Clerodendrumic Acid, a New Triterpenoid from Clerodendrum glabrum (Verbenaceae), and Antimicrobial Activities of Fractions and Constituents

Abstract

One new triterpenoid, (3β,11α,19β)‐3‐(butanoyloxy)‐11‐hydroxytaraxast‐20(30)‐ene‐23,28‐dioic acid (clerodendrumic acid; 1) was isolated from the hexane extract of the leaves of Clerodendrum glabrum var. glabrum along with heptadecanoic acid (2). The structure of the new compound was elucidated by interpretation of its NMR (1D and 2D), MS, and IR data. Combined fractions C and D from the column chromatography of the hexane extract exhibited significant antifungal activities (average MIC of 0.10 mg/ml) against Candida albicans and Cryptococcus neoformans. C. albicans was relatively resistant to clerodendrumic acid (1; MIC 125 μg/ml) and was resistant to heptadecanoic acid (2; MIC 188 μg/ml). Both compounds had low antibacterial activities against two Gram‐positive and two Gram‐negative bacteria with average MIC values of 157 and 172 μg/ml, respectively. Compounds 1 and 2 were relatively nontoxic against monkey kidney Vero cells in vitro with IC50 values of 202.6 and 108.4 μg/ml, respectively.

Review of Pharmacological Properties, Phytochemistry and Medicinal uses of Volkameria glabra

“…Amusan et al [49] and Ogundajo and Ashafa [60] identified anthraquinones, cardiac glycosides, flavonoids, phenols, polyphenols, saponins, steroids, tannins and terpenoids from the leaves of V. glabra. From an extract of the leaves and stem bark of V. glabra, Fouad et al [61], Masevhe et al [62], Wanas et al [63] and Teclegeorgish [64] isolated aliphatic glycosides, iridoid, phenolics, phytosterol and triterpenoids (Table 2). Some of these chemical compounds may be responsible for the biological activities of the species.…”

“…The following pharmacological activities have been documented from the bark, fruits, leaves, roots and stems, and the compounds isolated from V. glabra: 3β-hydroxy-5-glutinene -Leaves and stem bark [64] 3β-lup-20(29)-en3-ol -Leaves and stem bark [64] Clerodendrumic acid -Leaves [62] Heptadecanoic acid -Leaves [62] Other phytochemical compounds Total flavonoid (mg quercetin/g) 22.6 -47.0 Leaves [60] Total flavanol (mg rutin/g) 17.9 -173.7 Leaves [60] Total phenol (mg gallic acid/g) 61.5 -66.0 Leaves [60] acaricidal, anthelmintic, antibacterial, antifungal, antimycobacterial, anti-collagenase, antidiabetic, antielastase, anti-inflammatory, antileishmanial, antioxidant, antiplasmodial, antipyretic, cholinesterase enzyme inhibition, immune-stimulant and cytotoxicity activities.…”

“…The extract exhibited activities with minimum inhibitory concentration (MIC) values ranging from 0.3 mg/ml to 1.3 mg/ml in comparison to a MIC value of <0.02 mg/ml exhibited by the positive control [67]. Masevhe et al [62] evaluated the antibacterial activities of fractions of the hexane extract of V. glabra leaves and the compounds clerodendrumic acid and heptadecanoic acid isolated from the species against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli using twofold serial microdilution method with gentamicin as a positive control. Both the fractions and compounds exhibited activities with the MIC values ranging from 0.2 mg/ml to 1.3 mg/ml and 125.0 µg/ml to 188.0 µg/ml, respectively [62].…”

Ethnomedicinal application, phytochemistry and therapeutic effects of genus clerodendrum

“…It is occasionally grown for medical purposes in China and Vietnam and is frequently planted as an ornamental, with the double-flowered but sterile type being the most popular[42].Phytochemical screening of Clerodendrum species:[46]. Clerodendrum philippinum contains a variety of phytochemicals, including alkaloids, terpenoids, flavonoids, saponins, tannins, phenolics, and glycosides[47]. Carbohydrates, reducing sugar, hexose sugar, cardiac glycosides, saponins, tannins, and phenols were found in the hydroalcoholic extract of Clerodendrum phlomidis[48].Secondary metabolites found in abundance in Clerodendrum splendens leaves include Terpenoids, Saponins, carbohydrates, and glucosides.…”

Triterpenoids

“…301 Ovalifolones A 556 and B 557, from Garcinia ovalifolia, 302 Clerodendrumic acid 624, from Clerodendrum glabrum, has also be reported with this stereochemistry. 337 The acetonide 625 is likely to be an artefact from chromatography of the extract of Rhododendron hainanense. 338 Ilexpublesnin F is a taraxastane saponin with a known genin from Ilex pubescens.…”