Medicinal plants have gained much interest in the prevention and treatment of common human disease such as cold and fever, hypertension and postpartum. Bioactive compounds from medicinal plants were synthesised using effective extraction methods which have important roles in the pharmaceutical product development. Orthosiphon aristatus (OA), Eurycoma longifolia (EL) and Andrographis paniculata (AP) are among popular medicinal herbs in Southeast Asia. The major compounds for these medicinal plants are polar bioactive compounds (rosmarinic acid, eurycomanone and andrographolide) which have multiple benefits to human health. The bioactive compounds are used as a drug to function against a variety of diseases with the support of scientific evidence. This paper was intended to prepare a complete review about the extraction techniques (e.g. OA, EL and AP) of these medicinal plants based on existing studies and scientific works. Suitable solvents and techniques to obtain their major bioactive compounds and their therapeutic potentials were discussed.

Curcumin nanoemulsion was prepared using coconut oil, Tween 80 (surfactant) and polyethylene glycol (co-solvent) with the addition of honey and glycerol as additives. The nanoemulsion was optimized and systematically characterized for transdermal delivery. Small particle size (15.92 nm), low polydispersity index (0.17) and slight acidic (pH 4.18) curcumin nanoemulsion was obtained without any chemical degradation based on the Fourier transform infrared (FTIR) spectrum. The incorporation of curcumin inside nanoglobul improved curcumin stability and skin permeability. Its high permeability can be seen from Nile dyed curcumin in different layers of skin through fluorescent imaging. The release kinetic of curcumin followed the Higuchi model, which explains why the skin permeation was a Fickian diffusion-controlled process because the Korsmeyer constant was proven to be 0.3 (<0.5). Nanoencapsulation slightly decreased the antioxidant capacity of curcumin for about 7.9% compared to its free counterpart. It showed low cytotoxicity (EC₅₀ 2.3552 µg/mL) to human skin fibroblasts. Cell death was noticed at a high concentration (2.5 µg/mL) of treatment. Curcumin was also found to promote wound closure at low concentration 0.1563 µg/mL and was comparable with the performance of ascorbic acid based on scratch assay. Therefore, this nutritious curcumin nanoemulsion is a promising transdermal delivery system for topical application.

Primarily, optimization of ultrasonic-assisted extraction (UAE) conditions of Orthospihon stamineus was evaluated and verified using a central composite design (CCD) based on three factors including extraction time (minutes), ultrasound amplitude (A), and solvent concentration (%). The response surface methodology (RSM) was performed to develop an extraction method with maximum yield and high rosmarinic acid content. The optimal UAE conditions were as follows: extraction time 21 min, ultrasound amplitudes 62 A, and solvent composition 70% ethanol in water. The crude extract was further fractionated using solid-phase extraction (SPE), where six sequential fractions that varied in polarity (0–100% Acetonitrile in water) were obtained. Next, the six fractions were evaluated for their antioxidant and anti-cancer properties. This study found that Fraction 2 (F2) contained the highest rosmarinic acid content and showed the strongest antioxidant activity. Additionally, F2 showed an anti-proliferative effect against prostate cancer (DU145) with no harmful effect on normal cells.

The usage of non-degradable polymer as the main matrix for a cosmetic patch raises concern, as it can cause environmental pollution when discarded in landfill. Thus, biodegradable polylactic acid (PLA) was chosen in this study, as PLA has non-toxic properties and similar mechanical properties to conventional plastic materials. An active ingredient in a cosmetic patch serves the purpose of providing beneficial ingredients to the skin; therefore, phycocyanin, an extract from spirulina, was chosen, as it possesses antioxidant and anti-inflammatory properties. Alginate was also incorporated with the phycocyanin for fabrication onto the PLA matrix. A preliminary study was first carried out to identify the antioxidant properties and cytotoxic effect of the phycocyanin on skin cells. It was observed that phycocyanin had no cytotoxic effect on the skin and showed good antioxidant activity. PLA/phycocyanin–alginate composite was fabricated using a solvent casting method, and optimization of preparation conditions (phycocyanin/alginate ratio, stirring time, and temperature) were carried out using the one-factor-at-a-time (OFAT) method with responses of elongation at break and releasing properties. Attenuated total reflectance (ATR)–FTIR analysis was also conducted to further analyze the functional group of the composites. Surface morphologies were observed for samples before and after the releasing test. From the analyses conducted, PLA/phycocyanin–alginate composite prepared at a phycocyanin/alginate ratio of 40/60 for 20 h at 20 °C gave the best properties in terms of flexibility of film and releasing properties of phycocyanin.

Skin is the largest external organ of the human body. It acts as a barrier to protect the human body from environmental pollution, mechanical stress, and excessive water loss. The defensive function resides primarily on top of the epidermis layer commonly known as stratum corneum (SC). Human SC consists of three major lipids, namely ceramide, free fatty acid, and cholesterol that comprise approximately 50%, 25%, and 25% of the total lipid mass, respectively. The optimal composition of SC lipids is the vital epidermal barrier function of the skin. On the other hand, skin barrier serves to limit passive water loss from the body, reduces chemical absorption from the environment, and prevents microbial infection. In contrast, epidermal lipids are important to maintain the cell structure, growth and differentiation, cohesion and desquamation as well as formation of a permeability barrier. Multiple non-invasive in vivo approaches were implemented on a regular basis to monitor skin physiological and intercellular lipid properties. The measurement of different parameters such as transepidermal water loss (TEWL), hydration level, skin elasticity, collagen intensity, melanin content, sebum, pH, and tape stripping is essential to evaluate the epidermal barrier function. Novel non-invasive techniques such as tape stripping, ultrasound imaging, and laser confocal microscopy offer higher possibility of accurate and detailed characterisation of skin barrier. To date, these techniques have also been widely used to determine the effects of herbal plants in dermatology. Herbal plants have been traditionally used for ages to treat a variety of skin diseases, as reported by the World Health Organisation (WHO). Their availability, lower cost, and minimal or no side effects have created awareness among society, thus increase the demand for natural sources as the remedy to treat various skin diseases. This paper reviews several non-invasive techniques and evaluations of herbal-based product in dermatology.

Andrographis paniculata is a local medicinal plant that is widely cultivated in Malaysia. It is comprised of numerous bioactive compounds that can be isolated using water, ethanol or methanol. Among these compounds, andrographolide has been found to be the major compound and it exhibits varieties of pharmacological activities, including anti-cancer properties, particularly in the lipid-dependent cancer pathway. Lipids act as crucial membrane-building elements, fuel for energy-demanding activities, signaling molecules, and regulators of several cellular functions. Studies have shown that alterations in lipid composition assist cancer cells in changing microenvironments. Thus, compounds that target the lipid pathway might serve as potential anti-cancer therapeutic agents. The purpose of this review is to provide an overview of the medicinal chemistry and pharmacology of A. paniculata and its active compounds in terms of anti-cancer activity, primary mechanism of action, and cellular targets, particularly in the lipid-dependent cancer pathway.