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The first regioselective syntheses of 6-(1,1-dimethylallyl)- and 8-(3,3-dimethylallyl) chrysins have been designed. Claisen rearrangement of protected 5- O -(3,3-dimethylallyl) chrysin in N , N -diethylaniline at 200–217°C gave selective access to the 8-(3,3-dimethylallyl) isomer. Similar rearrangement in N , N -diethylbutylamine at 140–160°C, or in cycloheptane/Eu(fod) 3 at 100°C, led to the formation of the 6-(1,1-dimethylallyl) isomer. Four different protecting groups for position 7 of chrysin have been compared, and found to follow the order of interest Bz>MOM>TBDPS>MEM.

Regioselective control of the Claisen rearrangement of 7-MEM-5-prenyl chrysin was achieved by microwave irradiation. The nature of the products was influenced by the irradiation power and the type of solvent. Irradiation at 750 W in N,N-diethylaniline specifically yielded the 8-(3,3-dimethylallyl) para-rearranged product while refluxing in N,N-diethylbutylamine gave selective access to the 6-(1,1-dimethylallyl) ortho-rearranged compound.

A benzophenone glycoside has been isolated from Davallia solida. Its structure was elucidated by chemical and spectral means as 4-O-beta-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone. It bound with moderate affinity to the purified C-terminal cytosolic domain of P-glycoprotein, but the binding affinity was 6- to 10-fold increased for its aglycone derivative and other related benzophenones.A benzophenone glycoside has been isolated from Davallia solida. Its structure was elucidated by chemical and spectral means as 4-O-beta-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone. It bound with moderate affinity to the purified C-terminal cytosolic domain of P-glycoprotein, but the binding affinity was 6- to 10-fold increased for its aglycone derivative and other related benzophenones.

External lipophilic methylated flavonoids have been extracted from dried leaves of Mentha aquatica, M. spicata, M. x piperita and M. citrata. After separation and purification, twenty flavonoids have been identified by means of spectrometric methods (UV, EIMS, 1H NMR). The flavonoid patterns of these species and hybrid support the view that M. x piperita may be a hybrid of M. aquatica and M. spicata while a linalool-producing sample of M. citrata may be considered a variety of M. aquatica. Cytological data agree with the observed biochemical results.

Different steps of monoterpene metabolism—disappearance of limonene, accumulation of 1,8-cineole, reduction of menthone to menthol and acetylation of menthol—have been studied in different parts of Mentha × piperita leaves of different ages. The analyses of different samples (leaf strips, disks and individual peltate trichomes, translucent or containing crystals from either epidermis) show that all these dynamic changes start at the distal extremity of the leaf and shift progressively towards the base. Except for the peltate trichomes localized within the leaf area, in which a metabolic step is being realized, the trichomes of other parts present a homogeneous monoterpene composition. The measurements of amounts of chlorophyll in two parts, distal and basal, of youngest leaves of terminal buds show that chlorophyll biosynthesis starts also at the distal extremity of the leaf. The regulation of the menthone reduction is discussed.

From the aerial part of Thymus hirtus, eight flavonoids were extracted. Besides three common flavones, apigenin, luteolin and diosmetin, three derivatives of these flavones and two derivatives of quercetin and kaempferol, substituted by a p-hydroxybenzyl moiety, were isolated. The 8-C-substitution of apigenin, luteolin, diosmetin and quercetin was demonstrated by spectrometric data.

A qualitative study of free aglycones from one clone of Mentha × piperita growing natura carried out weekly for 2 months shows that the flavonoid pattern of the whole plant remained invariable. Moreover, the flavonoid composition of mint clones possessing different terpenoid patterns have been studied. A Principal Component Analysis recognizes three flavonoid groups which correspond to the three terpenoid groups. The study of the effects of photoperiodic treatments shows that the flavonoid pattern is affected by the day length.

From Mentha x piperita leaves, 16 free lipophilic flavonoid aglycones were isolated and identified. The variation of this flavonoid composition studied by the means of HPLC techniques from the youngest to the oldest leaves shows that the A- and B-ring O-methylation patterns of leaf pairs differ according to leaf age and would indicate the sequential activity of 4′-O- and 6-O-methyl-transferases.

Dimethylallyl (DMA) derivatives of a naturally occurring xanthone (decussatin 1) were prepared. Their activity as potential P-glycoprotein inhibitors was monitored by affinity of direct binding and compared to that of corresponding DMA-flavones. Both classes of compounds exhibited the same structure-activity relationships. Decreasing polarity enhanced the binding affinity for the P-glycoprotein C-terminal cytosolic domain since DMA derivatives were more active, but unsubstituted hydroxyl group close to the carbonyl was required for efficient activity.Dimethylallyl (DMA) derivatives of a naturally occurring xanthone (decussatin 1) were prepared. Their activity as potential P-glycoprotein inhibitors was monitored by affinity of direct binding and compared to that of corresponding DMA-flavones. Both classes of compounds exhibited the same structure-activity relationships. Decreasing polarity enhanced the binding affinity for the P-glycoprotein C-terminal cytosolic domain since DMA derivatives were more active, but unsubstituted hydroxyl group close to the carbonyl was required for efficient activity.

The monoterpene composition of leaves of Mentha x piperita has been studied by direct analyses of samples (Desorption-Concentration-Introduction Technique). Kinetic studies on individual pairs of leaves from plants subjected to different photoperiodic treatments (long or short photoperiod followed or not by an inversion of the initial photoperiod) show that the photoperiod received by the young leaves directly influenced the oil composition. Therefore the photoperiod as such is responsible for the variations of the monoterpene metabolic pathway. This conclusion is based on the likelihood that the reducing pathway (menthone-menthol) was developed in young leaves on condition that they are subjected to a long photoperiodic treatment and that the metabolic pathway originally induced by the daylength in the oldest leaves was not changed by the inversion of the initial photoperiodic treatment.

Two new flavonol glycosides: 4′-methylquercetagetin 7-O-(6″-E- caffeoyl-β- d -glucoside ) and quercetagetin 7-O-(6- acetyl-β- d -glucoside ) along with the 7- O -glucosides of 6-hydroxykaempferol, quercetin and quercetagetin have been isolated and characterized from the leaves of Eupatorium glandulosum .

In Mentha x piperita leaves, the peltate glands may be divided into two types according to the presence or the absence of crystals in the head of the trichomes. In both types, the free lipophilic flavonoid aglycones, characterized by UV and chromatographic data, are located in the head of the peltate glands, together with monoterpenes.

A new flavonol glycoside isolated from the leaves of Eupatorium glandulosum has been characterized as 6-hydroxykaempferol 7-(6″-caffeoylglucoside) by chemical and spectral methods.