Ocimum gratissimum L. is popularly used to treat diabetes mellitus. The hypoglycemic activity of this medicinal species has been confirmed by in vivo studies. The present study conducted a chemical investigation of a leaf decoction (10% p/v) of O. gratissimum monitored by in vivo hypoglycemic activity assays. Four phenolic substances were identified: L-caftaric acid (1), L-chicoric acid (2), eugenyl-β-D-glucopyranoside (3) and vicenin-2 (4). The acute hypoglycemic activity of the O. gratissimum decoction fractions Og1-S (300 mg/kg), Og1-A (240 mg/kg) and Og1-B (80 mg/kg) was evaluated intraperitoneally in normal and streptozotocin-induced diabetic mice. They reduced glycemia by 63%, 76% and 60% (in 120 min), respectively, in the diabetic mice. Subfractions of Og1-A were also evaluated under the same conditions: Og1-AS (200 mg/kg) and Og1-AP (40 mg/kg) produced a decrease of only 37% and 39%, respectively. Among the major phenolic substances, only chicoric acid (2; 3 mg/kg) reduced significantly the glycemic levels of diabetic mice by 53%, 120 min after treatment. This is the first study describing the hypoglycemic activity of chicoric acid in an animal model of diabetes mellitus. In addition, we suggest that there may be other substances contributing to this activity. Thus, for the first time, a correlation is established between the hypoglycemic activity of O. gratissimum and its chemical composition.

Leaves of Kalanchoe pinnata are used worldwide for healing skin wounds. This study aimed to develop and compare two creams containing a leaf aqueous extract of K. pinnata (KP; 6 %) and its major flavonoid [quercetin 3-O-α-L-arabinopyranosyl-(1→2)α-L-rhamnopyranoside] (0.15 %). Both creams were topically evaluated in a rat excision model for 15 days. On the 12 th day, groups treated with KP leaf-extract and KP major flavonoid creams exhibited 95.3  1.2 % and 97.5  0.8 % of healing, respectively (positive control = 96.7  0.8 %; negative control = 76.1  3.8 %). Both resulted in better re-epithelialization and denser collagen fibres. Flavonol glycosides are the main phenolics in KP leaf-extract according to HPLC-ESI-MS/MS analysis. KP major flavonoid plays a fundamental role in the wound healing. The similar results found for both creams indicate that the use of KP crude extract should be more profitable than the isolated compound.

The aim of this study was to evaluate the antidiabetic potential of a leaf extract and flavonoids from Sedum dendroideum (SD). Additionally, our goals were to establish a possible structure/activity relationship between these flavonoids and to assess the most active flavonoid on the glycolytic enzyme 6-phosphofructo-1-kinase (PFK). SD juice (LJ), a flavonoid-rich fraction (BF), and separately five flavonoids were evaluated intraperitoneally for their acute hypoglycemic activity in normal and streptozotocin-induced diabetic mice. First, the major flavonoids kaempferol 3,7-dirhamnoside or kaempferitrin (1), kaempferol 3-glucoside-7-rhamnoside (2), and kaempferol 3-neohesperidoside-7-rhamnoside (3) were tested. Then, the monoglycosides kaempferol 7-rhamnoside (5) and kaempferol 3-rhamnoside (6) were assayed to establish their structure/activity relationship. The effect of 1 on PFK was evaluated in skeletal muscle, liver, and adipose tissue from treated mice. LJ (400 mg/kg), BF (40 mg/kg), and flavonoid 1 (4 mg/kg) reduced glycemia in diabetic mice (120 min) by 52, 53, and 61%, respectively. Flavonoids 2, 3, 5, and 6 were inactive or showed little activity, suggesting that the two rhamnosyl moieties in kaempferitrin are important requirements. Kaempferitrin enhanced the PFK activity chiefly in hepatic tissue, suggesting that it is able to stimulate tissue glucose utilization. This result is confirmed testing kaempferitrin on C2C12 cell line, where it enhanced glucose consumption, lactate production, and the key regulatory glycolytic enzymes. The hypoglycemic activity of kaempferitrin depends on the presence of both rhamnosyl residues in the flavonoid structure when intraperitoneally administered. Our findings show for the first time that a flavonoid is capable of stimulating PFK in a model of diabetes and that kaempferitrin stimulates glucose-metabolizing enzymes. This study contributes to the knowledge of the mechanisms by which this flavonoid exerts its hypoglycemic activity.

Kalanchoe daigremontiana (Crassulaceae) is a medicinal plant native to Madagascar. The aim of this study was to investigate the flavonoid content of an aqueous leaf extract from K. daigremontiana (Kd), and assess its antiherpetic potential. The major flavonoid, kaempferol 3-O-β-d-xylopyranosyl-(1 → 2)-α-l-rhamnopyranoside (1), was isolated from the AcOEt fraction (Kd-AC). The BuOH-soluble fraction afforded quercetin 3-O-β-d-xylopyranosyl-(1 → 2)-α-l-rhamnopyranoside (2) and the new kaempferol 3-O-β-d-xylopyranosyl-(1 → 2)-α-l-rhamnopyranoside-7-O-β-d-glucopyranoside (3), named daigremontrioside. The crude extract, Kd-AC fraction, flavonoids 1 and 2 were evaluated using acyclovir-sensitive strains of HSV-1 and HSV-2. Kd-AC was highly active against HSV-1 (EC = 0.97 μg/ml, SI > 206.1) and HSV-2 (EC = 0.72 μg/ml, SI > 277.7). Flavonoids 1 and 2 showed anti-HSV-1 (EC = 7.4 μg/ml; SI > 27 and EC = 5.8 μg/ml; SI > 8.6, respectively) and anti-HSV-2 (EC = 9.0 μg/ml; SI > 22.2 and EC = 36.2 μg/ml; SI > 5.5, respectively) activities, suggesting the contribution of additional substances to the antiviral activity.