Acteoside (verbsacoside) is the one of the main active phenylethanoid glycosides from Cistanche deserticola, Lantana camara and some others herbs. It is known to have antioxidant and neuroprotective activity, and herbs containing it are used to enhance memory and can be studied for the treatment of Alzheimer's disease. It is known, that amyloid fibrils accumulation in cerebral can easily lead to neurodegenerative disorders. Acteoside has been reported to inhibit Aβ42 aggregation by activating nuclear translocation of the transcription factor NF-E2-related factor 2 (Nrf2), increasing heme oxygenase-1 (HO-1) expression. It has also been shown that acteoside could decrease nitric oxide synthase (NOS) activity and caspase-3 expression. Acteoside is a natural antioxidant product unlike other anti-tumor compounds, is an inhibitor of protein kinase C (PKC). In addition Reh-acteoside, a general acteoside of Rehmannia leaves was studied in phase 2/3 clinical trials for patients with IgA nephropathy.

Calphostin C (UCN-1028C), isolated compound from Cladosporium cladosporioides, is a cell permeable, potent and highly selective inhibitor of protein kinase C (IC50=0.05 uM). Calphostin C has been shown to compete at the DAG binding site and inhibit DGK (DAG kinase, DAGK). Calphostin inhibition of PKC is light dependent. At higher concentrations it inhibits myosin light chain kinase, PKA (cAMP-dependent protein kinase), protein kinase G, c-Src (pp60v-src protein TyK) (tyrosine kinase) and DGK. This compound also inhibits PC-PLD1 and -PLD2 (Phospholipase D1 and D2, PLD1 and PLD2). Calphostin C has been observed to induce apoptotic DNA fragmentation and cell death. This compound has demonstrated the ability to inhibit cardiac L-type Ca2+ channels. It has demonstrated the ability to Inhibit cardiac L-type calcium channel protein inhibitors. Calphostin C is an inhibitor of MYLK, PKA and PKD.

Hydroxyachillin, a sesquiterpene lactone, and the main component isolated from aerial parts of Tanacetum microphyllum DC, the last is used in folk medicine as an anti-inflammatory and anti-ulcer agent. Hydroxyachillin was also the effective anti-inflammatory agent in the mouse model of ear edema. Besides, the inhibition of protein kinase C may be one of the mechanisms of hydroxyachillin's effect.

ML-9 is a selective inhibitor of MYLK and CaMK that acts by delaying MYLK phosphorylation through binding at or near the ATP binding site. This naphthalenesulfonamide derivative has been shown to inhibit insulin-stimulated 2-deoxyglucose transport (IC50 = 27 μM), PP-1 activation in adipocytes, PKA, Akt1 (PKB) and Rsk (S6 kinase). ML-9 was also observed to disrupt microfilament bundles with accompanying decrease in P32 incorporation in rat astrocytes. Carbachol illicited cationic currents were inhibitied with ML-9 (IC50 = 7.8 uM) in HEK293 cells. ML-9 has also demonstrated to inhibit natural killer cell lytic acitivity by regulating microfilament contraction as well as catecholamine secretion in intact and permeabilized chromaffin cells. In addition, agonist-induced Ca2+ entry into endothelial cells was completely abolished in the presence of ML-9. ML-9 was found to be a new type of vascular relaxant. ML-9 produced the relaxation of vascular strips contracted by high K+. The relaxation induced by this compound was not affected by treatment with adrenergic and cholinergic blocking agents. Thus, the ML-9-induced relaxation is not due to a block of membrane receptor-associated mechanisms; rather it has an effect on more basic and common events in smooth muscle contraction. Moreover, ML-9 inhibited the Ca2+-induced contraction in chemically skinned vascular smooth muscle cells, suggesting that ML-9 is not a “calcium channel blocker.”

Threo-sphingosine, (-)- is a stereoisomer of naturally occurring D-erythro-sphingosine. It is a Protein kinase C inhibitor. Threo-sphingosine, (-)- is partly active in induction of apoptosis and inhibition of MAPK activity in different kinds of solid tumor cell lines. It can be phosphorylated by cells, but the resulting L-Threo-sphingosine 1-phosphate does not bind and activate sphingosine 1-phosphate receptors, excluding their role in Threo-sphingosine, (-)-induced growth inhibition. Cell culture experiments with Diffuse large B cell lymphoma cell lines that were incubated with Threo-sphingosine, (-)- manifested significant inhibition of cell growth, while incubation of cells with similar concentrations of sphingosine 1-phosphate was ineffective. These results suggest that Threo-sphingosine, (-)- accumulation could be an alternative treatment option for Diffuse large B cell lymphoma.

Threo-sphingosine, (+)-, also known as D-threo-sphingosine, is the less active form from all isomers of sphingosine, can inhibit protein kinase C in vitro.

Pseudohypericin is a predominant naphthodianthrone from St. John’s wort (Hypericum perforatum L.) phytomedicinal drug. It has been shown to specifically inhibit protein kinase C and dopamine-β-hydroxylase. Also, pseudohypericin induces apoptosis and selectively antagonizes corticotropin-releasing factor in murine models. Inhibition of thioredoxin system by pseudohypericin showed appreciable anticancer properties of this natural compound. Pseudohypericin has antiretroviral activity, it has potential therapeutic value in diseases such as AIDS. Pseudohypericin is implicated in the antidepressant efficacy of St. John's wort.