Three new flavonol C-glycosides: 3'-(3'',7''-dimethyl-2'',6''-octadiene)- 8-C-b-D-glucosyl-kaempferol 8-O-b-D-glucoside (1), 3'-(3'',7''-dimethyl-2'',6''-octadiene)- 8-C-b-D-glucosyl-kaempferol 3-O-b-D-glucosyl [1→4]-b-D-glucoside (2) and 6-(3''-methyl- 2''-butene)-3'-methoxyl-8-C-b-D-glucosyl-kaempferol 3-O-b-D-glucosyl [1→4]- b-D-glucoside (3) have been isolated from 80% ethanolic extract of the aerial parts of Sida cordifolia Linn followed by partitioning with ethyl acetate. Structures were established by chemical and spectroscopic methods.

From the aerial parts of Tanacetum balsamita L. (Compositae) a flavonol aglycon was iso­lated using chromatographic techniques. The structure of this compound was determined using spectroscopic methods (UV, H-NMR and MS) as 3’, 4’, 5, 7-Tetrahydroxy flavonol (Quercetin).

Four known flavonoids: quercetin 3-O -b-D-rutinoside (Q3Rut), myricetin 3- O -b-D-galactopyranoside (M3Gal), quercetin 3- O -b-D-galactopyranoside (Q3Gal) and quercetin 3- O -b-D-glucopyranoside (Q3Glc), for the first time were isolated from aerial parts of Euphorbia microsciadia. The chemical structure of them was elucidated on the basis of 1 and 2 D-NMR spectra and different spectroscopic techniques. The immunomodulatory activities of isolated compounds were compared using standard T-cell proliferation assay. These data showed that lymphocyte suppression activity of flavonoids (1-4) were comparatively lower than prednisolon as a standard drug. Immunosuppressive activity of flavonoids with hydroxyl groups at both 3′-and 4′-positions in their B-ring (Q3Gal) were more than those with 3′-, 4′-and 5′-hydroxyl substitution (M3Gal). In these compounds, Q3Gal showed the most inhibitory activity, whereas M3Gal showed the least lymphocyte antiprolifeartive activity.

Total phenol contents of O. vulgare were found between 54. 23 mg GAE/g (U4) and 124. 55 mg GAE/g (U2), respectively. While total phenol contents of O. minutiflorum change between 49. 50 mg GAE/g (U5) and 126. 92 mg GAE/g (S3), total flavonol contents were found between 623. 87 mg RE/g (U5) and 854. 53 mg RE/g (U2). Antioxidant capacity ranged from 42. 31 mg AAE/g (U5) to 103. 04 mg AAE/g (S3). Total phenol contents of O. majorana changed between 51. 86 mg GAE/g (S3) and 125, 23 mg GAE/g (S2). Antiradical activity and antioxidant capacity values were found between 695. 85 IC50= mg/mL (U5) and 1217. 51 IC50= mg/mL S3 and 55. 43 mg AAE/g (S3) to 110. 90 mg AAE/g (U5), respectively.

The main objective of this work was to determine the global and local chemical descriptors of two reagents, 2-hydroxy acetophenone and benzaldehyde, which form flavonol, using DFT at the B3LYP/6-311G(d,p) level. The global reactivity indices indicate that 2-hydroxy acetophenone acts as a nucleophile, while benzaldehyde is an electrophile. Electrostatic potential and local indices suggest the preferred interaction occurs between the ketone group of 2-hydroxy acetophenone and the aldehyde group of benzaldehyde. Additionally, the Ultraviolet-Visible and NMR (Nuclear Magnetic Resonance) spectra of flavonol were simulated, showing good alignment with experimental data, thereby confirming the effectiveness of the applied methods NMR in predicting chemical properties.