Pharmacological Evaluation of Secondary Metabolites and Their Simultaneous Determination in the Arabian Medicinal Plant Plicosepalus curviflorus Using HPTLC Validated Method

Plicosepalus is an important genus of the Loranthaceae family, and it is a semiparasitic plant grown in Saudi Arabia, traditionally used as a cure for diabetes and cancer in human and for increasing lactation in cattle. A flavonoid quercetin (P1), (-)-catechin (P2), and a flavane gallate 2S,3R-3,3',4',5,7-pentahydroxyflavane-5-O-gallate (P3) were isolated from the methanol extract of the aerial parts of P. curviflorus (PCME). The PCME and the isolated compounds were subjected to pharmacological assays to estimate peroxisome proliferator-activated receptors PPARα and PPARγ agonistic, anti-inflammatory, cytotoxic, and antimicrobial activities. Results proved for the first time the dual PPAR activation effect of the PCME and catechin (P2), in addition to the promising anti-inflammatory activity of the flavonoid quercetin (P1). Interestingly, both PCME and isolated compounds showed potent antioxidant activities while no antimicrobial effect against certain microbial strains had been reported from the extract and the isolated compounds. Based on the pharmacological importance of these compounds, an HPTLC validated method was developed for the simultaneous estimation of these compounds in PCME. It was found to furnish a compact and sharp band of compounds P1, P2, and P3 at R _f = 0.34, 0.47, and 0.65, respectively, using dichloromethane, methanol, and formic acid (90 : 9.5 : 0.5, (v/v/v)) as the mobile phase. Compounds P1, P2, and P3 were found to be 11.06, 10.9, 6.96 μg/mg, respectively, in PCME. The proposed HPTLC method offers a sensitive, precise, and specific analytical tool for the quantification of quercetin, catechin, and flavane gallates in P. curviflorus.

Molecular mechanisms that underlie the sexual stimulant actions of Avicennia marina (Forssk.) Vierh. and Crocus sativus L

The effects of extracts and sub-fractions of Avicennia marina, Crocus sativus and sildenafil on the sexual behavior of male rats and their effects on the intracavernosal pressure (I.CV), intracavernosal cyclic GMP and dihydrotestosterone plasma level were examined. The sexual behavior was followed for four hours using infra-red video cameras to quantify the effects on various male sexual behaviors. The results revealed that the active sub-fraction in case of A. marina was the hexane fraction of the chloroform extracts (C/H) whereas that of C. sativus was the hexane fraction of the alcoholic extract (A/H). (C/H), (A/H) and sildenafil significantly increased the total sexual stimulation index from 53.8±2.7 (control) to 406±7.8, 225±4 and 401±30.1, respectively (P<0.001, N=6). They significantly increased the index of successful mounting and ejaculation from 2.6±0.5 (control) to 40±2.7, 21±2.3 and 18±1.7, respectively (P<0.01, N=6). They significantly increased the cyclic GMP level from 0.94±0.07 (control) to 3.1±0.13, 1.59±0.11 and 3.66±0.19 ng/mg wet tissue, respectively (P<0.05, N=7). They did not affect dihydrotestosterone plasma level. (C/H), (A/H) and sildenafil increased the (I.CV) pressure by 4.8±0.3, 1.4±0.8 and 4.2±0.9 mmHg. The (C/H) seemed to be more active than sildenafil and twice active than (A/H). Both extracts and sildenafil acted via an increase in cyclic GMP.