane after basification using ammonium hydroxide, and finally extracted with n-butanol. Taking into account the ethnobotanic importance of Lonicera species, as well as the folk uses of L. nummulariifolia, a bioassay-guided phytochemical investigation was carried out on this plant. The shade-dried ground aerial part of the plant L. nummulariifolia (2.75 kg) was extracted with 80% methanol–water at room temperature for 7 days (5 × 4 L). The combined methanolic extract was evaporated, and the residue was suspended in water and successively partitioned with n-hexane, diethyl ether, ethyl acetate, dichloromethane, and n-butanol. Lipoxygenase inhibition studies on all crude fractions were carried out, since the lipoxygenases have been implicated in a wide range of human diseases, such as inflammation, allergy, asthma, and tumor. The results of enzyme inhibition studies showed that the hexane extract possesses 54.02% inhibition against lipoxygenase, while the ethyl acetate extract has been found to have a significant inhibitory potential (95%). All other extracts were found to be inactive against lipoxygenase. Base on the result of lipoxygenase inhibition, the ethyl acetate extract was select for further investigation, and nine compounds have been isolated from the fraction and reported for the first time from the plant L. nummulariifolia. The structural characterization of these compounds has been carried out using several techniques like MS, HR-MS, 1D and 2D 1H NMR, and 13C NMR spectroscopy, and they have good agreement with the reported literature. Quinqueloside (6′′-O-caffeoylcosmosiin) (1) was isolated as a white amorphous powder. The spectral data of the compound 1 was in good agreement with reported data of a known compound, 6′′-O-caffeoylcosmosiin (1), which was previously reported from Bellis perennis and Chamomilla recutita [9–11]. 7-epi-Loganin (2) was isolated as a white amorphous powder. This compound was previously reported from Rauwolfia serpentina (Apocynaceae) [12]. 3′-O-Caffeoylsweroside (3) was