A New Pentacyclic Triterpenoid from Albizia lebbekoides (DC) Benth (Leguminosae)

Albizia lebbekoides (DC) Benth is one of the five species of the genus Albizia found in the Philippines. Not much is known about the chemistry and potential uses of this species. Solvent partition followed by sequential and repeated liquid chromatographic purification over silica led to the isolation of a compound from the hexane extract of A. lebbekoides leaves. A review of related literature and spectral analyses showed that the isolated compound is a new pentacyclic triterpenoid with an oleanane skeleton. Its structure was determined as 3β, 16α-dihydroxyolean-6(7),12(13)-dien-28-oic acid.

CHEMISTORY: Integration of Creative Story Writing in Understanding Chemical Elements in Online Learning

This work presents a pedagogical exploration of Junior high school teachers in drawing an integration between creative writing and chemistry concepts in understanding the behavior of chemical elements as means of addressing the competencies of the Science and English learning areas in an online instructional delivery. Titled A SHORT CHEMISTORY, this paper explores the expected skills, challenges, and opportunities in the possibility of integrating the two disciplines as an innovative way of developing engagement and comprehension among learners in a remote platform. Results uncovered that the said interdisciplinary performance task was pedagogically possible despite the challenges encountered by the facilitators and the learners. Adequate foundational knowledge of the lesson and skills associated with the expected output for both teachers and students, and the need for purposeful interaction and collaboration, are identified as the essential skills expected to attain the objectives of the integration. Teachers found it challenging to see the seamless integration of the chemical element’s characteristics in the characters of the story through lack of depth of personification and time constraint. The integrated task paved the way for several opportunities for both teachers and students in terms of creativity, collaboration, and sense of fulfillment.

In Memoriam – Dr. Consolacion Y. Ragasa

On April 14, 2021, the Philippine chemistry community lost one of its most prolific researchers due to the COVID19 virus. Herein we reflect on the extraordinary life and work of Dr. Consolacion Y. Ragasa. We highlight her story, her scientific contributions, and the huge impact she left, not only on her students and colleagues but also on the scientific research community.

An Introductory Overview of C–H Bond Activation/ Functionalization Chemistry with Focus on Catalytic C(sp3)–H Bond Borylation

The direct and selective functionalization of C–H bonds provides novel disconnections and innovative strategies to streamline the synthesis of molecules with diverse complexities. However, despite the significant advances in the elaboration of techniques for C–H activation, the utilization of unactivated C(sp3)–H bonds remains challenging. In particular, asymmetric transformation of C(sp3)–H bonds is underdeveloped owing to the lack of catalytic systems that can competently discriminate among ubiquitous C–H bonds in organic molecules. This short review aims to outline the challenges and strategies for the catalytic functionalization of C(sp3)–H bonds giving a general and non-exhaustive explanatory approach. Current strategies on the basis of the substrates and reaction mechanisms are summarized in Section 1. Examples of enantioselective C–H bond transformations are then given in Section 2. Finally, in Section 3, an outline of current methodologies towards the direct borylation of C(sp3)–H bonds is described to showcase the importance of developing techniques for catalytic C–H bond chemistry. While we try to cover all excellent reports available in the literature on this topic, any omissions are unintentional, taking note of the most representative examples available.

Optimization of Formic Acid/Acetic Acid for Lignin Extraction in Talahib (Saccharum spontaneum L.) and the Analysis of the Adsorbent Properties of Lignin Towards Cu(II) and Pb(II) in Aqueous Solution

In this paper, Talahib (Saccharum spontaneum L), was subjected to lignin extraction using Formic Acid/Acetic Acid Pulping. The effect of the formic acid/acetic acid/water ratio and the reaction time to the lignin yield was determined. It was found that increasing the concentration of formic acid decreased the lignin yield due to the formation of formate esters, which in turn decreased its reactivity to condense with other materials in the solution. In terms of reaction time, highest yield was observed at lowest cooking time due to the absence of recondensation reactions. Then, the pulp was subjected to further delignification using peroxyacid treatment, which aided in the isolation of any residual lignin left. The isolated lignin was characterized using UV-Vis and ATR-FTIR spectroscopy. Analysis of the adsorbent capability of lignin towards Cu(II) and Pb(II) showed % equilibrium removal amounts of 14.149 ± 0.227 % and 11.384 ± 0.572 %, respectively, both with an equilibrium contact time of 20 minutes. Through kinetic analysis, it was observed that both adsorption processes follow a pseudo-second order model, which means that the adsorption rate depends on the concentrations of both the metal cation and the lignin adsorbent. It also showed that the substrate uptake was greater with Cu(II) (0.330 ± 0.0082 mg/g lignin) compared to Pb(II) (0.262 ± 0.0159 mg/g lignin).

Experimenting on Natural Acid-Base Indicators: A Home-based Chemistry Activity during the COVID-19 Pandemic as evaluated by Teachers

This study determined the feasibility of conducting a laboratory experiment on natural acid-base indicators as a home-based activity. Seven high school teachers from Cebu in Central Visayas, Philippines conducted the home-based activity, evaluated the activity using a validated questionnaire, and were interviewed for opportunities and challenges. Results showed that the at-home activity was feasible and satisfactory, however inaccuracies and inconsistencies were found in the results of the experiment. Nevertheless, the teachers viewed the experiment to have opportunities for holistic development and some challenges concerning material unavailability, safety issues, among others. In conclusion, the home-based activity can be done by students as evaluated by their teachers. Refinement of the activity may be done to correct experimental errors and consider factors that may affect the accuracy of the experimental results. Teachers should also consider resource availability, adult supervision, and safety concerns when dealing with home-based activities.

Alkali Lignin from Rice (Oryza sativa L.) Husk as Adsorbent for Aqueous Methyl Orange and Bromothymol Blue: Analysis of the Adsorption Kinetics and Mechanism

In this study, lignin was isolated from rice (Oryza sativa L.) husk using alkaline extraction method and was used as an adsorbent for aqueous solutions of methyl orange (MO) and bromothymol blue (BTB). The equilibrium removal rate of MO was found to be at 61.4%, with experimental equilibrium adsorbate uptake, qe, of 1.23 mg·g-1, achieved at 150 minutes contact time. For BTB, the equilibrium removal rate was found to be at 78.3%, with an experimental qe of 1.57 mg·g-1, achieved at 150 minutes contact time. Pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models were then used to investigate the kinetics of the adsorption process. Both MO and BTB on lignin were found to follow a PSO kinetic model, with rates of 6.84 x 10-3 g·mg-1·min-1 and 0.69 g·mg-1·min-1, respectively. Langmuir, Freundlich, Dubinin-Radushkevich (DR), Brunauer-Emmett-Teller (BET), Flory Huggins (FH), and Temkin adsorption isotherm models were then used to determine the appropriate equilibrium adsorption model for both substrates. Based on the calculations performed, the Temkin model best described the adsorptive removal of both MO and BTB. Based on the Temkin model, the adsorption processes of both MO and BTB were found to occur spontaneously, with equilibrium rate constants of 0.083 L·mg-1 and 0.012 L·mg-1, respectively.

Angiotensin I-Converting Enzyme (ACE) Inhibitory Activity of Peptides Isolated from Carabao Mango (Mangifera indica) Flesh

Hypertension has been reported as the second major cause of morbidity in the Philippines. One of the mechanisms to control blood pressure is through the inhibition of the angiotensin I-converting enzyme (ACE). This study specifically focused on the determination of ACE inhibitory activities of peptides from ‘Carabao’ mango flesh of three shell colors (SC1, SC3, SC5). The bioactive peptides were obtained upon a series of extraction, purification, and enzymatic hydrolysis steps. Among the undigested and digested crude and purified samples, the highest in vitro ACE inhibition was exhibited by the three-hour digest of SC3 (83.28 ± 0.83%). The most prominent peak from the fractionation of the mixture of peptides in SC3 digest was evaluated for ACE inhibition, and the decrease in activity inferred the synergistic effect of the peptides in exhibiting the inhibitory function. This selected bioactive peptide was revealed to have alanine and phenylalanine as the components, which can possibly be AF – an ACE inhibitory peptide determined from in silico analyses. Meanwhile, assessment of the in vivo antihypertensive activity showed no significant results due to insufficiently administered doses of the samples. Overall, the measured activity of the ACE inhibitory peptides inferred the potential of mango as a functional food in dealing with hypertension.

Optimization and Kinetics of Bioadsorption of Aqueous Potassium Permanganate in Charred Cacao Shells

In this study, charred cacao shells were tested for their capability as bioadsorbent for aqueous potassium permanganate. Optimization of adsorption parameters showed that the best amount of adsorbent is 0.5% w of cacao biochar/v of 0.005 N aqueous KMnO4 with a removal efficiency of 98.79%, and the optimum particle size is 212 mm, with a corresponding removal efficiency of 99.76%. Kinetics studies showed that the adsorption fits a pseudo-first order reaction with R2 = 0.9833. Lastly, the adsorption data fits the Elovich isotherm with R2 = 0.9712, which strongly suggests a multi-layer chemisorption on a heterogenous surface. Conclusively, the charred cacao shells were found to be effective as an adsorbent of aqueous potassium permanganate. Furthermore, the resulting product of adsorption can be used to study adsorption of other substances due to its multi-layer nature.

Multifaceted Chemistry Conceptual Profile of Selected Senior High School STEM Students from a Private School in Manila

Chemistry has always been identified as a discipline with pluralistic characteristics. This implies that chemistry can be viewed differently based on one’s conception, conceptual model, and conceptual change. Subsequently, this denotes into a diverse context, different profiles of conceptions, which then convey multifaceted view of the discipline. The polysemous view of chemistry was addressed and proposed into six chemistry conceptual profile zones - monist, epistemic, processual, pragmatic, aversive, and attractive. There is a need to recognize this and structure chemistry education based on conceptual profile, since the discipline is naturally complex, rich, and multifaceted. The objective of the study is to analyze, identify, and categorize the multifaceted conceptions in chemistry of selected senior high school STEM students enrolled in a certain private school in Manila City, under these six conceptual profile zones. More so, the study aims to determine the possible ways to improve the conceptions of students based on their own response and perspective. Descriptive qualitative research design through semantic thematic analysis and statistical inference using Chi-square of Goodness-of-Fit were employed to analyze the data. The result revealed that almost all of these (n=57) selected SHS STEM students can conceptualize the epistemic view in the profile zone but not the other five. Based on the two themes generated, it can be implied that there is always an opportunity for critical reflection on how to reconceptualize the discipline and take chemistry into a more authentic field of science and science education.