The study of the anti-inflammatory properties of original dry extracts of narrow-leaved lavender (Lavandula angustifolia mill.) herb

The aim of our work was to conduct experimental studies of the anti-inflammatory properties of original dry extracts of the narrow-leaved lavender herb of Ukrainian origin to justify their introduction into clinical practice. Materials and methods of the research. The objects of the study were experimental test samples: No. 1 ‒ dry extract of narrow-leaved lavender herb, obtained by extraction with purified water; No. 2 - dry extract of the narrow-leaved lavender herb obtained by extraction with a water-ethanol solution (40% ethanol); No. 3 - dry extract of the narrow-leaved lavender herb, obtained by extraction with a water-ethanol solution (70% ethanol). An experimental study of the anti-inflammatory properties of dry extracts of lavender herb was carried out on various models of acute inflammation in rats with proven mechanisms of development. Test samples were administered at doses of 25, 50, 100, and 150 mg/kg three days before edema modelling, intragastrically in the form of an aqueous suspension stabilized with Tween-80, in a volume of 1 ml/100 g of animal weight, the last administration was carried out half an hour before the administration of phlogogens - carrageenan or zymosan. As comparison drugs, diclofenac sodium (8 mg/kg) and quercetin (50 mg/kg) were used in the form of an aqueous suspension in a volume of 1 ml/100 g of animal weight half an hour before the administration of carrageenan or zymosan. Edema was induced by subplantar injection into the right hind foot of 0.1 ml of 1% carrageenan solution from Sigma (USA) or 2% zymosan suspension. The severity of the local reaction was assessed by the ratio of the paw volume before and after the administration of phlogogen. The volume of the affected paw was measured using a LE7500 plethysmometer (PANLAB, Italy) 1, 3, 4, 6 and 24 hours after the administration of carrageenan or zymosan. Statistical data processing was performed using the standard STATISTICA program package (version 6.0). The obtained data are presented as the mean value and its standard error or minimum and maximum values. The distribution of data in the studied samples was checked for normality using the Shapiro-Wilko test. In case of non-compliance with the normal distribution of data in the analyzed samples, intergroup differences were determined using the non-parametric Kruskal-Wallis test (analogue of variance analysis). The significance level was p<0.05. Results and their discussion. It has been experimentally proven that in the model of acute inflammation caused by the administration of carrageenan, moderate anti-inflammatory properties of the studied test samples of dry extracts of narrow-leaved lavender herb were established. The most active and stable anti-exudative activity was demonstrated by test samples No. 1 at a dose of 100 mg/kg (50%) and No. 2 at a dose of 150 mg/kg (52%). Test sample No. 3 showed moderate activity, and its maximum effectiveness was observed during the first hour of the experiment. Unlike test samples No. 1 and 2, which provided a stable uniform effect throughout the entire observation period, the effect of test sample No. 3 was less long-lasting. In the model of acute aseptic inflammation caused by zymosan, it was found that dry extracts of lavender herb showed significant antiexudative activity. However, there was no direct dose-dependent effect. The results of the studies show that among the three tested test samples, the most pronounced and stable antiexudative activity at the level of 61% and 71%, respectively, was demonstrated by extracts of lavender herb obtained by extraction (40 and 70% ethanol) at doses of 150 and 50 mg/kg. Their effectiveness was statistically significantly higher compared to quercetin. Based on the obtained results, certain assumptions can be made about the immunomodulatory properties of lavender extracts. The reduction of edema under the influence of the studied extracts indicates the suppression of excessive inflammatory reaction, which is one of the manifestations of the immunomodulatory effect. The aqueous extract can weaken the activation of the inflammatory response due to antioxidant properties, which reduce oxidative stress in tissues. Water-ethanolic extracts, due to the high concentration of essential oils (linalool and linalyl acetate), can affect the regulation of the production of both pro-inflammatory and anti-inflammatory cytokines (e.g., interleukin-1β, TNF-α, interleukin-10) and modulate the activity of TLR receptors, which is important for the regulation of macrophage activity and inhibition of the inflammatory response. Antiexudative activity, especially in test samples No. 2 and 3, indicates the ability to modulate vascular permeability, which depends on the activity of immune cells, such as macrophages and neutrophils. Conclusion. The results of the conducted studies indicate that in the carrageenan-induced inflammation model, the moderate effectiveness (52% and 35%) of test samples No. 2 and 3 is likely associated with a higher concentration of linalool, linalyl acetate, lavandulol and camphor - substances that are extracted with ethanol and block the synthesis of leukotrienes and histamine at the initial stage of edema development. In the zymosan-induced inflammation model, among the three studied test samples, the most pronounced and stable antiexudative activity was demonstrated by dry extracts of narrow-leaved lavender (Lavandula angustifolia Mill.), obtained by extraction with water-ethanol solutions (40 and 70% ethanol) in doses of 150 and 50 mg/kg (test samples No. 2 and 3) at the level of 61% and 71%, respectively. Their effectiveness was statistically significantly higher compared to quercetin. The results of the experiments are consistent with previous studies on the antimicrobial and anti-inflammatory properties of dry extracts of the herb Lavandula angustifolia, obtained by extraction with aqueous-ethanol solutions (40 and 70% ethanol), which strengthens the experimental evidence base of their therapeutic value in the treatment of inflammatory conditions.