Dobera glabra (Forssk.) Poir. (Salvadoraceae); phenolic constituents of the aqueous leaves extract and evaluation of its anti-inflammatory, analgesic activities

BACKGROUND

The plant kingdom is considered one of the most common sources for structural and biological diversity. In particular, the wild category acquires our attention to investigate the phytochemical and the biological evaluations.

METHODS

Dobera glabra was exposed to phytochemical examination using HPLC-ESI-MS analysis. Furthermore, the anti-inflammatory activity was evaluated using carrageenan-induced rat paw edema model, whereas both the central and peripheral analgesic activities were tested via hot plate test in rats and acetic acid-induced writhing in mice, respectively.

RESULTS

Twenty phenolic compounds of D. glabra aqueous leaves extract were emphasized by liquid chromatography coupled with mass spectrometry. Moreover, D. glabra exhibited both anti-inflammatory and peripheral analgesic activities. Furthermore, D. glabra significantly decreased the immune expression of MMP-9, TNF-α and TGF-β1 in the hind paw of rats.

CONCLUSION

D. glabra possess peripheral anti-nociceptive and anti-inflammatory effects in rats mediated through its anti-oxidant and anti-inflammatory activities. The activity of D. glabra leaves extract might be attributed to the presence of hydroxy and keto structures.

Sterols and Triterpenes from Dobera glabra Growing in Saudi Arabia and Their Cytotoxic Activity

A new lupane caffeoyl ester, lup-20(29)-ene 3β-caffeate-30-al (7), and a new oleanane-type triterpene, 3β-hydroxyolean-13(18)-en-12-one (17), were isolated from the aerial parts of Dobera glabra (Forssk), along with ten known triterpenes, including seven lupane-type lupeol (1), 30-nor-lup-3β-ol-20-one (2), ∆1-lupenone (3), lup-20(29)-en-3β,30-diol (4), lupeol caffeate (5), 30-hydroxy lup-20(29)-ene 3β-caffeate (6), and betunaldehyde (8); three oleanane-type compounds were also identified, comprising δ-amyrone (15), δ-amyrin (16), and 11-oxo-β-amyrin (18); together with six sterols, comprising β-sitosterol (9), stigmasterol (10), 7α-hydroxy-β-sitosterol (11), 7α-hydroxy-stigmasterol (12), 7-keto-β-sitosterol (13), and 7-keto-stigmasterol (14). Their structures were elucidated using a variety of spectroscopic techniques, including 1D (1H, 13C, and DEPT-135 13C) and 2D (1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC) nuclear magnetic resonance (NMR) and accurate mass spectroscopy. Subsequently, the different plant extracts and some of the isolated compounds (1-9, 11 and 13) were investigated for their possible cytotoxic activity in comparison to cisplatin against a wide array of aggressive cancer cell lines, such as colorectal cancer (HCT-116), hepatocellular carcinoma (HepG-2), and prostate cancer (PC-3) cell lines. Compound 11 displayed broad cytotoxicity against all of the tested cell lines (IC50 ≅ 8 µg/mL in all cases), and a high safety margin against normal Vero cells (IC50 = 70 µg/mL), suggesting that 11 may be a highly selective and effective anticancer agent candidate. Notably, the evidence indicated that the mode of action of compound 11 could possibly consist of the inhibition of phosphodiesterase I (80.2% enzyme inhibition observed at 2 µM compound concentration).